bluuebunny/crossref_metadata_2025 huggingface dataset:
Sand Production Prediction in High Rate, Perforated and Open-hole Gas Wells
Authors: Ong Seehong , Ramos Rico , Zheng Ziqiong
Published: December 2007

This paper presents an analytical model for the prediction of the on-set of sand production or critical drawdown pressure (CDP) in high rate gas wells. The model describes the perforation and open-hole cavity stability incorporating both rock and fluid mechanics fundamentals. The pore pressure gradient is calculated using the non-Darcy gas flow equation and coupled with the stress-state for a perfectly Mohr-Coulomb material. Sand production is assumed to initiate when the drawdown pressure condition (i.e. at CDP) induces tensile stresses across the cavity face. Both spherical and cylindrical models are presented. The spherical model is suitable for cased and perforated applications while the cylindrical model is used for a horizontal open-hole completion.

For input, the model requires cohesive strength and an internal friction angle that characterizes a Mohr-Coulomb material; preferably predicted using a log-based mechanical properties algorithm in order to generate a foot-by-foot profile of the maximum sand free drawdown for gas wells. The example GOM well illustrates a continuous profile of critical drawdown with depth, providing quick identification of potential sand producing zones. This allows a gravel pack decision to be made in the period between logging and completion. It also facilitates the design of selective perforation programs.

The model demonstrates that non-Darcy flow has a considerable effect on the sanding tendency of weak but competent rock, and completion decisions in high gas-rate wells that neglect the influence of non-Darcy flow could be overly optimistic. It also shows that the CDP of a horizontal well with slotted liner is less than that of the corresponding cased and perforated completion.
Predictability of Porosity and Permeability Alterations by Geochemical and Geomechanical Rock and Fluid Interactions
Authors: Faruk Civan
Published: December 2007

This paper presents improved models for interpretation, correlation, and prediction of the variations of permeability and porosity in petroleum-bearing rock, in which the pore topology is evolving by geochemical and geomechanical rock and fluid interactions during formation damage and stimulation processes. The permeability and porosity relationships considering pore evolution by precipitation and dissolution, and stress and temperature variation are developed. The present approaches are demonstrated and verified by analyzing a variety of reported data and shown to lead to accurate and functionally well behaving correlation. The applications demonstrate that the improved dynamic models accurately predict the measured porosity and permeability data. The associated analysis also lends itself to the physical interpretation of the variation of porosity and permeability in terms of the governing mechanisms.
Global Experiences and Practice for Cold Production of Moderate and Heavy Oil
Authors: Ehlig-Economides C. A. , Fernandez B. G. , Gongora C. A.
Published: December 2007

Today, most operators prefer to exhaust the opportunities for cold production of moderate and heavy oil before embarking on much more expensive and involved thermal recovery processes. Permeabilities of the order of 10’s of Darcies are common. However, the high oil viscosity causes low mobility, and hence, low well productivity. In some cases well productivity is 10–20 times higher than that explained by the usual Darcy’s law flow equations, because sand is produced with the oil ("worm holes"), or because gas in the oil comes out of solution and the gas-oil mixture has unusual flow characteristics ("foamy oil"). Frequently high initial productivity drops very quickly threatening the economic viability of the well. Assembled global experience with these phenomena coupled with critical fluid and rock property data and geological descriptions enables various generalizations to be made about observed production behavior, which, in combination, provide a means to design the optimal cold production strategy for a given reservoir.
Screenless Single Trip Multizone Sand Control Tool System Saves Rig Time
Authors: Hailey Travis , Cox Morris , Johnson Kirk
Published: December 2007

A new system of tools has been developed to complete multiple producing intervals in unconsolidated sandstones during one trip into the well. The system was developed to make efficient use of a previously developed pumping process, which simultaneously incorporates fracturing with proppant, and chemical consolidation of that proppant. The system provides sand control by installing resin coated proppant during the pumping process on each of the production intervals but leaves the casing across those intervals unobstructed except for isolation packers, which can be used for production management during the life of the well.

This new system enables low cost but highly productive completions, specifically enabling small and/or marginally economic reservoirs to be completed along with more valuable reservoirs. Multiple marginal reservoirs may be combined to make an entire project reach minimum required profitability. The system has been designed to allow low incremental cost for accessing additional reservoirs.

