bluuebunny/crossref_metadata_2025 huggingface dataset:
A Graphical Approach to the Quantitative Analysis of Porous Rock and Oil Recoveries Using Capillary Pressure Data
Authors: Vo T.
Published: December 2007

Collection of rock and fluid data in the early stage of development of many oil fields, especially the larger ones, is often considered good practice. In most cases, the collected information is essential for immediate or future applications in various calculations. However, there are times when costly data were acquired with little forethought because the data would not be truly utilized in future field development plans. Typical of these are many capillary pressure reports that were filed years ago, but only used occasionally in the calculation of information such as height above water table and pore radius. The practical values of these terms are so insignificant that they can hardly provide any economic or engineering justification for the collection of the reports.

The lack of usage of these capillary data must have come from the fact that, despite the tremendous amount of literature on the subject, there was not any technique capillary properties to reservoir future performances, under various operational techniques and conditions.

This simple reason has inspired this author's study and, as a result, the proposed method. It is hoped that application of this method could retroactively justify the existence of these "old" capillary reports, and would be used in the future as basis of many more capillary studies.
A Successful Gas-Injection Project in a Heavy Oil Reservoir
Authors: Garcia F. M.
Published: December 2007

Meneven, an affiliate of Petroleos de Venezuela, S.A., has been conducting since 1963 a natural-gas-injection project in a heavy-oil reservoir (14–20 °API), located in Eastern Venezuela, immediately north of the Orinoco Oil Belt.

Laboratory tests were made to investigate recovery mechanisms, and a black-oil simulator was used to match performance history and predict future performance under continued gas injection.

According to the results obtained, the high viscosity (low API gravity) of a reservoir crude is not necessarily a limiting factor in the successful applica tion of conventional gas injection. This unorthodox scheme has proven to be quite successful even in a relatively high oil-gas viscosity ratio reservoir, where cumulative recovery has been 32% of 00IP, and final recovery is estimated at 45% of OOIP.
A Producer's View: If the Investment Climate is Right, Why is Oil Activity Depressed?
Authors: McCall Robert R.
Published: December 2007

Thank you. I'm greatly honored to have this opportunity to speak with fellow engineers at this 58th annual meeting of the S.P.E.

Today, I'd like to discuss three things with you: the outlook for exploration and producing in the United States during the 1980's, the things that we should be doing to shake off the present depressed conditions in the industry, and the role petroleum engineers will play in this scenario.

If the recent past history of drilling rig activity is any indication of the upper and lower limits of enthusiasm within the industry, Any success in forecasting the near term outlook for the exploration and producing side of our business will require as much luck as skill.
Nitrogen Injection Into Water-Driven Natural Gas or Condensate Reservoirs Increases Recovery
Authors: Adler A. B. , Crawford P. B.
Published: December 2007

Many natural gas and condensate reservoirs are subject to secondary recovery by either water injection or a natural water drive. If the hydrocarbon is the non-wetting fluid, and water the wetting fluid, the hydrocarbon will be trapped by the water. The volume of trapped hydrocarbons at abandonment may be of the order of 20 to 45 percent depending upon the particular reservoir. It was believed that a tertiary recovery process could be applied which would increase the hydrocarbon recovery. Low cost nitrogen might be injected at the water-hydrocarbon contact. The nitrogen would result in miscible displacement with the hydrocarbon. Water would drive and trap the nitrogen, and such could result in an increase in ultimate hydrocarbon recovery. The cost of nitrogen from an air separation plant can be quite low, and the process might be applicable to both onshore and offshore reservoirs.

Computer simulation studies have been made to estimate the increase in hydrocarbon recovery which might result from injection of nitrogen into natural gas or condensate reservoirs subject to secondary recovery by either a natural water drive or water injection. The effect of dip-angle, porosity, slug size, permeability, gas-water contact and other variables were studied. It would appear that the injection of nitrogen may result in an increase in hydrocarbon recovery by 30 to 50 percent. The projected economics of the process appear to be favorable.
Increasing Oil Recovery From MIS Oil Shale Retorts by Offgas Cooling
Authors: Stevens A. L. , Jacobson C. L. , Purcupile J. C. , Zahradnik R. L.
Published: December 2007

Occidental Oil Shale, Inc., recently completed the demonstration of mining, rubblization, ignition, and simultaneous processing of two commercial-sized modified in situ (MIS) retorts at our Logan Wash Facility near De Beque, Colorado. Two hundred thousand barrels of shale oil were produced from the two retorts, a 70 percent yield of the oil-in-place in the rubbled rock. One of the control measures demonstrated, on this project was the use of water sprays behind the Product Level bulkheads to cool the offgas. When the offgas temperature began to increase as the high temperature region in the retort approached the bottom of the retorts, the water sprays cooled the offgas to acceptable levels and the extended retort life resulted in better oil recovery.
Graphical Reserve Estimation for Partial Water-Drive Gas Reservoirs
Authors: DeMoss S. J.
Published: December 2007

Combination of measured reservoir pressures with volumetric data derived from geologic mapping is necessary for meaningful reserve prediction in gas reservoirs affected by water influx. A method for combining these data to monitor reservoir performance and predict remaining reserves is presented.
Modeling the Performance of Observation Wells in Underground Storage of Natural Gas
Authors: Tek M. R. , Udegbunam E. O. , Wilkes J. O.
Published: December 2007

Performance of the observation wells related to the monitoring of the presence and extent of gas migration from storage horizons has been investigated using theoretical and laboratory models.

