bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical Turbine Pumps for Waterflood Injection
Authors: Wykes Claude E.
Published: December 2007

Vertical diffusers pumps for the development of reasonably high pressures have been available in one form or another for many years. With the increasing importance of secondary recovery operations in petroleum production, vertical turbine pumps appear more and more production, vertical turbine pumps appear more and more frequently as the most efficient energizer for waterflood injection systems.

Even with adequate performance records standing behind it, this type of pump is still not widely understood. Its inherent advantages of flexibility, simplicity, low initial cost and minimal maintenance expense have yet to be fully exploited. Greater familiarity with the machine, together with a study of actual applications, will demonstrate that the design, correctly applied, can often result in certain advantages to the knowledgeable user.

Like almost any kind of machinery, the vertical turbine pump has its range of best operation, within which it pump has its range of best operation, within which it excels over other equipment and beyond which it may be misapplied. Comparison with other types of pumps illustrates relative performance within these limits.

Introduction

Having been trained to an analytical turn of mind, engineers normally could be assumed to understand and to apply the basic concept of machine efficiency. However, the term "efficiency" has been distorted in the pump business, occasionally beyond recognition, because of the widely divergent paths of machine development through unrelated branches of industry. The result is a noticeable tendency to apply different rules depending on the type of equipment to be evaluated.

The data in Fig. 1 came from a company well known in secondary recovery oil production and represent the operation of a waterflood injection pump station through a period in which equipment was changed from positive displacement (PD) machines to vertical turbine pumps. Note how the power cost per barrel of water pumped, a direct function of the machine efficiency, decreased sharply after the PD's were supplanted by the verticals at lower purchase cost and in far less space. Yet the plunger units purchase cost and in far less space. Yet the plunger units are rated at 95 percent efficiency in their industry while the vertical turbines operate at 83 percent in terms used by centrifugal pump manufacturers. In this paper we shall attempt to reconcile this seeming paradox and to offer a sound engineering basis for quantitative evaluation of efficiency ratings as well as general design and construction details.
Reservoir Simulation With a Control-Volume Finite-Element Method
Authors: Fung L. S.-K. , Hiebert A. D. , Nghiem L. X.
Published: December 2007

This paper describes a control-volume finite-element (CVFE) method incorporating linear triangular elements for the simulation of thermal multiphase flow in porous media. The technique adopts the usual finite-element shape functions to evaluate flow potentials at the control-volume boundaries and uses the conservation equations for each control volume. The main advantage of the CVFE method over the finite-difference method is in the representation of complex reservoir geometries. In addition, desirable features, such as local grid refinement for near-well resolution, can be achieved simply and consistently. The control-volume approach enforces local mass conservation and permits a direct physical interpretation of the resulting discrete equations. These are significant advantages over the classical Petrov-Galerkin or variational finite-element methods. The method was implemented in a general-purpose thermal simulator. Numerical examples compare the proposed method with five-point and nine-point finite-difference schemes in terms of grid-orientation effects and run time. The CVFE method was found to reduce grid-orientation effects significantly. At the same time, computational cost was much lower than for the nine-point scheme. The geometric flexibility of the method also is demonstrated.
Simulation of EOR Processes in Stochastically Generated Permeable Media
Authors: Waggoner J. R. , Castillo J. L. , Lake Larry W.
Published: December 2007

This paper deals with the competition between effects during miscible displacements through heterogeneous permeability media. Displacements with an even front are dispersive, others are a type of bypassing: fingering, caused by an adverse mobility ratio, or channeling, caused by heterogeneity and autocorrelation. Under most flow circumstances, channeling is the predominant type.
3D Simulation of Viscous Fingering and WAG Schemes
Authors: Christie M. A. , Muggeridge A. H. , Barley J. J.
Published: December 2007

Water-alternating-gas (WAG) injection has been suggested as a way to reduce viscous-fingering. This paper presents 3D simulations to assess the combined effects of gravity segregation in the vertical plane and areal viscous fingering for miscible displacements with substantial viscous fingering and for WAG injection. The simulations illustrate variations in recovery with WAG ratio and viscous-to-gravity ratio. A procedure to recalibrate the Todd and Longstaff parameter for WAG schemes in which buoyancy forces have little effect is described. Use of this recalibration provided excellent agreement with results from detailed simulation. Where gravity is important, recalibration of the parameter is required; examples of recalibration coarse-grid calculations are presented.
A New Double-Porosity Reservoir Model for Oil/Water Flow Problems
Authors: Dutra T. V. , Aziz Khalid
Published: December 2007