The system was used for the first time in the Milne Point field on the North Slope of Alaska in a field operated by BP Exploration (Alaska). This paper will describe in detail the design and operation of this tool system, including component drawings, operational sequence drawings, and a field case history in which the equipment was used.
Pressure-Actuated Isolation Valves for Fluid Loss Control in Gravel/Frac-Pack Completions
Authors: Worlow D. W. , Grego L. V. , Walker D. J. , Green G. R. , Smith B. E. , Harris M. E.
Published: December 2007

A new, mechanical fluid loss control system, integral to the base pipe of gravel pack screens, has been developed for ‘smart’ completions. This system allows for positive fluid loss control through all phases of well work once the gravel/frac pack is in place including the running of the isolation tubing stinger through the upper screen assembly of stacked completions. The isolation valves are opened for production without wireline intervention by hydraulically opening the zonal isolation sleeve of the ‘smart’ completion and applying pressure down the tubing. A new screen coupling system has also been developed to allow fluid returns during gravel/frac pack operations when the pressure actuated valves are run. To date, this system has been designed, tested, and successfully run in two deepwater subsea completions (3200’ WD).
An Economic, Field-Proven Method for Removing Fines Damage from Gravel Packs
Authors: Stanley F. O. , Troncoso J. C. , Martin A. N. , Jamil Omar Ali
Published: December 2007

It’s a fact of life – many gravel packs plug up. As time passes, skin factors go up and production rates go down. Much of the money that was spent on creating a sand control completion with minimum skin may eventually count for nothing. In order to prolong the effectiveness of the gravel pack (GP) and as a added benefit reduce the need for workovers, a method was developed in the Far East to remove these fines and dramatically reduce the skin factor. The method employs relatively small volumes of a specialized HF (hydrogen fluoride) acid system, designed to penetrate into the GP and very near wellbore area. The HF acid system uses an organophosphonate (HV) acid to control the production of HF and to control and drastically reduce potentially damaging secondary and tertiary precipitates. The system will be referred to as HV:HF Acid in this paper.

This HV:HF Acid system can be applied to any well with a screen and/or GP that has damage caused by the migration of formation fines and/or drilling mud particles. It is not limited by the type of screen or gravel nor by the length or number of sets of screens. The method has potentially enormous implications throughout the world. Any well with a GP or screen could potentially benefit from this method of treatment, including long horizontal intervals, which up to now have been very expensive to treat, due to the larger volumes of acid normally recommended.

The results of this HV:HF Acid method will be illustrated by 3 case histories from the Far East, including horizontal wells. The observations from these treatments allow us to conclude that this method is highly successful, cost effective, and applicable to a broad spectrum of well conditions. The reduced stimulation volumes provide better economics, so that even long sections and horizontal wells can now be stimulated at reasonable costs.
Considerations for Conducting Coiled Tubing Well Control Operations to Minimize Formation Impairment
Authors: Sas-Jaworsky Alexander , Ghalambor Ali
Published: December 2007

Coiled tubing services are frequently used to conduct kill operations concentric to existing production tubulars. These kill operations are typically performed to temporarily effect a hydrostatic balance of formation pressure at the exposed completion. Because coiled tubing well control operations are conducted concentric to existing production tubulars, special attention to job design and implementation is critical to ensure proper placement of kill fluids within the wellbore to achieve the desired pressure balance and to minimize the potential of formation damage.

In those cases where wellbore operations subsequent to the kill program are not intended to return the existing completion to active status, formation damage induced by the kill practice is typically of little consequence. However, where return of the existing completion to active status is desired, the well control operation must be conducted with a complete understanding of the pressure balance and effect of kill fluid circulation on the completion. Many practices used in performing concentric tubing well control services lead to vaiying degrees of formation damage and impair completion flow performance.

This paper discusses typical damage mechanisms resulting from completed wellbore kill programs, along with the related formation damage consequences for these types of operations, alternative well control kill processes using coiled tubing and the potential for reducing formation damage by using coiled tubing well control processes. In addition, recommendations for planning and implementing coiled-tubing conveyed well control programs within existing production tubulars are provided to guide the user in conducting well control operations with minimal induced formation damage.
Optimizing the Selection of Bridging Particles for Reservoir Drilling Fluids
Authors: Dick M. A. , Heinz T. J. , Svoboda C. F. , Aston M.
Published: December 2007

Most water-based reservoir drilling fluid systems used today are comprised of four primary components: the base brine, viscosifier, fluid-loss additive, and bridging particles. With the exception of minor adjustments of loading levels, the first three components normally do not change. The two primary types of bridging agents include calcium carbonate and sodium chloride salt. Some companies offer as many as seven different grades or sizes of each type of bridging particle.

For the first time, the "ideal" pigment-size-distribution theory used widely in the paint industry has been transferred to practical oilfield use. This paper discusses the method and its use in selecting the optimum blend of bridging particles, focusing on an ideal packing sequence for minimizing fluid invasion. The authors examine the various procedures for optimizing sealing, as well as a management maintenance system.

