bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilization of Gravity Drainage Holes in Shallow Oil Recovery by Mining: Part I—Design Consideration
Authors: Ghalambor A. , Asadi M. , LeBlanc J. L. , Hayatdavoudi A.
Published: December 2007

Selected parameters in gravity drainage of oil mining have been studied. Like others, this method of oil recovery is affected by fluid and rock properties. Furthermore, the recovery is influenced by other parameters such as length, diameter, number of holes and the inclination angle of the drainage holes. A laboratory model of a gravity drainage system was designed and constructed to simulate a reservoir drainage area. The reservoir parameters were scaled down for the experiments. The model was saturated with a 35 degree API oil. A pressure of 40 psi (276 kPa) was maintained in the reservoir as the depleted reservoir pressure. Drainage holes were drilled from the bottom of the reservoir. The holes were drilled 45 and 90 degrees from horizontal. A total of five (5) drainage holes were monitored at various times and the recovery was monitored in three (3) separate stages. First, the model was allowed to produce conventionally from the top (primary recovery) and production was monitored. In the second stage, the model was produced by maintaining a constant injection pressure (secondary recovery). Finally, the model was produced by gravity drainage at the constant depleted reservoir pressure.

In each stage, the parameters were varied and production monitored. The experimental data from the laboratory model proved that the hole angle of inclination was the most critical factor to the rate of recovery than the other parameters. The diameter of the hole was found to be the least effective parameter in terms of recovery. The make up of the laboratory reservoir matrix materials and its mode of construction will certainly affect the rate and amount of oil recovery from the drainage holes. The overall results of the experiments using this specific laboratory reservoir matrix showed that, for optimum conditions of the most effective parameters 87% of the in-place oil was recovered by the drainage hole technique of oil mining compared to 37% recovery by the conventional (primary and secondary) method. The net increase in total production was 50% due to gravity drainage. The total recovery of oil in place by primary and secondary followed by gravity drainage was 91%, of which 37% accounts for primary and secondary recoveries, and 54% due to gravity drainage.
The Effect of Formation Damage Upon Maximum Sandfree Production Rate in Friable Sandstone Formations
Authors: Yassin A. A. M. , Peden J. M.
Published: December 2007

For the establishment of the highest sand-free production rate through a perforated completion in friable sandstone formation, the stability of the perforation tunnel is of critical importance. The stability of the perforation tunnel depends on the degree of formation damage in the vicinity of the tunnel, and on both the intrasic strength of the formation and the effective stress distribution around the tunnel.

A prediction model has been developed to predict sand stability in friable sandstone formations from stress analyses around a perforation tunnel whilst the formation is producing. Failure or instability of the perforation tunnel was studied in terms of a failure initiation.

The application of the model allows evaluation of the degree of formation damage upon the maximum sand free production rate. Examples of the application of the model are provided. The concept of a "stability ratio" is introduced to predict the degree of instability which can be anticipated under specific production conditions.
The Effects of Corrosion Inhibitors and Mutual Solvents on Matrix Acidizing Treatments
Authors: Davies D. R. , Lievaart L. , Nitters G.
Published: December 2007

The addition of corrosion inhibitors is necessary to protect the tubular goods during acid treatment in wells. Together with the acids, they also enter the formation, where their effects on matrix permeability and acidising results vary with the type of inhibitor.

An experimental study has been carried out to evaluate the impact of these materials on matrix acidising treatment results. Simple bottle and core flushing tests showed that recommended recipes could be incompatible with precipitates being formed. The texture of these precipitates was a function of the particular recipe used. The precipitates may block perforations or filter out at the formation surface and hence have a large impact on acid placement.

Single phase flow tests with compatible solutions showed that filtercake-forming inhibitors have a stronger effect on high-permeability rock, whereas the effects of adsorbing inhibitors are greater in low-permeability rock where they can reduce acid reaction rates. Filtered out or adsorbed inhibitors can be removed from the formation by mutual solvent. However, in the absence of an oil phase, the effects of the corrosion inhibitors tested were so small that they do not appear to justify the use of expensive mutual solvents (assuming acid formulation compatibility).

The experimental programme was extended to evaluate the effects of corrosion inhibitors and mutual solvents in the presence of an oil phase. It was shown that the stimulation of oil and water flow are, unfortunately, frequently not related – an increase in water cut being measured. In addition, adsorbed inhibitor appears to alter the wettability of formation fines, which then help stabilise crude oil/spent acid emulsions. The emulsions formed during acid treatments can severely reduce the effective permeabilities in the treated zones. Core-flooding experiments indicate that mutual solvents, which are frequently used to destabilise these emulsions, are less effective than expected from beaker experiments.