The theoretical model developed for short columns or shallow wells was first evaluated using laboratory data. The results indicated good agreement between theoretical and actual behavior, and the model was extended to field applications where the data from a water observation well going to a full gas column were studied.

It is concluded that the equations derived for both the short and tall columns can be used along with data collected at the wellhead to predict the performance of observation wells being encroached by the nigrating gas.
Through-Tubing Plug-Back Without Depth, Temperature, or Pressure Limitations
Authors: Weeks S. G.
Published: December 2007

Excessive downhole temperatures, as well as some well bore restrictions, may limit the use of wireline bridge plugs. With careful planning, Shell Oil Company has successfully utilized sand-slurries for plugging back through tubing in deep, high-temperature, geopressured, gas tests--without limitations. This has included isolation of water producing zones as well as temporary exclusion of lower intervals that did not warrant additional stimulation expense.
Evolution of Fair Market Value of Natural Gas in the U.S.
Authors: Smith Sol , Baumel J. K.
Published: December 2007

Paper traces the guidelines adopted by the Courts by which fair market value of natural gas can be determined. A history of the Natural Gas Industry is discussed with special emphasis on conditions that caused certain factors to be used in market value calculations. Each new factor on determination used gave greater comparability of natural gas in any particular case. Vela v. Texas Oil & Gas Corporation was the most influential and set factors that should be used in such determination of fair market value. The weighted average approach is the best method to determine the fair market value of natural gas; follows Vela's definition of comparable gas and uses good engineering precepts.
CO2 Flood: Design and Initial Operations, Ford Geraldine (Delaware Sand) Unit
Authors: Phillips L. A. , McPherson J. L. , Leibrecht R. J.
Published: December 2007

A miscible carbon dioxide (CO2) flood was initiated by Conoco Inc. in a 3850-acre area of the Ford Geraldine (Delaware Sand) Unit in Reeves and Culberson Counties, Texas in February, 1981, after a staged waterflood was nearing completion. The CO2 supply is a by-product source obtained from the Lone Star Pikes Peak Gas Plant near Fort Stockton. This previously vented product is compressed to a supercritical state and then transported to the Unit through a 112-mile pipeline which has a capacity of 30 MMCFPD. Compression and transmission system design has minimized start-up and operational problems. Capital costs were reduced by utilizing most of the existing waterflood distribution system. Lack of a sufficient and stable CO2 supply has caused most of the operational problems. New vessels have been installed to better handle production well testing. In addition, a system has been developed and installed to automate all injection and production data so as to provide the surveillance information to properly monitor the flood performance. Response to the limited and unstable CO2 injection supply has been encouraging. Once additional supplies are secured and response is verified, CO2 recycle facilities will be installed. In addition, the flood could later be expanded to the remaining 1430-acre northern area of the Unit, which is still under waterflood.
Drilling Technology: Present Trends and Future Prospects
Authors: Cheatham J. B.
Published: December 2007

This paper addresses the subject of how new technology can be expected to influence future drilling engineering and drilling operations. The work is based upon a review of past developments in drilling technology; a survey of current research and development efforts; personal contacts; and recent workshops, publications and presentations.

The impact of measurements while drilling, Polycrystalline Diamond Compact bits, downhole motors, and utilization of computers is discussed with regard to future developments of computer aided drilling, drilling optimization and hole direction control. Recent work by others on measurements while drilling, drilling simulators, and drilling optimization has been extended to emphasize setting goals for future drilling technology developments.
Transport Efficiency of High-Density Gravel Packing Slurries
Authors: Skaggs B. C.
Published: December 2007

A large-scale wellbore model was used to study gravel transport through the perforations during a simulated, high-density, squeeze gravel-packing operation. The effects of fluid viscosity, gravel concentration, annular velocity and perforation leakoff rate were investigated. Slurry consistency is presented as a means of describing the combined effects of fluid viscosity, gravel concentration and size. Results show that transport efficiency increases with increased fluid viscosity, gravel concentration and annular velocity.
The Effect of Break Mechanism on Gelling Agent Residue and Flow Impairment in 20/40 Mesh Sand
Authors: Almond S. W. , Bland W. E.
Published: December 2007

In hydraulic fracturing, the temperature at which a polymer is to be used determines the break mechanism and the breaker used for its degradation. The polymers most commonly used in fracturing were degraded under a variety of conditions and their resulting flow impairment characteristics were measured in 20/40 mesh sandpacks. Enzyme breaker was used for the low temperature tests (120°F), oxidizing breaker was used for the intermediate temperature tests (180°F) and thermal degradation processes were used for the high temperature tests (275° – 400°F).

