bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Interpretation of Injection/Falloff Tests for Coalbed Methane Wells
Authors: Zuber M. D. , Sparks D. P. , Lee W. J. 
Published: December 2007

ABSTRACT
This paper presents the results of a study undertaken to investigate the reasons why data from injection/falloff tests of coalbed methane wells were not interpretable using conventional well test analysis techniques and the results of a field study to investigate completion effectiveness during injection tests. The pressure transient test data obtained using the old injection/falloff test design were found to be interpretable only by history matching analysis. A modified test design is presented. A field example is presented which illustrates how application of the modified test design resulted in easily interpretable data using conventional well test analysis, techniques. Spinner surveys run during injection tests showed that breakdown/ballout treatments are required prior to simultaneous testing of multiple coals in cased-hole completions to ensure adequate communication between the well and all target coal seams.
Pulsed Neutron Log Interpretation Case Histories from Inland and Offshore South Louisiana
Authors: Thomson J. C. , Klimo C. R. 
Published: December 2007

ABSTRACT
In the Louisiana Gulf Coast and offshore areas accurately determining water saturation (Sw) and identifying problems in cased wellbores can be difficult. Reservoir potentials may be unknown because of poor or nonexistent mud and core data, incomplete logging data and sketchy production histories. Wellbore environments that are unknown and/or difficult can render cased hole formation evaluation misleading and difficult to interpret. Without accurate Sw values and other diagnostic data, successful completions and reserve estimates may be difficult.
Pulsed neutron logging has been a primary evaluation technique for many operators analyzing economics before recompletion. This is especially true in older wells with limited reservoir information and unusual well/casing mechanics. Estimating reservoir pressures of gas zones, identifying production problems in producing wells and in new wells with stuck drillpipe, and applying oxygen activation techniques to evaluate potential well problems in flowing conditions are the applications frequently seen in the Gulf Coast.
This paper presents detailed case histories of successful recompletions, hydrocarbon determination, and production/drilling problem identification in unusual or difficult reservoirs and boreholes. Interpretations were derived from Dual-Burst* TDT* measurements and confirmed by production results and/or other wireline log and core evaluations. Comparisons are made with previous pulsed neutron measurements and openhole evaluations to evaluate the measurements in difficult logging conditions.
Comprehensive Physical and Numerical Modeling of a Horizontal Well
Authors: Islam M. R. , Chakma A. 
Published: December 2007

ABSTRACT
Petroleum engineers have depended largely on empirical models for multiphase flow in pipelines and horizontal wells. While empirical models have been proven to be adequate in some cases (depending on flow regimes), they do not give any theoretical basis and, therefore, an extension of these models to much more complex flow, such as horizontal wells, is not justified. Despite recent advancement in horizontal well technology, little has been done in the areas of physical and mathematical modeling of horizontal wellbore itself. No study has been reported on three-phase (water-oil-gas)flow or gas-liquid flow when the liquid phases show emulsification of oil and water.This paper addresses the problem of both physical and mathematical modeling of horizontal wellbores. Experimental results gave insight into the type of flow occurring in a horizontal wellbore. This observation was used in developing a comprehensive mathematical model of the horizontal wellbore. Finally, the wellbore model is coupled with a reservoir simulator and a series of numerical tests is performed to study the effect of pressure drop in the wellbore on the performance of a horizontal well. The usefulness of this new modeling technique is pointed out vis a vis conventional modeling techniques.
How To Develop a Coalbed Methane Prospect: A Case Study of an Exploratory Five-Spot Well Pattern in the Warrior Basin, Alabama
Authors: Ely J. W. , Zbitowsky R. L. , Zuber M. D. 
Published: December 2007

