bluuebunny/crossref_metadata_2025 huggingface dataset:
Water Input Profile Determinations on Injection Wells in Secondary Recovery Fields
Authors: Adamson Bliss , Brown Bob Diggs
Published: December 2007

The knowledge of the distribution of input water in injection wells is important to the success of water flood secondary recovery projects. The presence of thief formations, the lack of complete well history, and improper completion methods all contribute to diverting the flood water from the producing horizon. Through the use of known tools and procedures, input profiles can be obtained.

The interface velocity procedure coupled with caliper and correlation logs give satisfactory input profiles. These provide the data to detect the presence of the undesirable conditions and for the method of correction. Under normal conditions the correlations between profile data and permeability data from cores is good.

Introduction

The application of secondary recovery methods to oil production has spread rapidly throughout the oil fields of the United States. This has created a desire for greater knowledge of the behavior of the oil reservoir under a secondary recovery program. In the case of water flooding projects and particularly during the early stages of pilot flood work, it is important to know the water is being directed through the proper zone.

In a recent paper on secondary recovery water flood projects which had been classified as unsuccessful, it was shown that a considerably larger quantity of water had been injected than fluid recovered. This indicated that the flood water was going into zones which were not part of the oil reservoir. Confirmation of this was not established since no attempt had been made to determine the distribution of the input water into the zone being flooded.

The need for this type of information on many water flood projects has caused the secondary engineers to seek means of obtaining this data in an effort to better understand and evaluate their various floods.

This would require a procedure which would work satisfactorily on wells completed either through perforations, open hole, or shot hole under the following water flooding conditions, namely:Surface injection of flood waters under pressure;Surface injection of flood waters at atmospheric pressure;Dump flood wells using water for flooding from a zone above the oil reservoir.

In addition, any tool involved would have to be small enough to work through 2-in. tubing, since a large number of injection wells have tubing in them. In some cases it is not desirable and in others it is not possible to remove it.
Successful High-Temperature/High-Pressure Well Testing From a Semisubmersible Drilling Rig
Authors: Davidson A. R. , Prise Gavin , French Clive
Published: December 2007

In 1990, Hamilton Oil Co. Ltd. (HOC) drilled and tested three high-temperature/high-pressure (HTHP) wells from a semisubmersible drilling rig in the North Sea. This paper identifies the main pitfalls encountered when planning and implementing an HTHP well test with reference to three case histories. These cases demonstrate the benefits of defining a clear philosophy of safety and simplicity to test such wells successfully.
Components of Produced Water: A Compilation of Industry Studies
Authors: Stephenson M.T.
Published: December 2007

Produced water contains many different constituents. Each has a different impact on the environment when present in discharged water. All these components have been studied at various times and for diverse reasons by several organizations. These studies, which cover dispersed and soluble oil, radionuclides, production chemicals, and heavy metals, are brought together here production chemicals, and heavy metals, are brought together here along with new data to present a complete picture of produced water. Many constituents of produced water have no known environmental effects, while others have only minor effects. In general, produced water is not harmful in the offshore environment where produced water is not harmful in the offshore environment where more than adequate dilution occurs.

Introduction

Produced water is the largest waste-stream source in the entire Produced water is the largest waste-stream source in the entire E and P process. Over the economic lift: of a producing field, the volume of produced water can be more than 10 times the volume of hydrocarbon produced. With volumes of this magnitude, the disposal of produced water becomes very important to the operator and the environment. The preferred disposal method for produced water is the one that adequately protects the environment at the lowest cost to the operator. Regulatory constraints often limit the options of the operator to methods that may not be necessary for environmental protection.

In many onshore areas of the world, produced water is injected into underground formations that contain water unsuitable for human consumption. In other onshore areas, in many wetlands, and offshore, produced water is discharged to the environment. The discharge of such large volumes of waste into the environment has caused concerns about uncontrolled, irreversible, and dreadful pollution in both government agencies and nongovernment organizations. pollution in both government agencies and nongovernment organizations. The basic source of these concerns is a lack of knowledge about the constituents of produced water and their effects. The basic components of produced water can be grouped into the following main categories: oil, heavy metals, radionuclides, treating chemicals, salt, and dissolved oxygen.

