bluuebunny/crossref_metadata_2025 huggingface dataset:
Renewable Resource Development in the Ecuadorian Rainforest
Authors: Hutton W. C. , Skaggs M. M.
Published: December 2007

This paper discusses the planning and execution of a multi-million dollar, heavy oil renewable resource development project in the Amazon Basin of Ecuador. The project work is authorized under a risk service contract with PETROECUADOR and employs new technology in order to minimize environmental and cultural impacts on the environment and the inhabitants of the areas. During the peak of the project, over 3,000 workers were employed and managed in the rainforest under special guidelines, in order to avoid damages to the environment.

The project guidelines are spelled out in a model Environmental Management Plan (EMP) which employs innovative well pad, road and pipeline construction and platform drilling methods to limit deforestation. Reforestation methods are reviewed; scientific baseline and archaeological pre and post construction methods were followed, and methods to control colonization pressures are executed as a part of the EMP described in this paper. In addition, the EMP covers methods used to minimize the disruption of the indigenous population of the area including medical, educational and other programs employed to reduce disease among the indigenous population of the area. Conventional aspects of the EMP include spill control techniques for remote areas of the rainforest, solid waste recycling programs, drilling and construction waste management, landfarming methods, pipeline construction and underground river crossing methods. All of these methods are employed to minimize the environmental and cultural impact of the project on the environment and its inhabitants.
New Real-Time Anticollision Alarm Improves Drilling Safety
Authors: Leder Pearl Chu , McCann D. P. , Hatch A.
Published: December 2007

A critical concern in directional drilling is ensuring the avoidance of collisions while drilling on multi-well locations. Collision avoidance planning is ordinarily carried out prior to well spud and is therefore valid only to the planned trajectory. Once drilling commences, deviation from the plan invariably occurs which may not only increase subsurface collision risk, but also compromise the ability to maintain adequate quality control of rigsite anticollision computations in an often stressful and demanding drilling situation.

New high performance, multi-user computer systems at the rigsite provide the capability for clear anticollision analysis in real time without the need for hand computations. In this paper we describe a unique computer application which performs traveling cylinder calculations automatically in real time. The present bit location, computed from survey and depth measurements, is shown on a rigfloor color display along with the trajectories of the offset wells. Position uncertainties for both the current hole location and all the offset wells are computed and plotted as error ellipses on the screen. In addition, the application has a "look-ahead" feature which projects the trajectory beyond the current bit depth, and a "Smart Alarm" is triggered if any of the offset wells come within a user specified alarm proximity.

Field data are shown which illustrate the effectiveness of the technique. The alarm has been designed to give early warning of potential collision situations. As a result, it improves safety and quality control at the rig and helps avoid the environmental damage that can result from well collisions.
Horizontal Drills and Their Cost Effective Use for Characterizing and Remediating Under Obstructions
Authors: Wilson David D. , Layne Roger
Published: December 2007

A survey completed in during the summer of 1995 indicates that there have been more than 400 horizontal environmental wells installed for subsurface remediation. This paper investigates the costs of installing a horizontal well and for obtaining subsurface samples using a directional drilling rig. Two case studies are presented that illustrate the diversity of horizontal well installations and their associated costs. Furthermore, it was found that the costs of obtaining soil samples using a directional drilling rig is based on a daily drilling rate. The daily drilling rates of two distinct systems are discussed.
Optimizing Reservoir Performance Under Uncertainty with Application to Well Location
Authors: Aanonsen S. I. , Eide A. L. , Holden L. , Aasen J. O.
Published: December 2007

Stochastic parameters representing geological uncertainties in reservoir modeling may be classified in 2 types: 1) Continuous stochastic variables (e.g., degree of communication through a fault); and 2) Discrete stochastic variables representing different geological interpretations (e.g., same/different channel observed in different wells) each with a given probability.

A method for optimizing reservoir performance is presented, which may take into account both these types of uncertainties in a consistent and simple way by finding values of reservoir management variables that optimize the expected performance over the population of possible reservoirs. The method is based on response surfaces and experimental design and is implemented in a user-friendly computer program which may be used together with any reservoir simulator or analytical flow model.

In this paper, the method is illustrated through 3 examples of optimizing well locations under uncertainty.
Accurate predictions for the production of vaporized water
Authors: Morin E. , Montel F.
Published: December 2007

The production of water vaporized in the gas phase is controlled by the local conditions around the wellbore. The pressure gradient applied to the formation creates a sharp increase of the molar water content in the hydrocarbon phase approaching the well; this leads to a drop in the pore water saturation around the well bore. The extent of the dehydrated zone which is formed is the key controlling the bottom-hole content of vaporized water.

The maximum water content in the hydrocarbon phase at a given pressure, temperature and salinity is corrected by capillarity or adsorption phenomena depending on the actual water saturation.

