bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and Evaluation of Slimhole Technology as a Method of Reducing Drilling Costs for Horizontal Wells
Authors: Hall C. R. , Ramos A. B.
Published: December 2007

Slim hole wellbores offer significant potential to reduce drilling costs in horizontal wells. This cost savings is especially important with the reduced capital budgets under current economic conditions in the oil industry. The savings can be achieved by the use of smaller drilling rigs and/or workover rigs, reduced casing sizes, minimized drilling wastes and other costs associated with hole size. However, the cost savings achieved from slim hole drilling can be offset by increased mechanical failures, reduced lateral hole length and lack of directional control.

The paper reviews the advantages provided by slim hole (4-3/4″ - 3-7/8″ I.D.) wellbores as compared to the known capabilities of using reduced hole (6 1/2″ - 6″ I.D.) and larger hole (8 1/2″ I.D.) technology. It uses information gained from horizontal drilling operations in the Austin Chalk Formation in the Pearsall Field in South Texas. Various improvements in directional drilling equipment are discussed as to their impact on reduced hole/slim hole drilling.

The paper also discusses the decision process which must be used to determine if a slim hole well is applicable. It concludes that slim hole drilling offers great opportunity for cost reduction in drilling operations, but requires interactive involvement from all areas associated with the well to prevent the limitations of a smaller wellbore from exceeding its benefits.
Directional and Stability Characteristics of Anti-Whirl Bits with Non-Axisymmetric Loading
Authors: Pastusek P. E. , Cooley C. H. , Sinor L. A. , Anderson Mark
Published: December 2007

One concept to avoid downhole vibrations with PDC bits requires a net side force that rotates with the bit and pushes a low friction gage pad against the borehole (anti-whirl bit). When drilling with an angle build assembly or in an angled hole, a non-rotating side load is applied to the bit. When drilling with a steerable assembly in the rotate mode, the bit axis is tilted relative to the profile of the bottom of the hole. This axis tilt affects the bit cutting forces and may consequently affect bit stability. This paper investigates these non-axisymetric loads for their effects on the stability characteristics of anti-whirl designs as they compare with standard PDC bits.

A second hypothesis holds that standard PDC bits occasionally whirl on directional bottomhole assemblies, which leads to overgage holes and ledging. The build rates, hole diameter, and ledging characteristics of anti-whirl bits are compared to standard PDC bits.

Comparisons were established in lab tests using standard and anti-whirl PDC bits both in an anisotropic formation (Green River shale) and in an isotropic formation (Carthage limestone) with a non-axisymetric loading.

Further, a comparison is made between two directional wells drilled at a field research facility using the same surface hole. One well was drilled with a standard PDC bit; the other with an anti-whirl PDC bit. The two wells are compared for surface vibration level, rate of penetration, build rate, dull condition of the bits, and hole diameter and ledging from calipers of the wellbore.
Optimal Applications Engineering and Borehole Stability Analysis Avoids Differential Sticking and Leads to Successful Openhole Completion of North Sea Horizontal Well
Authors: Gibson M. T. , Tayler P. J. , Fun Giin-Fa
Published: December 2007

Drilling in the ‘V’ Fields of the UK sector of the southern North Sea (particularly the long-reach horizontal type of well) has historically meant differential sticking problems as the reservoirs become depleted through continual gas production. Quite often, reservoir pressures are in the region 5.5-6.5 ppg EMW, with some reservoir compartments falling to as low as 4.2 ppg EMW, which poses considerable problems to the drilling process particularly with respect to differential sticking and the possible risk of hole collapse.

This paper describes the engineering which resulted in the success of the most recently drilled ‘V’ Fields horizontal well through the depleted Rotliegcndes sandstone reservoir with respect to borehole stability analysis, drilling and the operator’s first openhole completion in the UK sector of the North Sea.
Proactive Safety Approaches in the Seismic Industry
Authors: Dujmovich T. J.
Published: December 2007

In the last two years significant improvements have been made addressing seismic safety-concerns. The IAGC (International Association of Geophysical Contractors), in conjunction with the E&P Forum (U.K.) have undertaken initiatives to improve contractor safety performance. Efforts include the issuance of contract guidelines by the E&P Forum, with endorsement from the IAGC, compilation of international land and marine manuals by the IAGC with substantial input from the E&P Forum, a quarterly incident information exchange and standardization of training guidelines. These training guidelines include detailed syllabi which specify training required for country managers, and party managers as well as safety staff and crew members. The intent is for all employees working in the seismic industry to have a "passport" which details the training they have received. The ultimate goal is to raise the quality of employees in the seismic industry and, hopefully, to guarantee some degree of consistency. Proactive approaches, such as these, should be the driving force to improve safety, regardless of the industry. Too often, unfortunately, industry is reactive to the number of injuries/incidents rather than the programs (or lack of) that are causing the "numbers" to be unsatisfactory.