Oil

Oil is the common term applied to organic material that is dispersed or dissolved in produced water at the time of discharge. Dispersed oil consists of small discrete droplets suspended in the water while dissolved or soluble oil is present in the dissolved form. All oilfield water-treating equipment in use today is designed to remove these droplets from the water under Stokes' law. These devices operate by taking advantage of the difference in density between oil droplets and water. In addition to density, the other main parameter of concern in this separation is the size of the oil droplet. According to Stokes' law, the velocity at which the oil droplet rises through the water also varies directly with the square of the droplet diameter.
Offshore Disposal of Oil-Based Drilling-Fluid Wastes An Environmentally Acceptable Solution
Authors: Malachosky Ed , Shannon B. E. , Jackson J. E. , Aubert W. G.
Published: December 2007

Oily cuttings and waste fluid are byproducts of oil-based drilling muds. In such difficult drilling environments as the Gulf of Mexico, where oil-based fluids often are preferred, personnel safety, environmental, and economic concerns are exacerbated by the necessity to transport these cuttings and fluids to shore for disposal. This paper describes a process for on-site preparation and subsequent disposal of a slurry of cuttings by annular pumping. The disposal includes all cuttings and waste oil mud generated during drilling with oil-based fluids. Wastes are displaced down a casing annulus and into permeable zones below the surface casing setting depth. Descriptions of environmental and safety problems arising from onshore disposal, benefits of annular pumping, and equipment used for slurry preparation and pumping are described. This technique eliminates the need for platform cuttings storage, cuttings transportation to shore, and the environmental effects of onshore disposal.
Wettability Determination and Its Effect on Recovery Efficiency
Authors: Donaldson Erle C. , Thomas Rex D. , Lorenz Philip B.
Published: December 2007

A quantitative method for measuring the wettability of porous media containing brine and crude oil has been developed by the USBM using capillary pressure curves determined with a centrifuge. These measurements were reproducible within a standard deviation of 8.2 percent. The determination of fractional wettability has been compared with a method involving a combination of imbibition and displacement. Results are in agreement qualitatively as to whether a sample was water-wet or oil-wet.

When tested with outcrop cores of Torpedo Sandstone, wetting tendencies of oils from widely different fields range from highly water-wet to almost neutral. Silicone-treated cores vary in extent of wettability in a predictable manner, becoming more oil-wet as the concentration of silicone used in core preparation is increased.

Wettability, used as a parameter in designing linear mathematical models for predicting recovery efficiency, is equal in significance to viscosity and permeability.

Introduction

Wettability is one of the major factors that influences oil recovery. The importance of maintaining a water-wet condition in a field under water drive has been discussed by many authors. These authors have shown that oil recovery, as a function of the water injected, is greater from water-wet cores than from oil-wet cores. A few authors have indicated that recovery from strongly water-wet or oil-wet cores is less than recovery from cores that are at some intermediate wettability. One reason that the significance of wettability to oil recovery is still being evaluated is because a quantitative measurement of wettability has not been available when crude oil is involved.
Automatic Subsurface Liquid Removal from Gas Wells
Authors: Holladay C.H.
Published: December 2007

One of the main problems of producing gas wells is the removal of the fluid that is produced from the formation with the gas. Unless the velocity of the gas flowing up the wellbore is sufficient to carry liquids with it, the liquids will fall back to bottom and "drown" the well out by creating a backpressure and permeability block on the formation face. Many methods have been developed to produce these fluids. Among the older methods are installing a pumping unit or periodically blowing the well to the atmosphere in order to obtain sufficient velocity to remove the liquids. The main disadvantages of these methods are that they rely on the continuing stability of the producing conditions such as line pressure, flow rate, and bottom-hole pressure. The water removal is initiated by a change in surface conditions, such as well-head pressure or flow rate, or by a time clock that is set by experience; but by the time this surface condition has been reached, the liquid has already started to drown the well and cause formation damage before the liquid removal is initiated. A new type of removal system has been developed that maintains a set fluid level in the annulus, regardless of producing rate or pressure.
Mobility Control Experience in the Joffre Viking Miscible CO2 Flood
Authors: Stephenson Derril J. , Graham Andrew G. , Luhning Richard W.
Published: December 2007

This paper discusses mobility control in the Joffre Viking field miscible CO2 flood. Since 1984, three injection strategies have been tried: water-alternating-CO2 (WACO2), continuous CO2, and simultaneous CO2 and water. The studies showed that simultaneous injection results in the best CO2 conformance. CO2-foam injection has also been investigated.
A Method for Handling Spatially Varying Fluid Properties in a Simulation Model for a Fissured Reservoir
Authors: Sibley W.P.
Published: December 2007

The high relief, fractured carbonate reservoirs of the Asmari formation in Iran have extremely thick oil columns, with a large vertical change of reservoir temperature. This large change results in a significant effect on reservoir fluid properties. In contrast, there is a remarkable uniformity of PVT properties on a horizontal plane. Therefore, to properties on a horizontal plane. Therefore, to obtain meaningful results from reservoir engineering studies, PVT properties must be carefully weighted vertically.

Intensive study of the known oil recovery mechanisms within these highly fissured systems resulted in a sophisticated reservoir simulation model. The model is programmed to include these recovery processes, which occur essentially in horizontal layers or zones. It also includes a technique for volumetrically weighting the large vertical variation of the PVT data. A description of this weighting process is the primary purpose of this paper.