Describing the mass transfer of the water between the hydrocarbon phases and the aqueous phase into the tubing gives a clear idea of vaporization effects on the formation of scales. Field example are presented for gas fields with temperatures ranging between 140°C and 180°C, where water vaporization effects are significant. Conditions for salt plugging in the tubing arc predicted.
A Mechanistic Foam Model for Simulation of Steamfoam Field Applications
Authors: Hatziavramidis D. T. , Alameddine B. R. , Weinstein H. G. , Djabbarah N. F. , Revay J. M.
Published: December 2007

Starting in 1985, Mobil conducted a series of pilots and commercial-size steamfoam operations in South Belridge, California, which demonstrated significantly higher recoveries of heavy oil in combination with attractive process economics. To evaluate these succeses and guide future steamfoam field applications, a steamfoam model was incorporated into an in-house developed thermal simulator and was used in simulations to (1) match field performance, (2) confirm the extent and nature (i.e., accelerated vs. incremental) of additional oil recovered by steamfoam, and (3) determine optimum time for steamfoam injection termination.

The model is shown to be robust, with affordable complexity in the description of the relevant physics of the steamfoam process, and faithful in reproducing field performance.
An Overview of the North Ward Estes CO2 Flood
Authors: Ring J. N. , Smith D. J.
Published: December 2007

A CO2 pattern flood was initiated in a west Texas (Permian Basin), sandstone reservoir as a tertiary recovery process in 1989. This paper is an overview of the development and management of the North Ward Estes CO2 Flood. The primary objective of managing the CO2 flood has been to maximize oil recovery for maximum profitability. This has been accomplished by maintaining a consistent water-alternating-gas (WAG) process, optimizing CO2 utilization, and maintaining a proper balance between patterns. Reservoir modeling, which is emphasized in this paper, has also been critical in the development and management of this flood.
Pressure Falloff Testing of Enhanced Coalbed Methane Pilot Injection Wells
Authors: Seidle J. P. , McAnear J. F.
Published: December 2007

As part of the effort to interpret Amoco’s enhanced coalbed methane recovery pilot, each of the four nitrogen injectors was tested with a pressure falloff test (PFOT) after approximately five months of injection. An additional test was done on the final injector at the termination of the pilot. The tests were analyzed to obtain flow capacity, wellbore condition, and average reservoir pressure for use in subsequent simulation studies. Stress effects on reservoir permeability and wellbore skin were investigated. Results from the PFOTs yielded an injectivity index which can be used to estimate compression requirements for enhanced coalbed methane recovery projects.
The Effects of Stress on Coalbed Reservoir Performance, Black Warrior Basin, U.S.A.
Authors: Sparks D. P. , McLendon T. H. , Saulsberry J. L. , Lambert S. W.
Published: December 2007

This paper presents the first field scale measurements of in-situ stress effects on permeability of coal seams. The importance of these effects on a highly compressible reservoir such as coal is demonstrated by relating permeability and production to stress. Well testing complications and the implications of stress toward exploitation of existing reserves and exploration for new reserves are also discussed. Additionally, comparisons of this paper’s findings to prior theoretical work, core testing, and limited field data are presented.
The Relation of Diagenetic Clays and Sulfates to the Treatment of Coalbed Methane Reservoirs
Authors: Nick Kevin E. , Conway Michael W. , Fowler Kathleen S.
Published: December 2007

Field procedures and laboratory experiments to stimulate production from coalbed methane reservoirs have largely been designed from experience with fractured reservoirs and coal geochemistry. This paper descibes experiments to investigate the occurrence of cements in the permeability pathways in coal samples from mines and cores and how these diagenetic materials interact with completion and stimulation fluids based on core flow tests. Core flow testing of coals generally suggests damage by polymers and stimulation by several acids. Examination of cleat surfaces from the Mary Lee and Black Creek coal seams in the Black Warrior Basin and Fruitland coal from the San Juan Basin by light microscopy, SEM, and XRD analyses show the presence of carbonate, quartz and iron sulfide cements in impermeable cleats and quartz, illite, kaolinite, barite, gypsum, and iron sulfates in permeable fractures. Fracture morphology is also complex with many branching shapes and surface textures. Illite is typically the most abundant clay and is also interlaminated with or interspersed in the coal. Kaolinite is most likely to migrate and its occurrence in meniscus forms and packed against steps in the cleats document mobility. Coal fines are also present in the cleats, concentrated with clays at steps and bends in the cleats. Injection of fluorescin tagged guar through coal plugs demonstrated the polymer’s affinity for clay and identified permeability pathways in coal.
Application of Fuzzy Expert Systems for EOR Project Risk Analysis
Authors: Chung Ting-Horng , Carroll Herbert B. , Lindsey Rhonda
Published: December 2007