Future items that these industry groups plan to address include bird dog quality and health issues in remote conditions. It is refreshing to see that both groups have recognized the need for improving safety within the seismic industry, and have, without government mandate, initiated proactive programs to proceed to excellent safety performance.
SARA Sections 311-312 Compliance: Is It Worth the Cost?
Authors: Holliday G. H.
Published: December 2007

SARA Title III Sections 311 & 312 require notification and inventorying of Hazardous Chemicals at or above the 10,000 pound threshold (except in Louisiana, where the 312 threshold is 500 pounds). The original concept of Sections 311 and 312 limited applicability to Standard Industrial Classification (SIC) Codes 20–39. The courts extended the applicability to all SIC Codes. This includes the Petroleum Extraction Industry (SIC 13). SARA requires Hazardous Chemicals, such as cement, sand, xylenes and acids, even though they remain onsite at drilling and producing locations in closed trucks for 1–4 hours. The SARA program provides no funding for local agencies and local fire departments. Thus, these organizations have little incentive to process the information.

Near oil and gas fields, fire departments are typically manned by volunteers. Also, many of the Local Emergency Planning Committee (LEPC) chairpersons are without staff or assistance.

This paper discusses the results of surveys of fire departments and LEPC in rural petroleum producing areas regarding: What they do with the SARA 311 and 312 information,Depth of requests for information, andAvailability of SARA 311 and 312 data during emergencies.

Finally, the paper assesses economic impact of the SARA 311 and 312 programs on Voluntary Fire Departments, LEPC and the Petroleum Extraction Industry in remote areas.
Safety Equal to Other Management Challenges Means Profits
Authors: Avery W. S. , Sartain Randy
Published: December 2007

In late 1990, top management was introduced to the concept that safety is not FIRST, but is EQUAL to other management challenges facing the company — production, quality, morale, expenses. Careful management of any of these areas EQUALS increased profits from that area. Top management approved the investment required and a commitment was made to save $100,000 per year on worker’s compensation insurance by the end of the second year of the program. Reduction of this type of expense falls directly to the company’s bottom line and is readily understood by all managers. A comprehensive safety management program was implemented that included training on accident prevention and injury management for 120 managers and supervisors, including top management. A commitment was made to train employees to identify unsafe acts BEFORE they become accidents or injuries and make corrections. Then, when accidents occur, a program of active injury management was implemented that involved local management, headquarters safety and risk departments, the physician and the employee.
Safe Deployment of Specialized Coiled-Tubing Tools in Live Wells
Authors: Thomeer H. V. , Eslinger D. M.
Published: December 2007

Using coiled tubing (CT) for specialized work, such as logging, selective treatment, drilling, CT completions and CT with gas lift valves installed, requires running long specialized tool strings into live wells. The conventional method of deploying these tools poses several safety hazards and operational problems. A new method for deploying these specialized electrical and fluid tool strings has been developed and addresses the safety and operational concerns of previous methods.
Investigation of Stability of Three-Dimensional Condensation Fronts in Porous Media
Authors: Kocberber Sait , Miller M. A.
Published: December 2007

The stability of three-dimensional condensible gas (steam) displacements in porous media is investigated by precise simulation using a recently developed three-dimensional front tracking model. This model uses a finite element method with an adaptive grid redistribution scheme that accurately represents the front as a moving discontinuity. Frontal displacement is evaluated by precise calculation of the velocity field around the front. Abrupt changes in volumetric flux across the front is a consequence of conservation of mass and energy, which enhances stability. Model results show excellent agreement with data in the literature. Displacement patterns and sweep efficiency correlations are shown for selective flooding patterns using steam.
Evaluation of Horizontal, Radial, and Vertical Injection Wells in a Pilot Steamflood
Authors: Buller S. M.
Published: December 2007

A unique pilot steamflood incorporates one horizontal, one radial, and three vertical steam injection wells. The horizontal and radial wells were designed to alleviate steam override and improve sweep efficiency. The horizontal injector is a medium radius well with 400’ of completion in the horizontal section. The radial well has four completed, near-horizontal, ultra-short radius laterals drilled within a short vertical section. The vertical injectors are conventional completions, with perforations in one or two sand lobes. Production data from offset producers, injection profile data, produced fluid and downhole temperature data, and a comprehensive log suite conducted on three temperature observation wells were used to compare the three injection strategies. While a significant increase in oil production has not yet been seen, changes in water production, cut and flowline temperature provide clear indications that many of the offsets are being affected by steam injection.