The polymers evaluated were derivatized cellulose (0% w/w residue), derivatized guar gum (1-2% w/w residue), intermediate residue guar gum (5-6% w/w residue) and guar gum (8-10% w/w residue). The relative residue volumes for these polymers were determined and compared to their actual flow impairment values. The effect of polymer loading on the relative flow impairment was also determined for these polymers as a function of break temperature.
Formation Damage of Brine Corrosion Inhibitors
Authors: Potter G. F.
Published: December 2007

Brine corrosion inhibitors, varying from highly dispersed organic materials to low-molecular-weight salts, were evaluated for their effect on return oil permeabilities.

Cores used in these tests were 50-to 100-md and 1,0-to 3,000-md sandstone. Temperatures up to 300°F and two different density brines were studied. Results show that emulsion blockage was a problem at low temperatures for inhibitors that yielded low brine/oil interfacial surface tensions. At higher temperatures, emulsion blockage was greatly reduced.

Inhibitors that produce sulfide ions resulted in reduced return permeability with cores containing iron(III).
The Analysis of Filtration Under Dynamic and Static Conditions
Authors: Peden J. M. , Arthur K. G. , Avalos Margarita
Published: December 2007

This paper presents an overview of the work carried out to date on the dynamic and static filtration characteristics of drilling muds. Factors controlling fluid loss to the formation that have been investigated include annular velocity, fluid temperature, hole angle, shear rate and the effect of the filter media. The effect of pressure on static fluid loss and filter cake permeability is also reported. Fluid loss during sequential filtration has also been evaluated. The fluids used comprised a calcium chloride brine with fluid loss additive and two water based muds. The filter media consisted of synthetic core material and a natural sandstone. Conventional photographic techniques have been used to idenify filter cake response to backflushing.
Evaluating Fractured Well Performance Using Type Curves
Authors: Soliman M. Y. , Venditto J. J. , Slusher G. L.
Published: December 2007

This paper consists of three parts. The first part presents new type curves for a well intercepting a vertical fracture with finite conductivity. The type curves are for a well located in a limited reservoir and producing under constant flowing pressure. The second part describes how the type curves can be used in predicting and matching reservoir performance. Description of automated history match is also included. The match procedure considers the effect of turbulent flow inside the fracture as well as the change in fracture conductivity due to change in flowing pressure (crushing of sand).

The third part of the paper presents application of the first two parts to actual field cases. The discussed procedure is applied to two gas wells in South Texas. The paper presents the following for each well: A pre-fracturing build-up test analysis.Fracturing treatment design.History match of production data calculating the fracture length and conductivity.
Viscometric Measurement of Chromium(III)-Polyacrylamide Gels by Weissenberg Rheogoniometer
Authors: Aslam Sohail , Vossoughi Shapour , Willhite G. P.
Published: December 2007

Gelled polymers are being used increasingly to modify the movement of injected fluids in secondary and enhanced oil recovery processes. A common gelation process involves the reduction of Cr(VI) to Cr(III) in the presence of polyacrylamide. The Cr(III) reacts or interacts with the polymer to form a gel network. Although correlations of gelation time with principal process variables have been obtained, viscometric data have not been reported during or after gelation. These data are needed for fluid flow calculations in surface equipment and estimation of flow behavior in reservoir rocks.

A Weissenberg Rheogoniometer, with cone and plate geometry, was used to obtain viscometric data for the gelation of polyacrylamide and chromium (III). Solutions consisting of polyacrylamide polymer, sodium dichromate-dihydrate and sodium bisulfite were gelled under a steady shear field at constant temperature. The shear stress vs. time profile for the gelation process was interpreted to define a gelation time and to determine the apparent viscosity of the gelled fluid. The gelation time decreased as the applied shear rate increased up to about 14.25 sec−1 and was affected by shear rate history. Viscometric properties of the gelled solutions were determined. Apparent viscosity of the gelled solutions decreased as the shear rate under which they were formed increased.

Post gelation studies indicated that gels exhibited a residual or yield stress at zero shear rate and behaved as Bingham plastics under steady shear. Gels formed at low shear rates were more viscous than gels formed at high shear rates. However, the structure of these gels was susceptible to shear degradation.
Kinetics of Polymer/Metal-Ion Gelation
Authors: Prud'homme R. K. , Uhl J. T.
Published: December 2007

Polyacrylamide and partially hydrolyzed polyacrylamide solutions can be crosslinked by tri-valent chromium ions to form stable gels. In this study the kinetics of the gelation reaction are determined from the time dependence of dynamic mechanical measurements using classical network elasticity theory to relate the storage modulus of the gel to the number density of crosslinks. The reaction is second order in chromium ion concentration corroborating previous reports of a bi-molecular chromium ion complex. Gelation studies with anionic and nonionic polyacrylamides in NaCl, KI, and Na2SO4 solutions show that electrostatic interactions between chain segments alter the rate of reaction. The effects are successfully modeled using electrostatic theories of Odijk and Fixman.
A New Multicomponent Surface Tension Correlation Based on Scaling Theory
Authors: Lee Sheng-Tai , Chien M. C. H.
Published: December 2007