This work describes a new method for enhanced oil recovery (EOR) project preassessment. Instead of using the conventional costly simulation approach, a fuzzy expert system was developed. A database of EOR project costs and oil prices of the past decades was incorporated into the expert system. The EOR project risk-analysis includes three stages: (1) preliminary screening of EOR methods, (2) field performance estimation, and (3) economic analysis. Since this fuzzy expert system has incorporated both implemented EOR technology and experts’ experience, it thus reduces the requirements of massive laboratory and field data for input. Estimates of displacement efficiency (Ed) and sweep efficiency (Ev) were formulated for each EOR process. Ed and Ev were treated as fuzzy variables. The overall recovery efficiency is evaluated from the product of Ed and Ev using fuzzy set arithmetic. Economic analysis is based on the estimated recovery efficiency, residual oil inplace, oil price, and operating costs. Examples of the application of the developed method for a CO2-flooding project analysis is presented.
Modeling of Horizontal Well and Lifting Mechanisms to Improve Ultimate Recovery in a Depleted Field in Lake Maracaibo, Venezuela
Authors: Saputelli L. , Mata T. , Jimenez Z. , Banerjee S. , Lozada T.
Published: December 2007

Recovery of the remaining reserve of millions of oil barrels is inhibited by depleted reservoir pressures and existing exploitation policies in Lower Lagunillas Reservoir in Lake Maracaibo, Venezuela.

Numerical simulation results indicated that proper production and reservoir management policies such as, controlled drawdown, producing wells at rates below the critical rates, low gas-oil-ratio production will promote efficient gravity segregation process, and subsequent optimum final recovery. Combination of infill horizontal wells and adequate lifting mechanisms yielded the recovery of additional reserves.
Horizontal Injection Well Experience in the Valhalla Boundary Lake "M" Pool
Authors: Doerksen Timothy C. , Nicoud Richard A. , Lueers Kenneth H. , Yeung Wunbing S. , Ford W. Randy
Published: December 2007

Horizontal water injection wells were used to initiate a waterflood in the Valhalla Boundary Lake "M" pool. A simulation model of the pool indicated that vertical injection wells would not provide adequate injectivity to match withdrawals. Horizontal wells were proposed, drilled and used to repressure the reservoir to bubble point, achieve target injection rates and maximize production from the reservoir. The targets for the horizontal injectors and the associated waterflood have been surpassed to date.
Improved Reservoir Characterization and Management of a Mature Oil Field via Integrated Team Approach
Authors: Norris S. O. , Reinhardt B. K.
Published: December 2007

An iterative approach to reservor characterization, conducted by an integrated work team, proved to be essential to adequately understand and manage the late life production of the Trinity Shoal "N" Sand Reservoir. This paper describes the approach taken by the team in obtaining a superior simulation history match, which resulted in a more complete understanding of the reservoir, lead to the identification of successful infill well locations, and improved long term reservoir management plans.
Effect of Wettability on Adverse Mobility Immiscible Floods
Authors: Vives M. T. , Chang Y. C. , Mohanty K. K.
Published: December 2007

Many immiscible displacements in reservoirs occur at adverse mobility. Effect of wettability on these displacements is not well understood and often ignored in reservoir simulation. Recent macroscopic theories of viscous fingering treat adverse immiscible flows similar to miscible flows, the mixing in the fingered region being controlled by a Todd-Longstaff-type functional form. The wettability of the medium is taken into account only through the use of appropriate relative permeabilities. The goal of this paper is to understand the macroscopic bypassing in adverse mobility immiscible floods. Immiscible displacements are conducted in a quarter 5-spot model in both drainage and imbibition modes at similar effective mobility ratios and viscous-to-gravity numbers. The level of bypassing and gravity override is visualized and measured. Tertiary water-alternating-gas (WAG) displacements are also conducted at various WAG ratios and viscosity ratios. Fractional flow analysis and numerical simulation are used to understand these displacements.

Experiments show that macroscopic viscous fingering is present in adverse viscosity immiscible displacements where no saturation shock is expected from 1-D fractional flow theory. Bypassing due to both fingering and gravity override is higher in the drainage mode than in the imbibition mode, with other key parameters being the same. Optimum WAG ratio in water-wet rock is a function of oil/solvent viscosity ratio. The macroscopic flow theory needs to include capillarity and viscous fingering to match these experimental findings.
Steady-State and Unsteady-State Two-Phase Relative Permeability Hysteresis and Measurements of Three-Phase Relative Permeabilities Using Imaging Techniques
Authors: Eleri O. O. , Graue A. , Skauge A.
Published: December 2007

The objective of this work is to improve determination of two-phase and three-phase relative permeabilities by the use of saturation imaging techniques. The first part of the paper reports on steady-state and unsteady-state relative permeability experiments performed on restored-state carbonate reservoir cores. The aim was to study how relative pemeability test methodology impacts relative permeability curves, hysteresis and residual oil saturations in these intermediate-wet cores. Refined oil was used.