Introduction

Oilfield structures found in Iran have been described as very long, high relief, assymmetrical anticlines that contain unusually thick oil columns (see Fig. 1). The oil reservoirs generally are capped with large primary gas accumulations and are often affected by natural water drive. Producing formations include the Asmari, Bangestan, and Khami carbonates, with the Asmari being by far the most common and prolific. Although some Asmari reservoirs have been discovered that contain sandstones interbedded within the limestones and dolomites, most reservoirs in Iran contain the bulk of the oil in compact carbonates that have been contorted and highly fractured during structural deformation. The resulting anticlinal oil accumulations are produced mainly from complex fracture systems, which apparently exist quite uniformly throughout the dense matrix.

Study of surface rocks, cores and well producibility show that well developed fissure producibility show that well developed fissure systems are responsible for the excellent fluid communication. Because the fissures contain relatively little oil, maintenance of such prolific rates is dependent upon rate of oil replenishment from the adjacent matrix. The various productive mechanisms determine the rate of replenishment and duration.
Modeling of Fractal Patterns in Matrix Acidizing and Their Impact on Well Performance
Authors: Frick Thomas P. , Kürmayr Thomas P. , Economides Michael J.
Published: December 2007

This paper describes a model where wormholes, the primary feature of carbonate acidizing, are considered as fractals. The influences of acid volume, injection rate, fractal dimension, porosity, and the ratio of undamaged to damaged permeabilities on well performance are studied. Exact expressions of post-treatment skin effects are developed for vertical and horizontal wells.
Revised Casing-Design Criteria for Exploration Wells Containing H2S
Authors: Marshall D. W. , Asahi Hitoshi , Ueno Masakatsu
Published: December 2007

Sour-service casing is designed to meet standards set by the Natl. Assn. of Corrosion Engineers (NACE), as outlined in detail in NACE Standard MR 0175-91. However, rigorous application of this standard to casing design in exploration wells containing H2S can result in very conservative designs. This paper describes empirical and theoretical results that show under which circumstances the NACE standard is too conservative or too lax. A revised set of criteria was developed from these data specifically for application to sour-service casing design in exploration drilling. The paper also describes the application of this technique to the drilling of high-pressure, high-temperature (HPHT) wells in the North Sea and shows how casing with minimum internal yield strengths of 125,000 psi [862 MPa] may be used in exploration wells that may contain sour gas.
The Effect of Heat on Some Mechanical Properties of Igneous Rocks
Authors: Barbish A.B. , Gardner G.H.F.
Published: December 2007

The elastic moduli of most igneous rocks are greatly reduced by heating and depend, at room temperature, on the highest temperature to which they have been previously heated. This phenomenon was investigated by measuring velocity, attenuation, bending strength, and point penetration as functions of moisture point penetration as functions of moisture content, pore pressure, confining pressure, and highest previous temperature for a series of gabbro samples from French Creek, Pa. it was concluded that heating introduces a system of macrocracks between grains that is distinct from a system of microcracks that exists within grains. Thus bending strength is reduced by the introduction of macrocracks, but resistance to indentation, which depends on the microcracks, is not.

It is suggested that from the measurement of velocity and attenuation alone, the macro and microcracks can be detected and distinguished.

Introduction

In 1937 J. M. Ide reported on how heat affects the elastic constants of a wide variety of rocks. He found that the constants (Young's modulus and Rigidity modulus, measured at room temperature) were permanently reduced to values determined by the highest temperature to which the rock had been previously heated. He suggested that this might be explained by the development of microcracks in the framework of the rock. The microcracks would be caused by the unequal expansion of the various minerals in the rock. The greatest reduction of elasticity occurred with gabbros, which are composed of roughly equal mixtures of feldspars and pyroxenes. Almost no reduction in the constants was found for limestones.

In more recent years a revival of interest in this subject has followed the development of high power laser beams. The destructive effect of laser beams has been attributed primarily to the rise in temperature of the irradiated rock. This has two effects. One is the initiation of macrocracks by the creation of large tensile stresses. The other is the reduction of elasticity by microcracks, as noted by Ide.
Sequential Measurement of Compressional and Shear Velocities of Rock Samples Under Triaxial Pressure
Authors: Desai K.P. , Helander D.P.
Published: December 2007

A laboratory measuring system was designed that can precisely and sequential measure both compressional and shear velocities of rock samples under identical conditions of stress distribution and stress history. This is required if accurate and realistic dynamic elastic properties of rocks are to be determined. The hysteresis effect on velocity pressure characteristics of rock was determined to pressure characteristics of rock was determined to illustrate this point. Lead titanate zirconate transducers were used for measuring compressional wave velocity, and AC-cut quartz transducers were used for measuring shear wave velocity. The system was tested using samples of standard material such as aluminum, steel, brass and lucite. Measurements obtained were accurate within 1 percent. percent. Compressional and shear velocities were measured sequentially on 10 samples of Berea sandstone and two samples of Bartlesville sandstone. It was found that 1. Both compressional and shear velocities increased with an increase in applied external pressure. pressure. 2. Compressional velocity depends upon both external (Pe) and internal (Pi) pressure. 3. Shear velocity depends only upon the differential pressure (Pne-Pe-Pi). 4. The nature of the fluid saturant had little effect on compressional velocity. 5. Shear velocity decreased with an increase in the density of the saturant. 6. The Berea sandstone indicated very little anisotropy. 7. The Bartlesville sandstone showed definite anisotropy.