This paper presents a multicomponent surface tension correlation based on scaling theory. In addition to particular exponents employed, the correlation contains two new features: (1) A corresponding-states equation is derived for a correlation coefficient, commonly referred to as a parachor. As a result, the hydrocarbon pseudocomponent parachors can be calculated through this equation, once their pseudocritical properties are estimated. (2) An approach is proposed to calculate the parachors of mixtures. In contrast to the conventional approach, which calculates the mixture parachor via molar mixing of component parachors, this approach first obtains the pseudocrtical properties of the mixture and then employs the corresponding-states equation to calculate the mixture parachor.

For various reservoir-fluid related pure components, the corresponding-states equation predicts parachor values to within 1% of those listed in the literature. The surface-tension correlation developed was tested against 45 sets of measured binary surface tension data and four sets of multi-component CO2-reservoir oil surface tension data. Other existing surface tension correlations, i.e. Weinaug-Katz's and Stegmeier-Hough's correlations, are also tested and compared. For the 45 sets of binary data, the average deviation of the new surface tension correlation is 3.71%, which is about 50% smaller than the deviations of the other two correlation cited. In addition, for the CO2-reservoir fluid data, the average deviation is about 7.3%, which is also a significant improvement over the existing correlations. It is worth noting that the surface tension correlation developed does not involve any adjusted parameter and it is also completely compatible with existing compositional numerical simulators.
Evaluation of a-Olefin Sulfonates for Steam Diversion
Authors: Hu P. C. , Tuvell M. E. , Bonner G. A.
Published: December 2007

Enhanced oil recovery studies have consistently demonstrated the need to mitigate gas channeling in processes involving use of gaseous substances (such as steam, carbon dioxide, nitrogen and air) to stimulate oil production. The use of foam to control the mobility of the gas was suggested thirty years ago, and earlier field tests2,3 indicated that significant benefit in oil production could be achieved using this concept.

The use of foam to improve mobility control is based on the observation that most foams have great flow impeding characteristics and provide greater flow impedence in high permeability porous media than in low permeability media.

Sibree4 was probably the first to report that froth has an apparent viscosity much higher than either of its constituents. He compared the rheological behavior of a froth to that of a coarse emulsion and attempted to relate apparent viscosity to the volume fraction of gas in the liquid.
Relative Permeabilities of Surfactant/Steam/Water Systems
Authors: Monsalve Armando , Schechter R. S. , Wade W. H.
Published: December 2007

Surfactants are now being used in field application to help reduce the flow of steam into more permeable zones during steamflooding operations. Despite the increasing interest, little is known about how surfactants function to reduce the permeability to steam nor how surfactants are transported from the wellbore into the formation. An important aspect in helping resolve these issues is the relative permeabilities to both steam and water.

In this paper the relative permeabilities to both steam and water in the presence of two surfactants are reported. One important finding is that the steam saturation at residual increases with increasing surfactant concentration for the systems studied and the relative permeabilities to steam are shifted but the general shape of the curves is not changed.

Unlike previous findings for gas-liquid systems, the relative permeability to water has been found to increase with increasing surfactant concentration rather than remain constant. While the mechanism responsible for this unexpected finding is not understood, the experimental trends are well defined.

Considerable attention has been devoted to the design of the experimental apparatus. Calculations are presented which show that heat exchange with the environment can, in the absence of surfactants, give rise to both flow dependent relative permeabilities and abnormally low residual steam saturations. These same calculations also indicated that more reliable results may be obtained if the core is well insulated even though it is in a well controlled thermal environment.

In the absence of surfactant the relative permeabilities to both steam and water in Berea sandstone were found to be similar, although not identical, to oil-water relative permeabilities.
An Experimental Study of Water Imbibition in Chalk from the Ekofisk Field
Authors: Torsaeter Ole
Published: December 2007

The Ekofisk Field in the North Sea produces from two lithologically similar, low permeability fractured chalk formations. The Ekofisk Formation of Danian age is separated from the lower Tor Formation of Maastrichtian age by a tight zone of about 15 m thickness. With a projected primary recovery factor of only 18%, the secondary recovery target is substantial. A pilot waterflood has been conducted in the Tor Formation and expansion of waterflooding to a large area of the Tor is planned. For waterflooding to recover substantial oil in a highly fractured rock large saturation changes in the matrix rock must be achieved through water imbibition.

Water imbibition in Tor samples is high and variable and the imbibition in Ekofisk samples is low and also variable. The first objective of the laboratory investigation reported here was to establish correlations between imbibition and rock parameters in the highly water wet Tor samples. The second objective was to determine the reasons for differences in Ekofisk and Tor water imbibition.