The impact of these observations on field design are evaluated. It has been shown that the use of a mutual solvent – a frequently used co-additive – can compound the permeability impairing effect of the corrosion inhibitor via selective stimulation of water flow. This work needs to be extended to better understand the processes at work, an understanding which will no doubt stimulate the identification if improved products.
Statistical Analysis of Factors that Promote Drilling Fluid Corrosion at Elevated Temperatures
Authors: Okoye C. U. , Agusiegbe C. V. , Hayatdavoudi A.
Published: December 2007

In this study, statistical models which incorporate the techniques of linear, non-linear and multiple regression were employed to determine the relationship among corrosion variables such as temperature, corrosion rate, pH and flow rate. The data used in this statistical analysis were obtained from published experimental tests.

Correlation equations were developed showing the relationship among the corrosion variables such as temperature, pH and flow rate, and the rate of corrosion for static and dynamic filtration of drilling fluids, based on mud loop experimental data. Using field data, other correlation equations were developed relating the corrosion variables for drilling, completion and workover corrosive fluids. Because the relationship among these corrosion variables are non-linear in most cases, the statistical models provided linearization of these parameters by correlation.

The intensive corrosion often encountered in deep gas and geothermal wells, as well as in thermal oil recovery wells, can be minimized if adequate corrosion control measures are taken while formulating and treating: drilling, completion and workover fluids. Low pH of these fluids in the acid range, within the wellbore string, will initiate and promote chemical corrosion. The existence, in sufficient amounts of soluble acidic compound in the wellbore fluids will reduce the pH of those fluids enough to generate corrosion. Acid compound gases such as carbon dioxide and hydrogen sulfide in the presence of water and other corrosive agents cause chemical corrosion and must be dealt with in formulating; drilling, completion and workover fluids.
Calculation of Pressure Losses Across Gravel Packs
Authors: Yildiz T. , Langlinais J. P.
Published: December 2007

An analytical solution has been obtained for laminar flow across a gravel pack by solving the diffusivity equation in three dimensions, using proper boundary conditions. This solution describes the flow into the annular space from a perforation, through the gravel, and arriving at the gravel screen. The solution has the form of an infinite Fourier-Bessel series. Also, an electrical analog experiment was conducted to verify toe mathematical solution. In this experiment, the electrical resistance of a liquid measured between conductors representing perforations and a gravel screen is analogous to the Darcy equation for fluid flow in a porous medium. The mathematical solution compared very favorably with toe experimental results and was then extended to investigate such parameters as perforation density, perforation diameter, perforation phase angle, and gravel anisotropy.
A Theory of Resultant Burst Loads for Designing Production Casing: Principally in Abnormally Pressured Wells
Authors: Vorenkamp A. P. A.
Published: December 2007

This paper offers a theory and method of analyzing external back-pressure gradients opposing internal burst loads in order to design production casing. A "worst case" basis is used to analyze both internal burst loads and external back-pressure gradients. Internal burst loads are generally straightforward and accepted in the industry as occurring when the tubing hanger leaks; but views on external back-pressure gradients seem varied and somewhat arbitrary.

This theory strives for an economical and effective production casing design by analyzing the backpressure profile of, (1) the "degraded mud zone" above the mud-cement interface and, (2) the "openhole zone" between the mud-cement interface and TD.

The first zone is governed by the settling of drilling mud into its major constituent parts; generally a distribution of 65X water and 35X barite/solids. Tenets observed in cementing include "the best fluid to cement in is water" and the "next best fluid is thin mud." Settled drilling mud above the cement is the result.

The second zone is governed by open-hole pore pressures. The back-pressure gradient in this part of the annulus is a mirror Image of the pore pressure profile regardless of the condition of the primary cement job.

These opposing pressure systems are resolved into a resultant burst-load line for analysis. The resultant burst-load line identifies the most critical differential burst load to be opposite the degraded mud zone at the base of the water leg. This burst load is considered the most critical—because of its magnitude and proximity to the surface of the ground.
Drilling With Steerable Motors in Large Diameter Holes
Authors: Pruitt G. L. , Ross K. C. , Woodruff J.
Published: December 2007

Steerable motor drilling systems, initially used for intermediate and production hole sizes, have evolved to a point of efficient application in large diameter surface holes. These systems combine directional and straight hole drilling capabilities to provide precise directional control. With better directional control, dogleg severity is more precisely determined and is therefore often reduced in the critical surface hole section.

A brief summary of steerable systems is given, followed by applications and benefits of using these systems in large diameter holes. Also presented is a section that covers system design considerations when using steerable motors and briefly details a typical bottomhole assembly, surveying methods, and drilling parameters.

Finally, a series of case histories, based on successful applications in the Far East and the North Sea, will be presented to demonstrate the range of flexibility possible with steerable systems in large diameter holes.
A Method for Detecting In-Situ PDC Bit Dull and Lithology Change
Authors: Kuru E. , Wojtanowsicz A. K.
Published: December 2007

A mathematical diagnostic drilling model was derived from the balance of forces acting at the PDC bit cutter. The model combined the torque and the drilling rate equations, cutter's geometry and rock properties. It was verified using the laboratory drilling data from several research reports as well as the field drilling data collected by the authors.