This paper presents a model that takes into account the transient nature of the imbibition process and the effect of variation in fracture saturation. Gravity effect is included in the calculation of the matrix equilibrium water saturation. This simple method requires only one equation per block per component. This is attained by an analytical transfer function that depends only on the fracture variables and by the assumption of instantaneous pressure equilibrium. The transfer function assumes that capillary pressure is the only driving force of the process and eliminates the matrix saturation from the fracture flow equations. The assumption of instantaneous pressure equilibrium eliminates the matrix pressure. The resulting model has the same form as standard single-porosity models. Results of the new model are compared with those from published laboratory experiments, very fine-grid simulations of matrix/fracture transfer for a single matrix block, and simulation of field-scale water-injection problems by standard double-porosity models. These results demonstrate that the new model provides an economical and accurate means of predicting the performance of fractured reservoirs.
Well Cooling by Down-Ho Circulation of Water
Authors: Keller H.H. , Couch Earl J.
Published: December 2007

Damage to production wells subjected to the high temperatures associated with in-situ combustion projects has been a problem since the advent of projects has been a problem since the advent of this thermal recovery technique. Injection of water down the annulus of hot wells has been successfully utilized for cooling and prolonging the life of such wells.

A mathematical model that is suitable for predicting the effectiveness of cooling water in a predicting the effectiveness of cooling water in a particular application is developed. Typical results particular application is developed. Typical results for practical ranges of the various parameters involved are presented.

Introduction

In the normal course of in-situ combustion operations, highly damaging conditions develop in the production wells as the combustion zone approaches, and these wells are subjected to high temperatures (up to 1500F). The resulting well damage is recognized as one of the more serious operating problems unique to the in- situ combustion process. Even in operations where well completions process. Even in operations where well completions have been specially designed to cope with this problem, the question arises as to how this problem, the question arises as to how this destructively high temperature can be kept within tolerable limits. A simple and economical approach to this problem is to circulate cooling water downhole. This method has been used with some success in shallow reservoirs. At greater depths, however, the heat exchange with the overburden surrounding the well and between the fluids in the tubing and the annulus tends to equalize the temperatures of the two fluid streams so that the cooling capacity delivered to the bottom of the hole decreases with well depth. This method would provide no appreciable control over the bottom-hole temperature at great depths.

In order to delimit the condition under which cooling by water circulation is effective, the wellbore temperature must be related to the waterinlet rate and temperature; to the reservoir depth, production rate, and initial temperature; and to the production rate, and initial temperature; and to the combustion temperature at bottom-hole depth. A model that meets these requirements and that will offer an approach for developing engineering solutions to practical design and operating problems is described in this paper.
Corrosion-Resistant Tubulars for Prolonging Gravity-Water-Injection Well Life
Authors: Farooqui M. A. S. Z. , Holland Scott
Published: December 2007

Failure resulting from corrosion in gravity-water-injection (GWI) wells is a major concern in the Abqaiq field, Saudi Arabia. This paper presents alternatives investigated to prolong the life of the wells, results of in-situ corrosion tests of 13% Cr steel alloy, and studies of the effect of coupling 13% Cr alloy with carbon steel.
A Simple Approximation to the Pseudoskin Factor Resulting From Restricted Entry
Authors: Vrbik Jan
Published: December 2007

Several procedures for computing the pseudoskin factor have been reported in the past, but they are either insufficiently accurate or require the use of a computer to perform the actual evaluation. This paper derives a simple formula that can achieve an accuracy quite sufficient for any practical application by means of a few approximations and use of an ordinary calculator.
Evaluating Gas Content of Black Warrior Basin Coalbeds From Wireline Log Data
Authors: Colson J. L.
Published: December 2007

Coalbeds have long been known to contain natural gas in varying amounts. To the mining industry, this is basically a hazard to be controlled and avoided where possible. To the petroleum industry, it is an exploitable resource that holds significant economic potential because of shallow drilling and the promise of long well life. The variability of coal as a gas reservoir raises the need for oil-and gas-well explorers to develop the capability of evaluating coalbed gas content to identify and produce coal gas plays.

Current petrophysical models for gas reservoir analysis in traditional clastic or carbonate environments are notably inadequate for evaluation of gas content in coalbeds. However, numerous physical models exist for coals throughout the country, primarily from the efforts of the mining industry. A theoretical model was chosen and used to establish a method for evaluating gas content of coalbeds in the Black Warrior basin of Alabama. Core data in the form of proximate analysis, ultimate analysis, and gas desorption measurements were used, along with wireline data, to build the models. Results of data analysis in wells with coals ranging from low-volatile bituminous to high-volatile B bituminous are compared with core gas desorption measurements to demonstrate the accuracy of the process.