The volume of water imbibed and the initial water saturation in Tor samples correlated very well with porosity for the two wells examined. The water saturation after imbibition was constant at about 60 percent of pore volume, independent of porosity. Imbibition in the Ekofisk samples from the one well examined varied widely and did not correlate with any of the rock parameters examined. Pore structure studies and extraction experiments with strong solvents indicate that the difference between Tor and Ekofisk samples is due to rock surface chemistry differences.

The correlation developed here with the Tor samples provides a sound basis for comparing data from different wells, for examining the effect of various handling and laboratory procedures, and for data input in models. The indication of rock surface chemistry differences provides direction for further research aimed at explaining in greater detail differences between the Ekofisk and Tor rocks with respect to imbibition.
Comparison of Simulation and Experiments for Compositionally Well-Defined Corefloods
Authors: Giordano R. M. , Salter S. J.
Published: December 2007

The mechanisms which affect the efficiency of chemical flooding processes have been the focus of considerable research and speculation in recent years. One method to identify these mechanisms is the comparison of carefully conducted experiments with results generated using a mathematical model (simulator). In this paper we report both experimental and simulation results for II−, II+, and three-phase systems run so that the entire flood remains on a single phase diagram. In order to do this rigorously, we have used simple systems in which the complexities of non-pseudoternary behavior are absent. We simulated experimental core floods using a modified version of INTERCOMP's Chemical Flooding Simulator CFTE and tested the sensitivity of the results to a variety of process mechanisms. We also employed a method-of-characteristics solution to independently check the simulator. In doing so we extended the method-of-characteristics to three-phase, multicomponent flow in porous media. Our major objective is to show the interactions among the phase behavior, fluid flow, mixing, and mobility mechanisms which are present in chemical flooding processes.
Application of the Alkaline Flooding Process in the Torrance Field
Authors: Konopnicki D. T. , Zambrano L. G.
Published: December 2007

An alkaline flooding system has been designed for application in the Main Zone reservoir of the Joughin Unit in the Torrance Field. The flood will encompass the major portion of the Unit (Section B) and will consist of twelve inverted nine-spot patterns. With a caustic injection rate of 38,000 BPD (6042 m3/d), this flood will be the largest alkaline flood ever attempted in the world to date. A 30% pore volume pre-flush injection, which consists of softened fresh water, began on June 30, 1981 to reduce the divalent ion content and salinity of the reservoir. A 16% pore volume caustic slug consisting of 1.2% sodium orthosilicate is scheduled to begin in early-1985. Caustic injection will require approximately two years.

Extensive laboratory studies have been conducted to verify the viability of the alkaline slug process in this reservoir. Interfacial tension measurements demonstrated that extremely low interfacial tensions can be achieved with a dilute solution of sodium orthosilicate in softened fresh water and reservoir brine. Furthermore, core floods utilizing sodium orthosilicate solutions of 0.8% and 1.2% resulted in reductions in the residual oil saturation of up to 9.4% Vp over waterflooding alone. This data along with the caustic consumption laboratory data were utilized in a chemical flooding simulator to scale results to the field and to make oil recovery predictions. The study indicates that the injection of a 16% Vp slug of 1.2% sodium orthosilicate will result in a incremental oil recovery of 1875 MBO (298,125 m3) or 1.75% OOIP in Section B. Results of the laboratory studies, reservoir engineering work, and the computer simulation study to optimize the process are presented.
A Group Contribution Activity Coefficient Model for Enhanced Oil Recovery Process Involving Electrolyte Solutions: Part I—Solutions in the Absence of Partial Molecular Association
Authors: Chien M. C. H. , Lee Sheng-Tai
Published: December 2007

The assumption of ideal solution for the electrolyte solution in many mechanistic studies of enhanced oil recovery processes may be oversimplified because the mean ionic activity coefficient of an electrolyte is very sensitive to the mixture composition. A thermodynamic model is developed to account for the nonideality of electrolyte solutions and to serve as a tool for a more rigorous mechanistic study of enhanced oil recovery processes.

The model takes into account three important molecular and ionic force contributions: the long range ion-ion electrostatic force contribution, the intermediate range ion-solvent interaction (solvation) contribution and the short range force contribution of all species. It is demonstrated that the model can correlate the solution behavior of strongly polar and nonpolar nonelectrolytes as well as strong electrolytes over a wide range of concentrations. The solvation contribution is found to be important in correlating the thermodynamic properties, especially, the salting out of nonelectrolytes in aqueous solutions. Comparison shows that the new model is four times better than Chen's model (1982) in correlating the mean ionic activity coefficients. The parameters of sodium chloride, sodium hydroxide and calcium cation as well as magnesium cation are determined in this study. These parameters will be useful for the mechanistic study of alkaline flooding processes and surfactant/polymer flooding processes. Furthermore, the model employs the group contribution concept. Therefore, it can be used to estimate the solution behavior of a mixture in which the groups can be identified.
Analysis of Fracturing and Fluid-Flow Characteristics of the Monterey Formation, Santa Barbara Channel, CA
Authors: LaPointe P. R. , Belfield W. C. , Helwig J. A.
Published: December 2007