Based on the drilling model, a new method was developed for the in-situ measurements of the PDC bit condition and for the lithology change detection. In this technique, a diagnostic plot is made by correlating two dimensionless groups containing measured values of torque, weight on bit, rotary speed and penetration rate. Several laboratory and field data (presented in the study) confirmed linearity of such a plot. The diagnostic plot is a unique indicator of the bit-rock interaction and it is independent from the bit operational variables. Moreover, the instantaneous wear of a PDC bit can be computed from coordinates of the straight line points. This method is feasible for a graphical use supplemented with a computer program.

The technique was further verified by comparing the predicted and the measured PDC bit wear from the MWD records in the Gulf Coast area. Also provided, were the examples of a correlation between rapid formation changes and discontinuties in the diagnostic plots.

The new method contributes to the PDC bit drilling theory. Its importance lies in the MWD software development for the purpose of the in-situ rock detection and the PDC bit evaluation and control.
Polymer Deflocculants: Chemistry and Application
Authors: Wilcox R. D. , Jarrett M. A.
Published: December 2007

This paper presents capillary suction time (cst), zeta potential, and rheological properties of drilling grade clays and formation solids treated with a copolymer deflocculant (CPD) and lignosulfonate (LS) in fresh water and various concentrations of seawater. Also, the reaction of calcium with CO2 in the presence of CPD was investigated.

To better explain cst values, they were converted to specific resistance to filtration and slurry permeability. From permeability data, average pore diameter was calculated. Assuming parallel stacking of spheres based on porosity consideration, interparticle distance was calculated using a geometrical model. Interparticle distance calculated by this approach compares favorably to theoretical calculations by Van Olphen for sodium montmorillonite as a function of clay concentration.

Data from systems investigated was treated by the DLVO theory of colloid stability. Results with CPD and LS show that critical volume fraction or interparticle distance occurs with both systems between 5% and 7% by volume solids for the shale studied. Lower calculated attractive force was observed for solids treated with CPD. Also, rheological and shear strength tests on field muds show that CPD reduces colloidal interactions between particles. Studies in acid gas environment show that while CPD can solubilize calcium, calcium is available to react with CO2 in an alkaline environment to precipitate calcium carbonate. Results also show rheology is not affected by acid gas.
Errors Inherent in Rig Measurements of Drillpipe and Casing Pressures
Authors: Holden W. R. , Kelly O. A.
Published: December 2007

A common complaint of drilling personnel is that modern well control strategies require pressure measurement accuracies not possible with typical rig equipment. This paper documents a study made (1) to identify and quantify sources of significant error inherent in remote measurements of drill pipe and casing pressures, (2) to determine their cumulative effects on measurement accuracy and (3) to define the pressure response limits of a typical rig system. For this study, the pressure measurement system was duplicated in the laboratory using rig components supplied by several vendors.

Response characteristics of each system component were studied separately and are presented in four graphic displays and one table. A numerical example details their use in the analysis of a complete system. Comparison of predicted and observed pressure responses for several system configurations confirmed the results and method of analysis developed in this study.

Gage-reading correction factors can now be calculated with certainty. Of greater significance, is the ability to predict the upper limit of reliable response for a given pressure measurement system. A detailed analysis can show how it is possible that a system equipped with a 10,000 psi gage can indicate pressure extremes no greater than, say, 5000 psig.
Development and Field Testing of a High-Accuracy Full-Bore Return Flow Meter
Authors: Johnsen H. K. , Skalle P. , Podio A. L. , Sirevaag G. , Vigen A.
Published: December 2007

Measurement of return mud flow is the single most diagnostic indicator of potential well control and lost circulation problems during drilling operations. To date, except for electromagnetic induction flowmeters, which can only be applied for conductive drilling fluids, it has not been possible to have access to accurate measurements of return mud flow rate over a wide range of drilling fluid properties and adverse conditions such as drilling through gumbo shale, gas cut mud and other non ideal conditions.

This paper describes the design, development and field testing of a full bore mass flowmeter based on the measurement of forces generated due to change in momentum of the return flow stream. This is accomplished by attaching a short J-shaped extension to the return flow line just before the shale shaker. This extension is instrumented with force sensors that measure forces caused by the flowing fluid.

The first generation prototype has been extensively tested in the laboratory and in the field over a range of flow rates up to 1700 GPM and over wide ranges of mud weights.

