# Patent

## Title
Method of using surface modifying metallic treatment agents to treat subterranean formations

## Abstract

A method of treating a subterranean formation comprises pumping into a well penetrating the formation a surface modifying treatment agent having a metallic anchor and at least one hydrophobic tail attached to the metal of the anchor. The surface modifying treatment agent is covalently bound to the surface of the subterranean formation through the metal of the anchor.

## Background
This application claims the benefit of U.S. patent application Ser. No. 61/880,840, filed on Sep. 20, 2013; U.S. patent application Ser. No. 61/981,051, filed on Apr. 17, 2014; U.S. patent application Ser. No. 61/989,267, filed on May 6, 2014; and U.S. patent application Ser. No. 62/007,708, filed on Jun. 4, 2014; all of which are herein incorporated by reference.


FIELD OF THE DISCLOSURE
The disclosure relates to a method of treating a subterranean formation with a surface modifying treatment agent having a metallic anchor and a hydrophobic tail.
BACKGROUND OF THE DISCLOSURE
Alternatives for enhancing the productivity of hydrocarbons from hydrocarbon producing reservoirs have included methods which increase the permeability of the formation penetrated by the well. Other methods have been directed to those which increase the oil/water production ratios within the well. Others have been drawn improved methods for inhibiting the formation of undesirable materials in the formation including water borne scales, asphaltenes, salts, paraffins, etc. Some of these methods have involved the development of well treatment chemicals for enhancing productivity.
Attention has further been focused on improving methods of stimulating formations. Since well productivity depends on the ability of a fracture to conduct hydrocarbons from the formation to the wellbore, fracture conductivity has been an important parameter in determining the degree of success of a stimulation operation. The creation and/or mobilization of reservoir “fines” during fracturing and production has been instrumental in reducing fracture conductivity and reducing reservoir permeability due to plugging of pore throats by the fines. While the use of coated particulates, such as proppants, has been successful in minimizing the generation of fines, alternatives have been sought.
Alternatives have also been sought to decrease unnecessary water production during the treatment of subterranean formations. Excessive water production has a direct effect on the productivity of the well. The amount of oil and/or gas that may be ultimately recovered from the well is decreased since the water takes the place of other fluids that may flow or be lifted from the well. This increases the cost of production from the well.
While well treatment agents have been developed for the treatment or control of the deposition of scales, salts, paraffins, and asphaltenes within the well, less than desirable results are often achieved. Alternatives have therefore been sought for improving the overall efficiency of the well by controlling the deposition of such materials. Alternatives have especially been sought for controlling the deposition of such materials in low permeability formations, such as shale and coal.
Resources have also been spent on both chemical and physical techniques for effectively reducing frictional drag created during the flow of hydrocarbons within a hydrocarbon producing reservoir.
Alternatives for reducing friction have focused on drag reduction agents. Typically, friction reduction agents are large polymers with long chains which tend to build non-Newtonian gel structures. Drag reducing gels are shear-sensitive and often require specialized injection equipment (such as pressurized delivery systems). Further, since friction reduction agents are typically highly viscous, usually no more than 10 weight percent of polymeric friction reduction agents are present in the carrier fluid. Some attention has been focused on the use of slurries or dispersions of polymers to form free-flowing and pumpable mixtures in liquid media. However, such polymers often agglomerate over time, thus making it very difficult for them to be placed in hydrocarbon liquids where reduced drag is needed.
Further alternatives for lowering the frictional drag of fluids within a well have been sought in order to enhance the productivity of hydrocarbons from the well.
It should be understood that the above-described discussion is provided for illustrative purposes only and is not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the above-cited features or disadvantages merely because of the mention thereof herein.
SUMMARY OF THE DISCLOSURE
In an embodiment of the disclosure, a method of treating a subterranean formation is provided which comprises first pumping into a well, which penetrates the formation, a surface modifying treatment agent having a metal linked to a hydrophobic tail comprising an organo-silicon material, a fluorinated hydrocarbon or both a hydrophobic organo-silicon material and a fluorinated hydrocarbon. The metal of the surface modifying treatment agent is then bound to the formation.
In another embodiment, a method of treating a siliceous or metal oxide containing subterranean formation is disclosed which comprises first pumping into the formation a surface modifying treatment agent comprising a metallic anchor and a hydrophobic group. The surface modifying treatment agent is bound to the siliceous formation by attaching the metal of the metallic anchor to the formation.
In another embodiment, a method of treating a siliceous or metal oxide containing subterranean formation is disclosed which comprises first pumping into the formation a well treatment composition comprising a surface modifying treatment agent of the formula Y—Z, wherein Z is a metal containing organic ligand and Y is a hydrophobic tail and then binding the metal containing organic ligand to a silicon-oxo atom or an aluminum-oxo group of the formation. The surface modifying treatment agent may then be aligned to the subterranean formation.
In another embodiment of the disclosure, a method of treating a siliceous or metal oxide containing subterranean formation is provided wherein a well treatment composition comprising a surface modifying treatment agent having a metal anchor and a hydrocarbon tail is pumped into the formation. The metal of the surface modifying treatment agent is Group 3, 4, 5, or 6 metal. The metal of the anchor is bound to the formation through the Si-oxo linkage or an Al-oxo linkage.
In another embodiment of the disclosure, a method of treating a siliceous or metal oxide containing subterranean formation is provided wherein a well treatment composition comprising a surface modifying treatment agent having a metal anchor and a hydrocarbon tail is pumped into the formation. The metal of the surface modifying treatment agent is Group 3, 4, 5, or 6 metal. The metal of the anchor, but not the hydrophobic tail, of the surface modifying treatment agent is bound to the formation.
In another embodiment of the disclosure, a method is described of treating a siliceous or metal oxide containing subterranean formation is disclosed wherein a surface modifying treatment agent comprising the product of a metal containing organic ligand and an organo-silicon containing hydrocarbon based material is first pumped into the formation. The metal of the metal containing organic ligand may be a Group 3, 4, 5 or 6 metal and the organic ligand may be an alkoxide, halide, keto acid, amine or acrylate. The surface modifying treatment agent is then attached to the formation such that the metal of the metal containing organic ligand is bound to the formation.
In another embodiment, a method of treating a siliceous or metal oxide containing subterranean formation is provided wherein a well treatment composition comprising a surface modifying treatment agent having a hydrophobic tail (which may further exhibit oleophobic properties) is pumped into the formation. The surface modifying treatment agent is of the formula X—Y, wherein Y is a metal containing organic ligand and X is a hydrophobic organic tail, wherein the metal of Y is a Group 3, 4, 5, or 6 metal. A silicon atom or a silicon oxide group (of an siliceous formation) or a metal atom or a metal oxide group (of a metal oxide containing formation) binds with the metal of the metallic anchor of the surface modifying treatment agent.
In another embodiment of the disclosure, a method of enhancing the productivity of a hydrocarbon producing well is disclosed wherein a surface modifying treatment agent is pumped into the well. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail. When bound to a surface of a substrate, the surface modifying treatment agent reduces friction of a fluid within the well.
In another embodiment of the disclosure, a method of enhancing the productivity of hydrocarbons from a well is disclosed wherein a surface modifying treatment agent is pumped into the well and friction is reduced during hydrocarbon production by the presence of the surface modifying treatment agent. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail. During production of hydrocarbons, the surface modifying treatment agent is bound to at least portion of a substrate.
In another embodiment, a method of reducing drag during production of hydrocarbons from a subterranean formation is disclosed. In this embodiment, a well treatment composition is pumped into the formation. The well treatment composition has a surface modifying treatment agent. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail. The anchor of the surface modifying treatment agent binds onto the surface of the formation substrate.
In still another embodiment of the disclosure, a method of reducing drag of a fluid within a well penetrating a subterranean formation is provided. In this method, a well treatment composition containing a surface modifying treatment agent is pumped into the well. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail.
In another embodiment of the disclosure, a method of enhancing the production of hydrocarbons from a well is provided. In this method, saturated water on the surface of a siliceous subterranean formation or a metal oxide-containing subterranean formation is reduced by pumping into the well which penetrates the formation a non-aqueous fluid. A well treatment fluid comprising a surface modifying treatment agent having a metallic anchor and a hydrophobic tail is then pumped into the well. The surface modifying treatment agent binds to the surface of the subterranean formation by forming a monolayer or multi-layer assembly by self-alignment of the hydrophobic tail.
In another embodiment, a method of treating a siliceous or metal oxide-containing subterranean formation is provided in which a surface modifying treatment agent is pumped into the well penetrating the formation. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail. The surface modifying treatment agent binds onto the surface of the formation by forming a monolayer or multi-layer assembly by self-alignment of the hydrophobic tail. Prior to pumping the surface modifying treatment agent into the well, the surface of the subterranean formation is pre-treated with a non-aqueous fluid. Pre-treatment of the formation with the non-aqueous fluid increases the number of sites to which the surface modifying treatment agent may be bound.
In another embodiment, a method of producing hydrocarbons from a siliceous or metal oxide-containing subterranean formation is provided. In this method, the formation is pre-treated by pumping into the well a non-aqueous fluid. The non-aqueous fluid is capable of reducing saturated water on the surface of the formation. Water is thereby removed from the surface of the formation. After pre-treatment with the non-aqueous fluid, the surface modifying treatment agent is pumped into the well. The surface modifying treatment agent has a metallic anchor and a hydrophobic tail. The surface modifying treatment agent binds onto the surface of the formation through the anchor. The hydrophobic tail is aligned away from the surface of the formation.
In an embodiment, the surface modifying treatment agent alters the surface energy of a subterranean formation.
In another embodiment, the surface modifying treatment agent stabilizes fines in a subterranean formation.
In another embodiment, the surface modifying treatment agent decreases the amount of formation solids flowed back from the surface of a subterranean formation into a production well.
In another embodiment, the surface modifying treatment agent functions as a passive anti-microbial agent to minimize or prevent the retention of water on the surface of a subterranean formation.
In yet another embodiment, the surface modifying treatment agent is used to passively inhibit or control the deposition of water borne scales onto or within a subterranean formation.
In another embodiment, the surface modifying treatment agent passively prevents deposition of organic particulates onto or within the surface of a subterranean formation.
In another embodiment, the surface modifying treatment agent is used to prevent swelling of clay within a subterranean formation.
In another embodiment, the surface modifying treatment functions as a relative permeability enhancer by increasing relative permeability to oil/gas without increasing the permeability to water.
In still another embodiment, the surface modifying treatment agent is used to minimize condensation within a retrograde condensate gas reservoir thereby enhancing condensate production.
In yet another embodiment, the surface modifying treatment agent is used in the enhancement of the amount of flowback water and produced water from a gas or oil well following completion of a well treatment operation.
In another embodiment, the surface modifying treatment agent is used to control water condensation in the pores of a subterranean formation.
In still another embodiment, the surface modifying treatment agent is used to enhance the recovery of hydrocarbons from deposits within a tar sand formation.
In an embodiment, the surface modifying treatment agent is used in a hydraulic fracturing operation and is a component of the fracturing fluid.
In another embodiment, the surface modifying treatment agent is used in the treatment of a subterranean formation during acidizing in order to increase the penetration of acid into the formation.
Accordingly, the present disclosure relates to a surface modifying treatment agent having a hydrophobic tail and a metallic anchor wherein the surface modifying treatment attaches to a subterranean formation through its anchor. The present disclosure further relates to the use of such surface modifying treatment agents in well treatment operations where hydrophobicity at the surface of the subterranean formation is desired.