Significant hysteresis was observed in both the unsteady-state water and oil relative permeabilities. The characteristics of the unsteady-state water relative permeabilities imply that viscous instabilities were present during the waterflood. Centrifuge capillary pressure-wettability tests performed on companion core plugs both before and after the relative permeability tests showed good agreement with the unsteady-state results, but indicated change towards less oil-wetness during the steady-state tests. The main conclusion of this work is that extensive flushing of a restored-state core with refined oil may lead to a non representative relative permeability data and should therefore be avoided.

The second part of the paper presents a summary of results obtained from three-phase unsteady-state flow in water-wet sandstone (Berea and Clashach) cores. In-situ saturation measurements show that the water relative permeability is dependent on water saturation alone, and that there is no change in water relative permeability due to three-phase flow. The waterflood residual oil saturation was found reduced in the presence of a gas phase, and may depend on the phase (oil or gas) injected prior to waterflooding.
Determination of Relative Permeability and Recovery for North Sea Gas Condensate Reservoirs
Authors: Chen H. L. , Wilson S. D. , Monger-McClure T. G.
Published: December 2007

Laboratory experiments on gas condensate flow behavior were conducted under reservoir conditions. Two North Sea gas condensate reservoirs that have distinct rock and fluid properties were studied. The objectives of the corefloods were to investigate the effects of rock and fluid characteristics on critical condensate saturation (CCS), gas and condensate relative permeabilities during in-situ condensation, hydrocarbon recovery and trapping by water injection, and incremental hydrocarbon recovery by subsequent blowdown.

It was found that both CCS and relative permeability were sensitive to flow rate and interfacial tension. The results on gas relative permeability rate sensitivity suggest that gas productivity curtailed by condensate drop out can be somewhat restored by increasing production rate. Phase behavior and interfacial tension influence the extents of gas relative permeability reduction and condensate mobility. High interfacial tension ultimately caused condensate relative permeability to decrease with increasing condensate saturation. Condensate immobile under gas injection could be recovered by water injection, but more immediate and efficient condensate recovery was observed when the condensate saturation prior to water injection exceeded the CCS. Approximately 27 %PV gas was trapped by water injection. Subsequent blowdown recovered additional gas, but incremental condensate recovery was insignificant.
Thirty (30) Years of Steamflooding: Reservoir Management and Operational Experiences
Authors: Ramkhalawan C. D. , Khan J. , Bainey K. R.
Published: December 2007

The Petroleum Company of Trinidad and Tobago Limited (Petrotrin) has a heavy oil reserves base of 300 million barrels of heavy oil in the southern part of the island of Trinidad. The Company, and its predecessors, first embarked on a thermal recovery program in its acreage from 1963 with cyclic/steamflooding operations. At the present time, the Company is operating eleven (11) steamfloods and is currently implementing another major project. This paper presents a case history of the Company's thirty-two years experience in steamflooding, inclusive of reservoir management and monitoring methods, innovations and operating practices. To date (1995 June), the Company has recovered a total of 77 million barrels of heavy oil from its acreage, with a current production level of 9000 BOPD. During this period, new diagnostic methods were initiated, as well as new innovations. These include cluster drilling, slim-hole injectors, insulated tubing and packers, non-gravel packed injectors, high volume pumps, limited entry perforating, insulated casing completions, diverting agents, dual injectors, iso-fluid mapping and other reservoir management techniques. In summary, the Company has had extensive success in steamflooding operations and continues to utilise this method for exploitation of its heavy oil reserves. With its proven success and existing infrastructure for this type of operation, the Company still has major opportunities in heavy oil recovery. Additionally, new methods of operation, financing and project management are being pursued to exploit these reserves. Based on Trinidad's complex geology and heterogeneous reservoirs, heavy oil recovery has been a major success through the Company's scope of operations. Several innovations in reservoir management and operating strategies can be implemented in other similarly adverse environments for heavy oil recovery.
Effects of Capillary Heterogeneities on Spontaneous Imbibition
Authors: Zeybek M. , Gurakin G. , Donmez A. , Onur M.
Published: December 2007

This paper presents numerical studies of spontaneous imbibition phenomenon in a heterogeneous matrix block of porous medium in one and two dimensional systems. Heterogeneous distributions of permeability as well as wettability that could affect spontaneous imbibition are considered. Deterministic and stochastic heterogeneity profiles with correlated and uncorrelated fields for permeability and wettability distributions are considered. Both countercurrent with gravity forces and simultaneous cocurrent and countercurrent flows are studied.