The pilot steamflood is located in a 5-acre area in the southwest portion of Unocal’s Bremer lease, Midway Sunset Field. The steamflood targets the Mio-Pliocene age Potter formation, a highly permeable sand comprised of massive debris and grain flows deposited as proximal submarine fans. The pilot and surrounding areas have been cyclically steamed for over 10 years. The pilot steamflood has been in place for just under 2 years. In addition to comparisons within the pilot area, comparisons are also made with the eastern portion of the lease which has been successfully steamflooded for over 10 years.

The horizontal injector has efficiently heated a very localized, previously unswept, portion of the thick, sub-homogeneous reservoir being steamflooded. To date, the radial well has been used as a huff-n-puff producer. Despite the short steam injection periods, producers surrounding the well have responded dramatically. Observation well data, rates from offset producers, and temperatures in the offset producers confirm that the vertical injectors are distributing heat and affecting oil production less effectively than the horizontal and radial methods.
Quality Improvement: A Petroleum Industry Comparison
Authors: Presley G. F.
Published: December 2007

Most integrated petroleum companies began implementing continuous quality improvement (CQI) programs in the early to mid-1980s. The Chemical line of business was first to implement CQI, at least partly in response to their customers initiating total quality programs. The Downstream (refining and marketing) line of business followed soon thereafter. By now, these two lines of business have institutionalized several aspects of their CQI programs. Quality is being permanently woven into the organization’s culture.

The future of CQI in the Upstream (exploration and production) line of business is less certain. Towers Perrin assessed the status of CQI in the Upstream line of business of nine companies (see Table 1). We found that after some initial enthusiasm the implementation of CQI has slowed. At this point, it is unclear when these programs will be fully implemented.
Correlating Waterflood Ultimate Recovery With Controllable Field Operating Variables in Prudhoe Bay
Authors: Kwan G. W. L.
Published: December 2007

With over seven years of waterflood and five years of miscible gas alternating water injection (WF/EOR) performance data, a solid foundation has been established to evaluate these recovery processes at Prudhoe Bay. WF/EOR ultimate recovery was projected on a pattern-by-pattern basis from decline curves for all patterns currently under water or water-alternating-gas (WAG) flood.

The study attempts to correlate projected recovery with various controllable field operating variables and fully reconcile results using surveillance data. The comprehensive performance analysis presented here has immediate implications for reservoir management and development strategy in the WF/EOR areas of Prudhoe Bay.

Overall WF/EOR performance has been robust in Prudhoe Bay. However individual pattern recoveries vary across the field because of different operating strategies and reservoir heterogeneities. This study concluded that well spacing, geometric and production skew, pressure maintenance, ultimate throughput, water/solvent ratio and solvent injection rate show varying degree of impact on projected individual pattern ultimate recovery.

It is feasible to develop site-specific correlations for ultimate recovery by applying an empirical regression to these operating variables. An example correlation is applied toward evaluating infill potential in a selected waterflood region. This technique implicitly accounts for field performance and serves as a complementary tool to conventional infill benefit evaluations.
Transient Pressure Response of Horizontal Wells in Layered and Naturally Fractured Reservoirs With Dual-Porosity Behavior
Authors: Du Kui-Fu , Stewart George
Published: December 2007

Over the last decade, extensive studies have been carried out on the behaviour of vertical well tests in dual porosity systems. Although some research has been done on the horizontal well counterpart [1-5], most of this work has just dealt with a specific situation. No systematic investigation has been yet reported on the behaviour of transient horizontal well tests in dual porosity systems. One of the major purposes of this study is to bridge this gap. An approximate analytic solution in real time space modelling the horizontal well test in a dual porosity reservoir is given. Responses for both pseudo-semi-steady-state (PSSS) and transient dual porosity models in linear flow are investigated.

For homogeneous reservoirs the theory of pressure transient analysis for horizontal wells suggests that linear flow should be the dominant flow regime when L/h is large and the log-log derivative diagnostic would frequently exhibit a half slope. However field examples quoted in this paper do not show this feature nearly as often as one might anticipate and unexpectedly quarter slopes have been observed in many cases. The paper particularly illustrates how a bilinear flow can arise in the case of a horizontal well in a transient dual porosity (fractured or layered) reservoir.

Several field examples are analysed to illustrate the horizontal well transient pressure response in linear flow.
Making an Old Gem Sparkle: The Rejuvenation of McAllen Ranch Field, Texas
Authors: Hill D. W. , Lennon Russell , Wright Cary
Published: December 2007

Over the last three years, Shell's McAllen Ranch Field in Hidalgo County, Texas, has increased daily production rates by nearly 300%. This dramatic increase in production is due to a combined program of recompletions, commingling and an aggressive development drilling campaign supported by a 3D seismic survey. This recent development program has been very successful; the first eighteen wells have booked over 100 BCFG and additional drilling locations are being evaluated.