Characteristics and advantages of the present disclosure described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of various embodiments and referring to the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
The following figures are part of the present specification, included to demonstrate certain aspects of various embodiments of this disclosure and referenced in the detailed description herein:
FIGS. 1 and 2 depict schematic representations of the attachment of a surface modifying treatment agent (having a metallic anchor and a hydrophobic tail) to the surface of a subterranean formation.
FIG. 3 illustrates regain permeability in a Berea core by use of the surface modifying treatment agent described herein.
FIG. 4 demonstrates the inhibition in the swelling of clay using the surface modifying treatment agent described herein.
FIG. 5 demonstrates the lack of movement of fines in a synthetic core containing 325 mesh silica when using the surface modifying treatment agent described herein.
FIG. 6 illustrates the effect of pre-treatment on regain permeability in a Berea core by use of a surface modifying treatment agent.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Characteristics and advantages of the present disclosure and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of exemplary embodiments of the present disclosure and referring to the accompanying figures. It should be understood that the description herein and appended drawings, being of example embodiments, are not intended to limit the claims of this patent or any patent or patent application claiming priority hereto. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claims. Many changes may be made to the particular embodiments and details disclosed herein without departing from such spirit and scope.
Certain terms are used herein and in the appended claims may refer to particular components, process steps or well treatment operations. As one skilled in the art will appreciate, different persons may refer to a component, a process step or a well treatment operation by different names. This document does not intend to distinguish between components, process steps or well treatment operations that differ in name but not function or operation. Also, the terms “including” and “comprising” are used herein and in the appended claims in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Further, reference herein and in the appended claims to components and aspects in a singular tense does not necessarily limit the present disclosure or appended claims to only one such component or aspect, but should be interpreted generally to mean one or more, as may be suitable and desirable in each particular instance.
In an embodiment, the surface modifying treatment agent is characterized by a hydrophobic tail and a metallic anchor. For purposes herein, the term “hydrophobic tail” shall refer to the hydrophobic substituent of the surface modifying treatment agent. The “anchor” refers to the non-hydrophobic portion of the surface modifying treatment agent derivative. The anchor provides the site of attachment of the surface modifying treatment agent onto the subterranean formation. For instance, the metal of the metallic anchor may be engaged in covalently connecting the surface modifying treatment agent to a surface of the subterranean formation.
While the tail of the treatment agent exhibits hydrophobic characteristics, it may also exhibit oleophobic properties. The treatment agent may therefore be considered to be omniphobic.
The hydrophobic tail may be directly attached to the anchor. Alternatively, the hydrophobic tail may be indirectly attached to the anchor such that an organo-functional group is between the anchor and the hydrophobic tail. For instance, the hydrophobic tail and the anchor may be separated by a hydrocarbyl group such as a saturated or unsaturated alkylene, alkenyl, alkynyl, etc.
The hydrophobic tail of the surface modifying treatment agent is not believed to bind to the subterranean substrate. Thus, the tail of the surface modifying treatment agent is only indirectly attached to the formation substrate, through the anchor.
The tail of the surface modifying treatment agent may be aligned such that the hydrophobicity character of the treatment agent is imparted away from the surface of the subterranean formation.
In a preferred embodiment, the tail may self-align to the surface of the siliceous or metal oxide containing formation such that the hydrophobic/omniphobic tail is opposite to the surface of the formation.
Water and aqueous fluids within the well may easily slide across the surface of the substrate carrying hydrocarbons as lateral adhesion of the fluid to the formation surface is reduced. Thus, the hydrophobic tail lowers water saturation and enhances recovery of water from the formation surface.
The subterranean formation, onto which the surface modifying treatment agent is bond, may be a siliceous formation, such as sandstone, as well as a metal oxide containing formation, including carbonate formations. The formation may be enriched in clay and the metal may include alumina.
In an embodiment, the tail of the surface modifying treatment agent self-aligns with the formation substrate to form a monolayer or multi-layer assembly. It is believed that this occurs by chemical binding-induced spontaneous organization of the tail on the substrate surface.
The surface modifying treatment agents disclosed herein are effective in reducing frictional drag of a fluid within a hydrocarbon producing reservoir. The frictional drag may be created during the turbulent flow of fluids within the well. When bound to the surface of a substrate, the surface modifying treatment agents disclosed herein reduce the sliding angle between the fluid and the substrate within the well. The reduction in sliding angle may be between hydrocarbons and a substrate treated with the surface modifying treatment agent. Further, the reduction in sliding angle may be between water (aqueous phase) and a substrate treated with the surface modifying treatment agent. Fluid flow improvement has been evident in both hydrocarbon and aqueous phases.
The reduction in frictional drag within the well is thus attributable to the bonding of the surface modifying treatment agent onto the surface of the substrate. Thus, the modification of the substrate surface reduces drag and provides improved flow of hydrocarbon (or water phase) from the well. Productivity of the hydrocarbon producing well is thus enhanced by use of the surface modifying treatment agents.
The surface modifying treatment agents disclosed herein are of particular value in the reduction of frictional drag during the pumping of produced hydrocarbons from the hydrocarbon producing reservoir.
The reduction in sliding angle further is of benefit in enhancing load recovery of water by increasing the recovery of flowback water from the well after a fracturing fluid has been returned to the surface.
As used herein, the sliding angle (also known as tilting angle) is a measurement of the lateral adhesion of the drop to the substrate surface. Thus, the sliding angle of a fluid on a substrate having a surface modifying treatment agent bonded thereto is less than the sliding angle of the same fluid on the (same) substrate (“pristine unmodified substrate”) which does not have the surface modifying treatment agent bonded thereto. Where the surface modifying treatment agent is bond only to a portion of the substrate, the sliding angle of the drop of fluid on the portion of the substrate having the surface modifying treatment agent bonded thereto is less than the sliding angle of the fluid on the substrate not having the surface modifying treatment agent bonded thereto.
The reduction in frictional drag during the production of hydrocarbons from the well is thus measured by a reduction in the sliding angle of the fluid with the formation surface. The reduction in adhesion bond strength results in reduced drag between the liquid and the solid surface, allowing for easier fluid flow at a given stress. The decrease in sliding angle accelerates the flow of fluid from the well by lessening the amount of fluid trapped within the formation.
In an embodiment, the sliding angle of a fluid to a substrate surface treated with the surface modifying treatment agent may be less than or equal to 60°; in some cases less than or equal to 20°; in other cases less than or equal to 10° and in some other cases less than or equal to 5°. In one instance, the sliding angle for hydrocarbons has been observed to be less than 10°. In another instance, the reduction in lateral adhesion of a fluid has been observed by a reduction in the sliding angle from 80° (non-treated substrate) to 40° (treated substrate).
The reduction in sliding angle is independent of the contact angle. The contact angle refers to the angle between a drop of the liquid and the surface of the substrate. A high contact angle reduces the normal adhesion of a liquid droplet to the solid surface due to a reduction of the liquid-solid contact area.
The contact angle is a measure of hydrophobicity. Typically, a liquid is considered to be “non-wet” or hydrophilic when the contact angle is less than 90° and “non-wetting” or hydrophobic when the contact angle is greater than 90°. A surface having a water contact angle greater than 150° is usually termed “ultra-hydrophobic” characterizing a water-repellant surface. A superhydrophobic surface may have a contact angle hysteresis less than 10°; in some cases less than 5°. When the contact angle is less than 90°, the wetting tendency of the surface modified substrate may greater when the substrate is rough versus smooth. When the contact angle is greater than 90°, the substrate may repel more when the substrate is rough.
Since hydrophobicity prevents the formation of water blocks on the surface of the substrate, the contact angle is indicative of the capillary pressure within the substrate. Whereas the contact angle is representative of static conditions, the sliding angle is representative of fluid movement downhole. No relationship can be drawn between the contact angle and sliding angle. As such, the contact angle provides no indication of the sliding angle. Improvement in frictional drag has been seen with a reduced sliding angle and a contact angle less than or equal to 20°. Further, improvements in frictional drag have been observed with a reduced sliding angle and a contact angle greater than or equal to 120°. For instance, the effectiveness of surface modifying treatment agents on substrate surfaces to reduce frictional drag has been seen with fluids exhibiting a contact angle less than 20° and a sliding angle less than 20° and a contact angle greater than 120° and a sliding angle less than 20°.
In an embodiment, the surface modifying treatment agent contains a metal linked to an organo-silicon containing material or a fluorinated hydrocarbon.
The surface modifying treatment agent may be represented by the formula J-K, wherein K is the metallic anchor (such as that represented by a metal containing organic ligand) and J is the hydrophobic tail represented by the organo-silicon containing material, the fluorinated hydrocarbon or a combination of organo-silicon containing material and fluorinated hydrocarbon.
The metal of the surface modifying treatment agent is preferably a metal of Group 3, 4, 5, or 6. In a preferred embodiment, the metal is a Group 4 metal, such as Ti, Zr or Hf, a Group 5 metal, such as Ta or Nb, a Group 6 metal, such as W, or a metal of the lanthanide series, such as La.
While not being bound to any theory, it is believed that upon being pumped into the formation, the metal of the surface modifying treatment agent covalently binds to the formation. The formation may be a siliceous formation or a metal oxide containing formation, including carbonate formations. The metal oxide containing formation may be alumina. The metal may therefore be referred to as the “anchor” of the surface modifying treatment agent, a site that engages in covalently connecting the treatment agent to the surface of the formation. It is believed that the metal of the surface modifying treatment agent binds to the oxygen atom of the silicon-oxo or the metal-oxo linkage of the formation.
The organo-silicon or fluorinated hydrocarbon portion of the surface modifying agent is attached to the metal forming the anchor and is not believed to bind to the subterranean substrate. It is therefore referred to as the “tail” portion of the surface modifying treatment agent. Thus, the tail of the surface modifying treatment agent is only indirectly attached to the formation substrate, through the metal.
FIG. 1 and FIG. 2 depict schematic representations of the attachment of the surface modifying treatment agent onto the substrate wherein Z is the metal of the anchor, J is the hydrophobic tail and Y is either —Si (of a siliceous formation) or the metal (M) (of a metal oxide-containing formation). In FIG. 1, the surface of the formation contains a free —OH which may, for example, be attached to an aluminum atom or a silicon atom. As illustrated, the metal of the surface modifying treatment agent may bind to the oxygen atom of the silicon-oxo or the aluminum-oxo linkage of the substrate by reaction with the —OH group. In FIG. 2, the surface of the formation is shown as containing a silicon-oxo group without a free —OH. The mechanism of reaction of the surface modifying treatment agent is illustrated as being different from that set forth in FIG. 1.
The surface modifying treatment agent may be formed by reacting a metal containing organic ligand with the organo-silicon containing material or fluorinated hydrocarbon group.
The metal containing organic ligand may be formed by reacting a metal compound, such as a metal halide, like TaCl5, with an oxygen containing ligand. Depending upon the position of the transition metal on the Periodic Chart, the metal containing organic ligand may have from two to six organic ligand groups.
In an embodiment, the ligand of the metal containing organic ligand contains an alkoxide or ester. Suitable organometallic derivatives include metal derivatives of C1 to C18 alkoxides, preferably alkoxides containing from 2 to 8 carbon atoms such as ethoxide, propoxide, isopropoxide, butoxide, isobutoxide and tertiary butoxide. For instance, the metal containing organic ligand may be a transition metal tetra-alkoxide, such as zirconium tetra tert-butoxide.
The alkoxides may be in the form of simple esters and polymeric forms of the alkoxylates and esters as well as various chelates and complexes. For example, with the metal Ta, the simple esters could be Ta(OR)5 where R is C1 to C18 alkyl. Polymeric esters may be obtained by condensation of an alkyl ester and can have the structure RO—[Ta(OR)3—O—]x—R where R is defined above and x is a positive integer.
Further, the organometallic compound can include, for instance, when the metal is titanium or zirconium:

    
    
        (a) alkoxylates having the general formula M(OR)4, wherein M is selected from Ti and Zr and R is C1-18 alkyl;
        (b) polymeric alkyl titanates and zirconates obtainable by condensation of the alkoxylates of (a), i.e., partially hydrolyzed alkoxylates of the general formula RO[-M(OR)2O-]x-1R, wherein M and R are as above and x is a positive integer;
        (c) titanium chelates, derived from ortho titanic acid and polyfunctional alcohols containing one or more additional hydroxyl, halo, keto, carboxyl or amino groups capable of donating electrons to titanium. Examples of these chelates are those having the general formula Ti(O)a(OH)b(OR′)c(XY)d, wherein a=4-b-c-d; b=4-a-c-d; c=4-a-b-d; d=4-a-b-c; R′ is H, R as above or X—Y, wherein X is an electron donating group such as oxygen or nitrogen and Y is an aliphatic radical having a two or three carbon atom chain such as:
        
            (i) —CH2CH2—, e.g., of ethanolamine, diethanolamine and triethanolamine, or
        
        
    
    






    
    
        
        
            (ii) lactic acid,
        
        
    
    






    
    
        
        
            (iii) acetylacetone enol form, and
        
        
    
    






    
    
        
        
            (iv) 1,3-octyleneglycol,
        
        
        (d) titanium acrylates having the general formula Ti(OCOR)4-m(OR)n wherein R is C1-18 alkyl as above and n is an integer of from 1 to 3, and polymeric forms thereof, or
        (e) mixtures thereof.
    
    


Acetyl acetonates, alkanolamines, lactates and halides, such as chloride, can also be used as the ligand of the oxygen containing organic ligand. In addition, the oxygen containing ligand can contain a mixture of ligands selected alkoxides, acetyl acetonates, alkanolamines, lactates and halides.
In an embodiment, the organo-silicon containing material may be a silane, polysiloxane or a polysilazane.
Examples of organo-silicon containing materials are those having the formula R14-xSiAx or (R13Si)yB as well as organo(poly)siloxanes and organo(poly)silazanes containing units of the formula:




where R1 may be the same or different and is a hydrocarbon radical containing from 1 to 100, such as 1 to 20 carbon atoms and 1 to 12, preferably 1 to 6 carbon atoms and R3 may be hydrogen or a hydrocarbon or substituted hydrocarbon having 1 to 12, preferably 1 to 6 carbon atoms. In addition, R1 may be a substituted, hydrocarbon radical such as halo, particularly a fluoro-substituted hydrocarbon radical. The organo(poly)siloxane may further contain additional units of the formula: R52SiO2 where R5 is a halogen such as a chloro or fluoro substituent.

In an embodiment, the organo-silicon containing compound may be an organo(poly)siloxane or organo(poly)silazane of a number average molecular weight of at least 400, usually between 1000 and 5,000,000.
The substituent A in R14-xSiAx may be hydrogen, a halogen such as chloride, OH, OR2 or




wherein B in the above structural formula may be NR33-y, R2 a hydrocarbon or substituted hydrocarbon radical containing from 1 to 12, typically 1 to 4 carbon atoms. R3 is hydrogen or has the same meaning as R1. x is 1, 2 or 3, y is 1 or 2.

Preferably, R1 is a fluoro-substituted hydrocarbon. Preferred are such fluoro-substituted hydrocarbons are those of the structure:




where Y is F or CnF2n+1; m is 4 to 20 and n is 1 to 6; R2 is alkyl containing from 1 to 4 carbon atoms and p is 0 to 18. Also, fluoro-substituted hydrocarbons may be of the structure:





where A is an oxygen radical or a chemical bond; n is 1 to 6, y is F or CnF2n; b is at least 1, such as 2 to 10; m is 0 to 6 and p is 0 to 18.

Preferred organo-silicon materials include halogenated siloxanes, halogenated alkoxysiloxanes such as perfluoroalkoxysiloxane (PFOSi), alkoxy halogenated alkoxysilanes, such as alkoxy-perfluoroalkoxysilane; alkoxyacetylacetonate halogenated polysiloxanes, such as alkoxyacetylacetonate-perfluoroalkoxysiloxane, alkoxy-alkylsilylhalides; polyalkylsiloxanes, such as polydimethylsiloxanes, and alkoxyacetylacetonate-polyalkylsiloxanes, such as alkoxyacetylacetonate (acac) polydimethylsiloxanes. Exemplary surface modifying treatment agents include tantalum halide-perfluoroalkoxysiloxane, such as TaCl5:PFOSi; tantalum alkoxy-perfluoroalkoxysilane; tantalum alkoxyacetylacetonate-perfluoroalkoxysiloxane, like Ta(EtO)4acac:PFOSi; tantalum alkoxy-alkylsilylhalide; tantalum halide-polyalkylsiloxane, like TaCl5:PDMS; niobium alkoxide-perfluoroalkoxysiloxane, such as Nb(EtO)5:PFOSi and Ta(EtO)5:PFOSi; titanium alkoxide-perfluoroalkoxysiloxane, like Ti(n-BuO)4:PFOSi; zirconium alkoxide-perfluoroalkoxysiloxane; lanthanum alkoxide-perfluoroalkoxysilane, like La(iPrO)3:PFOSi; tungsten chloride-perfluoroalkoxysiloxane, like WCl6:PFOSi; tantalum alkoxide-polyalkylsiloxane, like Ta(EtO)5:PDMS; and tantalum alkoxyacetylacetonate-polyalkylsiloxane, like Ta(EtO)4acac:PDMS.
In an embodiment, the fluorinated hydrocarbon is Rf—(CH2)p—X where Rf is a perfluorinated hydrocarbon group including an oxygen substituted hydrocarbon group, such as a perfluorinated alkyl group or a perfluorinated alkylene ether group and p is 0 to 18, preferably 0-4, and X is a polar group such as a is carboxyl, like of the structure —(C═O)—OR; and R is hydrogen, perfluoroalkyl, alkyl or substituted alkyl containing from 1 to 50 carbon atoms.
Examples of perfluoroalkyl groups are those of the structure F—(CFY—CF2)m where Y is F or CnF2n+1; m is 4 to 20 and n is 1 to 6.
Examples of perfluoroalkylene ether groups are those of the structure:




where A is an oxygen radical or a chemical bond; n is 1 to 6, Y is F or CnF2n; b is 2 to 20, m is 0 to 6, and p is 0 to 18, preferably 2 to 4 and more preferably 2.