ABSTRACT
This paper summarizes MetFuel Inc.'s experiences in conducting a pilot" test of the coalbed methane potential of an undeveloped area in the southern Black Warrior Basin. The pilot project was designed to gather baseline reservoir data, determine the viability of further development by field experience, and learn how to complete and stimulate coal seams in this area. The pilot project provided valuable insights in terms of drilling practices, defining target intervals, hydraulic fracture geometry and height growth, perforation placement, canister test procedures, and reservoir permeability versus stress. A wealth of baseline reservoir data was also collected. Continued production from the pilot project wells is required to determine the economic viability of large-scale development in this area.
Well Test Requirements for Evaluation of Coalbed Methane Development Potential
Authors: Semmelbeck M. E. , Lee W. J. 
Published: December 2007

ABSTRACT
This paper presents methods for designing and analyzing prefracture and postfracture injection/falloff tests and multirate production tests in coalbed methane reservoirs. These tests should be conducted on selected wells in a coalbed methane pilot test. Pilot testing is the best way to evaluate the productive potential of coalbed methane reservoirs. A properly designed testing program can minimize the expense and maximize the reliability of estimating reservoir properties that are essential to a thorough evaluation of a coalbed methane reservoir.
A Comparison Between Predicted and Measured Walking Beam Pump Parameters
Authors: Tripp H. A. , Kilgore J. J. 
Published: December 2007

ABSTRACT
This paper quantifies the accuracy of a state-of-the-art computer program used to predict the performance of walking beam pumping systems. The program used for the predictions includes models of the fluid and rods, which are coupled along the rods, at each taper, and at the subsurface pump. An extension of the Doty and Schmidt pump model is used to simulate the down-hole pump. The method of characteristics is used to solve the coupled partial differential equations that describe the forces and motion along the sucker rod string and in the liquid column. In addition, the program considers motor slip and rotating and articulating inertia in calculating.the pumping unit speed variations
Comprehensive comparisons between field measurements and predicted parameters of 92 wells with depths ranging from 810 to 10,800 feet are given. In addition, comparisons between measured and predicted values are used to illustrate the effects of various details in modelling pumping systems. These comparisons show that when wells are carefully modeled, good agreement exists between measured and predicted parameters.
New Developments To Improve Continuous-Flow Gas Lift Utilizing Personal Computers
Authors: Schmidt Z. , Doty D. R. , Agena B. , Liao Tianlu , Brown K. E. 
Published: December 2007

Abstract
The design of continuous gas-lift installations has been examined in detail. Procedures are outlined showing how system analysis can be used to select optional components including tubing size, flowline size, surface operating pressure, perforation shot density, etc. An improved procedure is presented for the construction of the gas-lift performance curve, based on the gas injection rate rather than the GLR. Also, the importance of using the actual gas-lift valve performance relationship rather than the Thornhill Craver choke equation is addressed. It is shown that utilization of the Thornhill Craver choke equation can result in serious design errors. The two most commonly used unloading design procedures are examined with modifications and improvements being recommended. Finally, it is shown how software for the personal computer can be used to readily implement these ideas.
Horizontal Well Stimulation Results in the Austin Chalk Formation, Pearsall Field, Texas
Authors: Dees J. M. , Freet T. G. , Hollabaugh G. S. 
Published: December 2007

ABSTRACT
Since 1985, Oryx Energy Company has used horizontal drilling and completion technology in the Pearsall Field of South Texas for increasing production rates and developing reserves in the naturally fractured Austin Chalk formation.
This paper reviews the application of various stimulation techniques in horizontal wells based on field experience with over 20 Austin Chalk wells. The lateral hole lengths range from 150 to 4,800 feet. The three stimulation methods discussed are water fracs, acid washes, and acid fracs.
Synergistic Effects in the Polymer Treatment of Producing Wells
Authors: Zaitoun A. , Kohler N. , Coffin P. 
Published: December 2007