Analysis of fracturing in the Monterey formation in core and outcrop demonstrates the interrelations among the regional stress field, the fracture pattern geometry and connectivity, and the hydrocarbon migration and production characteristics of the Monterey. The spatially and temporally persistent fracturing consists of four predominant subvertical sets striking approximately N30E, N55E, N67W and N15-30W. The northeasterly sets possess the greatest areal density and are often the primary set against which others terminate. They are also the most frequently filled with tar and calcite, particularly where they are near oblique-slip faults. A regional northeasterly maximum compressive stress field that has persisted from Pliocene time to the present selectively enhanced subvertical northeasterly-striking fractures. This stress field made the northeasterly joints the favored fractures for the migration of fluids through the fracture network.

Statistical analysis of the joint network indicates a northeasterly direction for the maximum fracture network permeability, consistent with offshore production data. Computer-generated synthetic fracture networks constructed from the field data illustrate the impact that faults, major joints and slump or breccia zones may have on integrating poorly connected fracture network clusters, thereby enhancing directional flows.
Analysis of Pressure Transient Data Obtained in Hydraulically Fractured Wells: A Field Example
Authors: Ross Steven E.
Published: December 2007

The hydraulic fracture stimulation of low permeability reservoirs has been a successful technique for obtaining economic hydrocarbon production from many otherwise marginal fields.

The analysis of pressure transient data obtained in hydraulically fractured wells has been previously published by many authors.1–31

This paper utilizes these published theories for the purpose of illustrating that data from wells in a California Oil Field can be analyzed with the results used to guide future development.
The Performance Characteristics of a Hot Flowing Steamflood Production Well
Authors: Jurinak J. J.
Published: December 2007

The production of hot steamflood fluids as a low pressure vapor/liquid mixture driven by produced steam or by the flashing of hot liquids is studied using a numerical wellbore flow model. The effect of well depth, wellhead pressure, flow rate, tubing size, and wellbore heat loss on the performance of the flowing steamflood well is discussed. The wellbore model is also used to estimate the flowing production well bottom-hole history in a FAST process tar sand steamflood. The rate of noncondensible gas injection required for auxiliary lift in a cold well is determined. This study facilitates application of produced steam lift as a steamflood production technique.
Caustic Consumption by a Sandstone at Elevated Temperatures
Authors: Dehghani Kaveh , Handy L. L.
Published: December 2007

The effect of temperature on caustic loss due to its reaction with a representative sandstone was investigated in a series of laboratory experiments.

Consumption was measured for sodium hydroxide concentrations from 0.01 to 0.1 N at temperatures from 80° to 180°C in fired and unfired Berea sandstone. Three types of experiment were performed. One of these was a static, batch experiment with disaggregated sandstone for different contact times. The others were flow experiments in consolidated cores at various flow rates. In one case caustic was injected and effluent concentration were measured, and, in the other case, the produced fluids were recycled through the core.

The results show that caustic concentration is caused by a fast reversible Langmuir-type ion exchange and an irreversible reaction of dissolution of silica. An increase in temperature results in a higher amount of ion exchange for the same initial concentration and a higher rate of dissolution. The heat of the ion exchange reaction is constant in the range of temperature studied and as a result the equilibrium constant of ion exchange can be found for other temperatures. Dissolution for the lowest caustic initial concentration (0.01 N) can be represented by first order reaction but not for the higher injection concentration. Batch experimental results show that equilibrium is established in the caustic-silica reaction with stabilization of pH.
A New Drilling Technique Using Vortex Action at Rock-Bit Interface (Part 1)
Authors: Hayatdavoudi A. , Akhigbe A. , Okoye C. , Ghalambor A.
Published: December 2007

Due to a great deal of information available, this paper has been arranged in two parts. The paper presented here deals with Part I. In this part, theory and laboratory data of the DVG (Downhole Vortex Generator) Sub, which is run immediately on top of the standard bits, is introduced. In our models, we have emphasized changes in drilling strengths and crossflow as a result of vortex action.

The theoretical as well as field data indicate an average increase of penetration rate to fall within 10 to 75 percent for 9-7/8″ holes. Furthermore, on the basis of laboratory data, it was concluded that (1) the vortex pressure drop increases as the DVG sub nozzle angle to the horizontal plane decreases, (2) there is a non-linear increase of the vortex pressure drop with flowrate, (3) the DVG sub maximizes the crossflow velocities below the jet bit by suppressing the impact vortex formed as a result of the jet impact near the cones.
Geological and Production Characteristics of the Nonmarine Part of the Mesaverde Group, Rulison Field Area, Piceance Basin, CO
Authors: Peterson R. E.
Published: December 2007

Trends of subsurface structure, total sandstone isopachs and thickness variations are used to geologically characterize the depositional subdivisions of the non-marine part of the Mesaverde Group in the Rulison Field area of the southern Piceance Basin. Investigation of a gas production trend indicates that higher productivity may be controlled by structure induced fracturing and is independent of thicker sandstone accumulations. In addition, over-pressured gas reservoirs in a non-marine part of the Mesaverde Group have not been fully evaluated and may be an important exploration target.
Energy Transmission in Percussive Drilling
Authors: Fairhurst C.
Published: December 2007

A simple analysis of the mechanics of stress and energy transmission in percussive drilling is presented. Four basic components of the system are recognized:the hammer,the drill rod,the bit, andthe rock and the effect of each in determining the ultimate energy transmitted into the rock is considered.