Preferred fluorinated materials are esters of perfluorinated alcohols such as the alcohols of the structure F—(CFY—CF2)m—CH2—CH2—OH where Y is F or CnF2+1; m is 4 to 20 and n is 1 to 6.
Further preferred as fluorinated hydrocarbons are perfluorinated hydrocarbons of the structure Rf—(CH2)p—X where Rf is a perfluoroalkylene ether group or a perfluorinated alkyl group such as those described above, p is an integer of from 0 to 18, preferably 0 to 4, and X is a carboxyl group, preferably a carboxylic ester group containing from 1 to 50, preferably from 2 to 20 carbon atoms in the alkyl group that is associated with the ester linkage.
Further preferred as fluorinated hydrocarbons are perfluorinated hydrocarbons of the structure Rf—(CH2)p—Z where Rf and p are as defined above, preferably Rf is a perfluoroalkylene ether group such as those described above, and p is from 2 to 4, and Z is a phosphorus acid group. Examples of phosphorus acid groups are:




where R′′ is a hydrocarbon or substituted hydrocarbon radical having up to 200, such as 1 to 30 and 6 to 20 carbons, R′′ can also include the perfluoroalkyl groups mentioned above, and R′ is H, a metal such as potassium or sodium or an amine or an aliphatic radical, for example, alkyl including substituted alkyl having 1 to 50 carbons, preferably lower alkyl having 1 to 4 carbons such as methyl or ethyl, or aryl including substituted aryl having 6 to 50 carbons.

Preferably, the phosphorus acid is of formula II where R and R′ are H.
Suitable methods for preparing the surface modifying treatment agents wherein the organo portion of the metal containing organic ligand is reactive with the organo-silicon containing material or fluorinated hydrocarbon group are disclosed in U.S. Pat. Nos. 7,879,437 and 8,067,103. In one embodiment, for instance, the organo portion of the organometallic compound may be selected from those groups that may be reactive with the acids (or their derivatives) of a perfluoroalkylene ether.
As an example, the surface modifying treatment agent could be prepared by mixing the metal containing organic ligand and the silicon-containing material or fluorinated hydrocarbon in a closed system to avoid hydrolysis of the reactants. Reaction can occur neat or in the presence of a non-reactive solvent such as chlorinated or fluorinated solvent, for example, methylene chloride. Heat may be used to initiate and complete the reaction. Solvent may be removed by evaporation and the reaction product can be redissolved in a suitable solvent such as an alcohol, for example, ethanol or propanol, for application to the substrate. The mole ratio of the organosilicon-containing material to the metal containing organic ligand is typically from 100:1 to 1:100, preferably from 1:1 to 10:1 depending on the valence of the metal of the metal containing organic ligand. For example, the molar ratio of organosilicon compound to Ta(V) is typically 5 to 1.
In an embodiment, the surface modifying treatment agent may be represented by the formula Xa(OR)bM, wherein OR is a C1 to C18 alkoxide, X is the hydrophobic tail represented by the organo-silicon material or the fluorinated hydrocarbon, M is metal of the metal containing organic ligand and a+b equals the valency of M and further wherein neither a nor b are zero.
In an exemplary embodiment, the surface modifying agent may be formed by reacting an organosilicon compound such as an organosilane or a polysiloxane with a metal containing organic ligand, such as a derivatized alkoxide. The metal of the metal containing organic ligand is covalently bonded to the organosilicon compound to form the anchor and the hydrophobic tail. An exemplary reaction scheme of the surface modifying treatment agent, Xa(OR)bM, with a siliceous formation, —(—O—Si—O—Si—)n, may be represented as:

Xa(OR)bM+(—O—Si—O—Si—)n→Xa(OR)b-1M-(O—Si—O—Si—)n+R—OH.