The thin coals in the Black Warrior basin require high-resolution logging (especially neutron and density tools) to obtain acceptable results. Wireline computations on a prospective well can be obtained much sooner than core desorption measurements and can provide analyses in zones where samples were not recovered. Implementation of these techniques in conjunction with core measurements can help significantly in determining the economic viability of coalbed-methane prospects.
Reservoir Simulation Study of a Thermal Horizontal Well Pilot in the Cold Lake Oil Sands
Authors: Adegbesan K. O.
Published: December 2007

A reliable model was developed for evaluating and guiding the performance of horizontal wells in thermal operations to recover heavy oil in Cold Lake, Alta., Canada. The horizontal well model was developed with measured field data from the first thermal horizontal well pilot (HWPI) of Imperial Oil Resources Ltd.
Why Scale Forms in the Oil Field and Methods To Predict It
Authors: Oddo J. E. , Tomson M. B.
Published: December 2007

Predicting potential scaling problems can be difficult, and numerous saturation indices and computer algorithms have been developed to determine if, when, and where scaling will occur. The Langelier, Stiff-Davis, and the Oddo-Tomson saturation indices, all widely used in the oil field, are compared and contrasted relative to calcium carbonate scale. New saturation indices for barium, strontium, and calcium sulfate scale formation are introduced and discussed, along with an updated version of the Oddo-Tomson calcium carbonate index. An updated version of the CaCO3 saturation index is presented that includes correction terms for fugacity effects and changes in the solubility of CO2 in oil and gas wells as functions of temperature, pressure, water cut, and hydrocarbons present. The CaCO3 saturation index does not require a measured pH and can accommodate the presence of weak acids, such as H2S, and weak organic acids in the system. The sulfate scale prediction methods (for gypsum, hemihydrate, and anhydrite) are easy to use, reliable, and designed for field use by an operator who may be untrained in chemistry. The prediction methods can be applied to any production well where calcium carbonate, calcium sulfate, strontium sulfate, or barium sulfate scale occurs.
Field-Tested Model for Freeze Protection of Arctic Multiphase Pipelines
Authors: Eager Kelly
Published: December 2007

Freeze protection of water-bearing pipelines is an essential part of Arctic operations. Methods used to protect pipelines at the Prudhoe Bay field are discussed, including the development of an algorithm to predict the cooling times of multiphase flowlines and a field-tested program used to verify performance of the algorithm.

Introduction

The Prudhoe Bay oil field, located about 250 miles north of the Arctic Circle, is exposed to average winter temperatures of -35 degree Fahrenheit and below. Protecting outdoor pipelines from freeze damage is an integral part of field operation. Depending on the size, service, and location of an individual flowline, one or more methods can be used to protect it from freeze damage.

The field is laid out with centralized drilling and separation facilities, similar to large offshore fields. Wells are drilled from centralized well pads, with 10 to 50 production and injection wells tied to a common manifold. Commingled flow from the wellpad manifolds is routed to one of six central separation centers where crude is stabilized for shipment to the Trans-Alaska pipeline system. Produced water and pipeline system. Produced water and seawater, gas-lift gas, and miscible injectant are treated at the central plants and shipped to the well pads in cross-country flowlines. Injection fluids are routed to individual injection wells from the well-pad manifold. Pipelines between the wells and well-pad Pipelines between the wells and well-pad manifolds are called "well lines," and pipelines between central facilities and pipelines between central facilities and well pads are called "flowlines."

Freeze Protection Methods

When a pipeline is scheduled to be taken out of flowing service, or a production upset occurs, a reaction time is calculated. The reaction time is defined as the time required for ice to begin to form in the line minus the time required to protect the line. For example, in a water line to be protected by pigging, the reaction time is the estimated pigging, the reaction time is the estimated freeze time at current conditions minus the time required to displace water from the line with a gas-driven pig. Consideration of reaction times ensures adequate actions will be taken before the onset of freezing. Various protection methods were developed and protection methods were developed and tested as the field was developed and new facilities were added.

Fluid Displacement Methods. Displacement is a common means of protecting lines and can be completed by several different methods. Displacement of well lines with a heated water/methanol solution is used for production-well lines that are not level. The production-well lines that are not level. The solution is pumped into the line at the manifold building and the producing fluids are displaced to the wellhead and about 2,000 ft downhole to protect the wellbore from permafrost. Methanol displacement is the most common means of protecting shutin multiphase production and injection-well water lines.
In-Situ Stress Profiling and Prediction of Hydraulic Fracture Azimuth for the West Texas Canyon Sands Formation
Authors: Miller W. K. , Peterson R. E. , Stevens J. E. , Lackey C. B. , Harrison C. W.
Published: December 2007

This paper presents results of hydraulic fracture azimuth and in-situ stress measurements for two wells in the west Texas Canyon Sands formation. The paper gives information for designing infill drilling patterns and improving fracture treatment designs. Eight techniques were applied to measure fracture azimuth; the results from each are discussed. In-situ stress was measured in 12 intervals, and the results were used to calibrate long-spaced digital sonic logs. This paper also discusses the application of calibrated stress to fracture treatment design.
Reservoir Geometry and Internal Permeability Distribution in Fluvial, Tight, Gas Sandstones, Travis Peak Formation, Texas
Authors: Davies D. K. , Williams B. P. J. , Vessell R. K.
Published: December 2007

