bluuebunny/crossref_metadata_2025 huggingface dataset:
Rov Transportable Tool. Packages For Subsea Component Replacement
Authors: Chilton T. S , Pejaver D. R , White J.
Published: December 2007

Esso Exploration and Production UK Limited is undertaking a multi-year design development and component prototype testing programme at a cost of €4 M to €5 M pounds sterling. The objective of the programme, known as the Esso Deepwater Integrated Production System (EDIPS) development programme is to ensure that Esso has the production technology available for commercial development of potential deepwater discoveries in the UK. The paper, after providing a brief overview of the total project, focuses on the description of innovative designs for the diverless maintenance of valves and control pods on subsea installations.

While diverless maintenance capability is a must in deep water, simple systems that can be deployed using remotely operated vehicles (ROVs) can be cost effective in all water depths ranging from a few hundred to several thousand feet. This paper describes such ROV transportable systems being developed by Furness Underwater Engineering Limited and Wharton Williams Limited under contract to Esso. The work is being done under the technical stewardship and coordination of Esso's research affiliate, Exxon Production Research Company, and draws on Esso's prior expertise on diverless maintenance system design.

The objective of the work described is to develop detailed designs for the tool packages and undertake in-water prototype testing, if required, to gain confidence in the technology for commercial application. Cost effectiveness of the system is improved by the use of commercially available ROV systems and by designing the valve and pod replacement tool packages to handle a range of valve and pod sizes, respectively.
Development and Use of a Drilling Applications Module for a Programmable Hand-Held Calculator
Authors: Brewton J. , Rau W. E. , Dearing H. L.
Published: December 2007

The development of software for drilling applications has in recent years concentrated on mini and micro computer systems. While these systems have obvious uses in drilling departments, a low cost programmable calculator can perform many of the calculations needed in the office and at the rigsite with the development of an appropriate software system. This paper describes the development and use of a drilling applications module for the HP-41 calculator.

This applications module is novel in that it utilizes a 32k EPROM (Erasable, Programmable, Read Only Memory) and is designed with a standard program/user interface that is consistent throughout all programs. It's programming takes advantage of several advanced features of the HP-41 calculator in order to make the system "user friendly".

There has never been a greater need to increase productivity and reduce costs at the rigsite. The HP-41 software module described in this paper provides the "drilling man on location" with a powerful tool that can help him significantly impact well costs.
Field Comparison of 2-D and 3-D Methods for the Borehole Friction Evaluation in Directional Wells
Authors: Maidla E. E. , Wojtanowicz A. K.
Published: December 2007

The two new general procedures for the borehole drag prediction, based on the borehole friction factor concept were compared. The procedures employed iteration over the directional survey stations, numerical integration between the stations and mathematical models of the axial loads within a moving pipe in the borehole. The models considered several new effects such as hydrodynamic viscous drag, contact surface, and the bearing angle component of dogleg severity.

The study addressed the extent and conditions under which the two-dimensional and the three-dimensional procedures diverged significantly. The method was based on the computer calculated values of the borehole friction factor from the measured hook loads. The field data used included four casing runs from the offshore locations in the Gulf Coast area. In addition, the systematic theoretical study was performed with over 100 computer-simulated directional wells.

The study revealed a good agrement between 2-D and 3-D procedures for most common drilling conditions. Two 2-D model's accuracy was mostly affected by the bearing angle component of shallow doglegs. In addition, the reliability of the borehole friction factor field assessment was mainly controlled by the inclination angle and the length of the slant hole section of a well.
Effect of Natural Repressurization of Thawed Permafrost on Strain of Surface Casing for Prudhoe Bay Infill Wells
Authors: Perkins T. K. , Weingarten J. S. , Bohon W. M.
Published: December 2007

When hot oil is produced through closely spaced wells that penetrate a permafrost zone, large thawed regions can be created. Thawing initially produces a sudden, large decrease in permafrost pore pressure; this results in compaction of the soil and strain in the casing. Induced pipe strains initially increase with time as the thaw front expands. Later, water flows into the thawed region from above and below the permafrost and repressures the pore space. Repressurization limits the induced casing strain, thus permitting the selection of adequate permafrost casing from a number of conventional casings.
Roller Bit Model With Rock Ductility and Cone Offset
Authors: Winters W. J. , Warren T. M. , Onyia E. C.
Published: December 2007

This paper presents a model which relates roller bit penetration rates to the bit design, the operating conditions, and the rock mechanics. Rock ductility is identified as a major influence on bit performance. Cone offset is recognized as an important design feature for drilling ductile rock.