Numerical model is tested with an experimental study with input measured parameters. Deterministic profiles for permeability have strong effects on saturation and recovery curves for countercurrent imbibition in one and two dimensional systems. Uncorrelated permeability fields with log-normal and fBm statistics yield strong responses in saturation with high amplitudes. Correlated fields give smooth responses in saturation. However, recovery curves are affected considerably by correlated fields depending on realizations. Heterogeneous forms of wettability have strong influence on responses in saturation and weak influence on responses in recovery curves compared to responses in heterogeneous permeability fields. Interaction of gravity with heterogeneity is also considered for countercurrent flow in one dimensional systems. Some examples of heterogeneous forms of permeability and wettability are also considered in two dimensional systems.
Parachors in Terms of Critical Temperature, Critical Pressure and Acentric Factor
Authors: Broseta Daniel , Ragil Karine
Published: December 2007

The method of parachors is widely used in conventional thermodynamic codes and reservoir simulators to calculate oil/gas interfacial tensions of complex hydrocarbon mixtures. In the low-to-moderate interfacial tension regime, a value p≈11/3 has previously been shown to be the "best" parachor exponent. This exponent is a critical exponent and its value is consistent with the values of critical exponents characterizing the liquid/vapor critical behavior. Therefore parachors may be viewed as critical amplitudes.

By using critical scaling theory, parachors are related to other critical amplitudes and critical parameters that describe the bulk thermodynamic behavior of fluids. A simple expression relating the parachor of a pure compound to its critical temperature Tc, critical pressure Pc and acentric factor ω is proposed: P= (0.85-0.19ω)Tc12/11 /Pc9/11 where the parachor P is in units of (dyn/cm)3/11cm3/mol, Tc in K and Pc in MPa. This equation matches (within experimental error) the known parachor values of normal fluids (e.g. alkanes, aromatics, CO2, N2, H2S, etc…).
An Integrated 3D Model for Underground Coal Gasification
Authors: Biezen E. N. J. , Bruining J. , Molenaar J.
Published: December 2007

Underground coal gasification has received renewed interest in both Western and Eastern Europe because of the vast amounts of otherwise unminable coal deposits that occur on the European continent. A field test is currently being held in Spain, and other countries have also shown interest in this method of utilizing coal resources.

In this study we have developed a model to combine reactive heat and mass transport together with thermo-mechanical failure behavior. In the model, we use multigrid methods to solve the flow equations in the entire domain. This is combined with thermo-mechanical failure properties of both coal and rock overlying the coal formation. With this approach, a 3D picture of the development of an underground coal gasifier is obtained, and the influence of well-layout and the sensitivity of the process to other model parameters can be investigated in detail, with high computational efficiency.

The model consists of two modules: The first module solves the flow equations in the entire flow domain. The second module selects a block of coal for gasification and a block of coal and/or rock for thermo-mechanically induced spalling. Other features such as ash content, the possibility of including heterogeneities, and natural convection-driven cavity gasification are also incorporated in the model.
A Comprehensive Study of the Analysis and Economic Benefits of Radioactive Tracer Engineered Stimulation Procedures
Authors: Fisher K. , Robinson B. M. , Voneiff G. W.
Published: December 2007

Hydraulic Fracturing is an important technology to enhance production from tight gas reservoirs. Several techniques have been utilized to attempt to evaluate the effectiveness of hydraulic fracturing treatments. One technique, radioactive tracers, is currently used on over 15% of the stimulation treatments performed in the U.S. With proper materials, design, and execution, tracers can be used to locate the presence and concentration of proppant at the wellbore in order to evaluate vertical and radial proppant distribution. A comprehensive study of over 100 fracture treatments has been completed in which radioactive tracers were used along with production logs, stress logs, post-fracturing completion reports, and production history to analyze completion effectiveness in four different reservoirs. Additionally, an economic benefit model was constructed to evaluate the benefit/cost ratio of applying the technology.
Catalyzed Silicate Process Replaces Cement on Well-Deepening Operations
Authors: Shelley Robert F. , Sciullo Felix C.
Published: December 2007

The deepening and recompletion of existing wells has proven to be a good economic investment for many operators in eastern Kentucky. The deepening process involves squeezing the zone of initial completion, deepening the well, running casing, and recompleting in the Devonian shale. In many cases, problems occur after initial completions are squeezed. For example, fluids leaking into the drilled hole can compromise efficiencies if the well is drilled with air. If another cement squeeze is required to seal the zone, the operator incurs lost time and additional expense.

To produce an effective seal within the producing zone, operators may choose to use catalyzed silicates. This paper describes the catalyzed silicate process and explains why catalyzed silicates may often be more effective than cement. Case histories will show that catalyzed silicates are economically and operationally successful elements of the well-deepening process.
Down Hole Corrosion: Problems & Possible Solutions
Authors: Morrison William K.
Published: December 2007

Over the past several years the industry has encountered many production problems in the Antrim play. Among these are calcium carbonate scale, NORM and C02 removal. One problem, the oorrosion of steel within the production system, has developed due to the chemical nature of the Antrim gas and water. This corrosion has become a major problem for NOMECO and other operators. This paper will discuss the problem, its source and effects and some possible solutions.
Satellites and the Oilpatch or, Resolving the Heckarewe Problem
Authors: Walbe Kim A.
Published: December 2007

The Global Positioning System (GPS) is a navigation system consisting of a constellation of 24 satellites in 6 orbital planes that provide accurate 3-dimensional position and velocity as well as precise time to users anywhere in the world 24 hours a day.