Introduction

The various properties of an acoustic wave trainvelocity, amplitude, frequency, etc. may be modified, sometimes quite severely by the media through which the wave has traveled. This suggests the use of wave properties to determine, at least in part, the nature of the material through which the part, the nature of the material through which the wave has passed. To accomplish this successfully requires a reliable technique to for obtaining accurate values of all acoustic wave properties. One purpose of this paper is to describe a recently developed system that can precisely and sequentially record acoustic compressional and shear energies as functions both of time and of frequency. One example of the utility of this system is the accurate measurement of compressional and shear velocities through rock samples subjected to triaxial, i.e., simultaneous but independent vertical, circumferential and pore pressure. Since acoustic velocity and elasticity are closely interrelated, such a system would help to determine realistically the elastic properties of rock samples in the laboratory.
Integrated Well Performance and Analysis
Authors: Podio A. L. , McCoy J. N. , Becker Dieter
Published: December 2007

Computer acquisition, processing, and analysis of acoustic, dynamometer, and related data at the wellsite offer new capabilities in analyzing a well's performance.

A powerful lap-top computer is used in conjunction with a compact analog-to-digital (A/D) converter to acquire data from acoustic microphones, pressure transducers, load cells, accelerometers, motor current sensors, tachometers, and other transducers to analyze a pumping well's performance.

The system is used in conjunction with a gas gun, microphone, and pressure transducer to measure the annular liquid-level depth in a well acoustically. This measurement is combined with the casing pressure and the casing-pressure buildup rate to determine the producing bottomhole pressure (BHP). This flowing BHP is analyzed in conjunction with the reservoir pressure and an inflow performance model to establish the producing rate efficiency of the well.

The same equipment can be used with special software to acquire pressure-transient data. The computer is programmed to acquire data at a frequency specified by the operator. The computer automatically obtains the acoustic liquid-level depth measurement and the casing pressure. These data are processed to calculate the BHP as a function of test time. Conventional diagnostic plots [Horner, Miller-Dyes-Hutchinson (MDH), log-log, etc.] are presented at the wellsite to aid the operator in the analysis of the data and to determine appfopriate test completion time.

In beam-pumped wells the system is also used to perform dynamometer analysis by the acquisition of polished rod load, polished rod acceleration, and motor-current data. Accelerometer data are integrated to calculate polished-rod velocity and position. Conventional surface and pump dynamometer calculations allow presentation of results for a complete dynamometer analysis in the field.

All these data acquisition and analysis capabilities are available in one package. Software with operator prompts is used to aid in the proper acquisition and analysis of digital data. The acquired and processed digital field data are combined with a well database file and a pumping-unit library to assist the operator in obtaining a complete analysis of the well's performance.
Simulation of Paraffin Deposition in Reservoirs
Authors: Ring J. N. , Wattenbarger R. A. , Keating James F. , Peddlbhotla Sriram
Published: December 2007

Certain reservoirs have a recurring wellbore damage problem caused by deposition of solid paraffin particles in the pore space. This paper describes the simulation of the reservoir processes of paraffin precipitation, convection, and deposition. The effect of reservoir heating treatments is included.
Modeling Vertical and Horizontal Wells With Voronoi Grid
Authors: Palagi C. L. , Aziz Khalid
Published: December 2007

This paper discusses the treatment of wells in a flexible Voronoi grid. A new model problem is proposed to evaluate exact well indices for multiwell configurations and homogeneous reservoirs. A simplified model also is proposed and discussed. New exact and simplified well models for heterogeneous reservoirs are presented.
Role of Three-Hydrocarbon-Phase Flow in a Gas-Displacement Process
Authors: Mohanty K. K. , Masino W. H. , Ma T. D. , Nash L. J.
Published: December 2007