The surface modifying treatment agent may be pumped into the formation as a component of a well treatment fluid. The well treatment fluid may be pumped into the formation any time during the well treatment operation. The well treatment fluid may contain a diluent. Suitable diluents include alcohols such as methanol, ethanol or propanol; aliphatic hydrocarbons such as hexane, isooctane and decane, ethers, for example, tetrahydrofuran and dialkylethers such as diethylether. Diluents for fluorinated materials can include perfluorinated compounds such as perfluorinated tetrahydrofuran. Also, aqueous alkaline solutions such as sodium and potassium hydroxide can be used as the diluent.
The concentration of the surface modifying treatment agent in the well treatment fluid is 0.01% to 100% or more typically between 0.1% to 20% (v/v).
In an embodiment, the well treatment fluid may be a fracturing fluid, pad fluid, acidizing fluid, etc. In an embodiment, the well treatment fluid may be a component of a fracturing fluid, pad fluid, acidizing fluid, etc. When used in an aqueous fracturing fluid, the surface modifying treatment is preferably dispersed within the fluid.
The surface modifying treatment agents disclosed herein may alter the surface energy of the formation being treated. The attachment of the surface modifying treatment agent onto the surface of the formation reduces the surface energy of the substrate likely by reducing the charge density on the surface.
The attachment of the metal anchor of the surface modifying treatment agent onto the formation prevents spalling of fines by altering the zeta potential of formation fines. By covalently attaching the metal-containing ligand onto the Si or Al surface, migration of fines into producing areas of the formation is minimized and in-situ fines generation is minimized or stabilized.
The hydrophobic nature of the tail further alters the wettability of the formation surface. The self-assembled hydrophobic monolayer covalently attached to the formation surface lowers the water saturation and enhances recovery of water from the formation surface.
Particulates of a weakly consolidated, semi consolidated or unconsolidated formation may further be consolidated by use of the surface modifying treatment agents disclosed herein. The bonding of the anchor of the surface modifying treatment agent on the surface formation prevents or minimizes the influx of fluids into the formation. Aggregation of the particulates results from the reduction in charge density.
Upon being pumped into the formation, the surface modifying treatment agent may enter into the pore spaces of the formation. Multiple interactions of molecules of the surface modifying treatment agent with formation particulates causes aggregation or agglomeration of formation particulates. Further, it is believed, that the reactivity of the surface modifying treatment agent with formation surfaces or portions of formation surfaces creates an aggregation or agglomeration of the hydrophobic tail in near proximity to the formation surface. The use of the surface modifying treatment agents as a means to consolidate particulates of the formation is particularly effective in the treatment of shale formations.
The consolidation further provides stability to the formation since aggregated particulates allow fluid to flow back through the pumped fluids without flowing formation solids back to the surface. This phenomenon is attributable to the anchoring of the metal of the surface modifying treatment agent onto the surface formation and to the alignment of the tail of the treatment agent enabling limited contact-time of the fluid with formation surface.
In another embodiment, the swelling, dispersement, disintegration, migration and otherwise disruption of clay in oil and gas producing formations may be decreased by use of the surface modifying treatment agent and native fluid production may dislodge fines in a pore throat. The degree of swelling, as well as migration of clay particles, is often increased when formation clays are disturbed by foreign substances, such as aqueous well treatment fluids. Like fines formation, the swelling and migration of formation clays presents problems during stimulation and well completion, such as by increasing the bulk volume of treatment fluids. For instance, clays, in the presence of well treatment fluids, often expand and may be disrupted by becoming unconsolidated, thereby producing particles which migrate into a borehole. The presence of the hydrophobic tail on the surface modifying treatment agent prevents the swelling and migration of formation clay particles. Thus by obstruction of formation capillaries, swelling and migration of formation clay may be reduced or prevented by the use of the surface modifying treatment agent disclosed herein. Loss of formation permeability is thus minimized to create little, if any, reduction in the flow rate of hydrocarbons.
In a preferred embodiment, the surface modifying treatment agent is used in the treatment of a shale formation or a clay-rich formation in order to coat the surface of the formation to reduce water absorption or imbibement of water in order to reduce swelling.
The presence of the hydrophobic tail of the surface modifying treatment agent impedes the permeability of water in water saturated zones of a producing formation without reducing relative permeability to oil or gas. Since relative permeability is dependent on the pore structure and size, wettability of the formation surface and capillary pressure of the water within the formation, in some instances, such as where the formation is characterized by larger pores, water and oil permeability may be improved. With small pore surfaces, the hydrophobic tail of the surface modifying treatment agent attached indirectly to the mineral surface of the formation through the anchor is relatively non-damaging to oil permeability. For example, it is particularly effective in oil saturated sandstone formations while exhibiting the ability to decrease water permeability substantially in water saturated zones.
The surface modifying treatment agents disclosed herein may also be used in the treatment of rich gas or retrograde condensate gas reservoirs and thus presents value to retrograde gas fields by increasing condensate production. In such reservoirs, heavy end fraction of gases may be precipitated in liquid form from solution in the gas as the reservoir pressure within the well is decreased below the dew point of the gas. Condensed liquid drains downward by gravity when its saturation exceeds the irreducible condensate saturation. With retrograde gases, liquids cannot be reabsorbed into the gas phase even if pressure is increased by a rate reduction. When a well treatment fluid containing the surface modifying treatment agent disclosed herein is pumped into a retrograde gas well, the permeability of the formation may be maintained, and condensate dropout minimized. Thus, in turn, minimizes the possibility of the formation of an emulsion between precipitated hydrocarbons and the invading water from the aqueous based well treatment fluid. The pressure below the dew point of the hydrocarbons may therefore be maintained. By enhancing the permeability of the formation to liquid hydrocarbons, loss of light condensate liquids is minimized and light condensate liquids may therefore be more readily displaced.
The surface modifying treatment agents disclosed herein may also be used to enhance load recovery of water. The presence of the hydrophobic tail on the surface modifying treatment agent provides increased recovery of flowback water from the well after fracturing fluid has been returned to the surface. In some instances, flowback water may be as low as 25%, while in some cases can be as high as 75%, of the volume of fluid that was injected into the well. This application is particularly useful in shale fractures having a complex of narrow fractures with limited conductivity where a low range of fluid recovery values (30% or less) are typically experienced. This lack of recovery is often interpreted as causing formation damage (from residual polymer gels residues), resulting in lowered gas/oil production. Methods as described in this disclosure that results in increased water recovered from the shale-type formation can thus be interpreted to reduce formation damage, and hence improve well productivity. For instance, in a typical fracturing job on a Marcellus shale formation, 20,000 to 150,000 barrels of fracturing fluid may be pumped into the well, depending upon the number of stages pumped.
The hydrophobic nature of the surface modifying treatment agent may further serve to control water condensation in the pores of a near wellbore region of a permeable formation. Often, the liquid zone formed from the condensation of hydrocarbons within a gas reservoir close to the wellbore hampers gas flow, reducing the productivity of the well the formation of “water block” or “water bank” zones. Condensation of water in the pores of a near wellbore region of a permeable formation may be decreased by the presence of the surface modifying treatment agent. Fluid transfer and water flux through the pores of the near wellbore region of the formation may be controlled by inhibiting the formation of a water bank by the hydrophobic tail of the surface modifying treatment agent.
The surface modifying treatment agent may further be used to enhance the productivity of injection wells in a water flood operation. Field water or field brine pumped through one or more injection wells drilled into the formation causes displacement of oil within the formation and improvement in hydrocarbon recovery. In an embodiment, one or more injection wells may be spaced apart from each other and perforated so as to be able to direct the injection fluid containing the surface modifying treatment agent in the direction of one or more producing wells and into the hydrocarbon-bearing formation. The presence of the hydrocarbon tail on the surface modifying treatment agent enhances direction of water flow within the matrix of the subterranean formation. As the injection fluid is pumped into the formation, the surface modifying treatment agent in the well treatment fluid cause the water to be redirected through the formation. In so doing, hydrocarbons are displaced toward the producing well or wells. Thereafter, hydrocarbons will be produced from the producing well to the surface.
The surface modifying treatment agent disclosed herein may further be used in the treatment of tar sand formations. Conventional recovery of hydrocarbons from heavy oil deposits within the tar sand is generally accomplished by steam injection to lower the viscosity of the crude to the point where it can be pushed toward the production wells. The heavy oil is immobile at reservoir temperatures and therefore the oil is typically heated to reduce its viscosity and mobilize the oil flow. The surface modifying treatment agent enhances oil flow and thus recovery of oil from tar sand by minimizing the flow of water into the deposits. The hydrophobicity of the surface modifying treatment agent further minimizes the interference of steam in the removal of oil from tar sand deposits.
In another embodiment, the surface modifying treatment agent is used in an acidizing operation in order to increase the penetration of acid into the formation. Since the hydrocarbon tail of the surface modifying treatment agent is either on or in close proximity to the formation face, reaction of acid with the formation surface is retarded. The reactive acid may therefore etch the formation in more distant areas from the port of entry of the treatment fluid. Deeper acid penetration in the well may therefore result.
Further, the surface modifying treatment agent may be used to shut-off water into a formation. In this regard, the surface modifying treatment agent finds particular applicability in the treatment of matrix formations having finer grained particles between larger rock particles or finer grained particles in which the larger particles are embedded. The hydrophobic tail on the surface modifying treatment agent reduces the influx of water into matrix formations characterized by low permeability. Further, matrix formations produce a large amount of water due to an influx of water into the wellbore. Over time, the amount or percentage of produced water may increase resulting in a corresponding decrease in the production of desired hydrocarbons, eventually rendering further production of hydrocarbons from the well uneconomical. The hydrocarbon tail indirectly attached to the formation blocks the flow of water into the formation or otherwise abates the influx of water. This results in increased rates in hydrocarbon production and ultimately increases recoverable reserves.
In an embodiment, the surface modifying treatment agent may function as a passive anti-microbial agent in order to counter bacterial growth principally caused by nitrogen and/or phosphorus in formation water or within fluid injected into the formation. The hydrocarbon tail of the surface modifying treatment agent repels the fluid from the formation and thus decreases contact time of the fluid in the formation. This prevents the build-up of aerobic bacteria, anaerobic bacteria and other microbials.
In another embodiment, the surface modifying treatment agent may be used to passively inhibit, control, prevent or remove scale deposition onto or within the formation. The hydrophobic tail of the surface modifying treatment agent minimizes or decreases the ability of such materials to adhere to the formation. This may be attributable to the hydrophobic nature of such minerals scales as calcium, barium, magnesium salts and the like including barium sulfate, calcium sulfate, and calcium carbonate scales. The composites may further have applicability in the treatment of other inorganic scales, such as metal sulfide scales, like zinc sulfide, iron sulfide, etc. Since such scales tend to plug the pore spaces and reduce the porosity and permeability of the formation, the surface modifying treatment agent described herein improves the permeability of the formation.
When coated onto the substrate of the formation being treatment, the bulky nature of the hydrocarbon tail of the surface modifying treatment agent prevents or controls deposition of organic particulates onto the formation substrate, fines are returned to the surface with the fluid. In addition, bonding of the metal of the surface modifying treatment agent onto the formation minimizes binding sites for such organic particulates. Thus, the surface modifying treatment agents may be used to control or prevent the deposition of organic materials (such as paraffins and/or asphaltenes) within or onto the formation. Such solids and particulates are known to negatively impact the overall efficiency of completion of wells and, like scale inhibitors, can precipitate from produced water and create blockages in flow paths within the formation. The formation and deposition of such unwanted contaminants decrease permeability of the subterranean formation, reduce well productivity, and, in some cases, may completely block well tubing.
The surface modifying treatment agent may further be introduced into a non-hydrocarbon producing well in order to dispose of salt water. This application may be used in those instances where water flooding operations are not in use. In this operation, the salt water may be disposed of by injecting the water into permeable low pressure strata below the fresh water level in a salt water disposal well.
The bonding of a surface modifying treatment agent onto a subterranean formation is enhanced by first pre-treating the formation. In the pre-treatment, a non-aqueous fluid is first pumped into the well which penetrates the formation. The surface modifying treatment agent is then pumped into the well. The access to the sites for the surface modifying treatment agent to bind onto the surface of the subterranean formation is facilitated by pre-treatment of the subterranean formation with the non-aqueous fluid.
Any non-aqueous solvent capable of lowering water saturation and enhancing the recovery of water from the formation surface may be used. Typically, the non-aqueous fluid contains no more than 18 carbon atoms and may be composed of more than one solvent.
Exemplary of non-aqueous solvents are alcohols, such as a C1-C6 primary, secondary or tertiary alkanol like methanol, ethanol and propanol; hydrocarbons such as paraffin oil, mineral oil, and a C4-C18 hydrocarbon solvent like hexane, isooctane, decane, xylene, n-pentane, n-hexane, etc.; halogenated hydrocarbons such as chlorinated or fluorinated hydrocarbons like methylene chloride; glycols like ethylene glycol and methylbutyl ethylene glycol; C3-C18 ethers including heterocyclic ethers like tetrahydrofuran and alkyl ethers such as monobutyl ether and dialkyl ethers like diethylether monobutyl ether; glycol ethers like dipropylene glycol methyl ether; perfluorinated compounds such as perfluorinated tetrahydrofuran; and mixtures thereof.
In a preferred embodiment, the non-aqueous fluid is a mutual solvent (defined as any chemically mutually soluble solvent in hydrocarbons and water) such as glycol ethers and ethylene glycol monobutylether.
One or more stages of non-aqueous fluids may be pumped into the well prior to pumping of the surface modifying treatment agent. Where more than one stage of non-aqueous fluid is pumped into the well prior to pumping of the surface modifying treatment agent, each stage may be composed of the same non-aqueous fluid or different non-aqueous fluids. Thus, for example, the first and second stages of non-aqueous fluids pumped into the well may both be a hydrocarbon or the first stage may be an alcohol and the second stage a hydrocarbon. Where more than two stages of non-aqueous fluids are pumped into the well prior to pumping of the surface modifying treatment agent, all or more than one of the stages may be composed of the same non-aqueous fluid or each stage may be composed of different non-aqueous fluids and so on.
Prior to pumping the non-aqueous fluid into the well or in between pumping of different stages of non-aqueous fluids into the well, the surface of the formation may be further treated with an alkaline solution such as sodium hydroxide or potassium hydroxide.
Where the formation is treated with a salt solution, the formation is preferably treated with one or more subsequent stages of non-aqueous fluid prior to pumping of the surface modifying treatment agent into the well. The pumping of an alkaline solution into the well may be especially desirable in those formations composed of metal oxides in order to regenerate the binding sites for the surface modifying treatment agent onto the formation.
Preferred embodiments of the present disclosure thus offer advantages over the prior art and are well adapted to carry out one or more of the objects of this disclosure. However, the present disclosure does not require each of the components and acts described above and are in no way limited to the above-described embodiments or methods of operation. Any one or more of the above components, features and processes may be employed in any suitable configuration without inclusion of other such components, features and processes. Moreover, the present disclosure includes additional features, capabilities, functions, methods, uses and applications that have not been specifically addressed herein but are, or will become, apparent from the description herein, the appended drawings and claims.
All percentages set forth in the Examples are given in terms of weight units except as may otherwise be indicated.
EXAMPLES
Example 1
Berea sandstone cores measuring 1.0′′ in diameter and 1.5′′ in length and having nitrogen permeability of 200 and were evacuated with air and then saturated with either 2% aqueous solution of potassium chloride (KCl) or ISOPARTM paraffinic fluid of ExxonMobil Chemical Company. The core was then installed in a hydrostatic core holder apparatus. Approximately 200 psi back pressure was applied at the exit end and approximately 1,000 psi confining stress (overburden pressure) was applied around the entire cylinder. The confining stress pressure simulated stress in the downhole formation. When saturated with KCl, a flow of the paraffinic fluid was flowed through the core in order to establish a base line permeability to the core to the oil followed by a flow of KCl solution to establish a baseline permeability to water. When saturated with the paraffinic fluid, a flow of the KCl solution was flowed through the core in order to establish a base line permeability to the core to the water followed by a flow of paraffinic fluid to establish a baseline permeability to oil. Pressure drop was measured across the entire length of the core and was used to calculate individual baseline permeability to water and to oil.
In separate cores, a five pore volume of neat fluids of H1-F and Aculon E, 2% of treatment agents in an organic solvent, the treatment agents having a transition metal linked to a fluorinated hydrocarbon tail, and AL-A, 2% treatment agent in an organic solvent having a transition metal linked to a hydrophobic tail, all commercially available from Aculon, Inc., were then injected into their respective core and allowed to soak for about one hour. After treatment, oil was flowed first and a comparison of permeability to oil right after treatment versus permeability to oil before treatment was made. After oil, water was flowed measuring permeability of water at residual oil after treatment and this was compared to the water right before treatment. As such, the oil at irreducible water saturation and the water at residual oil saturation were measured and the percent retention in permeability was then determined.
FIG. 3 illustrates the percent water regain and oil regain of the testing for H1-F and Aculon E. FIG. 3 illustrates oil regain permeability to be slightly higher than water regain permeability. FIG. 3 also illustrates the percent gas regain for AL-A to be in excess of 100%. FIG. 3 establishes that treatment of the core with a treatment agent having a metal linked to a hydrophobic tail provides an improved rate of return of fluids from the well. The data further demonstrates that the treatment agent stabilizes fine movement since decreased permeability would be noted if movement of fines existed. Further, FIG. 3 illustrates that use of the treatment agent would reduce solids flowback to the surface in light of the increase in permeability. Further, the lack of reduced permeability evidences minimal clay swelling. Further, the ability to readily produce water by use of the treatment agent provides for minimal residence time for microbes, scales as well as organic deposits such as asphaltenes. The increase in the capacity of the reservoir to transmit to transmit hydrocarbons illustrates enhancement in recovery of hydrocarbons from deposits within tar sands. Further, the hydrophobic coating of the formation with the treatment agent further provides for inhibition in the reactivity of acid such that deeper penetration of acid into the formation is possible.
Example 2
About 5 g of clay containing 92 weight % silica (or quartz) and 8 weight % montmorillonite (simulating Wyoming drilling clay) was treated with H1-F fluid described in Example 1 and placed into an oven having a temperature of approximately 150° F. wherein the solvent was evaporated, leaving a coating of the treatment agent onto the clay. Untreated clay was also placed into an oven and heated under the same conditions.
Capillary suction time tests were performed by placing the clay samples onto filter paper within a funnel and pouring water through the funnel. In separate examples, the water contained clay stabilizers—2 vol. % KCl, 1 gpt ClayCareTM and 1 gpt Claytreat 3CTM (ClayCare and Claytreat are products of Baker Hughes Incorporated). In a comparative experiment, fresh water was poured through the funnel. Two electrodes were attached to the filter paper. The amount of time between the water first touching an electrode on the paper and the water reaching a second electrode on the paper was then measured.
FIG. 4 illustrates the amount of time for fresh water to reach the second electrode as being almost six times less when the sand was treated with H1-F than not treated with H1-F. This time further decreased when the water contained clay stabilizers —KCl, ClayCare and Claytreat 3C. The data demonstrates that clay treated with H1-F inhibits the swelling of clay.
Example 3
Permeability testing was performed on synthetic cores composed of 20-40 mesh gravel, 100 mesh sand and 325 mesh silica. The 325 mesh silica mimics fines in formations. The synthetic cores were 1.0′′ in diameter and 2.0′′ in length and having nitrogen permeability of 100 and was saturated with 2% aqueous solution of potassium chloride (KCl). The cores were then installed in a hydrostatic core holder apparatus. Approximately 200 psi back pressure was applied at the exit end and approximately 1,000 psi confining stress (overburden pressure) was applied around the entire cylinder. The confining stress pressure simulates stress in the downhole formation. ISOPARTM paraffinic fluid was then flowed through the cores in order to establish a base line permeability to the cores to the oil. When saturated with the paraffinic fluid, a flow of the KCl solution was flowed through the cores. Pressure drop was measured across the entire length of the cores and was used to calculate individual baseline permeability to water and to oil.
Into separate cores were injected a five pore volume of a neat fluid of H1-F, Aculon E and AL-A and the fluids were allowed to soak for about one hour. After treatment, paraffinic fluid was flowed through each of the cores and permeability of oil at irreducible water saturation was then measured and the percent retention in permeability was then determined. After oil, water was flowed measuring permeability of water at residual oil after treatment and this was compared to the water right before treatment. As such, the oil at irreducible water saturation and the water at residual oil saturation were measured and the percent retention in permeability was then determined.
The data is illustrated in FIG. 5 wherein the lack of reduction in permeability demonstrates the lack of fines movement.
Example 3
The effect of surface modifying treatment agents on water and hydrocarbons was determined for three substrates. Each of the surface modifying treatment agents had a hydrophobic tail and an anchor. The anchor through a covalent bond secures the surface modifying treatment agent onto the surface of the substrate. The surface modifying treatment agents were H1-F and Aculon E [comprising 2% of a treatment agent having a transition metal (anchor) linked to a fluorinated hydrocarbon tail in an organic solvent] and AL-B [comprising 2% of an organophosphonate (anchor) having a hydrocarbon polymeric hydrophobic tail in an organic solvent blend]; all commercially available from Aculon, Inc. Aculon-E and AL-B exhibited hydrophobic and oleophobic properties while H1-F exhibited hydrophobic properties only.
The surface modifying treatment agent was sprayed onto a glass slide (having a more homogeneous surface than natural rock), a core of Ohio sandstone and a core of Berea sandstone to provide a coating approximately 1 to 10 nm thick. The cores of Ohio sandstone and Berea sandstone were approximately 1.0′′ in diameter and 1.5′′ in length. The anchor of the surface modifying treatment agent reacted with oxides on the surface of the substrate. As a result, the surface modifying treatment agent was covalently bonded onto the surface of the substrate. The samples were then kept in an oven at 150 F until completely dry to remove the solvent. After being modified, all of the substrate surfaces were hydrophobic. Contact angle and sliding (or roll-off) angle were then determined and used as the primary measure of performance. The contact angle demonstrates wettability characteristics of the surface while the sliding angle and contact angle hysteresis characterized the ease of fluid roll off from the substrate.
Glass Slide.
Table I show the contact angles obtained with both water and ISOPAR-LTM paraffinic fluid (Isopar-L simulated oil). As demonstrated, AL-B was the most oleophobic and the amount of hydrophobicity imparted by each of the three surface modifying treatment agents was about the same. Glass treated with Aculon E had a sliding angle of 20°, while modified surfaces using H1-F and AL-B exhibited a large contact angle hysteresis with water. Drops of fluids stayed pinned on the surface even at a 90° rotation angle. The sliding angle using Isopar-L was 8 to 10° when H1-F was used as the surface modifying treatment agent, 30° for AL-B and little roll off for Aculon E. In this last case the hysteresis between advancing (liquid drop front) and receding (rear end) angles was large and the drop stay pinned on the surface of the modified glass. The wettability behavior is set forth in Table I and demonstrates Aculon-E to be more effective as surface modifying treatment agent to move water while H1-F was more effective in the flow of oil.