Results indicate that the flowmeter has performed successfully under adverse field conditions for extended periods of time without the need of extensive modification of the existing mud flow system.
Centralized Operations Control: A Driller's Cabin for the 1990's
Authors: Price M. J. , Loevaas E. L. , Netland K.
Published: December 2007

Since 1981, work has been carried out at the Rogaland Research Institute in Stavanger, Norway, to develop an integrated system allowing centralized monitoring and control of the whole drilling operation. By combining the most advanced handling and process equipment with a central computer-contro1 system and wider technical competence among the operatives, the project places control of all drillstring, mud and cementing operations in the same room. The benefits to be gained are rationalization of man-power usage, more effective control of the drilling process as a whole, and a considerable improvement in safety and the working environment. Following the building of Rogaland Research Institute's unique drilling-control simulator and its use in a series of personnel experiments, the Institute's work has encompassed drilling automation and the evaluation of mechanical, fluid and computer-control systems and their suitability for integration. Results of these studies are now incorporated in a detailed specification for an integrated control-room for the next generation of dri11ing-rigs. Combined with a specified restructuring of the traditional dri11ing-crew, this aims at achieving as high a degree of control automation in the drilling industry as is already in use in production and processing.
Hazardous Area Classifications and Definitions
Authors: Hinds J. J.
Published: December 2007

This paper lists and defines hazardous area considerations typically encountered around drilling rigs. Both North American and European definitions are listed and compared. Memory aids are presented, to help the reader remember the definitions and areas of applicability of such terms as "Division", "Zone", and "T4". Finally, two views of one offshore rig are presented, illustrating how hazardous area definitions differ between North American and European conventions.
New Fiberglass Liner Completion Technique Salvages Old Injection Wells for Use as WAG Injection Wells
Authors: Millard Robert L.
Published: December 2007

Fiberglass liners with polished bore seal assemblies are being successfully used to salvage old injection wells at less than half the cost of drilling the wells again. Components of conventional waterflood fiberglass liner completion equipment used in the past to improve well conditions and injection profile control were modified or changed.
Annulus Packoff System Provides Economy in Recompletion of Permian Basin Wells
Authors: Giroux R. L. , Brandell J. T. , Scott T. A.
Published: December 2007

Permian Basin operators are using a cup-type tool system to economically recomplete old wells that have deteriorated casing. The system employs high pressure cups, similar to those used on retrievable bridge plugs, to pack off the annulus below the damaged portion of the old casing. New casing installed inside the old casing is limited by the collar OD the old casing will permit.

This tool system was developed in response to the recent oil price downturn, which prompted many operators to plug and abandon water injection wells rather than repair casing leaks with squeeze cementing processes. The technique of recompletion with smaller diameter casing inside the old casing evolved, requiring installation of a barrier at the bottom of the new casing to prevent cementing off the injection formation. Barriers of many forms were developed. Cast iron bridge plug set below new casing, inside old casing. Expensive and difficult to drill out through new casing.Mechanically set packer system to pack off annulus. Economical but capable of holding only about 1000 psi differential pressure.Inflatable packer system. More costly than mechanical, but rated for high differential pressure.

Both 2 and 3 above require use of small ID inner casing due to the packer configuration.

Cup-type packoff systems offer the following advantages. Size is limited only by casing collar OD.Well can be put back on production without drilling out.A slotted liner can be run below packoff tool.Tool can be passed through damaged casing without affecting its capability.

Subject paper presents (1) discussion of barrier systems in use in the Permian Basin, (2) design variations of the new system, (3) job design considerations, and (4) case histories of Permian Basin wells in which the system was used to recomplete wells having damaged casing.
The Well-Site Real-Time Formation Pressure Transient Analysis System
Authors: Smart C. R. , Fertl Walter H.
Published: December 2007

Formation pressure transient analysis techniques are generally applied some time period after data acquisition. However, post test transient analysis, such as pressure buildup, is counter-productive in non-flowing wells. The well may be shut-in for either too long or too short a period to meet the objectives of such a test. Under these circumstances, production could be sacrificed needlessly.

Such constraints can be virtually eliminated with the use of a well-site analysis system described here. The system uses commercial microprocessors to readily record and process all the available logging information. With this downhole information accessible during well test data acquisition, it is no longer necessary to limit the scope of real-time pressure transient analysis to only time and pressure parameters.

The Real-Time Pressure Transient Analysis (REALITY) system utilizes principally analytical techniques, such as Ramey and Agarwal type curves; linear, spherical, and radial flow models; and a p2 gas model. Fast, user-friendly, and flexible plotting routines allow for quick analysis of massive amounts of data. The use of interactive full-color CRT graphics for both parameter input and plot output increases the accuracy of the analysis and the quality of the data presentation.