The objective of this work is to identify the role of three-hydrocarbon-phase flow in the displacement of a reservoir oil by light-hydrocarbon-gas mixtures (methane through n-butane). Slim-tube displacements were conducted with several hydrocarbon-gas mixtures. A compositional simulator capable of handling three nonaqueous phases was used to simulate these 1D displacements. Slim-tube experiments show that as dilution with lean gas increases, the displacements go from first-contact miscible to multicontact miscible to three-phase, 3ϕ, immiscible to two-phase, 2ϕ, immiscible. Recovery is high (> 85%) at high enrichment, but nonmonotonic with dilution. Simulation results mimic experimental slim-tube recovery and gas-breakthrough behavior qualitatively; especially the increase in oil recovery with increasing methane dilution of the solvent. High oil recoveries in the 3ϕ cases appear to be the result of condensation of solvent into the oil, resulting in (1) low oil viscosity and (2) effective displacement of oil by the second liquid phase that forms.
Predictive Theory for Viscous Fingering in Compositional Displacement
Authors: Blunt M. J. , Barker J. W. , Rubin Barry , Mansfield Mark , Culverwell I. D. , Christie M. A.
Published: December 2007

A theory of compositional viscous fingering with no adjustable parameters that reduces to the Todd and Longstaff model for miscible floods is presented. The theory gives excellent predictive agreement with simulation results for a wide range of recovery processes. The high-resolution compositional simulations used to validate the theory are the first to resolve viscous fingering adequately in flow other than miscible flow.
Acreage Portfolio Management
Authors: Schneider Georges
Published: December 2007

The need to manage U.K. North Sea acreage portfolios arises from fragmentation of holdings and complex partnerships. This management has generated friendly rationalization deals motivated by differences in perception of values and aimed at building up heartlands and balancing cash-flow forecasts. The business process includes identifying, evaluating, and negotiating deals. The economist plays a central role within the evaluation team and supports the negotiators.

Introduction

The U.K. North Sea has seen the emergence of acreage portfolio management in recent years. The resulting deals are made between companies that want to "rationalize" their acreage - i.e., to upgrade the value of their holdings through acquisitions and divestments while maintaining their overall position in the area. These companies often have well-established links within multiple joint-venture partnerships. The deals include conventional farm-ins and farm-outs and straightforward cash sales and purchases. They also include an increasing number of acreage swaps, which are a relatively new type of deal.

In the distribution of prospective acreage, most of the cards have been dealt and the many players now have to negotiate among themselves to improve their hands. These negotiations have to recognize the mutuality of interest between the parties to be successful. In this game, there can be many winners, with each player finding his niche eventually.

This article presents the situation in the U.K. North Sea and discusses how the deals are made and the role of the petroleum economist in the process. This article will have wider applications as other areas of the world reach maturity and look to the North Sea as a model.

Background: Setting the Scene

Acreage portfolio management has emerged from the distribution of license blocks among companies.

Overview: U.K. North Sea Acreage. In the U.K. continental shelf, licenses are awarded by the U.K. government, mainly on a discretionary basis, in license rounds held at regular intervals. These blocks are smaller than the Dutch or Norwegian blocks. Originally the area of a block was approximately 260 km2 in the far south and 200 km2 in the far north. After subdivision through partial relinquishments and subsequent reissues, however, the average block size is now around 120 km2. This decrease in size has increased the chance that discoveries will extend across block boundaries. At the end of 1990, 668 offshore blocks or subblocks resulting from relinquishments were under license in the North Sea part of the U.K. continental shelf. Another 70 blocks were awarded in the 12th round of licensing in May 1991.
3D Visualization for Improved Reservoir Characterization
Authors: Cairns Janet L. , Feldkamp Lynne D.
Published: December 2007

This paper demonstrates visualization, modeling, and data integration in a 3D stratigraphic framework achieved with a computer workstation. Displaying petrophysical data in three dimensions on a graphics computer allows the interpretation of facies distributions and reservoir quality necessary for effective exploitation. Interactive computer modeling allows the flexibility in both visualizing and calculating data parameters for predicting flow patterns and hydrocarbon recovery. This viewing allows identification of numerous relationships among reservoir parameters derived from core, well log, and seismic information, as well as the integration of rock, pore, and fluid-flow data quantified at varying scales. Finally, a 3D computer model provides a common platform for all exploitation disciplines to enhance characterization of the reservoir and to prepare for numerical simulation.
User-Led Approach to Information System Investments
Authors: Pferd J. W. , Fuller A. G.
Published: December 2007

Information-system (IS) expenditures for upstream E&P have come under strong review along with other overhead expenses. Increasing frustration with IS budgets and concern about their business value led Unocal Corp. to change the way it begins, manages, and implements IS projects. Successful IS investments are aligned with the goals and functions of work groups or business units and are balanced against other investments. The twin demands of business needs and sound technical design must be served together to achieve long-term success from IS investments. This paper describes project organizations and methods to achieve these two objectives.
Development, Distribution, and Utilization of Reservoir Engineering Workstation Software
Authors: Thomas L. K. , Evans C. E. , Sandoval R. K. , Reist R. D.
Published: December 2007