Each roller bit style is characterized via a laboratory drilling procedure. Mechanical behavior of the laboratory rocks is characterized via triaxial compression tests. The model relates these factors to predict the drilling response of each bit under reasonable combinations of operating conditions. Decomposition of the model provides a quantitative analysis of the bit mechanics.

The roller bit model provides two modes of field application. First, field data can be interpreted to generate a continuous rock strength log. These strengths correlate closely to the triaxial compressive strength of the rock at a confining pressure that is equal to the effective bottomhole differential pressure. The rock strength log can then be utilized to predict and interpret roller bit performance in offset wells.
Viscous Fingering Utilizing Probabilistic Simulation
Authors: King M. J.
Published: December 2007

The local variations and fluctuations in fluid flow through porous media constantly excite the instabilities of a laboratory or reservoir flood. If the flooding process is dynamically stable, then the fluctuations will decay. Alternatively, the local fluctuations may grow to macroscopic size (viscous fingers). The method of probabilistic simulation (SPE #14366) includes fluctuations, and provides a computational framework for assessing fluid flow stability. Viscous fingers are produced by unstable floods. Stable floods exhibit smooth solutions, despite the ability of the method to naturally incorporate noise.

Solvent (miscible) flood is examined in detail. Scaling of breakthrough recovery, and its dependence on mobility ratio, M, is determined for .1 < M < 1000. Unstable floods self-stabilize on sufficiently fine grids; the cross-over to stable flow depends upon M.

The probabilistic algorithm of SPE #14366 is generalized to include the effects of physical dispersion, capillary pressure, and permeability heterogeneity. As expected, solvent flood is stabilized by the inclusion of sufficient amounts of physical dispersion.

Waterflood (immiscible flood) is examined including the effects of capillary pressure and spatial heterogeneity. The stabilizing effects of relative permeability and of capillary pressure are demonstrated. Correlated permeability variations lead to flow channelling. A low tension flood is demonstrated utilizing a simple modification of a waterflood.
The Nature of CO2-Induced Organic Deposition.
Authors: Monger T. G. , Fu J. C.
Published: December 2007

This paper is an experimental investigation of reservoir parameters which influence CO2-induced organic deposition. A prototype high pressure/temperature apparatus is described which quantifies the onset and duration of heavy hydrocarbon flocculation, the extent of organic precipitation, and the alteration of wettability in porous media traps. CO2 is contrasted with pentane as a precipitating agent. Stainless steel filters were used to ascertain the role of miscibility, and to examine oil compositional effects. Native and treated Berea cores were utilized to probe the effects of initial rock wettability, brine, and clay activity.

The results show that CO2-induced organic deposition resembles asphaltene precipitation by n-paraffins. Significant distinctions include that deposition using CO2 can be more extensive, is less abrupt, and is associated with liquid-liquid phase equilibria rather than the bubblepoint. The extent of CO2-induced organic deposition correlates with pressure and temperature as they relate to the development of miscibility. Deposition caused by CO2 was somewhat inhibited by rich gas. Sufficient levels of CO2-induced organic deposition typically made Berea cores less water wet and more oil wet regardless of the initial core wettability. Native cores could be altered to a mixed-wettability condition, and artificially neutral cores became strongly oil wet. The presence of brine reduced but did not eliminate CO2-induced organic deposition in strongly water-wet cores. Clays appear to be important deposition sites.
Displacement Behavior of the Condensing/Vaporizing Gas Drive Process
Authors: Stalkup F. I.
Published: December 2007

There is mounting evidence for some reservoir fluids that phase behavior in condensing-gas drives departs substantially from traditional concepts deduced for three-component fluids and that transition-zone compositions are established by a condensing/vaporizing mechanism rather than by condensation alone. To what extent does displacement behavior depart from traditional concepts as well and what is the significance of any departures? This paper addresses these questions through a series of compositional simulations for displacement in a one-dimensional slim-tube.