Experiments to check the validity of simple theory are described, indicating reasonable agreement with the predicted square wave form generated by the hammer. Further work is required to fully check the theory of transmission through a conical bit. Experimental determination of the force-displacement characteristic of the rock for a given bit configuration is required before a more complete analysis is possible.

Introduction

Percussive drilling is a process of rock drilling in which repeated blows are applied to the rock surface through a pointed tool. Basically, it is probably the oldest known method. It is still, however, the most successful way of drilling hard rock and has recently been improved by the development of the percussive-rotary technique, in which positive rotation of the tool, together with a high static thrust on it, have been superimposed on the basic percussive action.

This paper describes work in progress at the U. of Minnesota to study the factors influencing stress and energy transmission in percussive drilling as a first step towards obtaining an understanding of percussive-rotary drilling.

Theory

It will be assumed that all of the energy used in rock breakdown in the percussive drilling system is transmitted from the hammer to the rock in the form of longitudinal vibrations of the drill rod. Due to the mathematical difficulty of satisfying boundary conditions, no exact solution to the problem of longitudinal vibrations in a finite elastic bar has been obtained. By making simplifying assumptions of varying degree several approximate solutions have been obtained.
Sand Fracturing vs. Fracture Acidizing
Authors: Bailey D. E. , Wickham J. F.
Published: December 2007

Two producing oil wells were used against a fracture model to determine actual fracture parameters. Results of these comparisons was used to examine possible acid jobs of cost equivalent stimulation. The results of these comparisons are discussed. The fracture model was also used to look at different sized treatments to get seme idea on optimum size job that should be run. The economics of net present worth, benefit cost ratio, continuous internal rate of return and internal rate of return are examined.
An Accurate Method for Extending the Analysis of C7+
Authors: Ahmed T. H. , Cady G. V. , Story A. L. , Verma Vidya , Banerjee Salil
Published: December 2007

The main objective of this paper is to present an accurate method for extending the molar distribution of the heptanes-plus fraction. The method originated from studying the extended analysis of ten natural gas-condensate mextures. A FORTRAN subroutine to perform this computation is presented, along with a graphical form of the proposed method.
Pressure Drawdown and Buildup Analysis Techniques for Reservoir Monitoring Tests
Authors: Murphy R. J.
Published: December 2007

Methods for analysing drawdown and buildup data during reservoir monitoring test sequences are described and illustrated. Reservoir monitoring well tests are characterised by a short shut-in period to run pressure gauges followed by a drawdown-buildup sequence.

A new approach to analysing drawdown test data following a short shut-in period during reservoir monitoring efforts is presented. The method employs a variation of the classical Horner1 plot technique and is applicable to radial flow and pseudo radial flow systems. The flowing bottomhole pressure immediately prior to running the gauges in the hole can be determined from the plot and thus aid in the analysis of the first shut-in period data.

The effect of the ratio of the first shut-in period to the test drawdown period on the final shut-in Horner plot slope is presented. The correct method of plotting the final buildup data along with the error involved by using conventional plotting techniques is discussed.
Analytical Solutions for Pressure Buildup and Falloff Analysis of Water Injection Tests of Partially Penetrating Wells: Nonunit Mobility Ratios
Authors: Thambynayagam R. K. M.
Published: December 2007

Approximate analytic solutions are presented for pressure build-up and fall-off analysis of water injection tests of partially penetrating wells. The three basic cases of interests, infinite, bounded and constant pressure outer boundary reservoirs are considered. The validity of the analytic solutions are demonstrated by comparison with the results of a conventional black oil finite difference program. The method allows reservoir characteristics to be determined from short-term water injection tests.
Evaluation of Clay Control Additives for Matrix Acidizing Operations
Authors: Hsi C. D.
Published: December 2007

Clay control additives are often used in matrix acidizing operations to minimize formation permeability damages and to prolong stimulation results. However, some of these additives were developed originally for application in fracturing fluids, and their performance and stability in strong acidic solutions have not been thoroughly tested.

In the study, the clay stabilization performances of one inorganic and three organic polymer type clay control additives were evaluated using core flow tests. The relative effectiveness of an individual additive was judged by its ability to prevent permeability damages due to either chemical incompatibility (fresh-water sensitivity) or mechanical dislodging (particle migration) at higher fluid velocities. The influence of temperature, acid concentration and carrier fluid composition on their performance was also studied.