TABLE I





Surface Modifier
Contact Angle (Water)
Contact Angle (IsoparL)







None
36
Wetting state


H1-F
95
10


E
83
48


AL-B
97
58









Ohio Sandstone.
The contact angle and sliding angle measurements for Ohio sandstone are demonstrated in Table II below:











TABLE II








Work of



Surface

Surface Energy
Adhesion


Modifier
Fluid
(mJ/m2)
(mJ/m2)
Sliding Angle (°)







H1-F
Water
 1.67 ± 0.01
11.10 ± 0.01
Pinning effect


H1-F
IsoparL
NA
NA
Goes through*


E
Water
extremely low,
 7.81 ± 0.01
17-20




cannot be




calculated


E
IsoparL
28.12 ± 0.02
58.20 ± 0.03
Goes through**


AL-B
Water
 1.67 ± 0.01
11.10 ± 0.01
Pinning effect


AL-B
IsoparL
12.49 ± 0.04
37.34 ± 0.06
Goes through***





*surface modified glass had a very low sliding angle (7-10)


**IsoparL drop stayed pinned on E modified glass


***roll-off angle of IsoparL on AL-B modified glass was 30°






In the case of Aculon H1-F and AL-B, the contact angle was 147° and the surface energy was 1.67 mJ/m2. However, hysteresis between advancing and receding angles in the range of 20 to 40° leading to a pinning effect and retention of the water drop even where the sample was rotated at 90°. Adsorption studies also demonstrated that when the sandstone was treated, water did not flow through the stone. After 30 minutes the water drop was still on surface of the modified sandstone, while for control Ohio Sandstone the water passed through instantaneously. When Aculon E was used as the surface modifying treatment agent, the water contact angle with the surface of the rock was 153°. The surface energy was very low. In this case the interaction between the support and water was less than that of the dispensing pipette tip and water. The drop had to be big enough so that its weight allowed it to be removed from the pipette tip. In this case, a sliding angle of 17-20° was observed. As the sample was left flat, water flowed more easily off the surface of the rock with increase in drop size. No adsorption of the water drop was left on the surface of the rock.