Reservoir dimensions and heterogeneities are predicted for sand bodies originating in meandering and braided fluvial channel systems. Diagenesis significantly alters original porosity and permeability characteristics in tight gas sandstones and operates within the sedimentary framework established at the time of deposition. Depositional environment therefore exercises fundamental control on reservoir dimensions and quality.
Rheological Modeling and Scale-Up of a Delayed-Crosslinked Gel in Nonhomogeneous Flow
Authors: Cameron J. R.
Published: December 2007

Previous work has shown that delayed-crosslinked fracturing fluids can flow as nonhomogeneous fluids in Couette and tubular geometries and therefore may exhibit nonhomogeneous flow in fractures. In this case, laboratory-measured power-law parameters no longer can be used for design without proper scale-up. Methods were evaluated for scaling data among Couette, tubular, and fracture (slot) geometries with a nonhomogeneous slip-flow model that avoids the limitations of a zero-thickness slip layer. The best scaling method uses a variable wall-fluid thickness that scales the apparent consistency index on the basis of equal wall-fluid volume per surface area at the same apparent shear rate. Data for an organometallic gel crosslinked at 400 seconds−1 and 70 seconds−1 were scaled successfully between Couettte and tubular geometries. Wall-fluid thicknesses of the gel crosslinked at 400 seconds−1 were about 0.015 cm and more shear-rate dependent than those for the gel crosslinked at 70 seconds−1, which were about 0.003 cm thick and nearly constant.
Performance Auditing System for Drilling Units and Platforms
Authors: Aardse Oscar A. , Houtman Karel L. , Zantkuijl Harrie
Published: December 2007

For a number of years, the drilling industry has measured a negative aspect, "lost time accidents" (LTA), to indicate the safety performance of a drilling unit or performance of a drilling unit or platform. The performance auditing platform. The performance auditing system presented here is a positive approach to measuring the safety performance of a drilling unit or performance of a drilling unit or platform. The system gives the rig owner platform. The system gives the rig owner indicators to help steer and improve safety management and an attractive incentive for crew to contribute to a safe drilling unit or platform.

Introduction

Although safety and health always have had considerable attention within our organization, the number of LTA's became unacceptably high in 1984. At that time, it was decided to restructure safety management within the company. A qualified nautical officer dedicated his time to set up a safety management system.

In this phase, safety policies and procedures were written for the operations procedures were written for the operations manual. The condition of the safety hardware on the drilling units was further improved. The available accident reports were reviewed, and the results showed that most accidents occurred on the rig floor. On the basis of this evaluation, management decided to install an automatic pipe-handling system for making up and breaking out tubulars on all drilling units.

These steps (new procedures and policies, better hardware, and drill-floor mechanization) resulted in a drastic improvement in the accident frequency rate. Also, considerable funds and manpower were made available for safety improvement drives and programs aimed to ensure the safety of the programs aimed to ensure the safety of the employees in their work environment. Safety programs covered a wide range of activities, such as on-the-job supervision, safety introductions for newcomers, in-house training courses on safe maintenance and operation of drilling equipment, regular safety hardware inspections, procedures to handle chemicals safely, anonymous near-miss reporting, accident investigation and analysis, emergency contingency plans, and engineering process control.

Periods without LTA's were rewarded with cash or gifts. A downward trend in the frequency rate continued until 1988, alter which the number of LTA's increased. The cause of this increase was not immediately identified. More accidents occurred worldwide, as reflected in an increase in the frequency rate.

New initiatives were launched in 1989 to curb this trend. A separate department put even more effort into safety and created a positive image of safety progress by means positive image of safety progress by means of the performance auditing system.
Incentive Drilling Contracts: A Logical Approach for Enhancement of Drilling Efficiency
Authors: Moomjian C. A.
Published: December 2007

Incentive drilling contracts historically have been based on the footage and turnkey concepts. Because these concepts have not been used widely in the international and offshore arenas, this paper discusses other innovative approaches to incentive contracts. Case studies of recently completed or current international and offshore contracts are presented to describe incentive projects based on a performance bonus (Case 1), lump sum per well (Case 2), target time and "cap" for a specified hole section (Case per well (Case 2), target time and "cap" for a specified hole section (Case 3), and per-well target time (Case 4). This paper concludes with a review and comparison of the case studies and a general discussion of factors that produce successful innovative incentive programs that enhance drilling produce successful innovative incentive programs that enhance drilling efficiency.
Permeability and Effective Pore Pressure of Shales
Authors: Chenevert M. E. , Sharma A. K.
Published: December 2007