The basic philosophy and conceptual considerations for the complete hardware and software system are reviewed. Processing flow charts and pertinent mathematical algorithms are presented as well as a field case example.
Gels for CO2 Profile Modification
Authors: Martin F. D. , Kovarik F. S. , Chang P-W. , Goldman I. M. , Philips J. C.
Published: December 2007

A recent study (SPE paper 16728) described a preliminary investigation of the effects of some commercial gelants on reduction in CO2 permeability. That paper presented a method for examining gelant systems by vial tests, core tests, and two-dimensional, flow visualization studies in high-pressure, glass micromodels. For the preliminary study, tests were conducted with CO2, San Andres crude oil, and brine at 1500 psi and 105°F to simulate west Texas/southeast New Mexico conditions. The micromodel studies were coupled with the core tests to assess the pore-level mechanisms responsible for permeability reduction. Each of these commercial gelant systems demonstrated some deficiency in the desired performance in the brine/CO2 systems under investigation.

This paper presents follow-up lab-scale studies with newer gelant systems that are shown to be more stable under the same brine/CO2 conditions. Gelation kinetics are discussed, and results of core tests with a phenolic gel and a vinyl gel are described. These gels are more rigid than the gels first investigated, and the micromodel studies indicate that they are much more effective in remaining stationary in channels or high-permeability flow paths.
Detailed Simulations of the Effects of Process Parameters on Adverse Mobility Ratio Displacements
Authors: Crump J. G.
Published: December 2007

This paper describes research in modeling unstable displacement processes (especially related to the application of CO2 flooding) with the ultimate goal of predicting recoveries in unstable field scale displacements. The research has focused on understanding and quantifying the effects of process parameters, such as reservoir heterogeneity, phase behavior, fluid properties, and solvent/water injection ratio, on the stability of displacements. Numerical simulation using very fine grids was used to obtain these results. These fine grid simulations were compared to simulations using the more standard models based on the mixing parameter concept of Todd and Longstaff and the theory of Koval.

This work produced the following observations: In secondary miscible displacements in heterogeneous reservoirs, the value of the mixing parameter can be strongly dependent on mobility ratio.In displacements which are not first contact miscible, the shockfront mobility ratio is generally less than the fluid viscosity ratio. This effect tends to stabilize the displacement front. The mixing parameter model can, in some cases, be used to model such processes, and the value of the mixing parameter can be estimated from knowledge of the mobility ratio across the displacement front.In general, for displacements which are not first contact miscible, the mixing parameter model is inadequate due to its inability to account for thermodynamic nonequilibrium between zones of oil contacted and uncontacted by solvent.In tertiary displacements the frontal mobility ratios, as computed from a one-dimensional solution, are in general not sufficient to compute the stability of the displacement.
Enhanced Oil Recovery by Inert Gas Injection
Authors: Kantzas A. , Chatzis I. , Dullien F. A. L
Published: December 2007

Downward displacement of oil by inert gas injected at the top of the formation using horizontal wells, has the potential of becoming an efficient method of oil recovery for reservoirs either at initial oil conditions or for reservoirs depleted by waterflooding. Advances in horizontal well drilling technology can make this method of oil recovery feasible for a wide variety of oil reservoirs. This | paper presents experimental results of nitrogen or air injection into strongly water-wet unconsolidated and consolidated samples. Production characteristics are discussed, displacement mechanisms are formulated and the applicability of this method on the field scale is examined.
Evaluation of Steam-Surfactant-Fuel Gas Co-Current Injection Into Two Patterns of a Mature Steamflood
Authors: Yannimaras D. V. , Kobbe R. K.
Published: December 2007

This is a comprehensive evaluation of the background, operations and results of applying the emerging steam-foam technology to two patterns of a mature steamflood suffering excessive steam breakthrough.

Care was taken: (a) to establish a valid baseline for injection and production before the treatments, (b) to hold injection in the surrounding patterns at or below pretreatment levels, in order to isolate the causes of any oil rate increase, and (c) to monitor in detail the two pilots over an extended period of time.

Aspects of the project discussed include its design and implementation, the inferred reservoir mechanisms, the associated production operations and field performance, as well as the economics of the project.
Fosterton Northwest: An In-Situ Combustion Case History
Authors: Mikkelsen P. L. , Cook W. C. , Ostapovich G.
Published: December 2007

Fosterton Northwest Unit has undergone 18 years of in-situ air combustion under both dry and wet combustion modes. Oil recovery by tertiary wet combustion has been more successful than dry combustion, and a portion of the Unit's oil production is considered to be incremental. Evaluation of the combustion process is currently being hampered by operational problems such as pumping and corrosion.
Evaluation of Low-Concentration Surfactant Flooding in the Absence of Mobility Control Agents
Authors: Raterman K. T. , Kremesec V. J. , Suffridge F. E.
Published: December 2007

In some micellar/polymer flooding pilots, severe problems associated with polymer stability and/or polymer injectivity have been experienced. These problems have contributed to less than optimal pilot performances. As a result, process strategies which do not employ polymer have been actively considered.