The paper expands on Abrams’ Median Particle-Size Rule by going beyond the size of particle required to initiate a bridge. In the discussion, the authors examine the ideal packing sequence for formulating a minimally invading (non-damaging) fluid.
Mechanisms of Mud Cake Removal During Flowback
Authors: Zain Zulkeffeli M. , Suri Ajay , Sharma Mukul M.
Published: December 2007

External filter cakes are used to minimize fluid loss and solids invasion to a formation from drilling and completion fluids. Subsequently, the cake must be removed in order to increase the flow area and minimize skins, especially for openhole and gravel packed completions in horizontal and deviated wells. Experimental data is presented to show that the pressure required to initiate flow into the wellbore after building up a filter cake is affected by rock permeability, mud properties such as particle size and cake yield strength, flow back velocity, and overbalance pressure.

Mud cake lift-off tests, mud particle size, and rock pore throat size distribution measurements were performed to understand the factors that contribute to cake removal. The mechanisms that control filter cake removal are discussed.

In this study, it is clearly shown that the flow initiation pressure during flow back is controlled by solids invasion, i.e. internal formation damage rather than by the external mud cake. Flow initiation pressures show a minimum with increasing rock permeability due to two competing effects. Larger pore sizes result in smaller flow initiation pressures, however, more solids invasion increases ΔPfi. Higher overbalance pressures also increase the internal formation damage and flow initiation pressure. A simple model to calculate the flow initiation pressure during flow back is proposed. The model correctly predicts the experimentally observed trends with rock permeability, mud particle size distribution, extent of solids invasion, and the yield strength of the mud cake. The model provides a systematic method for designing fluids with low flow initiation pressures. It is also shown in this study that low flow initiation pressures do not imply complete cake removal. Cake removal is primarily controlled by the permeability of the cake and its mechanical properties.
Experimental and Modeling Studies on Foam in Porous Media: A Review
Authors: Nguyen Quoc P. , Alexandrov Alexander V. , Zitha Pacelli L. , Currie Peter K.
Published: December 2007

Foams have been used for several decades to decrease the mobility of drive gas or steam, thereby enhancing the reservoir sweep efficiency. More recently foams found application in near-wellbore production enhancement operations such as acid diversion for matrix stimulation, gas shut-off, water shut-off and hydraulic fracturing. The optimization of these operations requires a thorough knowledge of the physical aspects involved in foam flow through porous media. In spite of the copious amount of experimental and theoretical investigations found in the literature, this knowledge is lacking.

The present paper is aimed at reviewing experimental and modeling studies on foams in porous media, to stress the latest achievements and highlight the areas that are the least understood. The focus of the analysis is twofold. First, we review the most representative core flow experiments that were undertaken to investigate the behavior of relative permeabilities and mobilities with emphasis on the key microscopic mechanisms proposed. Second, the different classes of models of foam flow through porous media are presented, outlining their advantages and weaknesses. A comparative analysis of the models is presented.
Formation Damage Resulting from Biocide/Corrosion Inhibitor Squeeze Treatments
Authors: Nasr-El-Din H. A. , Rosser H. R. , Al-Jawfi M. S.
Published: December 2007

To control sulfate-reducing bacteria (SRB) populations, and minimize operational problems noted in the water supply wells, a biocide/corrosion inhibitor squeeze program was applied. Because of the weak nature of the formation and potential sand production, an extensive coreflood study was conducted to determine the effect of a commercial biocide (formaldehyde, nitrogen and phosphorous compounds) and a biocide-enhanced corrosion inhibitor on the permeability of reservoir core plugs. Coreflood experiments were conducted using reservoir core plugs at reservoir temperature (50 °C) and pressure (2000 psi).

The results obtained indicated that high concentrations of the biocide or the biocide enhanced corrosion inhibitor caused up to 90% reduction in the initial permeability of reservoir cores. Several damaging mechanisms were identified: dissolution of the cementing material by the biocide (acidic), swelling of montmorillonite present in the formation and precipitation of calcium sulfate. Based on lab results, a detailed biocide squeeze treatment was designed to treat water supply wells. The treatment was able to control SRB populations while maintaining the integrity of the formation. This paper examines the design of the treatment and the results obtained from extensive lab testing and field trials.
Determination of Basic Geometrical Characteristics of Fractured Porous Media by X-Ray Computerized Tomography and Digital Photography
Authors: Martinez-Angeles R. , Perez-Rosales C.
Published: December 2007

Computerized Tomography (CT) and Digital Photography (DP) are new naturally fractured reservoir engineering imaging techniques that measures density inside fractured cores and micromodels samples during laboratory experiments. An image processing method for determining, simultaneously, some of basic geometrical characteristics of homogeneous and fractured porous media such as porosity, specific surface, mean pore width, mean grain thickness, mean fracture width, and absolute permeability is presented. The proposed method is characterized by its simplicity and by use of a X-ray tomography equipment and a digital camera. The experimental procedure used to evaluate various geometrical characteristics is based upon the surface analysis of a sample for a digital camera and upon a cross-section of a core model for a X-ray CT. In view of this fact, the applicability of the method is extended for heterogeneous and anisotropic samples such as fractured and vugged cores and micromodels.