Results indicate that some additives are not effective in preventing fresh-water sensitivity when applied di rectly in acids. Test results were also compared with cores treated with HCl-HF acid under similar conditions. In general, HCl-HF acid treatments are more effective than clay control additive type treatments in preventing permeability damages due to mechanical dislodging (particle migration) at high fluid velocities. The advantages and disadvantages of each method in preventing formation damages during matrix stimulation are also discussed.
Three Strategic Improvements in Petroleum Investment Analysis
Authors: Cotton F. E.
Published: December 2007

High rates of inflation, interest, and discounting have increased the degree and importance of error in evaluating investments and in making investment decisions. This is particularly strategic to investment-intensive industries such as petroleum and to high-growth industries such as high technology.

The petroleum industry can offest this error by modifying its use of payout, by using inflation-adjusted profitability measures, and by incorporating new options and several refinements that are especially vital to long-term investments.
Case History: Underbalance Drilling the Midway and Navarro Formations Successfully in Hallettsville, TX
Authors: Louison R. F. , Reese R. T. , Andrews J. P.
Published: December 2007

Underbalanced drilling proves to be a sound and economical procedure with an average of $500 M being saved per well. An average reduction of 19 days to total depth has also been experienced with this method of drilling.

The major advantages of drilling underbalanced are lower cost, reduced drilling days, and reduced trouble time (i.e., differential sticking and hole drag due to thick mud cake across shallow depleted Wilcox sands).
Analysis of Alcoholic and Thiocyanate Type Tracers in Core Studies and Field Samples
Authors: Gregory S. D. , Kocsis D. L.
Published: December 2007

Analytical techniques have been developed and validated for the determination of alcoholic and thiocyanate tracer content. The tracer content was determined in steamflood production effluent and in low interfacial tension (LIFT) injection and production fluids.

A gas chromatographic procedure was used for determining alcohol content and a complexation/colorimetric detection technique was employed for the analysis of thiocyanate tracers. The procedures have been automated to allow for maximum sample throughput and minimum operator interaction. As many as 66 samples can be analyzed automatically per day. The tracer analyses have been employed in the analysis of laboratory core samples and field production samples.
The Effect of Decontrol on the Price of Natural Gas
Authors: Horvath R. S.
Published: December 2007

Under the NGPA, the wellhead prices of certain categories of interstate natural gas are partially decontrolled on January 1, 1985. It is generally acknowledged that unless producer/pipeline contracts are renegotiated, the average price of interstate natural gas may increase upon decontrol. The determination of the average price increase in 1985 depends on the mix of contracts and their provisions, as well as on the mix of gas as categorized by the NGPA. This paper summarizes the analysis of a survey of interstate natural gas pipelines to estimate the 1985 average price increase, focusing on the variations within the pipeline industry.
Trends in Natural Gas Regulation
Authors: Kumar J. , Griggs J. W.
Published: December 2007

In recent years the natural gas market in the United States has been beset with high prices for consumers, declining demand for natural gas and excess quantities of deliverable natural gas. These market distortions are a result of existing regulation and pipeline marketing practices. Legislation to address these problems has been introduced in the U.S. Congress. This paper assesses the current problems and the prospects for change in the regulatory environment.
A Simplified Procedure for Gas Deliverability Calculations Using Dimensionless IPR Curves
Authors: Mishra S. , Caudle B. H.
Published: December 2007

A new method for deliverability calculations of gas wells, which eliminates the need for conventional multipoint tests, is presented. Using the analytical solution for real gas flow under stabilized conditions, and a broad range of rock and fluid properties, an empirical relation for calculating gas well deliverability in an unfractured reservoir is developed. This relationship is similar to Vogel's dimensionless Inflow Performance Relation (IPR) for solution-gas drive reservoirs. Also developed in this study is a second empirical relation, which estimates future deliverability from current flow test data. A simple procedure for gas deliverability calculations, utilising these two relations, is suggested.
A Statistical Structural Model for Unsteady-State Displacement in Porous Media
Authors: Alemán-Gomez M. , Ramamohan T. R. , Slattery J. C.
Published: December 2007

A statistical structural model was used in the context of local volume averaging to examine the effects of interfacial tension, the interfacial viscosities, and wetting upon the capillary pressure and relative permeability functions in an unsteady-state displacement. The statistical structural model is a highly simplified idealization of the local pore structure, in which pores are randomly oriented in space, but no pore interconnections are recognized.

Whether we are concerned with an imbibition or a drainage, it is not important to distinguish between steady-state and unsteady-state relative permeabilities when the local capillary number Nca << 1. Unless the interfacial tension is very small everywhere or the overall pressure gradient very large, it may be satisfactory to use steady-state representations for the relative permeabilities everywhere except in the immediate neighborhood of a displacement front. The local capillary number Nca will always be largest in the immediate neighborhood of the displacement front. Within the immediate neighborhood of a displacement front, simulations, especially of imbibitions, should employ unsteady-state relative permeabilities.