User receivers measure their apparent range to the satellites by processing the received signals to determine transit time and correcting for atmospheric delay using stored and broadcast models. Since the location of the satellites, at the time of signal transmission, is known from the broadcast ephemeris, the location of the receiver can be triangulated from the range measurements.

Similarly, the user receiver’s velocity can be solved by comparing the measured Doppler shift of the received signals to the expected Doppler shift based on the satellites velocity vector, calculated from the ephemeris, projected on the line of sight to the satellite. After the receiver’s clock error is eliminated, by over determination, the residual Doppler is attributed to the user velocity.

The viable utilization of the GPS in the Appalachian Oilpatch comes from the ability to take small handheld units, the size of a pocket calculator, to the field to quickly position by latitude and longitude or by UTM the location of fixtures or facilities for which there is no surveyed data (examples would include older non-platted wells, the location of old pipeline systems and the location of new well roads that are not yet shown on topographic or company maps). This data can be obtained and stored in the field and later downloaded to mapping software such as AutoCad.

The system can be used in reverse with surveyed positions uploaded into the GPS system in the office before leaving for the field and then using the navigation capabilities of the GPS unit to lead you to the surveyed location or site.

The simplicity of use together with the low cost and pocket size makes a GPS unit one more viable tool for the field engineer or geologist.
Effects of Wall Slip and Shear-Induced Transition on the Viscosity Measurements of Crosslinked Fracturing Fluids
Authors: Fan Yong , Holditch S. A.
Published: December 2007

This paper presents a method to correct results of laboratory measurements where we investigated the effects of wall slip, wall roughness and shear-induced slip on the viscous properties of crosslinked fracturing fluids. Our research indicates that crosslinked gels exhibit wall slip. The measurement of viscosity is dependent upon the surface roughness of the bob used in the tests. Unless an appropriate correction is made, the measured viscosity will be less than the true viscosity because of wall slip. Our study also demonstrates the occurrence of a rheological transition of polymer gel induced by shear forces. The critical shear rate, which we define as the beginning of stress transition from one state to another, may vary between 10-90 sec-1, depending upon the fluid nature, test procedure and temperature. Viscosities calculated using data from the different stress states at the same nominal shear rate can be different by a factor of 3 to 5. The gel with the higher critical shear rate exhibits more stable viscous properties when subjected to the thermal and shear degradation.
Completion Methods and Results Comparison of Devonian Shale in the Big Sandy Field
Authors: Friend Michael L. , Keenan Robert L. , Huck Donald R.
Published: December 2007

Considerable effort has been made by various research groups and exploration companies to improve completion techniques in the Devonian Shale. Completions in the Devonian Shale in the Big Sandy Field run the gamut from natural completions, shot-hole completions, Nitrogen fracturing, Nitrogen foam fracturing, C02 foam fracturing, and gelled water fracturing, to the latest technique promoted by the DOE, sand-laden C02 fracturing. Production rates from wells using the different completion techniques in this field vary widely. Of these techniques, Nitrogen foam fractured wells have been observed to have by far the lowest production rates.

This paper compares production rates and well test results of the various completion techniques and attempts to quantify the problem with the Nitrogen foam fractured wells in terms of reservoir parameters. This will establish a base from which any improvement can be measured.

The conclusions will be drawn from the case histories of approximately 105 wells located within the Big Sandy Field. A summary comparison of production data will allow a fair analysis of the techniques investigated. Well test data from a sampling of these wells will help define reservoir parameters and fracture geometry.
Putting Technology to Work: The Petroleum Technology Transfer Council
Authors: Rowell D. , Benton J. H.
Published: December 2007

As the domestic oil and natural gas industry strives to become more competitive, technology has been presented as one answer to reduce instability in oil and gas markets and escalating regulatory compliance costs. To exploit the remaining resources of the eastern US, operators need access to new technologies that reduce the costs of finding, drilling for and producing hydrocarbons from mature reservoirs. The problem is that new and emerging technologies are often beyond the reach of domestic producers, both large and small.

The Petroleum Technology Transfer Council (PTTC) is a new national, producer-driven organization designed to make technology work for independent and major producers. Formed by the Independent Petroleum Association of America (IPAA) in cooperation with state and regional industry associations, and the Gas Research Institute (GRI), the PTTC's mission is to enhance and accelerate the transfer of upstream petroleum technologies to and among producers. The US Department of Energy (DOE) has provided start-up funds to help this important project become a reality.

The PTTC technology transfer program has several components: problem identification workshops, focused technology workshops, regional resource centers with electronic information systems, and producer outreach. Through these steps, the PTTC will make the latest advancements in exploration, reservoir characterization, drilling, production, offshore and environmental technologies accessible to the producer in the field. The PTTC is interdisciplinary, involving petroleum geology, engineering and geophysics. Many state geological surveys and universities are involved in implementing the PTTC regional activities.