Four experimental cases, digital images included, are presented: homogenous, one fracture, one vug, and a combination matrix-fracture-vug. Finally, two experiments of imbibition in fractured systems of one and four blocks of Berea sandstone are presented, where digital image processin procedure has been applied in terms of water saturation.
Linearly Supported Radial Flow -- A New Flow Regime Identified in Dual-Porosity Reservoirs
Authors: Guo Boyun , Stewart George , Toro Mario
Published: December 2007

Modern welltest analysis and interpretation techniques are based on match between actual reservoir pressure response and analytical models. In most well and reservoir configurations the analytical techniques are sufficient. However, recent technology advances in drilling and completion, and reservoir heterogeneity detected by modern pressure gauge have identified complex well and reservoir configurations where existing analytical well test models are not adequate for retrieving reservoir properties. This paper presents case studies where a new flow regime was indicated in two hydrocarbon reservoirs when the two wells were tested.

Log-log plot of pressure derivative versus time is called diagnostic plot in welltest analysis. Special slope values of the derivative curve are usually used for identification of reservoir and boundary models. These slopes include 0-slope, ¼-slope, ½-slope, and unity slope, etc. However, in many cases the derivative curves do not exhibit slopes of these special values, and it can be assured that the non-special slopes reflect certain flow patterns in the reservoirs. One type of these reservoirs has been observed to be thick reservoirs with either bottom or down-dip water drive. The slopes of the pressure derivative curve for this type of reservoirs are normally below ½ and not equal to ¼. A slope of as low as 0.2 has been observed in a gas reservoir. This paper demonstrates that these low slopes can be attributed to a new flow regime namely Linearly Supported Radial Flow (LSRF). The LSRF may exist in the drainage area of a vertical well where a radial (normally horizontal) flow prevails in a high permeability layer and a linear (normally vertical) flow into the high permeability layer dominates in a low permeability layer. The LSRF may also exist in the drainage area of a horizontal well after pseudo radial flow in the high permeability layer is reached. The linear flow in the low permeability layer may be supported by an aquifer. Analyses using a numerical welltest simulator support this LSRF theory.
Dilute Surfactant IOR - Design Improvement for Massive, Fractured Carbonate Applications
Authors: Yang H. D. , Wadleigh E. E.
Published: December 2007

Surfactants may be one of the best options to improve recovery from geologically challenging reservoirs. For over forty years, concepts and results of surfactant applications have been published. During recent years, depressed oil prices have limited surfactant consideration. However, surfactant recovery can be economically attractive for reservoirs where recovery is dominated by gravity and imbibition processes. Massive and/or fractured formations of moderate 30-50% recovery may warrant consideration for surfactant processing. Applications must meet laboratory performance hurdles for high incremental recovery at relatively low surfactant concentrations (quantified wettability and bond number). Placement of chemical in the reservoir at optimum concentration is the next challenge. This paper presents analytical and simulation assessment of chemical placement within a massive fractured carbonate formation undergoing surfactant EOR field testing. Placement methods can range from continuous injection to interrupted "huff-n-puff' application. The gravity stabilized reservoir management process currently being applied in the reservoir avoids some of the chemical flood conformance challenges of classic applications.

Oil mobilization by surfactant huff-n-puff in a naturally fractured reservoir is a complex process. The success of the application depends not only on surfactant chemical and physical properties and surfactant concentration injected, but also on fracture surface area treated by chemical solution and penetration depth of surfactant into matrix rock. In order to optimize the design of a dilute surfactant treatment in the Yates Field, an analytical model was developed to investigate effects of various parameters on the fracture surface area treated and penetration depth of surfactant solution into matrix block. These parameters include surfactant injection rate, injection volume, chemical diffusion, convection and fracture properties. Results of the analytical application are compared to simulator solutions. Laboratory testing, formation target screening, and field application are also discussed.
The Reliability of Permeability-Anisotropy Estimation From Interference Testing of Naturally Fractured Reservoirs
Authors: Hidayati Dewi T. , Chen Her-Yuan , Teufel Lawrence W.
Published: December 2007

Naturally fractured reservoirs normally exhibit high horizontal permeability anisotropy. Orientation of anisotropy, degree of anisotropy, and maximum/minimum permeabilities are required to describe the reservoir flow anisotropy. These parameters are normally obtained from interference testing. A series of sensitivity study was conducted to investigate the reliability of these estimated parameters from an interference analysis. The results show that interference test analysis gives reliable estimate of the orientation of anisotropy. However, the degree of anisotropy, maximum/minimum permeabilities, and total compressibility are very sensitive if the degree of permeability anisotropy is high and if the well configuration is unfavorable. Among the above parameters, the degree of anisotropy is the least reliable.
Test of Hydraulic Jet Pump in the Balam 91 Well
Authors: Morales H. Ramos , Castro H. Salgado , Maldonado O. Ruiz , Munive A. Salazar
Published: December 2007

When the natural energy of a reservoir is not enough in order to elevate the oil to the surface, it is necessary to use an artificial lift system that supply the additional energy required to continue the exploitation of the reservoir. Likewise, the artificial lift system is installed to increment the production in flowing wells. This is achieved by the energy that is added to fluids in the bottom of the well.