This paper describes the development of the reservoir engineering workstation (REW) that includes software for reservoir simulation modeling and interpretation, well-performance modeling, and other petroleum engineering functions. The REW software package is installed on a company-wide network that consists of one or more high-performance color workstations in domestic and overseas offices. The workstations are networked internationally through use of Ethernet. This network also allows communication to the Cray Y-MP 232 and IBM 3090 computers at the company's major offices. REW features graphical-user-interface (GUI) interfaces, X terminal access, interactive input with on-line context-sensitive help, data checking, and units conversion.
Digital Images of Core Photographs
Authors: Hall J. D. , Howard W. E.
Published: December 2007

Core photographs become more valuable when scanned and digitized into a database. The ability to zoom, enhance color contrasts, and compare directly with other log and well data allows details to be identified and interpreted that are barely visible on the original photographs. Examples of core images are shown that compare various photographic scales and scanning densities to illustrate effects on image quality. Core images are compared with microresistivity and acoustic images, demonstrating the interpretations available by combining various data sets. Thin-section and scanning electron microscope (SEM) images, which have been stored in the same database, are also displayed. Steps to create digital images of core photographs, including core preparation, photography, and data-set transfer, are discussed. High-quality digital images produce large blocks of data. Data-set sizes are compared for variations in scanning density, photographic scale, and color resolution. Some applications that use quantified image data, including thin-bed corrections, definition of pore geometry, and improved relative depth control, are discussed.
Computer Networks and Advanced Communications: Weighing the Pros and Cons
Authors: Koederitz W. L. , Macon B. S.
Published: December 2007

One main method for optimizing computer usage is networking. However, for those who are contemplating a change from standalone computers to a network system, investigation of actual networks in use presents a paradox: network systems can be highly productive and beneficial, but they can create many complex, frustrating problems. The issue becomes a question of whether the benefits of networking are worth the extra effort and cost.

Here we review the implementation and management of an actual network in the Louisiana State U. (LSU) Petroleum Engineering Dept. The network, which has been in operation 4 years, is large and diverse (50 computers, 2 sites, PC's, UNIX RISC workstations, etc.). The benefits, costs, and method of operation of this network are described, and an effort is made to weigh these elements objectively from the viewpoint of the average computer user. Our intent is to provide those who may be considering the change to a network system with the benefit of experience gained in the actual operation of such a system.
Coiled-Tubing Drilling
Authors: Leising Larry J. , Newman Kenneth R.
Published: December 2007

In the 1980's, a "coiled-tubing revolution" began when coiled-tubing services were expanded to include most workover services. In 1991, this revolution expanded to include openhole drilling with a coiled-tubing unit (CTU) in place of a drilling rig. This paper discusses the design process and the limits associated with the use of coiled tubing (CT) to drill new wells and horizontal re-entry wells.
Oil Recovery from Fracture Blocks by Cyclic Injection
Authors: Felsenthal M. , Ferrell H.H.
Published: December 2007

Results obtained from a number of laboratory tests confirm the previously proposed idea that a cyclic pressuring/depressuring process in fractured pressuring/depressuring process in fractured reservoirs may have considerable merit over conventional waterflooding. A new idea brought out by our tests is that conservation of reservoir gas and supplementary gas injection appear to be necessary for the success of pressure pulsing in applicable reservoirs. We conducted laboratory experiments on 1- and 2-ft square X 2-in. thick limestone and sandstone "fracture matrix blocks," surrounded on all four sides by vertical fractures, and simulating portions of a naturally fractured reservoir. Results of the experiments were meant to apply as well to reservoirs dissected by networks of interconnected vugs, solution channels or stringers of large diameter pores. The sandstone was Berea outcrop (permeability to air, about 200 md; porosity, about 20 percent) and the limestone was Indiana limestone (permeability to air, about 10 md; porosity, about 18 percent). The blocks were first saturated with 50,000 ppm NaCl brine and oil-flooded to irreducible water saturation (Swi) by 80 pale oil. The 80 pale oil then was displaced by Soltrol-ethane mixture (bubble point, 300 psig; Bo, 1.3) at a displacement pressure point, 300 psig; Bo, 1.3) at a displacement pressure of 400 psig. The resulting average Swi equaled 29 percent of pore space. Pressure was lowered from 400 percent of pore space. Pressure was lowered from 400 psig to 100 psig in gradual steps to obtain primary psig to 100 psig in gradual steps to obtain primary oil production.