This paper highlights the development program which concentrated on optimizing well locations through a better understanding of structure and stratigraphy. A detailed study of the ‘S’ sand in North McAllen has shown this reservoir to be a stratigraphie trap with structurally related porosity development and capillarity controlled downdip limits. Updip production limits have been identified by the event amplitude on the 3D seismic survey and are supported by well control. Structural mapping from the 3D survey was combined with detailed isopach mapping of individual sands to locate development wells for highest reserve recovery.
The "Gypsyy" Field Research Program in Integrated Reservoir Characterization
Authors: Doyle J. D. , O'Meara D. J. , Witterholt E. J.
Published: December 2007

Integrating information from varied data sources is the technology of this decade. The use of geostsatistical tools to combine descriptions of reservoir heterogeneity, derived from outcrop analogues, with measurements of subsurface properties forms the basis of a growing list of published works. However, the verification of geostatistical or measurement or reservoir description tools requires data sets usually not provided by standard production operations. BP Exploration has, over the past several years, engaged in a research program for integrating reservoir description tools which uses a highly characterized field laboratory in Oklahoma to bring focus to tool development. This field laboratory, known as "Gypsy", consists of coupled outcrop and subsurface sites which have been characterized to a degree of detail not possible in a production operation. The geological, geophysical, petrophysical and well test data gathered to date is valued at about two and a half million dollars. The next phase of the project will be a pilot flood designed to confront and verify the descriptive and predictive tools with an equally detailed set of flow measurements.

At the time of this writing, BP Exploration has reached an agreement to cede the existing Gypsy resources (sites and data) to the University of Oklahoma who will make the Gypsy project accessible to industry and government researchers through a university consortiu m.
Detection of Bed Continuity Using Crosswell Data: A Gypsy Pilot Site Study
Authors: Turpening W. R. , Chon Yu-Taik , Pepper R. E. F. , Szerbiak Robert , Schultz Thomas , Thielmier Gary , Ballard Richard
Published: December 2007

BP’s Integrated Reservoir Description project has been the basis for development of a number of new geophysical techniques for reservoir description. This paper introduces two new reservoir description techniques, namely crosswell bed continuity detection and full waveform sonic formation analysis. These are presented in the context of the full geophysical data sets collected at the Gypsy Site.

The crosswell seismic surveys were used to generate conventional velocity tomograms. These data were also used to generate bed continuity maps between wellbores. This technique identifies and analyzes the low velocity wave guides.

The full waveform sonic logs were consistently recorded. The waveform amplitudes were analyzed for formation discriminating characteristics. Results from one well are used to clearly discriminate between clean and dirty sands.

The sonic log amplitude analysis combined with the bed continuity mapping and velocity tomography adds new information to the conventional surface seismic mapping and greatly helps the correlation between the wells in this complex reservoir.
Computer-Based Downhole Data Acquisition and Transmission in Well Testing
Authors: Veneruso A. F. , Ehlig-Economides C. A. , Akmansoy A. M.
Published: December 2007

Data acquisition techniques for computer-based systems are discussed for making continuous pressure, temperature and flow measurements. To ensure that the data faithfully represent the essential signal content over the time interval of interest, the important considerations for each system are measurement resolution, signal bandwidth, sampling, filtering and aliasing.

Key data transmission techniques are discussed, starting with downhole recorders that must be hauled out of the hole for data retrieval, to telemetry systems for sending real-time or bulk data transmissions to the surface. The important issues for downhole recorders are storage media and capacity. For signal transmission systems, the issues are information modulation, data and error rate, and signal-to-noise ratio.
Effects of Thermal Convection on Oxygen Activation Logs
Authors: Wydrinski Ray , Katahara K. W.
Published: December 2007

Oxygen Activation (O/A) logging is becoming a popular method of determining whether there is water movement inside the casing or the annulus. The EPA is considering a requirement that this tool be run in all injection wells to determine if water is moving into the U.S.D.W. (Underground Source of Drinking Water). Although Oxygen Activation logs can detect water movement, they cannot differentiate water channeling from thermal convection.

Previous studies indicates that convection is present in most wells. This paper examines a few wells where the O/A log may have been affected. The O/A log should be run to detect flow in both the up and down directions. Convective flow will give comparable flow rates in either direction. For the Water Flow Log, the character of the count rate decay combined with the raw data counts can help identify whether thermal convection is the cause of the water movement. Mistaking naturally-occurring convection for channel flow may trick one into wasting millions of dollars attempting to repair a well.
Some Influences of Stratigraphy and Structure on Reservoir Stress Orientation
Authors: Bruno M. S. , Winterstein D. F.
Published: December 2007

The orientation of maximum horizontal stress in a reservoir, which strongly influences several drilling, stimulation and production operations, can vary significantly with both depth and structural position. This paper presents field observations, analytical solutions, and numerical model results to illustrate some mechanisms by which stratigraphy and structure act to reorient the direction of maximum stress within anisotropic and heterogeneous reservoir formations.
Influence of Composition and Texture on Compressive Strength Variations in the Travis Peak Formation
Authors: Plumb R. A. , Herron S. L. , Olsen M. P.
Published: December 2007