The simulations show that displacement behavior for a reservoir fluid does not depart substantially from traditional condensing-gas drive concepts for three-components even though the transition-zone building mechanism is one of condensation/vaporization. They show that when injection gas enrichment exceeds a critical value, displacement behavior of the reservoir fluid becomes miscible-like in the following important respects: 1) recovery is essentially 100% after one pore volume of injection in the limit of no dispersion, and 2) for a realistic level of dispersion, recovery at 1.2 pore volumes injected is insensitive to both relative permeability and relative permeability end-point saturation. Also, as with traditional concepts, the critical enrichment can be determined from slim-tube displacements by finding the point of breakover in a plot of oil recovery at 1.2 PV of injection vs. gas enrichment. However, with the reservoir oil, gases enriched above the critical value show a converging/diverging type of phase behavior on a pseudoternary diagram, and they leave a residual oil saturation, both of which are contrary to traditional concepts. The magnitude of the residual oil saturation depends primarily on mixing caused by diffusion/dispersion and should be relatively small, less than about 5% PV, in reservoir floods and even less in slim-tube displacements.

All the simulations were highly sensitive to the number of grid blocks used to model the slim-tube. This effect must be accounted for when simulated slim-tube behavior is compared with experiments, and it must be addressed in reservoir simulations. Simulations of 20% HCPV enriched-gas slugs driven by water show that a very high level of mixing shifts the point of optimum solvent enrichment to higher values. Numerical dispersion will cause this shift, even in simulations with as many as 100 grid blocks representing displacement length. Whether or not physical dispersion in the reservoir is great enough to cause it is an unanswered question.
Early Performance of a Large Hydrocarbon Miscible Flood at the Mitsue Field, Alberta
Authors: Omoregie Z. S. , Jackson G. R.
Published: December 2007

The early performance of Stage 1 of a large three-stage hydrocarbon miscible flood project at the Mitsue field, Alberta, Canada, is presented. The project area was almost completely waterflooded before project initiation. Hence, this is largely a tertiary oil recovery project. The incremental recovery due to infill drilling is discussed. Project and individual well responses to solvent injection are presented and discussed. The performance of the observation well confirmed the ability of the injected solvent to mobilize tertiary oil. Other producing wells have since shown similar responses to solvent injection. Composition and production data are presented for the observation well. Asphaltene precipitation problems in producing wells and profile control measures taken to improve vertical sweep efficiency are documented. The project is already an economic success. Projections of future project performance are made in the light of performance to date.
Mechanism of Microgel Formation in Xanthan Biopolymer Solutions
Authors: Kolodziej E. J.
Published: December 2007

A crucial concern in using Xanthan biopolymers for EOR applications is the susceptibility of the biopolymer to formation plugging. One particular plugging problem of interest is that of microgels. This microgel plugging problem has been studied in detail by others1,2,3,4, yet several key issues have remained unresolved. Two such issues include: an adequate description of what a microgel actually is, and a physical mechanism of how a microgel is formed. These issues are specifically addressed in this paper. Several interesting results are described in the paper, which indicate that the formation of microgels is dependent on two critical components – denatured proteins and salt. A mechanism is proposed to explain the role of these components in the formation of microgels.
Estimation of Absolute Permeability from Capillary Pressure Measurements
Authors: Thompson A. H. , Katz A. J. , Raschke R. A.
Published: December 2007

We report extensions of our earlier work on permeability estimation from mercury injection to include carbonates with complex pore-size distributions. Excellent estimates of absolute permeability are obtained with no adjustable parameters in the estimate. We also discuss the effects of sample size and inhomogeneity and show that good estimates of permeability can be obtained in inhomogeneous samples when injection is performed on the same sample used for permeability measurements.
Stability of Flow of Viscoelastic Liquids
Authors: Fong C.F. Chan Man
Published: December 2007

The turbulent flow behaviors of viscoelastic liquids has aroused considerable interest in recent years. It has been observed that one of the characteristics of the turbulent flow of slightly viscoelastic fluids is a very pronounced suppression of turbulence accompanied by major reduction in drag coefficient.