The strategy evaluated in this paper consists of a low concentration (<2 wt% active) micellar fluid which is injected as a large bank (>20% PV) and which forms a lower phase microemulsion under prevailing reservoir conditions. This micellar bank is in turn displaced by a water drive with no provisions for mobility control. Such a process was deemed to be simplified in application and to be potentially of low economic risk in that a large bank, lower phase displacement was assumed to be less susceptible to the deleterious effects of reservoir heterogeneity in the absence of mobility control agents.

Performance predictions were based first upon the successful simulation of laboratory field core tests for which fluid physical properties, phase behavior, chemical retention, and oil recovery were well-quantified for a commercially available surfactant system. Simulation matches were obtained with a nonproprietary chemical flooding simulator. Once suitably calibrated, the simulator was then applied in a predictive mode to a field scale displacement in a typical 21-acre, four-layered five spot in the target reservoir.

The sensitivity of the process to slug size, chemical concentration, capillary desaturation characteristics, injection rate, microemulsion viscosity, and other design strategies was determined.

The results suggest that the current laboratory system is unacceptable for field testing because the system fails to produce sufficiently low interfacial tensions to significantly desaturate waterflood residual oil in the lower phase environment. The study does, however, point out useful goals, guidelines, and evaluation strategies by which the economic potential of future process designs can be assessed.
Caustic Consumption by Kaolinite and Quartz and Their Mixtures at Temperatures up to 120°C
Authors: Johnson J. R. , Dehghani K. , Hawkins D. B.
Published: December 2007

Hot caustic waterflooding has been shown to improve oil recovery by a number of different mechanisms. To design properly a hot caustic waterflood the consumption of caustic by reservoir minerals at high temperatures must be considered. This study presents the results of a series of batch experiments in which the interaction of quartz, kaolinite and caustic was examined at temperatures expected during hot alkaline waterfloods.

The reaction of quartz, kaolinite, and a mixture of the two minerals with 0.1 N NaOH at 120°C was examined. Also, the dissolution of kaolinite at 70°C and 100°C was studied.

The results show that at 120°C a mixture of 80% quartz/20% kaolinite by weight appears to consume as much or more caustic than either of those minerals alone. The major difference between pure quartz dissolution and that of the mixture was the mechanism of caustic consumption. In quartz dissolution, the hydroxide ion was consumed by silica speciation reactions. When pure kaolinite or a mixture of quartz and kaolinite was reacted, the bulk of the caustic was irreversibly consumed through the formation of new aluminosilicate minerals. The new mineral was identified as the synthetic zeolite Na-Pc, a structural relative of the zeolite phillipsite.

In the case of kaolinite dissolution, increasing temperature from 100°C to 120°C caused a five-fold increase in the rate of caustic consumption. The initial rates of Si and Al dissolution from kaolinite was found assuming first-order kinetics. An Arrhenius plot of the data gave psuedo-activation energies of 8.5 and 1.1 Kcal/mole for the dissolution of Si and Al from kaolinite.
Simulation of Thermally Induced Waterflood Fracturing in Prudhoe Bay
Authors: Garon A. M. , Lin C. Y. , Dunayevsky V. A.
Published: December 2007

Waterflooding operations in the Prudhoe Bay field result in temperature reductions of up to 130 °F within the flooded region. As a result, the fracture gradient is significantly reduced, and the injection pressures may have to be reduced to avoid formation parting. The phenomena of fracturing resulting from thermally induced stress reduction was investigated to provide guidance for decisions on waterflood operating strategy.

Thermal reservoir simulation was performed to determine the in-si tu temperature and pressure distributions following various periods of water injection. A finite-element stress-analysis model was developed to calculate the changes in in-si tu stress field. A three-dimensional fracture simulator was used to predict fracture growth and shape based on the calculated stress distribution. A thermal reservoir simulator was modified to include a simplified fracture mechanism and calibrated against step-rate test data. Fracture areas were then predicted with the modified reservoir simulator and correlated with the fracture shapes obtained with the fracture model.

The fracture predictions confirmed field data which indicated that fractures created during well testing were short and confined to within the perforation interval. In addition, fractures created with clean water injection at pressures above the reduced fracture gradient were predicted to reach equilibrium lengths of less than about 200 ft.
Waterflood Potential of Diatomite: New Laboratory Methods
Authors: Wendel D. J. , Kunkel L. A. , Swanson G. S.
Published: December 2007

Diatomite reservoirs in the San Joaquin Valley contain vast reserves in high porosity, thick pay zones. Waterflooding could substantially increase recovery if implemented successfully. Unfortunately, the presence of fractures in a low permeability matrix makes waterflooding difficult to evaluate by conventional methods. Presented here are unique laboratory methods and results of laboratory tests designed to provide operators with data to better evaluate the secondary recovery potential of diatomite.