P. 141
A Note on the Theory of Temperature Logging
Authors: Romero-Juarez Antonio
Published: December 2007

Interest in temperature logs has been renewed recently. One of the main problems of temperature logs in injection wells is that of determining the zones that are taking fluids. A great step toward solving this problem has been reported in a recent paper. paper. The purpose of this paper is to point out another aim of temperature logging namely, that of relating the flow rate in water injection wells to some characteristics of the temperature logs. It has been stated that a factor of 6:1 gives approximate values in converting into B/D. The factor F, which has been found empirically, may be explained from theoretical considerations and because of this, it may be estimated more accurately. It has been shown that, for flow of a liquid

,............................(1)

where

.......................(2)

a quantity that is different from zero. Eq. 1 can be written as

,..................................(3)

which shows that, as is defined in Ref. 2, is identical to A. For injection down casing, the over-all heat transfer coefficient, U, may be considered infinite. Therefore,

...................................(4)

Considering the wellbore as a linear point source,

....................(5)

or, if

........................................(6)

.......................(7)

It has been observed that surprisingly good results are obtained by using the values

k = 33.6 Btu/day-ft-F

and

a = 0.96 sq ft/day

for different locations. Taking the values

p = 350 lb/bbl, c = 1 Btu/lb-F,

one obtains:

........................(8)

It should be noted that the lower curve of Fig. 1 of Ref. 3 does not agree, for low values of t, with the solution

.........................(9)

corresponding to the constant heat flux line source and for this reason the graph should be used with caution. Eq. 8 has been plotted in Fig. 1 for three values of the external radius r'. It may be used to estimate the rate of water injection down casing from the shape of the injecting temperature log above the zone of entry of fluids.

P. 375
New, Simple Completion Methods for Horizontal Wells Improve Production Performance in High-Permeability Thin Oil Zones
Authors: Brekke Kristian , Lien S. C.
Published: December 2007

Simple alterations to the completion can be used to enhance the performance of long horizontal wells producing from high-permeability formations. Production performance and operational feasibility of the investigated completion methods are compared. The methods should be considered for horizontal wells where frictional pressure losses along the perforated section restrict production performance.
An Experimental Study of Two-Phase Slug Flow in Hilly Terrain Pipelines
Authors: Zheng G. H. , Brill J. P. , Shoham Ovadia
Published: December 2007

Experiments were conducted in a 76.2-mm diameter, 420-m long two-phase flow loop to study slug flow behavior in hilly terrain pipelines. Complex physical phenomena were observed, including generation of pseudoslugs at the horizontal/uphill elbow, variation of slug length along the pipeline, and persistent existence of slug flow in the downhill section.
Depth Constraint of Electric Submersible Pumps
Authors: Powers Maston L.
Published: December 2007

This paper summarizes the various factors that limit electric submersible pump (ESP) operation at increasing depth. It explores in detail two parametrically related constraints, pump-shaft horsepower capacity and thrust-bearing load capacity. The former limits the product of head and rate; the latter limits head. Optimum shaft diameter for standard-configuration pumps is shown to be a compromise between these two factors. Head and rate limits resulting from these constraints are mathematically defined and graphically displayed, and means for expanding deep pumping capabilities are discussed. This paper also analyzes the effect of increased pumping depth on motor cooling. It shows that the temperature increase of fluid traversing a motor is proportional to head, independent of rate, and very sensitive to pump and motor efficiencies. This work also demonstrates the effect of elevated fluid temperatures associated with increasing depth on motor heat transfer coefficients.

The purpose of this paper is to help resolve a perceived dilemma. Pump manufacturers do not develop pumps with ultradeep capability because there is no market for them. Oil producers might abandon ultradeep discovery wells with low reservoir pressure because there is no way to pump them. This paper is intended to promote the interest of both groups in potential deep pumping capabilities.
Development of Analytical Design Equation for Gas Pipelines
Authors: Tian Shifeng , Adewumi Michael A.
Published: December 2007

Based on mass and momentum balance, a rigorous analytical equation is derived for compressible fluid flow in pipelines. This equation gives a functional relationship between flow rate, inlet pressure, and outlet pressure. It is very useful in design calculations where any of these variables need to be estimated if the others are given. The equation can be used for any pipeline topology and configuration, including size and orientation. A number of problems of engineering importance are studied with this equation. They include bottomhole pressure (BHP) calculations in gas wells, gas injection calculations, and long-distance gas pipeline design calculations. The excellent agreement between predicted results and field data, with this equation for this wide variety of problems and conditions, demonstrate the efficacy of this equation for engineering applications. Simple computer programs, in both FORTRAN and BASIC, are developed to handle these applications. The BASIC program can be run on any programmable calculator with 3 kilobytes of memory.
Waterflood Improvement in the Permian Basin: Impact of In-Situ-Stress Evaluations
Authors: Nolen-Hoeksema R. C. , Avasthi J. M. , Pape W. C. , Rabaa A. W. M. El
Published: December 2007

We evaluated in-situ-stress magnitudes and directions to support waterflood improvement programs in McElroy field and North Westbrook Unit. In-situ-stress and hydraulic-fracture directions coincided with directional floodwater effects. This information contributed to successful waterflood realignment programs.
Economic Assessment of Applying Advances in Fracturing Technology
Authors: Voneiff G.W. , Holditch S.A.
Published: December 2007

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering.