The evaluation of rock strength from geophysical well logs is fundamental to engineering problems associated with wellbore stability, sand control and hydraulic fracture containment. Meaningful inversion of geophysical data for rock strength requires a better understanding of how intrinsic rock properties affect rock strength as well as new models to capture this understanding. A study of the relationships between compressive strength and rock composition and texture was conducted on cores from the Travis Peak formation. Travis Peak lithologies vary from mudstones to quartz arenites, and porosities range from 5.5% to 8.5%. After identifying the dominant composition and texture elements controlling strength variations in the Travis Peak formation, we explain our results in terms of micromechanical deformation mechanisms. A simple predictive model of rock strength is developed, based on measurable quantities physically linked to the governing deformation mechanisms. We show that the most accurate strength models include explicit information on both extrinsic and intrinsic rock properties. Our method suggests a new approach to quantifying rock strength from well logs.
Wettability of Porous Media by NMR Relaxation Methods
Authors: Hsu Wen-Fu , Li Xiaoyu , Flumerfelt R. W.
Published: December 2007

Determination of the wettability characteristics of reservoir rock is difficult and time-consuming. Nuclear Magnetic Resonance (NMR) relaxation measurements provide a quantitative, fast, and relative easy technique for determining rock wettabilities. We have used NMR relaxation experiments to study the wettability of various bead packs and rock samples. Specifically, we have used T1 (longitudinal relaxation time in laboratory frame) and T1ρ (longitudinal relaxation time in rotating frame) measurements in H2O or D2O in porous media to characterize the wetting.

Such studies enabled us to explain the apparent contradictory observations of previous investigators. The data indicate that in the absence of magnetic impurities on the surfaces, both H2O and D2O have shorter relaxation times in water-wet porous media than in oil-wet media. Carbonate core samples were treated to create preferentially water-wet and preferentially oil-wet systems, and NMR measurements of such cores were compared with the combined Amott/USBM method. The results showed good agreement between the wetting behavior obtained from NMR relaxation and that from the combined Amott/USBM method.
A New Approach for Injection Water Quality
Authors: Bansal K. M. , Caudle D. D.
Published: December 2007

With increasingly strong environmental concerns in the disposal of produced water onshore and offshore, it has become even more important to have a better understanding of the water injection processes both technically and economically. No reliable models are currently available to predict injection water quality requirements. This paper discusses a new comprehensive and multidisciplinary approach for establishing injection water quality guidelines by correlation and interpretation of actual field water quality, injection well surveys, and injection data (injection rates and pressures), A decision tree approach to facilitate interpretation of the data for design purposes is discussed.

Field data from two existing waterflood systems was gathered and evaluated to illustrate the decision tree approach. The new interdisciplinary approach has potential applications for existing systems to give a meaningful economic evaluation of water quality needs and for establishing more realistic water quality specifications for new systems.
Design and Implementation of a Microbially Enhanced Oil Recovery Field Pilot, Payne County, Oklahoma
Authors: Knapp R. M. , Mclnerney M. J. , Coates J. D. , Chisholm J. L. , Menzie D. E. , Bhupathiraju V. K.
Published: December 2007

A multi-well microbially enhanced waterflooding field pilot was conducted in the Southeast Vassar Vertz Sand Unit in Payne County, Oklahoma. Selective reductions in the interwell permeability between the injection well and the three production wells were observed after the microbial treatment. The permeability in the pilot area was more uniform after microbial treatment than before. More importantly, a major flow channel from the injection well to another portion of the reservoir was blocked. Changes in the alkalinity and sulfide concentrations indicated that the above observed alterations in flow paths and permeability were the result of in situ microbial growth and activity.
Fracture Measurement Using Hydraulic Impedance Testing
Authors: Paige R. W. , Roberts J. D. M. , Murray L. R. , Mellor D. W.
Published: December 2007

Hydraulic Impedance Testing (HIT) is a technique which has been developed to measure formation fractures intersecting wellbores. Fracture dimensions are determined by introducing a pressure pulse into a well and interpreting the resulting pressure trace. The method only involves the use of wellhead equipment and is therefore a very cost effective method for obtaining information about fractures in the formation. This paper describes a method for interpreting HIT data and demonstrates its validity through laboratory and field measurements.

Direct comparisons between HIT field measurements and independent evidence for fracture dimensions are presented for a number of water injection wells. The most striking results are that HIT estimates of fracture height correlate well with the flowing intervals obtained from spinner logs, and HIT estimates of fracture length tend to agree with those obtained from PFO’s. HIT derived fracture dimensions are also comparable to those obtained from computer simulation of thermal fracturing.