Oleophobicity of the surface treated with the surface modifying treatment agent was determined with Isopar-L. When the surface modifying treatment agent was H1-F, Isopar-L was observed to go through the surface instantaneously. The contact angle with AL-B modified sandstone was 60°. The adsorption through the sandstone core was slower than in the case of H1-F but the core was observed to be very permeable to Isopar-L. The surface properties of modified sandstones are presented in Table II. (The surface energy and work of adhesion represent how easy it is to remove a drop of the fluid perpendicular to the surfaces while the sliding angle represents the ease of moving the fluid tangentially to the surface and represents the movement of the fluid through a porous media.) The data shows similar conclusions as observed with modified glass slides, i.e., the movement of water was easier when the surface modifying treatment agent was Aculon E while H1-F provided a better flow of hydrocarbons (due to low surface energy of the surface). It is likely that a reduction in the roughness of the surfaces contributes to a decrease in drag and improved flow of hydrocarbon.











TABLE III








Work of



Surface

Surface Energy
Adhesion


Modifier
Fluid
(mJ/m2)
(mJ/m2)
Sliding Angle (°)







H1-F
Water
 1.67 ± 0.01
11.10 ± 0.01
Pinning effect


H1-F
IsoparL
NA
NA
Goes through*


E
Water
extremely low,
 7.81 ± 0.01
17-20




cannot be




calculated


E
IsoparL
28.12 ± 0.02
58.20 ± 0.03
Goes through**


AL-B
Water
 1.67 ± 0.01
11.10 ± 0.01
Pinning effect



IsoparL
12.49 ± 0.04
37.34 ± 0.06
Goes through***





*surface modified glass had a very low roll-off angle (7-10°)


**Isopar-L drop stayed pinned on E modified glass


***sliding angle of Isopar-L on AL-B modified glass was 30°






Berea Sandstone.
Berea sandstone showed the same hydrophobic behavior as the Ohio Sandstone. No contact angle could be measured using Isopar-L. For oil the absorption was very quick. Absorption of AL-B was a little slower than H1-F. The hydrophobic properties and surface energy results are presented in Table IV where it is illustrated that surfaces modified with A1-B and H1-F exhibited low surface energy.










TABLE IV






Average




Surface
Contact


Modifier
Angle
Surface Energy
Work of Adhesion (mJ/m2)


















H1-F
122.83
10.15
33.33


AL-B
143.11
2.5
14.58









As illustrated in Tables I, II, III and IV, substrate surfaces modified with the described surface modifying treatment agents provide for improved flow of produced hydrocarbons.

Example 4
Longevity studies were undertaken using glass slides and modified glass slides kept in brine (2% KCl, 11.6 ppg CaCl2, 19.2 ppg ZnBr2, 12.5 ppg NaBr, 13 ppg CaBr2/CaCl2) for five months and sandstone kept in produced water for one month. Atomic Force Microscopy (AFM) was used to determine the smoothness of the surfaces. Several glasses slides were kept in the same fluid and every month one slide was removed and analyzed. The slide was then washed with deionized water and dried and then tested for hydrophobicity. Surfaces modified with H1-F and Aculon E demonstrated good stability in brine after five months. In the case of AL-B, a decrease in the contact angle through time was observed. In the five month period, the sliding angle for the H1-F modified substrate decreased up to 4°.
The methods that may be described above or claimed herein and any other methods which may fall within the scope of the appended claims can be performed in any desired suitable order and are not necessarily limited to any sequence described herein or as may be listed in the appended claims. Further, the methods of the present disclosure do not necessarily require use of the particular embodiments shown and described herein, but are equally applicable with any other suitable structure, form and configuration of components.
Example 5
An effective method for depositing self-assembled monolayers from a surface modifying treatment agent onto an oxide surface was first determined. The surface modifying treatment agent had a hydrophobic tail and an anchoring site. The anchoring site through a covalent bond secured the surface modifying treatment agent onto the surface of the substrate. The surface modifying treatment agent exhibited hydrophobic properties and was commercially available from Aculon, Inc. as H1-F [comprising 2% of a treatment agent having a transition metal (anchor) linked to a fluorinated hydrocarbon tail in an organic solvent]. In the first test, Test A, a clean and dry glass slide was directly modified with the monolayer by spraying the surface of the slide with H1-F. In the second test, Test B, the surface of a glass slide was wet with a thin film of water. H1-F was then applied onto the coating. In the third test, Test C, the surface of the glass slide was wet with a thin film of ISOPAR-LTM paraffinic fluid, a product of ExxonMobil Chemical Company. The ISOPAR-L simulated oil wet reservoirs. H1-F was then applied onto the slide.
After applying the nanocoating, each of the samples was then left for about five minutes for the reaction to occur on the surfaces. The surface was then dried. A drop of water was then put onto the surface. If the drop spread on the surface then the quality of the bonding was concluded to be unacceptable. If the sample demonstrated hydrophobicity, then the coating was concluded to be successful. Test A demonstrated hydrophobicity while Test B and Text C did not. It was concluded that the glass slides were not modified successfully and did not enhance the ability of the surface modifying treatment agent to adhere onto the surface.
When Test B was repeated and the slide was kept exposed to air for a period of time in order for complete evaporation of the liquid to occur. HF-1 was then applied to the glass slide. The surface modified glass was then noted to exhibit hydrophobicity. No interaction of the oily surface of Test C was observed. It was concluded that binding efficiency of the monolayer would be very low when the surface of the rock being treated was exposed to oil or a large amount of water. It was further concluded that the surface of the rock being treated would need to be dry and clean from organic material as well as other contaminants in order for the surface modifying treatment agent to have the best access to the binding site of the rock.
Example 6
Two Berea sandstone cores measuring 1.0′′ in diameter and 1.5′′ in length were used. The first core had a nitrogen permeability of 804 md and the second core had a nitrogen permeability of 773 md. Both of the cores exhibited a porosity of about 20%. Both of the cores were evacuated with air and then saturated with either 2% aqueous solution of potassium chloride (KCl) or ISOPARTM paraffinic fluid. The cores were then installed in a hydrostatic core holder apparatus. Approximately 200 psi back pressure was applied at the exit end and approximately 1,000 psi confining stress (overburden pressure) was applied around the entire cylinder. The confining stress pressure simulated stress in the downhole formation.
The first core was not subjected to a preflush but was saturated in oil. Initial permeability to oil and water was determined in the production direction. First the permeability to water at residual oil was determined by flowing water through the core until differential pressure was stabilized. Oil was then flowed through the core and the permeability to oil was determined until there was irreducible water at stable differential pressure. The core was then treated with a surface modifying treatment agent exhibiting both hydrophobic and oleophobic properties and commercially available from Aculon, Inc. as Aculon-E [comprising 2% of a treatment agent having a transition metal (anchor) linked to a fluorinated hydrocarbon tail in an organic solvent] in the injection direction. Finally, permeability to oil and water was re-established in the production direction. Both permeability to water and oil cycles were repeated and determined. Then % regain permeability was calculated.
The second core was preflushed by saturating it in 2% KCl. Initial permeability to oil and water was determined in the production direction. Permeability to water at residual oil was first determined by flowing water through the core until differential pressure was stabilized. Oil was then flowed through the core until irreducible water was established at stable differential pressure. Permeability was then determined. This was followed by an injection of 10 pore volume of methanol as the pre-flush flowed through the core. The sample was then treated with the Aculon-E in the injection direction. Permeability to oil and water was then re-established in the production direction. Both permeability to water and oil cycles were repeated and determined. The % regain permeability was then calculated.
FIG. 6 shows the results obtained for regain permeability. As illustrated, the water regain increased from 106% for the first core (no pre-flush) to 548% for the second core (pre-flush). This demonstrates better efficiency for bonding of the surface modifying treatment agent when the core is pre-flushed. The regain to oil remained essentially similar with or without pre-flush.
The methods that may be described above or claimed herein and any other methods which may fall within the scope of the appended claims can be performed in any desired suitable order and are not necessarily limited to any sequence described herein or as may be listed in the appended claims. Further, the methods of the present disclosure do not necessarily require use of the particular embodiments shown and described herein, but are equally applicable with any other suitable structure, form and configuration of components.
While exemplary embodiments of the disclosure have been shown and described, many variations, modifications and/or changes of the system, apparatus and methods of the present disclosure, such as in the components, details of construction and operation, arrangement of parts and/or methods of use, are possible, contemplated by the patent applicant(s), within the scope of the appended claims, and may be made and used by one of ordinary skill in the art without departing from the spirit or teachings of the disclosure and scope of appended claims. Thus, all matter herein set forth or shown in the accompanying drawings should be interpreted as illustrative, and the scope of the disclosure and the appended claims should not be limited to the embodiments described and shown herein.