The hydraulic pumping, is an artificial lift system that transmits energy in the bottom of the well by a power fluid that flow through a pump.

There are two types of hydraulic pumping; the denominated piston type, that consists in a pair of reciprocating pistons, where one of them is driven by the power fluid and the other pumping the well fluids. And the hydraulic pumping jet type, which converts the pressurized power fluid to a high velocity jet that is mixed directly with the well fluids.

A description is presented and the result reached in a pilot test of hydraulic jet pump, effected in the Balam 91 well of the Ek-Balam field.
Genetic Algorithms Applied to the Optimum Design of Gas Transmission Networks
Authors: Montoya-O. S. J. , Jovel-T. W. A. , Hernández-R. J. A. , González-R. C.
Published: December 2007

This paper describes the application of a modified genetic algorithm (GA) to optimize the design of gas transmission networks operating under steady-stable conditions.

The gas-network optimization system is implemented by means of a genetic algorithm that executes an "intelligent search" in a "gas transmission networks" space.

It obtains automatically and with a low computational work a distribution of pipeline segment diameters for a minimum investment cost, accomplishing some restrictions initially fixed.
Anagas 2000: A Powerful Tool to Analize Orifice Metering Systems Used for Flow Measurement of Natural Gas
Authors: Santamaria N. E. , Mancilla S. F.
Published: December 2007

Orifice plate technology represents one of the most accepted and versatile methods for measuring flow; however, to achieve the full performance of this technology, a considerable amount of details must be attended to. This paper describes the development and the applications of a computer program denominated ANAGAS 2000, which allows in quick and reliable form to analyze or select an orifice metering system. Their use helps to identify operative problems, and to define quickly what a modifications it is necessary to carry out to optimize the operation of these metering systems Among other options, it can be used for the following purposes: (1) to calculate the flow rate delivered with a meter in operation; (2) to determine the maximun and minimun flow rate that can be handled with a meter tube installed, using different orifice plate bore diameters and pressure ranges of a mechanical chart recorder; (3) to define the physical arrangement that must have an orifice metering system to install, to quantify a well-known flow rate fulfilling the applicable recommendations strictly. The computer program was developed with base in the rigorous procedure that the latest editions of the API and the AGA recommend to calculate the gas flow rate measured with orifice plate, and considering also the applicable recommendations for its operation.
JU2000 - Efficiency by Design
Authors: Day Howard , Williams Mike
Published: December 2007

A drilling rig, either fixed or mobile, can be described as a factory that digs a hole. The purpose of this paper is to examine the fundamentals of the well bore construction process and how this has traditionally influenced rig design. By using an economic justification analysis to evaluate the tubular handling processes, a step change in performance and a breakthrough in rig design will be achieved.

This paper will outline the developmental steps taken by the rig designer, and in parallel, the technological development of tubular handling systems, that contribute to this step change in performance. Actual field performance for the pipe handling systems will be presented, including the innovative process that allows casing to be assembled in stands and racked back in doubles in preparation for casing the well.

Additionally, the handling of single 80' or 90' joints of casing and/or drill pipe is considered under parameters such as eliminating couplings and the subsequent reductions in make up and break out time, tool joint maintenance, and casing wear that can be attributed to tool joint hard banding.

The innovative use of both an automated vertical and horizontal pipe racking system, potentially providing the rig design with a smaller, lighter derrick structure and increased efficiency, will be illustrated. An example of the computer modeling system will be used to present an animation of the tubular handling process.

The resultant benefits of this combined approach can yield overall performance advantages of up to 20%, with associated up front economical benefits, over traditional jack up designs.
Advanced Hydraulics Analysis Optimizes Performance of Roller Cone Drill Bits
Authors: Ledgerwood L. W. , Wells M. R. , Wiesner B. C. , Harris T. M.
Published: December 2007

For nearly 30 years after the introduction of jet bits, all tricone bits had virtually identical nozzle systems. Nozzles were aimed toward the corner of the borehole bottom, more or less equidistant between the cones. More recently, tricone bits with unique patented nozzle systems have appeared and today drillers can choose between at least five different nozzle configurations. It is recognized that cone cleaning nozzle systems perform best in bit balling environments and borehole cleaning nozzle systems perform best in bottom balling environments. Another characteristic of bit hydraulics, which has not received much attention in the literature, is the ability of a bit to evacuate cuttings. Since one bit may encounter both bit and bottom balling environments during its life and all bits must evacuate cuttings, it is most ideal if one nozzle system can be developed which performs well in all three of these aspects.