ABSTRACT
Some polymers used as water control agents in the treatment of producing wells are also good clay stabilizers. Both a nonionic polyacrylamide (PAM) and a biopolymer (Polysaccharide G) induce a selective reduction of relative permeability to water of natural sandstones without affecting the relative permeability to oil, although the presence of adsorbed polymer in the core increases the irreducible water saturation. The same polymers are shown to stabilize montmorillonite clay dispersed in sandpacks by lowering the critical salt concentration (CSC) below which clay is released. Adsorption of such polymers in clayey sandpacks also prevent, to some extent, the swelling of montmorillonite clay, with PAM having greater efficiency than Polysaccharide G. The treatment of a heavy-oil horizontal well producing in a poorly consolidated sandstone reservoir by an innovative process using PAM as the base polymer has confirmed good lab results. The treatment induced a decrease of both the water cut and sand cut, thus markedly improving well performances.
Reserve Pit Drilling Wastes - Barium and Other Metal Distributions of Oil and Gas Field Wastes
Authors: Deuel L. E. , Holliday G. H. 
Published: December 2007

Abstract
This study was conducted to evaluate the distribution of barium (Ba), chromium (Cr), lead (Pb), Zinc (Zn), arsenic (As), iron (Fe), manganese (Mn), sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) in drilling wastes relative to the point of discharge into the reserve pit. Metals are conserved species (from a mass balance point of view) and serve as index parameters for establishing materials variance and associated chemical composition of reserve pit solids.
A large (&gt; 50,000 bbl) reserve pit was divided into 6 sections, then sampled by taking 12 cores within each section down to consolidated native soil. Location samples were blended in the field yielding one composite sample for each section. Section composites were subsampled for analysis then biended together to yield one pit composite. Section samples and the pit composite were analyzed according to procedures recommended by Louisiana Office of Conservation. The volume of solids and concentration of regulated metals was greatest near the point of discharge. There was good agreement between weighted metal averages determined for section samples and pit composite values, suggesting from a mass balance perspective, that metals are not randomly distributed in reserve pits. EPA SW-846 method No. 3050 digest (1984 edition) provides a good index for total metals, except for barium. Barium can be accurately determined for drilling fluids using conventional spectrometric analysis by modifying the amount of sample and volume of nitric acid used to partition barium from the solid phase.
Oil Property and Composition Changes Caused by Water Injection
Authors: Eakin B. E. , Mitch F. J. , Hanzlik E. J. 
Published: December 2007

ABSTRACT
Cores from a newly drilled observation well close to a long-time water injector showed 20% lower residual oil saturations than anticipated. Laboratory measurements were made on four live oils at 215° F and 3015 psia to study this phenomena. The results showed: –residual oil volumes decreased by 18%,–density of the live oil increased up to 10%,–Stock Tank Oil gravity dropped 3° API,–the bubble-point pressure dropped by 82%, and–viscosity of the oil in the reservoir tripled.
All the changes observed are detrimental to the later recovery of the residual oil remaining after a water flood.
A Field Case Study of Replacement Well Analysis: Guymon-Hugoton Field, Oklahoma
Authors: Ebbs D. J. , Works A. M. , Fetkovich M. J. 
Published: December 2007

SUMMARY
This study analyzed the initial pressure data and the performance results of replacement wells drilled in 72 sections of the Guymon-Hugoton Field, Oklahoma. Reservoir lateral continuity was confirmed and the current 640 acre well spacing was determined to be adequate for effective drainage of the field.
Effects of Steam Quality on Cyclic Steam Stimulation at Cold Lake, Alberta
Authors: Ho D. W. , Morgan B. T. 
Published: December 2007