More than 50 water injection wells have been tested with HIT and found to be intersected by formation fractures. Determination of fracture geometries in water injectors can be used for the optimisation of both areal and vertical waterflood sweep and increase understanding of the processes controlling injectivity. HIT may also provide a useful tool in hydraulic fracturing work.
Design and Installation of a Polyethylene Natural Gas Gathering System: A Case Study
Authors: Carlisle Todd
Published: December 2007

In certain applications, the use of polyethylene pipe in a natural gas gathering system offers substantial advantages over a conventional welded steel line. Polyethylene flowline is ideal for use in a natural gas gathering system where average field pressures are below 250 psig. A polyethylene line may be the only alternative when economics dictate the expense of a costlier steel une impractical, or when corrosion is a major concern.

This paper covers the design process and installation of a polyethylene natural gas gathering system in south Ohio. Methods used to calculate pressure drops in the system based on anticipated field conditions, including length, size and schedule of pipe, throughput, and compressor inlet pressure, are discussed. Procedures used to evaluate the pressure limitations of a polyethylene flowline are also examined. Other design factors such as state and federal regulations and line protection systems are presented. Project costs are compared and contrasted to a comparable conventional welded steel line. Installation techniques, equipment, and pitfalls are addressed. Post installation pressure drop data is analyzed to determine the accuracy of the pressure drop methodologies used to design the gathering system and those methodologies modified to more closely match field performance.
A Mechanistic Model of a Nitrogen-Charged, Pressure-Operated Gas Lift Valve
Authors: Sagar R. K. , Schmidt Zelimir , Doty D. R. , Weston K. C.
Published: December 2007

For any gas lift system installation it is important to know the dynamic opening and closing pressures and valve throughput to yield an efficient and optimized gas lift system installation. A comprehensive theoretical and experimental study was performed to develop an improved mechanistic model of a pressure operated nitrogen charged gas-lift valve.

Experiments are conducted on a Teledyne Merla N-15R, 1.5 inch, nitrogen charged, bellows operated gas-lift valve. A static probe tester is used to determine the load rates as a function of the initial dome pressure. Empirical equations quantifying bellows behavior are developed. Quasi-one dimensional flow theory for a convergent-divergent nozzle is used to model and describe the complex high velocity gas flow through the ball-seat configuration. The reduction of flow rate in the critical flow region of the throttling and transition flow regimes is achieved by the occurrence of a normal shock wave in the ball-seat configuration. A model incorporating compressible flow theory and the behavior of the bellows assembly is developed. Experimental and theoretical sensitivity studies indicate that a nitrogen charged pressure operated valve is very sensitive to performance parameters. Changes in pressures and temperatures by as little as 1% can change the maximum flow rate by as much as 30%.
The Field Application of a Surfactant for the Production of Heavy, Viscous Crude Oils
Authors: McCafferty J. F. , McClaflin G. G.
Published: December 2007

A surfactant, water, hydrocarbon diluent system designed to produce heavy crude by forming an oil-in-water emulsion has been successfully field-tested. The new process significantly lowers the production costs for viscous crude by reducing the hydrocarbon diluent usage.
Compressibility Factors for Naturally Occurring Petroleum Gases
Authors: Corredor J. H. , Piper L. D. , McCain W. D.
Published: December 2007

The Stewart, Burkhardt and Voo (SBV) equations, as modified by Sutton, give values of pseudocritical properties which, when used with the Dranchuk and Abou-Kassem (DAK) representation of the Standing and Katz (SK) chart, currently provide the most accurate estimates of compressibility factors for naturally occurring petroleum gases. However, other correlations must be used to account for the properties of the heptane plus fraction and the presence of acid gases. A modification of the SBV equations is presented which takes into account the effects of the heptane plus fraction, acid gases and nitrogen. The new correlation provides more accurate estimates of the compressibility factor than can be obtained by current methods and also eliminates the need for involving additional correlations for properties of the heptanes plus fraction and presence of acid gases and nitrogen. The modification was developed using a set of 896 data points, ranging in composition from lean, sweet to rich, acid gases, and was tested against representative gases from the literature.
Graphical System Analysis of Gasfield Production
Authors: Skarsholt L. T. , Asheim Harald
Published: December 2007

The graphical technique presented enables characterization of gas field production performance by 6 parameters. These can be estimated from production data, as shown for the Frigg field example. The parameters can be scaled to represent similar fields and to quantify the effect of design modifications. Among other applications, this allows optimization of the production system design.
Simulated Annealing for Interpreting Gas/Water Laboratory Corefloods
Authors: Ouenes Ahmed , Fasanino Guy , de France Gaz , Lee R. L.
Published: December 2007