A bit with a new nozzle system, described in this paper, has been shown to achieve superior rates of penetration to all other nozzle systems currently available in both laboratory and field tests. Three dimensional Computational Fluid Dynamics (CFD) models of the flow field between tricone bits and boreholes have been used to quantify the bit cleaning, bottom cleaning and cutting evacuation characteristics of this new bit and two other tricone nozzle designs.

Cone cleaning is not the only factor to be considered in designing a nozzle system for bit balling environments. Today's rock bit is expected to drill long intervals and therefore must drill through several different types of rock, which can often mean the bit may encounter several different drilling environments in its lifetime. Furthermore, nozzle systems that clean the cones may erode the cones in abrasive environments. CFD models have also been used to quantify and minimize the potential for erosive wear of the cone shell.
Removing Subjective Judgment From Wettability Analysis Aids Displacement
Authors: Heathman James , Wilson J. Michael , Cantrell James H. , Gardner Craig
Published: December 2007

This paper demonstrates how simple instrumentation can be used for evaluating the wettability of cementing spacers and preflushes in a laboratory. With detailed knowledge of a solution's "apparent" wettability, service companies and operators can more effectively choose the surfactants required for displacing nonaqueous drilling fluids and leaving the casing "water-wet." Water-wet casing allows the cement to adhere more easily to the surface, reducing the potential for remedial zonal isolation treatments.

A new laboratory device has been developed that more precisely assesses wettability. This device indicates "apparent" wettability by measuring the electrical activity in the test fluid during the water-wetting process. Oil-external drilling fluids do not conduct electricity; water-external spacers do. As the oil-wet surface of the test container becomes water-wet, the device registers electrical activity and a meter displays the "apparent" wettability in dimensionless units called Hogans (Hn).
Success with Electronic IADC Report
Authors: Opsal C. M. , Johnson S. E. , Holmberg C. J.
Published: December 2007

IADC, recognizing the need for operators and contractors to gather and disseminate drilling data electronically, while still maintaining the industry standards for format and content, issued license requirements for software to meet this need. How these requirements are met and how industry is accepting this new product is discussed. Field tests on drilling rigs show how electronically capturing and disseminating daily drilling information in the industry accepted method and format saves hundreds of dollars per day, and avail additional information and savings to the Operator and Contractor. Meeting IADC license requirements for an exact replication of the Time-tested IADC DDR insures ease of input, accuracy, reliability, consistency, and legality of the data and the format. By creatively utilizing new computer technology, additional information can be captured, processed, stored, and disseminated more accurately and quickly than with the current multi-part paper forms. This paper discusses the development of the electronic IADC report, utilizes field test results to illustrate the implementation, and demonstrates how the much needed new technology is cost effective and enables significant future efficiencies for Contractors and Operators. Creative data capture methods are detailed and field tests illustrate the cost savings, as well as the acceptance level of the new technology. Field tests results are used to quantify specific time and money savings both on the rig and in the office—how repetitive data entries are minimized, how handwriting is converted to accurate data, how the electronic DDR can be integrated into other systems, such as, accounting and engineering programs, and how secure the reports are. Field tests also illustrate the acceptability of the new technology on the rig, and define the basic training required. Additionally, this paper discusses how and why the IADC paper format has become accepted as a legal document and how the same legal status occurs with the electronic/computer form.
Overcoming Hard Rock Drilling Challenges
Authors: Santos H. , Placido J. C. R. , Oliveira J. E. , Gamboa L.
Published: December 2007

Drilling through hard rock has been a limiting factor to economically develop significant hydrocarbon reserves in several areas. The high cost to explore and develop an oil/gas accumulation is the key factor to be overcome. This paper describes a Joint Industry Project (JIP) that has been started to select and field test the most promising technologies under development that will allow a significant reduction on well cost. Problems faced while drilling hard rocks are not only restricted to slow penetration rate, but also the non-productive time associated to drill string failure, wellbores out of gauge, stuck pipe associated to block instability that falls into the well, and fluid losses due to fractures.
PCD Technology Advances Sidetracking Capabilities
Authors: Childers Ronald D. , Miller Gregory C.
Published: December 2007

Innovative materials technology advances sidetracking capabilities and offers a cost-effective approach to creating multiple laterals from the same mother bore. The key component to this sidetracking system is a mill designed with polycrystalline diamond (PCD) inserts. Current technology dictates that sidetrack milling be performed with mills dressed with crushed or pre-formed tungsten carbide that is manually applied. Regardless of technology, the success of the sidetrack is dependent upon on the skill and experience of the welder to properly dress the mill. The PCD mill eliminates the dressing process and the related performance uncertainties.

This paper discusses how PCD cutters, which are commonly used in drilling, were modified and applied to a casing-sidetracking mill. The mill design capitalizes on their ability to effectively and swiftly cut a window in the casing and drill a rat hole in formations with compressive strengths of up to 40,000 psi.