To obtain optimal results from the fracturing process, several new fracturing technologies can be applied to prevent inappropriate stimulation designs and catastrophic fracture-fluid problems. Despite industry awareness of these technologies, they are not applied routinely because of their added expense. In addition, the benefits are difficult to quantify and often are not clearly understood. In this paper, we present an economic assessment of fracture-treatment quality control, in-situ stress profiling, and 3Dfracture-propagation models that indicates that these technologies increase gas reserves by 10% to 20% for a 5% to 10% increase in the well cost. The application of these technologies is profitable when the formation gas permeability is between 0.001 and 0.3 md.

Introduction

In recent years, hydraulic fracturing research performed by the Gas Research Inst. (GRI) and other industry organizations has generated a wealth of new technology, including the GRI Mobile Testing and Control Facility, the GRI Rheology Unit, FRACPRO (a 3D fracture design program), the Treatment Analysis Unit, procedures for developing in-situ stress profiles, and microseismic processing techniques to determine fracture height and azimuth. Also, field experiments performed on Cooperative Research and Staged Field Experiment (SFE) wells have provided comprehensive data sets for developing and testing new ideas.

Our field research shows that the in-situ stress contrasts between rock layers and fracture-fluid viscosity are often quite different from the values assumed or estimated by the design engineer. Errors in assumed values of the in-situ stress contrast lead to inaccurate reservoir descriptions and inappropriate stimulation designs. Fracture-fluid problems compound the situation through poor proppant transport or fracture plugging with unbrokengel.
Screening of Crude Oils for Asphalt Precipitation: Theory, Practice, and the Selection of Inhibitors
Authors: de Boer R. B. , Leerlooyer Klaas , Eigner M. R. P. , van Bergen A. R. D.
Published: December 2007

This paper describes a simple method to screen crude oils for their tendency to precipitate asphalt, which may cause problems during production. The method is based on a thermodynamic model of asphalt solubility, derived earlier by Flory and Huggins. The most important parameters in this model are the Hildebrand solubility parameters for oil and asphaltene, and their molar volumes. The oil parameters can all be correlated with the in-situ density of the crude.

The relative change in asphalt solubility in the crude per unit pressure drop is shown to be highest for light crudes that are undersatu-rated with gas, which usually contain only a small amount of asphaltenes. Hence, the chance that asphalt will precipitate will be greatest for these light crudes. For pressures below the bubblepoint, depres-surising of the crude will cause a rapid increase in asphalt solubility, due to changes in liquid composition.

It is shown that heavy crudes usually will give fewer problems with asphalt precipitation, despite their higher asphaltene content, certainly if the reservoir pressure is close to bubblepoint pressure.

Consequently, the tendency for asphalt precipitation is mainly determined by three parameters: the extent to which the crude is under-saturated with gas, the density of the crude at reservoir conditions, and its saturation with asphalt at downhole conditions.

Apart from the simple screening method, more elaborate methods are described to assess the potential for asphalt precipitation more accurately; asphaltene analysis on produced reservoir fluid and tank oil; n-heptane titration of the tank oil; visual inspection of a bottom-hole sample in a high-pressure cell during pressure reduction; and dynamic flow tests on tank oil after η-heptane addition.

An ultrasonic back scattering technique is described for monitoring the influence of different asphalt precipitation inhibitors. Using above techniques asphalt precipitation inhibitors have been identified that can be applied in the field.
Propped Fracturing as a Tool for Sand Control and Reservoir Management
Authors: Bale Arthur , Owren Kjell , Smith Michael B.
Published: December 2007

Hydraulic fracturing has historically been a prime engineering tool for improving well producing rates, either by circumventing near-well damage or by stimulating well performance. This paper describes a somewhat new fracturing application where increasing rate was not the primary goal. In this case, the goal for fracturing was modification of the flow profile to allow a more uniform vertical production profile and thereby maximize sand-free rates over the perforated section of the reservoir. In best cases for such applications, this technique allows perforating of "weak" rock to be skipped, reduces risks of sand production, and allows greater wellbore drawdown through perforated intervals in more competent reservoir rock. This allows better long-term productivity and improved recovery and total project economics. In short, it was hoped that propped fractures would improve reservoir management of the Etive/ Rannoch formations in the Gullfaks field.
Reservoir Compartmentalization Assessed With Fluid Compositional Data
Authors: Smalley P. Craig , England William A.
Published: December 2007

Fluid composition is a valuable addition to the battery of "static" data available during reservoir appraisal that can be used to predict the dynamic behavior of the reservoir later in field life. This is because fluid data are not truly static; natural fluid mixing is a dynamic process that occurs over a long (geologic) time scale. Oil compositional differences, especially those that parallel changes in density, should be mixed rapidly by convection; their preservation indicates barriers to fluid flow. Water variations, now measurable on conventional core samples by use of residual salt analysis (RSA), help identify barriers to vertical fluid flow in oil and water legs.