This paper presents a new approach for the simultaneous estimation of relative permeability and capillary pressure curves from two-phase laboratory corefloods. The new technique enables us to retrieve a discrete representation of the flow functions by using a discrete optimization method called simulated annealing. The number of discrete points for each flow curve can be very high and yet will not affect the convergence of the algorithm specially designed for multidimensional optimization problems. Moreover, the algorithm is totally independent from the forward model; therefore, changes in the objective function, boundary conditions, or numerical scheme do not affect the formulation of the optimization problem. Simulated annealing as a global optimization method does not require the evaluation of objective function gradients. Hence, costly gradient computations by finite differences or lengthy derivations of adjoint equations for the optimal control theory are not necessary. The flow functions are estimated after minimizing a least-squares objective function containing all available and reliable experimental data obtained from standard drainage or imbibition experiments. The automatic history-matching code is demonstrated with actual and synthetic experiments, and good matching is obtained for various cases tested. Since the convergence of the algorithm is no longer the major concern, other physical problems such as end effect and the dependence of relative permeability curves on the flow rate are addressed.
3-D Finite Difference Modeling of Wireline Formation Tests in Tight Gas Sands
Authors: Xu Hui , Bassiouni Zaki , Desbrandes Robert
Published: December 2007

In tight gas sands, conventional models of wireline formation testers (WFT) yield non-representative estimates of formation permeability because several important conditions found in real well situations are neglected. These conditions include flowline storage, skin permeability, formation anisotropy, supercharging pressure, and test geometry.

The three-dimensional finite difference model presented in this paper incorporates all these conditions. The effect of these conditions on the WFT pressure response are discussed. The model was verified using the spherical model with boundary conditions set close to those prevailing in a spherical flow regime.

The 3-D model was used to interpret three field data sets obtained in low permeability formations. The formation permeabilities were determined by matching the data to theoretical curves computed from the 3-D model.
Development and Validation of a Modified Well Model Equation for Nonuniform Grids with Application to Horizontal Well and Coning Problems.
Authors: Sharpe H. N. , Ramesh B. A.
Published: December 2007

In this paper we demonstrate the important limitations of trie standard Peaceman well model equation when applied to non-uniform areal cartesian grids and when used in flow problems with a significant vertical flow component near the well. We present and validate simple modifications to the Peaceman well model which restore its validity for non-uniform areal grids and for problems which model vertical flow processes like gas and water coning.
An Experimental Study of Capillary and Gravity Crossflow in Fractured Porous Media
Authors: Firoozabadi Abbas , Markeset Tore
Published: December 2007

Physical phenomena such as capillary, gravity, and viscous cross flow at the interface of two different porous media or in the fracture space between matrix blocks are believed to affect the flow of multiphases. We have not found any reported work on capillary and gravity cross flow in fractured porous media.

An experimental and theoretical work has been initiated to understand cross flow in fractured porous media. In this paper, the results of our experimental effort on capillary and gravity crossflow in fractured porous media are presented. Drainage performance of a stack of 12 matrix slabs, three in each row, was measured. The angle between the stack and the vertical direction varied from 0° to 45°. Experiments on a stack of matrix blocks were also conducted to compare the results. The data show that capillary cross flow across side faces of a matrix block is an important flow mechanism. Capillary cross flow enhances drainage performance in fractured porous media.
Simulation of Carbon Dioxide Flooding Using Horizontal Wells
Authors: Lim M. T. , Khan S. A. , Sepehrnoori Kamy , Pope G. A.
Published: December 2007

A compositional equation-of-state simulator has been used to make comparisons of CO2 process performance with several combinations of horizontal and vertical wells and various alternative reservoir descriptions. This is the first time that the performance of CO2 flooding using horizontal wells has been reported. We have used the reservoir and fluid properties of an actual West Texas carbonate reservoir that is currently being waterflooded. The phase behavior and properties of the CO2 used in these simulations are typical of those of multiple-contact- miscible field conditions of West Texas. A layered-type reservoir description was initially used to investigate the effect of water- altemating-gas (WAG) ratio with various combinations of well types. We then investigated the effect of vertical permeability, length, and position of the horizontal injector using the same reservoir description and a horizontal injector-vertical producer combination. Similar investigations using an unconditioned stochastic permeability field having a Dykstra Parsons coefficient (VDP) of 0.81 were made. Our final three-phase flow simulation was performed using a stochastic permeability field conditioned with core data. Since three nonaqueous phases can occur at low temperatures typical of West Texas floods resulting in up to four-phase flow with mobile water, we investigated the impact of four-phase flow in one of these simulations. This is the first time that three-dimensional, four-phase flow reservoir simulations have been reported with either vertical or horizontal wells.
Early Performance and Evaluation of the Kuparuk Hydrocarbon Miscible Flood
Authors: Reinbold E. W. , Bokhari S. W. , Enger S. R. , Ma T. D. , Renke S. M.
Published: December 2007

A small-scale hydrocarbon miscible flood was initiated at the Kuparuk River Unit on the North Slope of Alaska in mid-1988, three years after the start-up of waterflooding. This Small Scale EOR (SSEOR) project, along with an infill drilling program, is improving recovery from a stratified and highly faulted sandstone reservoir.