Laboratory-derived permeability and pore-pressure data obtained for Wellington and Pierre shales are used to describe swelling pressure, and spalling types of wellbore instability. Tests showed that increased pore pressures can lead to wellbore failure. The laboratory pore-pressure information developed displays a time-dependent swelling process followed by a Darcy type of flow. A "total aqueous chemical potential" concept is presented that describes the driving potentials that operate during both phases of flow. Experimental methods are presented to determine the "storage" of water shale during the swelling phase and the permeabilities with steady-state-flow and transient-flow techniques. Permeability values measured under effective stresses up to 8, 000 psi show the Wellington shale to have values as low as 0.30 × 10−6 md.
Optimization of Rock-Bit Life Based on Bearing Failure Criteria
Authors: Fear M. J. , Thorogood J. L. , Whelehan O. P. , Williamson H. S.
Published: December 2007

Recent advances in rock bit seal technology have allowed greater predictability of bearing life. Cone loss following bearing failure incurs predictability of bearing life. Cone loss following bearing failure incurs costs related to remedial activities. A risk analysis approach, utilising hearing life relationships and the inter-dependence of drilling events, is used to formulate a bit run cost optimisation method. The procedure enables a choice to be made between elastomeric and metal seals on a lowest replacement cost basis. The technique also provides a formal method for assessing the opportunity cost for employing a device for the downhole detection of bit bearing failures.
Repairing Casing Leaks Using Small-Particle-Size Cement
Authors: Meek J. W. , Harris Kirk
Published: December 2007

Emerging small-particle-size cement technology has been applied successfully to one of the oil field's most frustrating problems, repairing tight casing leaks. Because of these leaks, a continuous injection rate cannot be established, yet test pressure leaks off 300 to 500 psi in 10 to 20 minutes. Confirmed through experimental data and more than 100 field operations, a new approach offers exceptionally high success rates for these troublesome leaks. This paper presents a detailed introduction to these new cement systems, along with comparative studies of small-particle-size cement vs. standard oilfield cements. This paper also discusses repair methods, several case histories, and field jobs performed to date.
Case History of an Opposed-Bore, Dual Horizontal Well in the Austin Chalk Formation of South Texas
Authors: Cooney M. F. , Rogers C. T. , Stacey E. S. , Stephens R. N.
Published: December 2007

Petro-Hunt Corp. used a unique horizontal-well design to optimize development of an irregularly shaped lease in the Austin Chalk formation in Texas. Two medium-radius horizontal bores were drilled in opposite directions from one vertical hole to maximize horizontal displacement in the lease. Underbalanced drilling techniques were used to prevent formation damage. The well design resulted in a significant cost savings per horizontal foot compared with 24 offset wells that the operator drilled. This paper reviews well planning and drilling and emphasizes techniques used to intersect thin horizontal targets and to initiate the second horizontal bore. Production results and drilling economics are discussed briefly, and ideas on future dual-horizontal-well applications are presented.
Operational Decision Making for Stuck-Pipe Incidents in the Gulf of Mexico: A Risk Economics Approach
Authors: Shivers R. M. , Domangue R. J.
Published: December 2007

The purpose of this study was to identify the most effective methods to free stuck pipe and to quantify the success rates of these methods under various wellbore conditions on the basis of historical data. This information has been integrated into a decisionmaking flow chart based on risk economics to determine when to begin and terminate operations to free stuck pipe.
Arctic Bioremediation—A Case Study
Authors: Liddell Bill V. , Smallbeck Donald R. , Ramert Paul C.
Published: December 2007

This paper discusses the use of bioremediation as an effective method to clean up diesel-range hydrocarbon spills in northern latitudes. The results of a laboratory study of microbial degradation of hydrocarbons under simulated arctic conditions showed that bioremediation can be effective in cold climates and led to the implementation of a large-scale field program. The results of 3 years of field testing have led to a significant reduction in diesel-range hydrocarbon concentrations in the contaminated area.
Experimental Phase Densities and Interfacial Tensions for a CO2/Synthetic-Oil and a CO2/Reservoir-Oil System
Authors: Gasem Khaled A. M. , Dickson Kenneth B. , Shaver Ronald D. , Robinson Robert L.
Published: December 2007

Experimental data are presented for equilibrium vapor and liquid densities and interfacial tensions (IFT's) for two multi-component mixtures. Data are presented at 120 and 150°F for a CO2/synthetic-oil (containing the n-paraffins, methane to tetradecane) and at 130°F for a CO2/recombined-reservoir-oil system. In both systems, measurements include the near-critical region, where IFT's become very low. These data should be useful in developing and testing models to predict phase behavior and IFT's for CO2 EOR operations.
Pressures, Hydrocarbon Accumulation, and Salinities Chocolate Bayou Field, Brazoria County, Texas
Authors: Fowler William A.
Published: December 2007

The hydrocarbon accumulation at Chocolate Bayou field appears to be intimately related to the fluid environments there. An understanding of the processes at work in this field can be used in planning the development of active fields where comparable fluid data are available.