Subsidence-oriented compressibility tests revealed extreme sensitivity to standard core cleaning and drying procedures. All subsequent tests, including brine sensitivity, relative permeability, and spontaneous imbibition were performed following miscible solvent cleaning with no drying step. Spontaneous water imbibition was investigated in detail, showing promise for oil movement from the tight matrix into adjacent fractures during a waterflood.
Kern River Field Test of a Steam Quality Measurement Technique
Authors: Redus C. L. , Schoen D. M. , Chien S. F. , Hall D.
Published: December 2007

In large steamflood operations, there is a need to measure accurately the steam quality and mass flow rate at the injection wellhead. At Texaco's steamflood operation at the Kern River Field in Bakersfield, California, a novel technique which incorporates an orifice plate in series with a critical flow choke has been developed and tested in the field.

Results from field testing proved the technique to be a potentially viable, low-cost and reasonably accurate method with an accuracy of +/- 5 quality points for steam quality and +/- 32 BSPD-CWE [5.09 m3/day - CWE] for flow rate. The method was tested at steam qualities ranging from 15 to 88% and at mass flow rates ranging from 200 to 800 BSPD-CWE [32 to 121 m3/day - CWE]. Upstream pressures ranged from 300 to 700 psia [2068 to 4826 kPa].
Effect of Wellbore Steam Quality Variation on Steamflooding Thick Formations
Authors: Kasraie M. , Farouq Ali S. M.
Published: December 2007

In designing steamfloods for thick formations, usually steam quality is assumed to be uniform over the formation face, even if multiple offtake points are present. This can lead to errors in steamflood oil recovery predictions. This paper addresses this question, and examines, first, the effect of multiple offtakes on steam quality and pressure, and second, the effect of variable vs. uniform steam pressure and quality on steamflood recovery predictions.

A wellbore model was developed, which accounts for steam pressure, quality, and flow regime variation, and the added feature of multiple offtake of the steam stream. The model was used to examine a variety of steam injection situations, with steam offtake at a halfway point. Effects of steam splitting on steam quality and pressure was examined for various wellhead pressures and injection rates. The wellbore simulator thus developed was then coupled with a three-dimensional steamflood simulator, to study steam injection performance in formations of various thicknesses, when steam is divided into two streams.

The results show that if the wellbore steam quality variation is not allowed significant errors in the predicted steamflood recovery can result. A number of examples are presented, showing discrepancies as large as 50%.
The Potential of Natural Gas in the Alaskan Arctic
Authors: Sharma G. D. , Kamath V. A. , Godbole S. P. , Patil S. L.
Published: December 2007

The natural gas in the Alaskan arctic represents a truly significant resource; a resource which should be exploited in the most appropriate manner. Currently, the proven reserves of natural gas in Alaska are estimated to be 19.7% (36.7 TSCF) of the total U.S. reserves (186.7 TSCF). In addition, the undiscovered recoverable natural gas resources of Alaska are about 89 TSCF compared to 610 TSCF in the lower 48 states. Furthermore, the Alaskan unconventional gas resources are more than 500 TCF.

The purpose of this paper is to review the potential of natural gas resources in Alaska and to address various important issues related to utilization of natural gas. The paper provides a brief summary of various gas fields and their geologic settings. The different options for utilization of natural gas in the Alaskan arctic such as; transportation of gas to lower 48 states via gas pipeline, conversion to liquified natural gas and transport, conversion to fuel grade methanol and/or gasoline, natural gas for enhanced oil recovery, gas based petrochemical complex, gas utilization in the form of utilities are critically reviewed with respect to merits and demerits addressing engineering, economic, environmental, supply/demand, market and political aspects.

The use of North Slope gas for the enhanced oil recovery on the North Slope fields is considered as the most attractive option. Furthermore, it may be worthwhile to convert part of the natural gas into methanol and transport it through the existing TAPS pipeline; The unavailability of market place does also present opportunities for gas utilization in novel processes.
Optimum Plan of Depletion
Authors: Eden A. L. , Fox M. J.
Published: December 2007

Through the use of reservoir simulation, consideration of operational conditions and constraints, and application of economic analysis, an Optimum Plan of Depletion for a geologically complex reservoir located in a high operating cost environment has been formulated. This paper describes the approach used to formulate the depletion plan. Additionally, the reservoir model lends itself to extensive future use in evaluating operational changes and providing the necessary data to determine the economic viability of any potential changes. The model is and will continue to be a valuable reservoir management tool.
Applicability of Expert Systems To Diagnose Formation Damage Problems: A Progress Report
Authors: Alegre L. , Dougherty E. L.
Published: December 2007