No consistent theoretical interpretation of the turbulent flow behaviors has yet appeared in the literature. It is thought that a study of the stability of the flow of viscoelastic liquids would be a useful first step. In this paper the problem of the stability of parallel flow of viscoelastic fluids is studied. The analog of the Orr-Sommerfeld equation is solved by the method used by Michael.

It is found that the presence of elasticity destabilizes the flow and this is apparently contrary to recent experimental observations. Possible reasons for this discrepancy are discussed.

Introduction

In recent years there has been a growing interest in the study of the turbulent flow, behaviors of viscoelastic fluids. Several investigators have observed that the addition of very small amounts of certain polymeric solutes to a Newtonian fluid can greatly reduce the turbulent drag coefficient.

A consistent theoretical interpretation of the turbulent flow behaviors of viscoelastic fluids has not yet appeared in the literature. As the problem of turbulence is related to the stability problem, it is thought that a study of the stability of parallel flow of a viscoelastic liquid would be a useful first step. Furthermore, Seyer observed that the transition from laminar to turbulent flow is delayed by the addition of polymeric solutes. This observation suggests that the flow of viscoelastic liquids is more stable. Thus, a study of the stability of parallel flow of viscoelastic liquids would be of great practical importance.

STABILITY EQUATION

The linearized theory of stability of a viscoelastic liquid has been formulated by Walters. By considering a parallel flow with velocity components [U(y), 0, 0] referred to a Cartesian coordinate axis [x, y, z], with the x-axis along the direction of flow, and by superposing a small two-dimensional disturbance, the analog of the Orr-Sommerfeld equation for Liquids A and B has been shown to be:

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

subject to one boundary conditions v = Dv = 0 at y = 1. It is worth noting that the analog of the Orr-Sommerfeld equation for a second-order fluid is identical with Eq. 1 above.

SOLUTION FOR PLANE POISEUILLE FLOW

The method used is similar to that employed by Michael and the reader is referred to that paper for the details.

Suppose (, RO) be a point on the neutral stability curve for a Newtonian fluid, with vo and co the corresponding wave function and wave velocity. We consider a perturbation about that point and write:

........................................(2)
Some Applications of Pressure Derivative Analysis Procedure
Authors: Ozkan E. , Vo D. T. , Raghavan R.
Published: December 2007

The derivative analysis has been shown to be an important tool in identifying flow regimes and also to be of assistance for type curve matching pressure data. This paper extends procedures to analyze pressure data by suggesting new applications of the derivative method to determine formation parameters and initial reservoir pressure. It is shown that specific equalities exist between pressure changes and its derivative and that these relations can be used to analyze buildup data when the effect of producing time on buildup data is important including data following a slug test or an "impulse"test. It is also shown that the derivative method can provide a quantitative measure of the accuracy of the slope of the semilog straight line.
Petroleum Engineering Manpower Demand The 1987 SPE Manpower Survey – A Summary
Authors: Calhoun John C.
Published: December 2007