As a grassroots organization, the PTTC has nearly finished holding problem identification workshops around the country. This process is helping producers to assess current technology and communicate their technological needs to the government, universities, GRI, national labs, service companies and others in the research and development (R&D) community.
Field Tests of the Water/Liquid Oxygen Injection Process
Authors: Andersen Len
Published: December 2007

Two field tests were done injecting a mixture of water and liquid oxygen near Graham, Texas. On the first test the results were on initial decrease in injection pressure and a 20% increase in production for 40 days. The oil field was an irregular six spot water flooded, Gun Sight Sand unconsolidated channel sand formation at a depth of 520 ft. (158 m.). In the second field test oil production increased 20% for 300 days, water injection pressure done on a batch basis increased from 0 to 230 psi (0 to 1590 kPa) to a range of 300 to 550 psi (2068 to 3790 kPa), and oil production from a deeper formation doubled. The oil field was an irregular, five spot, water flooded, Strawn Sand (consolidated sand with limestone formation at a depth of 1900 ft. (579 m.). These tests indicated the water/liquid oxygen process would be an economic success done on an going basis in similar oil formations.
The Value of Wellhead Electronic Flow Measurement in Gas Storage Fields
Authors: Brown K. G. , Meikle D. E.
Published: December 2007

The design, operation, and value derived from a wellhead electronic flow measurement (EFM) system recently installed in the Belle River Mills (BRM) gas storage field in southeastern Michigan are discussed. The automated process of corporate data integration to identify problem wells on a daily basis is presented. Four specific examples are cited which demonstrate the value of such a system: immediate identification of operational problems occurring during routine operations which rendered several 35 MMSCFD wells inoperable; empirical assessment of the impact of subsurface safety valves on well deliverability; pressure transient analysis using wellhead data collected at 10-second intervals during routine operations; automated daily assessment of individual well performance to alert operators of deteriorating well performance. The potential to monitor inventory using EFM data and pressure transient analysis techniques is discussed, including the difficulties encountered when using wellhead data for such analyses.
Using Geologic Modeling and Reservoir Simulation to Increase Gas Storage Efficiency: A Case Study
Authors: Ammer James R. , Mercer James C. , Mroz Thomas H. , Koperna George J. , Harris Ramon P.
Published: December 2007

The U.S. Department of Energy/Morgantown Energy Technology Center (METC), through partnerships with industry, is demonstrating the importance of geologic modeling and reservoir simulation for optimizing the development and operation of gas storage fields. METC entered into a Cooperative Research and Development Agreement with National Fuel Gas Supply Corporation (NFGSC) to investigate the expansion of an existing gas storage field in western New York.

A geologic model of the reservoir was developed using data from 14 existing vertical wells, mainly concentrated in the center of the field. A good history match of simulator predicted and field measured flowing wellhead pressure was achieved through 2.5 injection and withdrawal cycles. Biannual inventory shut-in pressures were matched within 5 percent.

Forecasts of reservoir performance were made for various field development strategies that included the operation of 11 existing vertical wells plus (1) 14 additional vertical wells, (2) four, 2000-foot horizontal wells, and (3) a combination of horizontal and vertical wells.

Although there has been no field verification of the modeling results, the results of the study have shown that geologic modeling and reservoir simulation can be very important to the efficient development of a storage reservoir. The modeling results have shown the possible advantages of using horizontal wells and have also focused efforts to gather additional data necessary to make the final decision on a field development strategy. While cost savings opportunities have been identified through this modeling effort with NFGSC, the need for additional reservoir description will require three to four vertical step-out wells before proceeding with full field development, especially with horizontal wells.
Case Study: Hydraulic Fracturing with Cross-Linked Gels in the Oriskany Formation to Improve Gas Storage Deliverability
Authors: Stiles Edward K. , Reese Rhys R.
Published: December 2007

During the summer and fall of 1994, CNG Transmission Corporation fracture-stimulated thirty (30) gas storage wells with a cross-linked gel fluid system. The work was done to increase late-season field deliverability. Individual well tests taken to date have shown that, on average, per-well deliverability has increased by a factor of five. The text that follows will detail the engineering and geologic aspects, procedures, results, and analysis of the project.

A discussion of the strategic placement of the storage fields involved will be presented, along with a review of FERC Order 636 and it's impact on the current gas storage business mechanics.

Overviews are presented on the geology, reservoir properties, and characteristics of the storage fields involved in the project. General well design and well completion configuration are discussed. Fracturing/refracturing candidate selection criteria are presented. Basic fracturing design criteria are discussed including: fluid parameters, geometry, proppant selection, and concentration. Discussions of observations and minor changes in treatment designs which occurred between the different fields are discussed.