Because of the diversity of problems which can and do arise, diagnosis of formation damage is a complex task requiring considerable practical experience and technical knowhow. To qualify as an expert in this field an individual must read, understand and remember findings reported in a myriad of technical publications and be able to apply this knowledge in a logical and systematic way. Recently programs, called Expert or Artificial Intelligence (AI) Systems, have been developed which perform the activities of a qualified expert in a specialized area. To use these programs the "knowledge base" must first be codified and introduced into the computer's memory, after which the Expert System can (approximately) simulate the expert's analyses. This paper presents a progress report on an Expert System developed to analyze formation damage problems. The goal of the development is to demonstrate the practicality of making available to an average engineer an automated formation damage consultant. We conclude that diagnosis of formation damage is a fruitful application of AI.
A Model for Development, Sensitivity Analysis, and Optimization of Gas Reservoirs with and without Aquifer: Part II-The Sensitivity Analysis
Authors: Alcocer C. F. , Ghalambor A. , Hayatdavoudi A. , Tussaneyakul S.
Published: December 2007

A computational model for development and optimization of the gas reservoirs with or without water inflow was presented in Part I of this series of two papers. In this Part II, a sensitivity analysis will be presented. The most important variables involved in the development of a Gas Reservoir with or without aquifer will be studied. Furthermore, the effect due to neglecting the rock and water compressibility terms for volumetric, steady state, and steady state system on the development of a gas reservoir will be studied. The model used for the sensitivity analysis was written in Fortran 77 and run by using the Multics System. The main purpose of the model is to determine the number of wells to be produced, and reservoir pressure at each period of time that depends upon the production schedule. The conclusions from the sensitivity analysis performed are as follows: Permeability and water viscosity do not have a great effect on finite aquifer but create high affect on infinite aquifer, especially low permeability and high water viscosity; rock and water compressibility affect finite aquifer more than infinite aquifer; each value of porosity will limit the minimum value of reservoir pressure for an infinite aquifer; and the rock and water compressibility term in material balance equation must be considered in the case of problems involving economic decisions.
Tracing Fluid Movements with a New Temperature Technique
Authors: Johns Earl
Published: December 2007

This paper was prepared for the SPE Symposium on Mechanical Engineering Aspects of Drilling and Production to be held in Fort Worth, Tex., March 5–7, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

A new, "a priori" differential temperature survey has been developed which overcomes the flaws that made earlier systems of little use. Although every portion of the system employs new techniques, the key to its new and surprising capabilities is the memorizing and comparing of two absolute measurements made by the same sensor, on the same run into a well.

This new tool has successfully performed tasks not previously assigned to temperature equipment, including; behind-pipe oil-finding and oil-water contact location injection profiles fracture treatment evaluation, lost circulation location and production profiles.

A priori profiles have not only shown the relationship between fluid input and shut-in temperature slope, but have led us to theorize that in profile situations, a true temperature distribution probably exists in the macro-annulus, but that it must be moved into the near annulus, or the borehole, in order to be measured.

Further study has caused us to doubt the common idea that all of an intake zone takes fluid of similar temperature, and to theorize that each increment of intake zone takes fluid of a different temperature. To provide this temperature spectrum fluid column thermodynamics are envisioned that create a radial temperature gradient whereby the topmost intake increment takes its fluid from the warmest outer annulus of the column, while the coolest, central fluid continues to the deepest intake increment. Laboratory experiments indicate that such a distribution is entirely possible.

Introduction

A few years ago the first attempts were made to employ a differential temperature tool; that is a tool that seeks to measure the difference in temperature between two proximate points in the bore hole.
Optimum Field Development With Seismic Reflection Data
Authors: de Buyl M. H.
Published: December 2007

Predicting reservoir parameters such as lithology, porosity, permeability, and fluid saturation is essential for estimating" reserves, selecting placement of development wells, and forecasting production. To this end, new methods are presented that integrate three-dimensional (3-D) seismic data with well-log, core, and geological information and significantly improve the spatial characterization of reservoirs. Seismic data are used not only to derived detailed 3-D depth images of the reservoir geometry and faulting, but also to infer spatial and temporal variations of rock parameters relevant to production.

To illustrate the contribution of seismic data to reservoir description, we discuss a case study in the Taber area, Alberta, Canada. The reliability of an integrated reservoir description based on estimates of petrophysical properties (such as porosity and net pore volume) deterministically derived from seismic data is assessed. We compare, at two well locations, the accuracy of different projections of these parameters obtained through an integrated approach incorporating seismic information, and by a conventional approach relying solely on well log and core data. In addition, we further evaluate the validity of the seismically enhanced model by comparing results of history matching obtained from each model. This comparison highlights the importance of including seismic data at earlier stages of a field development program.

An alternate approach to extract petrophysical properties from seismic data capitalize on the existence of patterns of correlation in the data. Geostatistical techniques analyze patterns of variations using spatial correlation functions to produce detailed reservoir models consistent with both seismic and well data. Errorqualified estimates of reservoir properties are derived in keeping with uncertainties in the various measurements. These techniques are presented and also applied to the Taber data set.