Responses to the survey were received from nine companies, but three of the replies were not complete, and one of the companies that reported complete date employed less than 10 engineers. Consequently, the heart of the analysis is based on data from five oil producing companies, each of whom employed more than 500 engineers at year end 1983. Seven of the companies (the group will be called set A) reported complete year end totals for engineers employed for the past five years and both high and low projections for the next five years. These companies report a past four year decline in the employed engineering staff from the end of 1982 to the end of 1986 of 12.4%. They roject a five year change, from year end 1986 to year end 1991, that ranges from an increase of 0.2% to a decline of 7.12. In short, they see little prospect for an increased engineering work force and a high probability that the engineering work force will continue to fall. The year-by-year tabulation is given in Table 1. Seven companies, which will be called set 8, reported not only the year end totals for engineering staff but also the year end totals for those who held degrees in petroleum engineering. (These are not the same seven companies that make up set A). The percentage of those holding petroleum engineering degrees varied by year from 39.3% to 43.7%. Over the four year period, from the end of 1982 to the end of 1986, the decline in year end petroleum engineers employed was 7.6% compared to the decline for all engineers of 16.4%. The year-by-year tabulation is given in Table 2.
Engineering Salary Trends in the Petroleum Industry
Authors: Brown D. C.
Published: December 2007

To understand the changes that occur cyclically in engineering manpower supply/demand trends in the petroleum industry, it is desirable to have an awareness of some of the major activities and factors affecting such trends; of starting Petroleum Engineering salaries relating to that background; of the on-going engineering salary status which developed from these activities; and of the large effect that high starting and on-going salaries do have in attracting and retaining engineers within the petroleum industry. It is important to realize that changes in industry trends can be brought about both by economic and political decisions, in both domestic and international activities.

There is no single entity or group, which by itself sets the climate for engineering manpower trends in all of the parts of the petroleum industry. Rather, it is set by the political and economic decisions of nations affecting the industry, and by the interactions of a very large number of companies and individuals, from the diverse and multiple parts of the industry, in creating demand for engineers of the various types and levels needed by their organizations.

Each organization must continually monitor and find ways to meet its needs for engineers for the present and foreseeable future, as to the various engineering subfunctions which must be filled in drilling, production, reservoir, process, mechanical, electrical, and other engineering activities.
Selection of a Discount Rate or Minimum Acceptable IRR
Authors: Sinha M. K. , Poole A. V.
Published: December 2007

Most oil and gas companies use some form of discounted cashflow analysis (DCF) as a primary measure for investment decision. Internal Rate of Return (IRR) and Net Present Value (NPV) are the two most commonly used investment analysis methods in the industry. Selecting the appropriate discount rate to use with these investment analysis methods is important if stockholder wealth is to be increased. All opinions expressed herein are the authors' own and do not necessarily reflect those of Morgan Guaranty Trust Company.
Flow of Viscoelastic Fluids Through Porous Media
Authors: Gaitonde Narendranath Y. , Middleman Stanley
Published: December 2007

This paper was prepared for the Society of Petroleum Engineers Symposium on Mechanics of Rheologically Complex Fluids, to be held in Houston, Tex., Dec. 15–16, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Introduction

This communication presents an extension of an earlier study by Christopher and Middleman of the applicability of a non-Newtonian generalization of the Blake-Kozeny equation to the laminar flow of non-Newtonian polymer solutions through porous media. The earlier work, done with dilute aqueous solutions of carboxymethylcellulose, indicated that the model put forth correlated data with an average error of 18 per cent and a standard deviation of the friction factor of 0.21 over a range of three orders of magnitude in a modified Reynolds number.

A survey of the literature available at that time indicated some evidence of viscoelastic effects, in contrast with the conclusions drawn by Christopher and Middleman it was decided to extend the earlier study by examining a more elastic fluid, polyisobutylene dissolved in toluene. In addition, data were obtained for tubes packed with sand, and for tubes packed with binary mixtures of glass spheres. We still fail to see viscoelastic effects.

The basic experimental techniques, and the methods of reducing and correlating the data, are as described by Christopher and Middleman and in more detail by Christopher and by Gaitonde. Polyisobutylene [PIB L-100, Enjay Co.] solutions in toluene were run at 25.0 deg C. Power-law parameters were obtained from capillary viscometry performed over a range of shear rates corresponding to the shear rates achieved in the porous medium. Table 1 shows the solution properties, including the zero-shear viscosities of the solutions and the viscosity average molecular weight of PIB L-100.