Abstract
Reservoir simulations of cyclic steam stimulation (CSS) at Cold Lake show that both the oil recovery level, and the efficiency of the process as measured by the oil produced/heat injected ratio (OHR), are independent of steam quality. However, with constant volume (rather than constant energy) injection, the calender day oil rate (CDOR) decreases with a reduction in steam quality. Therefore, the higher the steam quality the more economic the CSS process becomes. Present boiler technology enables a practical maximum of 80 percent quality steam.
The study also demonstrates that a temporary reduction in steam quality results in a temporary efficiency gain for the same cumulative energy injection, accompanied by a corresponding drop in CDOR. The reduction has no permanent impact on well performance in the subsequent cycles, since the CDOR rebounds to normal levels after higher steam quality injection is resumed.
Leming pilot field data show that an uneven steam quality split resulted in some wells consistently receiving higher quality and others receiving lower quality steam. Nevertheless, analysis indicates that each well still received approximately the same energy due to flow nozzle meter calibration. The net result was no harmful effect on well performance and recovery, consistent with the simulation predictions. As a result, accurate wellhead steam quality measurements are not deemed necessary to further optimize performance.
Comparison and Analysis of Radioactive Tracer Injection Response With Chemical Water Analysis Into the Ekofisk Formation Pilot Waterflood
Authors: Skilbrei O. B. , Hallenbeck L. D. , Sylte J. E. 
Published: December 2007

Abstract
This paper documents the design, operation, analysis and use of two different radioactive tracers, tritium and iodide-125, which were injected in the Ekofisk Formation Pilot Waterflood Project. This paper also describes how chemical analysis of water produced in the offset producers during the pilot project was successfully analyzed, interpreted, and used as a second tracer method.
Both tracer methods were used to evaluate waterflood mechanisms and were invaluable to the overall interpretation of the Ekofisk Formation Pilot. A comparison of both methods is made to demonstrate their repeatability for possible future use.
During the pilot water injection program, clear responses from the injected radioactive tracers were identified from the three production wells within the pilot. Analysis of the produced water from these wells was carried out in the laboratories of IFE ("Institutt for Energiteknikk") in Oslo with an accuracy within 1–2 percent.
Chemical composition of the produced water was monitored during the same tracer injection period which showed a direct correlation. The large differences in sulfate concentration between Ekofisk formation water and the injected seawater makes this ion a good alterative to the more ideal radioactive tritium tracer.
Careful analysis of the various tracers in the Ekofisk Formation Pilot confirmed that both waterflood recovery mechanisms capillary imbibition and viscous displacement were contributing to the overall waterflood recovery. This was a key element in the interpretation and simulation of the pilot.
Analytical Modelling of 2-D Flow in Gravity Stable Secondary Gas or Water Drives
Authors: Schulte A. M. , Niko H. , Swinkles W. 
Published: December 2007

ABSTRACT
Up-dip gas injection or down-dip water injection into a dipping oil reservoir leads to a stable displacement for a certain range of injection velocities. Two (extreme) models are available to predict the steady-state tilt angle of the injectant/oil interface: the fully segregated-flow approximation and the fully diffuse-flow approximation. The predictions of these models may differ considerably and a good criterium to judge the validity of the approximations is not available. A new 2-D analytical model has been developed that takes into account both along-dip and across-dip flow and establishes a link between the two approximations. It predicts the tilt angle and velocity of the injectant/oil interface and iso-saturation lines in the invaded zone for any situation in between fully segregated and fully diffuse along-dip flow. The model can also be used to gain insight into the relative importance of the effects caused by the injection well and the validity of the steady-state solution. This paper outlines the new model, concentrating on the gas injection process. Example calculations are presented that show good agreement between numerical simulations and the predictions of the 2-D model.
Casing Collapse Analysis Associated With Reservoir Compaction and Overburden Subsidence
Authors: da Silva F. V. , Debande G. F. , Pereira C. A. , Plischke B. 
Published: December 2007

ABSTRACT
Pressure decline associated with production induces compaction of high porosity reservoirs and overburden subsidence in fields of the North Sea Chalk Basin. More than ninety casing failures have been observed in this area which are related to the increase of axial and radial loads on the wellbore.
A numerical technique was developed to describe the mechanism of casing failure in compacted reservoirs as well as in associated overburdens. A 3D finite element modelling procedure was set up to simulate and predict the onset of casing failures. Important characteristics of this numerical model are the introduction of the concept of sliding interfaces and the transfer of deformation parameters from a large scale displacement (field) to a more refined scale analysis (casing).
This 3D finite element simulation identified the failure modes and allowed an appropriate revision of casing design throughout the field area. Furthermore, it has been demonstrated that the revised design solutions extend the casing lives for a large number of years.
Careful Planning and Sophisticated Laboratory Support: The Key to Improved Acidisation Results
Authors: Nitters G. , Hagelaars A. M. P. 
Published: December 2007