The project design was aided by limited compositional reservoir simulation. The design calls for the injection of a 30% hydrocarbon pore volume (HCPV) slug of miscible injectant (MI) which is injected alternately with water at a 1:1 water-alternating-gas (WAG) ratio for mobility control.

An extensive laboratory program was conducted to understand the displacement process and to develop an equation of state (EOS) fluid characterization. The displacement process is characterized as a condensing/vaporizing gas-drive process, providing a high unit displacement efficiency.

A comprehensive surveillance program was implemented to quantify reservoir continuity and vertical conformance. A gas tracer program has helped in interpreting the influence of faulting on interwell continuity and regional fluid flux. Injection and production well surveys indicate that permeability stratification controls vertical conformance.

Preliminary evaluation of project performance indicates significant incremental recovery associated with both infill drilling and enriched gas injection. Typical EOR response includes a significant increase in the oil production rate, with an associated decreasing watercut and increasing gas-oil ratio.
Crossflow Mechanisms by Gas Drive in Heterogeneous Reservoirs
Authors: Fayers F. J. , Lee Sheng-Tai
Published: December 2007

In this paper a number of factors contributing to mass transfer by cross flow in gas displacement are examined. The mechanisms involved are diffusion, dispersive mixing, capillary pumping, interfacial tension variation, and relative permeability modification. The use of a modified Wilke-Chang correlation for bulk diffusion coefficients in multi-component systems is suggested. The performance of this correlation is tested against the limited experimental data available on diffusion coefficients. A general formulation of the terms needed to be included in compositional simulators for cross flow effects is reviewed, and thence some of the key aspects are analyzed using measurements from the IFP-diffusion experiment. The role of the gas phase tortuosity factor is investigated, but spatially varying capillary force is also found to be a dominating mechanism. An example reservoir application with a two-layer heterogeneous character is then studied to determine the relative magnitudes of cross flow, and how these compare between a nearly miscible displacement and a dry gas vaporizing process.
The Second Long-Term Horizontal Well Test in Troll: Successful Production From a 13-in. Oil Column With the Well Partly Completed in the Water Zone
Authors: Haug B. T.
Published: December 2007

Inspired by the success of the first long-term test with a horizontal well on Troll1, a second long-term test was carried out in 1991. This 4 months long-term production test with an 800 m horizontal well was performed in a 13 m oil column sandwiched between a large gas cap and an active aquifer in the Troll West Gas Province. The horizontal section target depth was 1 m above the WOC, but approximately 25% of the well trajectory was actually below the WOC.

The observed production data from the test were history matched with a numerical simulator. The effects of various geological features on water cut and GOR development were studied, and several simulation models matching the production history were built. These models were used to evaluate the effects on oil recovery of various design parameters such as; length of the horizontal section, completion depth, liner diameter and liner roughness.

The production history indicated that inverse coning took place in the parts of the well situated below the initial WOC. The history matching confirmed the results from the first long-term test, but also demonstrated the strong sensitivity of history matching and long-term production predictions to small changes in geological interpretations and to frictional pressure loss in the horizontal section.

Large upside potential was found in the Troll West Gas Province for longer horizontal wells, deeper completions and super-critical production.
National Petroleum Regulatory Policy Options: A Review
Authors: Stultz-Karim S. P.
Published: December 2007

This paper is intended to provide guidelines for petroleum legislation and regulation for developing, petroleum exporting nations and the transitional nations of the Commonwealth of Independent States and the petroleum producing nations of Eastern Europe. Included in this survey of methods of petroleum regulation and legislation are concepts of ownership of petroleum rights, contractual arrangements between host countries, and investing international petroleum companies, components of petroleum regulation, the differing perspectives of investing companies’ and host national governments of petroleum regulation, and an expected monetary value model of petroleum regulatory design which incorporates the consideration of exploration risk to enable national governments to maximize public revenue while encouraging exploration investment and the obtainment of domestic political economic policy objectives.
New Techniques for Solving Cementing Problems in a Field Laboratory
Authors: Moulin E. M. , Roy M. L. , Caddell S. E. , Vidick Benoit , Hughes T. L.
Published: December 2007

In recent years, the quality of oil well cements has become increasingly variable. Using a cement characterization program provides a highly reliable means of determining the relative quality of a proposed cement. Furthermore, results can be used to determine the origin of poor performances by some cements in the field. This paper briefly presents techniques such as calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and pycnometry which provide useful tools for supplementing conventional testing methods. In addition, several case studies are presented which use these same techniques to solve field.