The treatments are summarized and compared on a pre and post fracturing deliverability test analysis. Explanations are offered for wells with exceptional results, as well as marginally successful treatments.
Pore and Throat Network Model and Its Application to the Optimal Selection of Temporary Plugging Particles
Authors: Wenrong Mei , Shihong Shu , Tianhua Lai , Wenzhong Liu , Guoheng Hu
Published: December 2007

To a great extent, experiment selection of temporary plugging particles(TPP) in the temporary plugging techniques (TFT) is blind at present. Based on the investigation of particle migration, deposition and plugging mechanism in the porous media, network model, the inter-connected pore and throat network on the basis of reservoir pore structure, is applied to the optimization of TPP in the TPT. It is shown that the result of simulation has a good agreement with that of core flooding experiment and can be used to guide the study of core flooding experiments. The main advantages of this method are: 1. the model can be repeatedly used many times and can be used in the simulations of various purposes and aspects; 2. the results are highly comparable by the simulation while much less by the core flooding experiments.
Comparison of Numerical and Analytical Inflow Performance Modelling of Gravelpacked and Frac-Packed Wells
Authors: Burton Robert C. , Rester Stephen , Davis Eric R.
Published: December 2007

Estimation of completion pressure losses in gravelpacked and frac-packed wells is generally performed through use of empirical or semi-empirical analytical relations. This paper reports on work conducted by Conoco to compare numerical simulation results with analytical inflow performance relations. The work shows how and where completion pressure losses occur in flow to gravelpacked and frac-packed wells.

A fine gridded finite difference model has been developed to simulate flow and pressure loss behavior in the reservoir/well system. The grid system employs elements as small as 1 cm5 to model complex near well and intra-well flow effects including near-wellbore flow convergence to perforations, flow distribution between perforations and flow through gravel-filled perforations. These near-wellbore effects are reviewed for both symmetrical gravelpacked well flow cases and asymmetrical flow cases associated with frac-packed wells. Intra-well flow through gravel-filled perforation tunnels and the casing/screen annulus is also modelled for both cases.

Pressure losses and skin effects due to damage, fracturing and wellbore geometry are calculated through the flow system and compared to predictions from analytical relations. Results of these comparisons lead to an improved understanding of the effects of damage and flow asymmetry on gravelpacked and frac-packed well performance. Further, they show how current analytical skin relations can be enhanced to provide more effective completion pressure loss predictions.
Effect of Acids and Stimulation Additives on the Cloud Point of Nonionic Surfactants
Authors: Nasr-El-Din H. A. , Al-Ghamdi A. M.
Published: December 2007

Nonionic surfactants are commonly used during well stimulation for several reasons. They reduce interfacial tension between the acid and oil phases, thus improving acid/rock interaction. They are also used to form a stable foam which improves the sweep efficiency during acidizing. However, these surfactants should be employed at temperatures below their cloud point (defined as the temperature at which the surfactant solution becomes cloudy). This temperature signifies the onset of the surfactant salting out, which will reduce the efficiency of the stimulation and may damage the formation.

An experimental study was conducted to assess the effect of various acids and stimulation additives on the cloud point of nonionic surfactants. The influences of acids (inorganic and organic), mutual solvents, friction reducers, hydrogen sulfide scavengers, sequestering agents, short chain alcohols, simple salts, scale inhibitors, anionic surfactants on the cloud point of several nonionic surfactants were examined over a wide range of parameters.

The results indicated that the cloud point monotonically increased with the acid concentration. However, the rate of increase depended on the acid type and the number of ethylene oxide groups of the surfactant. Salts depressed the cloud point of nonionic surfactants at all hydrochloric acid concentrations examined. Alcohols, methanol and isopropanol enhanced the cloud point of nonionic surfactants. The effect of mutual solvents was found to be a function of the number of ethylene oxide groups of the surfactant, acid and mutual solvent concentrations. Anionic surfactants depressed the cloud point of nonionic surfactants at all sodium chloride concentrations examined. Clay stabilizers (cationic polymers) and hydrogen sulfide scavengers depressed the cloud point whereas scale inhibitor and phosphonic acid did not affect the cloud point significantly.

It is extremely important to measure the cloud point of nonionic surfactants before performing a stimulation job. It is also recommended to use the acid formulation and mixing waters that will be used in the field
Effects of Completion Fluid Loss On Well Productivity
Authors: Foxenberg William E. , Ali Syed A. , Ke Mingjie
Published: December 2007

Laboratory studies and field case histories are presented that demonstrate enhanced well productivity when selection and formulation of solids-free, high density completion fluids are optimized prior to field use. Results of return permeability studies and compatibility tests between completion fluids and formation fluids are presented. These results illustrate the tendency for high density completion fluids to form stable emulsions with certain crude oils. Studies supporting the treatment of these fluids with non-emulsifiers, surface tension reducing surfactants or mutual solvents to reduce formation damage are discussed. Preliminary data describing unique chemistry of calcium chloride, calcium bromide and zinc bromide solutions are provided. These properties influence recovery of high density fluids from oil or gas formations.