Introduction

The Chocolate Bayou field is located in east-central Brazoria County, about 25 miles south of Houston, Tex. Production in the field is from Oligocene Frio sands ranging in depth from 8,600 to 12,200 ft. About half the approximately 2Tcf of gas reserves in the field is found in reservoirs with pressures substantially above hydrostatic. Data collected since the discovery of this field in 1939 permit an evaluation of the effects of abnormally high pressures on the migration and entrapment of hydrocarbons and the salinity of formation waters in the field. An understanding of the relationship between fluid properties and hydrocarbon entrapment in this field may be applicable to the development of other Gulf Coast fields.

Geology

The Chocolate Bayou field produces from a faulted anticline in the downdip Frio trend. A large growth fault divides the field into two producing areas. Fig. 1 shows the producing area of the field and the approximate location of the fault separating the two principal producing segments. The downthrown, eastern fault producing segments. The downthrown, eastern fault block produces from a closed anticlinal structure; the upthrown, western fault block produces from a closure against the regional fault crossing the field. A number of minor faults are present, but have little effect on the pattern of hydrocarbon accumulation in the field. The two major fault blocks are referred to as East Chocolate Bayou and West Chocolate Bayou in this paper. Structural maps of the field are given by Allen and Allen and Myers.

The producing Frio section is an alternating sand and shale sequence overlying a thick section of Oligocene and older shales. Above the Frio is the Anahuac shale wedge, which is about 2,200 ft thick in the field. About 6,500 ft of undifferentiated Miocene and younger massive sands interbedded with comparatively thin shales extends from the top of the Anahuac to the surface.

Radical changes in the lithology and thickness of the Frio section across the growth fault bisecting the field indicate that movement along this fault was contemporaneous with deposition of the Frio field pays. Movement continued intermittently along the fault during the deposition of the Anahuac shales and the lowermost Miocene sands. The increased Frio sand deposition in the area of the present structural high suggests that movement of the producing structure had already begun by Frio time. Uplift continued well into Miocene, where the feature is expressed as a faulted nose at depths as shallow as 6,000 ft. This long history of structural uplift has resulted in an increase of structural relief with depth and an abundance of minor faults associated with this structural deformation.

JPT

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Modular Development and Integration of a Corrosion Control System
Authors: Elder M. S. , D'Alves B. M.
Published: December 2007

This paper describes the consolidation and expansion of Saudi Aramco's computer systems used for capture and analysis of petroleum-facilities-related corrosion. Specifically, modular development techniques coupled with a prototyping methodology are highlighted as key contributors to the success of the project.

A mainframe resident Corrosion Control System (CCS) was developed through joint efforts between the Northern Area Producing Operations Engineering (NAPOE) and Petroleum Engineering Applications Services (PEAS) departments. CCS takes full advantage of Saudi Aramco's extensive computing network to manage data on corrosion coupons, water quality, bacteria, chemical use, and cathodic protection.

Selection of a centralized computer system over a distributed computing environment has yielded many benefits. The data management, user interface, and results presentation components are consistent. Remote users can take advantage of the installed computing infrastructure, workstations, and peripherals. The installed base of high-speed printers, color plotters, and slide equipment can be used easily for hard copy. Databases are virtually unlimited in size and are backed up daily during normal data center operations. Data entry is distributed to staff directly involved with data collection, thus conserving valuable engineering time for analysis. Finally, ongoing system development and maintenance functions are ensured through the designated computer support organization.

Experienced field engineers actively participated during CCS development to ensure that constructive feedback was available during prototype development. As with all computer systems, CCS is evolving to take advantage of proven technology to satisfy operational requirements.
Efficient Field-Computer File Transfer Methods for Suboptimum Conditions
Authors: Sisk L. B.
Published: December 2007

This paper describes a project to upgrade the file-transmission capabilities of a system using modem-linked PC’s to acquire production data in remote fields and subsequently transfer these data to an area production office for further processing. The method initially specified for accomplishing this task failed repeatedly under adverse conditions. After the modems and file-transfer software were replaced, communications became much more reliable, and the time required to transfer files was reduced by orders of magnitude, resulting in a corresponding reduction in telecommunications costs. The technology described is applicable to any computer-based system doing file transfers, particularly in areas with suboptimum telephone networks.
Effect of Wettability on Waterflood Recovery for Crude-Oil/Brine/Rock Systems
Authors: Jadhunandan P. P. , Morrow N. R.
Published: December 2007

This paper presents a definitive account of the effect of wettability on oil recovery from Berea sandstone based on the results of more than 50 slow-rate laboratory waterfloods. Closely reproducible wettability conditions and waterflood recoveries were obtained with wettability, depending on the crude oil, brine composition, aging temperature, and initial water saturation. Maximum oil recovery by waterflooding was obtained at very weakly water-wet conditions from shortly after breakthrough up to discontinuation of the test at 20 PV of water injected. In most of the tests, coproduction of oil and water continued long after breakthrough.
Base Number and Wetting Properties of Crude Oils
Authors: Dubey S. T. , Doe P. H.
Published: December 2007