## Claims

1. A method of treating a siliceous or metal (M) oxide-containing subterranean formation penetrated by a well comprising:
a) pumping into the formation a surface modifying treatment agent having a metallic anchor and a hydrophobic tail; and
b) binding the metal of the metallic anchor of the surface modifying treatment agent to the surface of the siliceous formation or the metal, M, of the metal (M) oxide-containing subterranean formation.

2. The method of claim 1, wherein the hydrophobic tail of the surface modifying treatment agent comprises a hydrophobic organo-silicon material, a fluorinated hydrocarbon or both a hydrophobic organo-silicon material and a fluorinated hydrocarbon and further wherein the metal is linked to the hydrophobic tail.

3. The method of claim 2, wherein the hydrophobic organo-silicon material is a silane, polysiloxane or a polysilazane.

4. The method of 2, wherein the metal of the surface modifying treatment agent is a Group 3, 4, 5, or 6 metal.

5. The method of claim 4, wherein the metal of the surface modifying treatment agent is selected from the group consisting of Ti, Zr, La, Hf, Ta, W and Nb.

6. The method of claim 2, wherein the hydrophobic organo-silicon material has a formula selected from:


R14-xSiAx and (R13Si)yB

or an organo(poly)siloxane or organo(poly)silazane of the formula:




where:
R1 are identical or different and are a hydrocarbon or substituted hydrocarbon radical containing from 1 to 100 carbon atoms;
A is hydrogen, halogen, OH, OR2 or






B is NR33-y;
R2 is a hydrocarbon or substituted hydrocarbon radical containing from 1 to 12 carbon atoms;
R3 is hydrogen or R1;
x is 1, 2 or 3; and

y is 1 or 2.

7. The method of claim 6, wherein the fluorinated hydrocarbon is of the structure:



where Y is F or CnF2n+1; m is 4 to 20 and n is 1 to 6; R2 is alkyl containing from 1 to 4 carbon atoms and p is 0 to 18.

8. The method of claim 6, wherein the fluoro-substituted hydrocarbon is of the structure:



where A is an oxygen radical or a chemical bond; n is 1 to 6, y is F or CnF2n; b is at least 1; m is 0 to 6 and p is 0 to 18.

9. The method of claim 2, wherein the hydrophobic organo-silicon material is of the formula


R14-xSiAx 


wherein R1 is a fluoro-substituted hydrocarbon and A is OR2.

10. The method of claim 9, wherein R1 is of the structure:



where Y is F or CnF2n+1; m is 4 to 20 and n is 1 to 6; R2 is alkyl containing from 1 to 4 carbon atoms and p is 0 to 18.

11. The method of claim 2, wherein the hydrophobic organo-silicon material is an organo(poly)siloxane or an organo(poly)silazane.

12. The method of claim 11, wherein the organo(poly)siloxane or an organo(poly)silazane have units of the formula:



where R1 are identical or different and are a hydrocarbon or substituted hydrocarbon radical containing from about 1 to about 12 carbon atoms; and R3 is hydrogen or R1.

13. The method of claim 12, wherein the hydrophobic organo-silicon material contains additional units of the formula: R52SiO2 where R5 is halogen.

14. The method of claim 11, wherein the organo(poly)siloxane and organo(poly)silazane has a number average molecular weight of at least 400.

15. The method of claim 14, wherein the organo(poly)siloxane and organo(poly)silazane has a number average molecular weight between from about 1000 to about 5,000,000.

16. The method of claim 2, wherein at least one of the following conditions prevail:
(a) the surface modifying treatment agent alters the surface energy of the formation;
(b) the surface modifying treatment agent stabilizes fines in the subterranean formation;
(c) the well is a producing well and the surface modifying treatment agent decreases the amount of formation solids flowed back from the surface of the subterranean formation into the producing well;
(d) the surface modifying treatment agent is a passive anti-microbial agent and minimizes or prevents the retention of water on the surface of the subterranean formation;
(e) the surface modifying treatment agent passively inhibits or controls scale deposition onto or within the subterranean formation;
(f) the surface modifying treatment agent passively prevents or controls deposition of organic particulates onto or within the surface of the subterranean formation;
(g) the surface modifying treatment agent decreases the swelling of clay within the subterranean formation;
(h) the surface modifying treatment increases the relative permeability of the formation to oil/gas with respect to water, thus preventing water banking behind the formation surface;
(i) the well is a retrograde condensate gas reservoir and the surface modifying treatment agent minimizes condensation within the reservoir while maintaining the permeability of the reservoir;
(j) the well is a gas or oil well and the surface modifying treatment agent enhances the amount of flowback water and produced water from the well following completion of a well treatment operation;
(k) the surface modifying treatment agent is within a pad fluid;
(l) the surface modifying treatment agent is within a well treatment fluid and the well treatment fluid is pumped into the well at a pressure sufficient to create or enlarge a fracture in the subterranean formation;
(m) the surface modifying treatment agent is dispersed in a well treatment fluid;
(n) the surface modifying treatment agent controls water condensation in the pores of the near wellbore region of the subterranean formation;
(o) the formation is a tar sand formation and the surface modifying treatment agent enhances the recovery of hydrocarbons from deposits within the tar sand;
(p) the subterranean formation is subjected to acidizing and the surface modifying treatment agent increases the penetration of acid into the formation; or
(q) the subterranean formation is a matrix formation and the surface modifying treatment agent reduces the influx of water into the formation.

17. The method of claim 2, wherein the subterranean formation is a carbonate formation or a sandstone formation.

18. The method of claim 2, wherein the metal oxide-containing formation contains aluminum.

19. The method of claim 2, wherein step (b) comprises binding the surface modifying treatment agent to a surface of the subterranean formation by forming either (i) a O—Y—O—Si covalent bond between the anchor and a siliceous formation; or (ii) a O—Y—O-M covalent bond between the anchor and a metal oxide-containing formation wherein Y is the metal of the metallic anchor and M is the metal of the metal oxide-containing formation.

20. The method of claim 19, further comprising reducing drag of a fluid within the well.

21. The method of claim 20, wherein the sliding angle of the fluid on the surface of the subterranean formation treated with the surface modifying treatment agent is less than the sliding angle of the fluid on a surface of the subterranean formation not treated with the surface modifying treatment agent.

22. The method of claim 1, wherein the surface modifying treatment agent is of the formula J-K, wherein K is the metallic anchor and is a metal containing organic ligand and J is the hydrophobic tail and is directly or indirectly attached to the metal containing organic ligand and further comprising aligning the surface modifying treatment agent to the subterranean formation.

23. The method of claim 1, further comprising producing hydrocarbons from the well and reducing frictional drag during hydrocarbon production.

24. The method of claim 23, wherein the sliding angle of the fluid on the surface of the substrate treated with the surface modifying treatment agent is less than the sliding angle of the fluid on a surface of a substantially similar untreated substrate.

25. The method of claim 1, wherein prior to pumping the surface modifying treatment agent into the well, reducing saturated water on the surface of the siliceous or metal (M) oxide-containing subterranean formation by pumping a non-aqueous fluid into the well.

26. The method of claim 25, further comprising removing water from the surface of the subterranean formation.

27. The method of claim 1, further comprising forming a monolayer or multi-layer assembly by self-alignment of the hydrophobic tail.

28. A method of treating a siliceous or metal oxide containing subterranean formation penetrated by a well comprising:
(a) pumping into the formation a surface modifying treatment agent comprising the product of a metal containing organic ligand and an organo-silicon containing hydrophobic material wherein the metal of the metal containing organic ligand is selected from the group consisting of a Group 3, 4, 5 or 6 metal and the organic ligand of the metal containing organic ligand is selected from the group consisting of alkoxides, halides, keto acids, amines and acrylates;
(b) attaching the surface modifying treatment agent to the surface of the subterranean formation.

29. The method of claim 28, wherein the organic ligand of the metal containing organic ligand is an alkoxide or ester.

30. A method of treating a siliceous or metal (M) oxide-containing subterranean formation penetrated by a well comprising:
(a) pumping into the well a treatment fluid comprising a surface modifying treatment agent having a metallic anchor and a tail; and
(b) binding the surface modifying treatment agent onto the surface of the subterranean formation by forming a monolayer or multi-layer assembly by self-alignment of the tail

wherein prior to step (a) the amount of sites for the surface modifying treatment agent to bind onto the surface of the subterranean formation are increased by pre-treating the subterranean formation with a non-aqueous fluid.

31. The method of claim 30, wherein subsequent to pumping the non-aqueous fluid into the well and prior to pumping of the surface modifying treatment agent, the surface of the siliceous or metal oxide-containing subterranean formation is treated by pumping into the well a salt solution.

32. The method of claim 31, wherein the salt solution is an alkaline solution of sodium hydroxide or potassium hydroxide.

33. The method of claim 31, wherein subsequent to pumping the salt solution and prior to pumping the surface modifying treatment agent into the well, the surface of the siliceous or metal oxide-containing subterranean formation is treated by pumping a second non-aqueous fluid into the well.

34. The method of claim 33, wherein the non-aqueous fluid of step (a) and/or the second non-aqueous fluid is a hydrocarbon, an alcohol, a glycol, a glycol ether or a mixture thereof.