ABSTRACT
The decision to treat oil and gas wells with acid is often based on the general belief that acid will dissolve any skin damage and/or part of the rock matrix. Often acid recipes are selected on the basis of experience in other areas, usually with a fair amount of subjective engineering judgement. As a result the success rate of acid treatments is sometimes rather disappointing.
Proper evaluation of a formation's response to matrix acidising requires knowledge of the various parameters before the acid-response testing. Mineral composition and potential sources of formation damage, e.g. invaded barytes, can be identified by the application of sophisticated instrumental analysis techniques such as X-ray diffraction (EDX) and scanning electron microscopy coupled with automated mineral identification by complex image processing.
Correlation of analytical results on core samples before and after treatment with acid with the acid response curves helps to explain the phenomena observed in the tests. Automated mineral identification based on EDX analysis and scanning electron micrographs of the relevant samples may provide additional information without which differences in the response of closely related samples might remain unexplained.
The application of these procedures in the design of acid treatments for a number of Dutch gas wells resulted in an improved acid treatment design and more successful stimulation treatments. A total of seven gas wells, producing from a reservoir with a rather unusual rock composition, were treated, resulting in a total production gain of some three million m3/day, more than twice that expected on the basis of previous stimulation experience.
The paper illustrates how a carefully planned acidising campaign can benefit from a thorough laboratory study and fruitful cooperation between research and operating company.
Hydraulic Fracture Stimulation of Permeable North Sea Oil Wells
Authors: Clancey B. M. 
Published: December 2007

ABSTRACT
The vast majority of fracture stimulations conducted to date in the North Sea have been hydraulically propped fractures of tight sandstone gas reservoirs or acid fractures of carbonate oil reservoirs. This paper demonstrates that hydraulic fracturing technology is applicable to permeable sandstone formations and can enhance the economic viability of marginal North Sea oil reservoirs.
In 1989, Mobil North Sea successfully conducted its first hydraulic fracture stimulation of a North Sea oilwell in the A45 well on the Beryl Alpha condeep production platform. The formation stimulated was the Triassic Lewis Unit I Sandstone, characterised by average permeability of 10 md (streaks over 100 md), and capable of producing 500 – 1000 BFPD. The stimulation was successful in increasing the well's PI from 0.7 BPD/psi to 1.4 BPD/psi and resulted in post-frac production rate of 2400 BOPD.
Technical highlights of the stimulation were the use of large propping material to achieve maximum fracture conductivity, and the use of resin coated proppant to minimise its flowback. The formation stimulated was at 16,155ft MD with wellbore inclination of 55°.
Gas Blockage by Nonaqueous Foams
Authors: Hanssen J. E. , Haugum P. 
Published: December 2007

Abstract
This paper reports some results of on-going research efforts to develop a method to reduce undesired gas production in oil wells by using foam as a barrier. Exploitation of the gas-blocking properties of foam by using it as a gas-coning barrier is an old idea that, to our knowledge, still has not been applied successfully. An attractive means of achieving a favorable barrier geometry is by using low-density non-aqueous foaming-agent solutions. This work is, to our knowledge, the first study of non-aqueous foams as gasblocking agents. We are focusing on two alcohols using fluorinated well-stimulation surfactant formulations. The ability of foam to reduce gas mobility in porous media was measured by a gas-blockage test. Most experiments reported are for a model system, but some data at higher temperature and in the presence of crude oil and brine are included. Experiments in porous media show that non-aqueous foams are capable of producing the same drastic changes in flow patterns as aqueous gas-blocking foams. Gas blockage is shown to be possible over an extended period, or at high pressure gradients, with a non-aqueous foam. The effects on gas blockage of varying the absolute permeability, porous-medium length, and temperature are also reported.