The benefits of such a mill are: 1) using the same cutting element for both steel and hard formations, 2) substantial cost savings when constructing multiple laterals from the same mother bore, 3) increased consistency in mill manufacture, 4) reliable milling performance and 5) improved efficiency in the sidetracking operation.

This paper profiles the development and testing from concept to a field-proven tool. The paper details: 1) laboratory-milling tests that identify the best material for cutting steels, 2) Oklahoma field tests in 9-5/8 in. casing to verify the feasibility of PCD casing milling and formation drilling, 3) West Texas and Colombia field runs in operators'

7 and 9-5/8 in. casing to mill a window and drill hard formations. Additionally, the paper will elaborate on the future potential of integrating this technology to a directional drilling assembly to drill laterals with the same equipment and preferably in the same trip for short laterals.
Gravity Azimuth: A New Technique To Determine Your Well Path
Authors: McElhinney G. A. , Margeirsson A. , Hamlin K. , Blok I.
Published: December 2007

Hot Holes with a geothermal gradient over 7 Degrees Fahrenheit per 100ft, high levels of magnetic interference and no returns. In this environment drilling deviated holes to a confined target can tax today's technology.

This paper describes the use of a new and novel technique that uses the Earth's Gravity field to determine the direction of a well. Direction from Gravity may normally, not be considered technically possible. However measuring the difference in the spatial position between two sets of accelerometers 30m apart gives the change in azimuth over this interval. These changes accumulate to show the well path trajectory.

The use of the Gravity Azimuth technique may help solve the problems associated with magnetic interference when surveying with magnetic survey instruments. The wider application of this technology into areas with localized magnetic interference, like drilling out of Casing Windows, Multi Well Avoidance, Casing drilling, 3D rotary steering devices and Multi Laterals is discussed. The paper compares the Gravity results to Gyroscopic and Magnetic instruments and discusses the operational consequences of the different methods.
Drilling The Limit*- A Practical Approach to Breakthrough Performance
Authors: Jones J. Adrian , Poupet Pascal.
Published: December 2007

"If you always do what you have always done, you will always get what you have always got". After 5 wells drilled recently in the South Halibut Basin, Central North Sea and with considerably more offset experience gained through other partners, Shell Expro embarked on the Drilling The Limit* philosophy for the Goldeneye E&A well.

The result was significantly above expectations, with a 20% improvement on the best previous offset well and a 30% improvement on the planned 50:50 AFE time. This translated into a cost reduction of 25% from the original AFE. It validated the hope that a true step change in performance in the North Sea is possible, even for a one-off well. By fully involving the lead drilling contractor and making the most of internal and external learning a "Best-in-Class" performance was achieved and demonstrated Shell Expros' ability to be a Low-cost operator.

In mature areas, where marginal developments depend on performance, DTL* is a worthwhile alternative to compromising the workscope and the well objectives in order to reduce expenses. It is a robust way to unlock opportunities and to contribute positively to the business.
Case History of Integrating Multisource Data for Pore Pressure Prediction
Authors: Smith John Rogers
Published: December 2007

The abnormally high formation pressures encountered in the deeper sections of many sedimentary basins influence both the accumulation of hydrocarbons and the drilling cost to develop the hydrocarbons. Consequently, accurate pore pressure prediction can be important to the economically successful exploration and development of deep reserves. This report focuses on the integration of pressure-related data and interpretations from multiple sources and disciplines to successfully predict pore pressures for a proposed drilling well.

A logical, consistent process of identifying, acquiring, interpreting, and integrating drilling, logging, production, geophysical, and geological data is described. This integrated approach to pore pressure prediction can provide a higher quality prediction than is possible with a single data source or method and can help to explicitly quantify uncertainties. The case history of a prediction for an actual well, including the results, is used to exemplify how the process can be applied. The well was drilled, in a previously troublesome area, for 20 per cent less cost than expected and without taking any kicks.
Milling Variable Window Openings for Sidetracking
Authors: Desai Praful C. , Dewey Charles H.
Published: December 2007

Historically, the profile of the window milled with a conventional whipstock system resembles an inverted tear drop shape. The resulting full gage window opening is relatively cramped for subsequent drilling assemblies and liner completions. For example, in 7" casing the total window opening is usually 10 feet long out of which only about 2 feet of the opening has full diameter access for drilling and completion tools.

This paper presents a unique whipstock design and milling tool design, the combined performance of which produces a full gage window opening of up to 85% of the total window length and thereby provides an abundant clearance for drilling assemblies and liner completions. Test conducted on 7"-29 lbs./ft. casing resulted in a total window opening of 9.8 feet (118") out of which 7.5 feet (90") was a full gage 6.00" opening. Test on 9-5/8"-47 lbs./ft. casing produced 16.83 feet (202") total window length of which 14.50 feet (174") of the opening measured full gage width of 8.50".