Oil acid and base numbers influence wetting through their effect on electrostatic interactions with the mineral surface. An improved nonaqueous potentiometric titration has been developed that correctly quantifies weak bases in crude oils. In crude-oil/silica systems, wetting behavior correlates with base/acid ratio and is consistent with wetting theories based on disjoining pressure.
CO2 Huff 'n' Puff Revives Shallow Light-Oil-Depleted Reservoirs
Authors: Bardon Charles , Corlay Philippe , Longeron Daniel , Miller Bernard
Published: December 2007

Bretagne has experimented successfully with CO2 huff 'n' puff injection since 1985 in the Shoemaker field in Kentucky. Numerical simulations were performed with a compositional model to review and to quantify the influence of all parameters that could be responsible for the production improvement observed in the wells. Laboratory studies were conducted to get relevant physical data, particularly concerning relative permeabilities with three phases present. These data were integrated into the numerical model, giving good agreement with field results, and predicted production performance more accurately. Finally, the optimization of the huff 'n' puff process in Shoemaker is presented.
Responses of Commingled Systems With Mixed Inner and Outer Boundary Conditions Using Derivatives
Authors: Gao Chao , Jones Jack R. , Raghavan Rajagopal , Lee W. John
Published: December 2007

This work presents a spectrum of possible derivative responses in wells producing commingled reservoirs. Three issues pertaining to commingled reservoir buildup behavior are studied: (1) derivative responses for commingled systems, with emphasis on unequal layer radii; (2) pressure distributions in the layers with a view toward understanding backflow, particularly the origin of rate reversals during buildup; and (3) an application of Peaceman's probe radius formula to obtain pressure distributions in each layer at shut-in. Several approaches are developed from Issue 1 to estimate the areal extent of the smallest layer. Some general information that should be useful, or at least pertinent, to the design of production logging surveys is derived from Issue 2. Issue 3 also has application in miscible flooding for the location of areas below minimum miscibility pressure (MMP).
Gas-Lift Valve Performance Testing and Data Correlation
Authors: Decker K. L.
Published: December 2007

This paper presents a method for analyzing data from gas-lift valve performance tests. This method relies on the ability to determine the true dynamic stem position of the valve during flowing conditions. The types of tests required to obtain the data needed by this analysis method are explained. The data analysis method is applicable to any pressure-operated gas-lift valve and yields predictions within 10% of actual flow rate.
A Model for Estimating the Life of Electrical Submersible Pumps
Authors: Patterson M. M.
Published: December 2007

This paper presents a mathematical model to estimate the life expectancy of an electrical submersible pump (ESP). The premise uses a statistical method known as the "Poisson pure death process, " which calculates the probability of system failure on the basis of sparse data. The technique needs only one parameter and was tested on ESP failure data from a west Texas field.
New Continuous-Mix Process for Gelling Anhydrous Methanol Minimizes Hazards
Authors: Thompson J.E. , McBain C. , Gregory G. , Gerbrandt D.
Published: December 2007

This paper discusses a novel approach to well stimulation with anhydrous methanol-based fracturing-fluid that significantly reduces hazards to personnel and equipment during the fracturing process. Research is presented on the various chemical and engineering process technologies used to develop and evaluate continuously mixed anhydrous methanol fracturing-fluid performance. Field case histories are also discussed.

Introduction

Since the development of hydraulic fracturing technology as a well completion technique hazardous fluids frequently have been used. These fluids include refined oils, formation condensates, crude oils, acids, alcohols, and a variety of other chemicals and additives. Batch mixing is a common technique used to formulate fluids for fracturing applications. The fluid viscosity is adjusted to the desired level by circulating the base fluid through blending equipment while adding the polymeric gelling agents, buffers, and other chemicals. The fluid must circulate through the equipment many times for the fluid to develop the desired viscosity. When hazardous materials are handled in a multiple-circulation process, the potential for accidents is high.

Technological advances in recent years have provided sophisticated fracturing-fluid systems and field equipment, along with microprocessor systems that monitor and control the pumping treatment. These advances have been implemented without compromising the efficiency of the total operation. In many cases, the overall system performance improved significantly. For example, the development of oil-slurried polymer concentrates and polymer hydration units led to the widespread application of continuous-mix processes to mix fracturing fluids.