The whipstock can easily be modified to produce the desired length of full gage opening. Optionally, the window can be milled without the need for drilling a rat hole.

The benefits of a longer full gage window are (1) trouble free entries and re-entries through the window for drilling and completion of lateral, (2) ideal for short radius departure, (3) allows sidetracking in hard formation without drilling rat hole, (4) compensates for any mismatch in depth tally calculations, and (5) eliminates problems associated with skewed window (longer full gage window is vertically straight).

The paper details the test set up, test results, photograph and profile of actual milled windows and summarizes field run results.
Ream While Drilling Technology Solves Difficult South Texas Drilling Problem
Authors: Kelley Scott , Swadi Mohammad , Charles Chris
Published: December 2007

The authors will discuss the use of ream while drilling (RWD) technology in two wells, the S.K. East #4 and #5. RWD technology was used to reduce problems associated with drilling through several Frio sands from 11,000 ft to 14,000 ft, in the Sarita Field, Kenedy County Texas. This hole section has reservoirs that are difficult to drill, log and case due to a high potential for differential sticking (e.g. drillpipe, liner, openhole logging tools). Additionally, because the reservoir pressure is close to the fracture gradient, it was necessary to minimize equivalent circulating density (ECD) during both drilling and cementing operations. Another challenge in this interval is the tendency for some reservoirs to compact, reactivating faults. Finally, deviation tendencies were critical because of complex geology and lease constraints.

The operator selected to drill an oversized hole with a 12¼" RWD tool as a contingency to address the problems described above. Overall, sticking tendencies were eliminated, and lower ECD's allowed the interval to be drilled and cased with reduced lost returns. After drilling the section, caliper logs indicated a nearly in gauge hole diameter, and the deviation tendency of the interval was reduced compared to offset wells. The final survey showed only ½°and 1/3° of divergence from vertical for wells SKE #4 and SKE #5 respectively.
Managing the Client/Contractor Relationship to Maximise Safety Performance
Authors: Allwright Tony
Published: December 2007

Managing and developing the relationships and mutual understanding between clients, drilling contractors and service contractors can lead to the next significant breakthrough in improving the safety performance of drilling operations. Though demanding much personal effort on the part of managers, it is a low-cost high-impact approach. It will also impact favourably on technical and operational performance.

The contractor must develop his own safety identity, apply his own solutions and totally believe in what he is doing, albeit in full cooperation with his client. But this will work only if in turn the client understands and respects the needs and contribution of his contractors and sub-contractors.
Screening and Coreflood Testing of Gel Foams to Control Excessive Gas Production in Oil Wells
Authors: Wassmuth F. R. , Hodgins L. H. , Schramm L. L. , Kutay S. M.
Published: December 2007

The use of foams for controlling gas oil ratio (GOR) has been tested successfully in the North Sea,1,2 and North America.3,4 However, foams have a limited lifetime (weeks to months), and the treatment often needs to be repeated. A more permanent solution, with the same placement advantage, is to use gelling foams. During the gelation processes the foam structure solidifies, imparting greater stability and increased gas blocking ability to the gel-foam.

In this work, several polymer-enhanced foam and gel-foam formulations were screened, and tested for their gas blocking ability under reservoir conditions. Initially, chromium crosslinked gelation experiments were undertaken to obtain suitable gelation times at 85 °C. Polymer-enhanced foam and gel-foam formulations were injected into Berea sandstone cores, and carbonate packs (in the presence and absence of oil), to examine their injectability, and gas-blocking capability. In addition, the effects of shear degradation, permeability, and flow rate on the effective viscosity of polymer-enhanced foams were investigated. It was determined that gel-foams, with suitable gelation delay, can be injected, and propagated into packed cores in a similar manner to polymer-enhanced foams. The gas blocking ability of cured gel-foam was far superior to that of polymer-enhanced foam. The gel-foam blocked gas flow completely, even in the presence of oil, and a significant pressure differential had to be exceeded before the gas could channel through the gel-foam and flow through the core.
Modelling of Foam Flow in Porous Media Based on Multivariate Statistics
Authors: Alexandrov Alexander V. , Currie Peter K. , Nguyen Quoc P. , Zitha Pacelli L. J.
Published: December 2007

The objective of this study is the development of a mechanistic foam flow model which is based on the reconciling of the most important pore level phenomena. Pore morphology is described statistically by a correlated bivariate probability distribution of pore throats and aspect ratios. Pore level mechanisms such as snap-off, lamella mobilisation and destruction, are used to partition pore space. The pore space is partitioned into pores occupied by liquid only and pores occupied by foam (gas and lamellae). The pores occupied by foam are partitioned into those that contain mobile, immobile lamellae or no lamellae at all. The described above occupancy statistics is imposed on a network to determine gas relative permeability in presence of foam. Bretherton's theory is used to determine gas viscosity.