The damage characteristics of any fracturing-fluid system are of paramount importance to successful reservoir stimulation. Formations that have low bottomhole pressure or contain significant concentrations of water-sensitive clays are typically candidates for stimulation with non-water-based fracturing fluids. Problems with clay swelling and migration commonly are encountered in formations containing significant amounts of smectite and illite-type minerals. The degree of formation sensitivity depends on the concentration and type of clay components, clay or mixed clay orientation in the pore channel, and the ion balance between connate water and clay minerals. In low-permeability formations, capillary forces can have a significant effect on production rate and total hydrocarbon recovery. Capillary forces increase proportionally with the surface tension of the formation fluid. When the capillary forces exceed the formation-fluid driving force, a water block may occur. The use of methanol has long been recognized as an effective technique to remove formation water blockage. The miscibility of methanol with formation fluids reduces surface tension, which promotes removal of the water block and enhances fluid recovery.
Evaluation of Gas Hydrate Formation and Deposition in Condensate Pipelines: Pilot Plant Studies
Authors: Dholabhal P. D. , Kalogerakis Nicolas , Bishnol P. R.
Published: December 2007

A recirculation flow loop was operated to simulate the flow of light condensate oils in subsea pipelines at hydrate-forming conditions. Pressure drop across sections of the loop and the flow through the section were used to measure hydrate accumulation indirectly in addition to visual observations at a "see-through" section.
Surfactant-Based EOR Mediated by Naturally Occurring Microorganisms
Authors: Thomas C. P. , Duvall M. L. , Robertson E. P. , Barrett K. B. , Bala G. A.
Published: December 2007

Oil recovery experiments using Bacillus licheniformis JF-2 (ATCC 39307) and a sucrose-based nutrient were performed with Berea sandstone cores (permeability 0.084 to 0.503 μm [85 to 510 md]). Oil recovery efficiencies for four different crude oils (0.9396 to 0.8343 g/cm3 [19.1 to 38.1°APr|) varied from 2.8% to 42.6% of the waterflood residual oil. Microbial systems reduced interfacial tension (IFT) ≍20 mN/m [≍20 dyne/cm] for all oils tested. After the microbial flood experimentation, organisms were distributed throughout the core, with most cells near the outlet.
Examination of a Cored Hydraulic Fracture in a Deep Gas Well
Authors: Warpinski N. R. , Lorenz J. C. , Branagan P. T. , Myal F. R. , Gall B. L.
Published: December 2007

A hydraulic fracture stimulation conducted during 1983-84 in nonmarine, deltaic, Mesaverde strata at 7, 100 ft [2164 m] was cored in a deviated well in 1990. The observed fracture consists of two fracture intervals, both containing multiple fracture strands (30 and 8, respectively), abundant gel residue on the fracture surfaces, and many other complexities.
Injection-Above-Parting-Pressure Waterflood Pilot, Valhall Field, Norway
Authors: Ali Nazir , Singh P. K. , Peng C. P. , Shiralkar G. S. , Moschovidis Z. A. , Baack W. L.
Published: December 2007

This paper discusses the execution, analysis, and results of an unconventional waterflood pilot in a major, naturally fractured chalk, oil reservoir in the North Sea. Pilot operation above formation parting pressure (FPP) solved the low-injectivity problem but required use of new and innovative techniques to interpret and to predict pilot behavior properly.
Performance Review of Brazeau River Nisku Dry-Gas Miscible-Flood Projects
Authors: Lee Jong I. , Astete Ernesto L. , Jerhoff Tim F.
Published: December 2007

This paper reviews 10 years of dry-gas miscible-flood operations in three Brazeau River Nisku pinnacle reefs in Alberta. In addition, actual pool performance is compared with the original black-oil-model simulation forecasts. Through June 1991, the pools recovered 50% to 70% of original oil in place (OOIP), exceeding estimated waterflood recovery for each pool. Ultimate recoveries are expected to be 60% to 80% of OOIP, the range originally predicted.
A Single-Well Tracer Test With In-Situ-Generated CO2 as the Oil Tracer
Authors: Wellington S. L. , Richardson E. A.
Published: December 2007

A single-well tracer test (SWTT) that uses soluble amounts of in-situ-generated CO2 as the oil tracer is described. Water-soluble-only injectants simplify test interpretation and improve residual-oil-saturation (ROS) determination. The CO2-generator chemistry allows the test to be tailored over a wide range of injectivities and reservoir temperatures.
Aspects of Wellbore Heat Transfer During Two-Phase Flow
Authors: Hasan A. R. , Kabir C. S.
Published: December 2007

Wellbore fluid temperature is governed by the rate of heat loss from the wellbore to the surrounding formation, which in turn is a function of depth and production/injection time. We present an approach to estimate wellbore fluid temperature during steady-state twophase flow. The method incorporates a new solution of the thermal diffusivity equation and the effect of both conductive and convective heat transport for the wellbore/formation system. For the multiphase flow in the wellbore, the Hasan-Kabir model has been adapted, although other mechanistic models may be used. A field example is used to illustrate the fluid temperature calculation procedure and shows the importance of accounting for convection in the tubing/casing annulus. A sensitivity study shows that significant differences exist between the predicted wellhead temperature and the formation surface temperature and that the fluid temperature gradient is nonlinear. This study further shows that increased free gas lowers the wellhead temperature as a result of the Joule-Thompson effect. In such cases, the expression for fluid temperature developed earlier for single-phase flow should not be applied when multiphase flow is encountered. An appropriate expression is presented in this work for wellbores producing multiphase fluids.