CORRELATION OF DATA

Fig. 1 shows the friction factor-Reynolds number correlation of the data obtained using tubes packed with glass spheres of a narrow size range. The data are correlated with an average error of 9.8, per cent and a standard deviation of 0.14 by

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

where

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

and

........................................(3)
Restructuring for Long-Term Survival
Authors: Hassell R. L.
Published: December 2007

The past ten years in the energy business have tended to be typical of the industry--cyclical--with periods of great optimism followed by years of even greater pessimism. The true nature of our industry has never been more evident nor the opportunities for success or failure greater.

During ten years, we have seen a very active period of industrial restructuring throughout the United States: from automobiles and airlines to steel, banking and farming. The bankruptcies, consolidations, joint-ventures, mergers and hostile takeovers seem to be in the headlines daily.

We in the energy industry have experienced all of this and more as the problems/opportunities this last decade have brought many to their knees. But now there is, according to some, "a light at the end of the tunnel," "price stability" and "guarded optimism." Surely, we are now on the road to recovery, aren't we?
The Role of Natural Gas in the European Gas Market and East-West Energy Trade
Authors: D'Andrea L. A.
Published: December 2007

The importance of energy for economic growth and regional co-operation has held a promiment role in the activities pursued by the Economic Commission for Europe (ECE). The ECE was created by the United Nations in 1947 for the purpose of promoting co-operation and strengthening relations among member countries, with varying economic and political systems, in virtually every economic activity.

Over the years, the Energy Division of the ECE has been intimately involved in analyzing and evaluating energy developments and markets in the ECE region; and in serving the needs of member governments in their endeavour to promote regional co-operation. In the context of east-west relations, energy trade has played a prominent role in the economic interchange that has prevailed in the recent decades, and natural gas has become an increasingly important fuel commodity in the development of trade relations across most member states, and in trade relations between east and west. Drawing upon the experience and knowledge available in the ECE Energy Division in these matters, this paper provides an insight on the importance attached to natural gas in the energy markets of Europe, and the reliance placed on gas trade to sustain increased demand for natural gas in European gas markets.

The ECE consists of thirty-four member countries (Table 1), of western and eastern Europe, including the USSR, Canada and the United States. Unless otherwise noted, reference to Europe in this paper excludes North America.
Superpressured Gas Reservoirs: Case Studies and a Generalized Tank Model
Authors: Prasad R. K. , Rogers L. A.
Published: December 2007

Pressure decline data from 21 superpressured gas reservoirs in the Gulf Coast were reviewed to determine the characteristic slopes of the P/Z (pressure divided by the gas non-ideality factor) vs. cumulative production plots. Twelve of the reservoirs were substantially depleted. The data were fit with one or two straight lines which would indicate a change in the reservoir pressure support mechanism. The slopes of the plots were reviewed in particular to determine whether the apparent compressibility at reservoir pressures above the hydrostatic level was different than the apparent compressibility below the hydrostatic level, as proposed by Hammerlindl and others. Only four of the plots could reasonably be fit by two straight lines which indicated that the rock compressibility correction factor proposed by Hammerlind1 and others, that changes at the hydrostatic pressure point is not general and the method cannot be used indiscriminately.

To better identify the factors that cause downward curving P/Z plots the gas law equation for a gas/aquifer reservoir was rewritten in a generalized form with additional coefficients included the fluid and rock compressibility changes with pressure and gas exsolving from solution. The P/Z plot calculated by the generalized model departs from a straight line, and curves downwards depending on the compressibilities and aquifer size. The generalized equation, with appropriate expressions for the non-ideal factors, can be solved analytically or with numerical computer methods to fit both the shape and position of the decline data. An example fit, using both the two straight line method and the generalized tank model, to a reservoir with a curving P/Z plot is given.
Inert Gas in Tønder Aquifer Storage: A Complete Preliminary Computer Study
Authors: Labaune F. , Knudsen J. E.
Published: December 2007

Inert gas may be injected into underground gas storages as a part of the cushion gas, and thus provide significant reduction of the project cost. This is being considered for the Tønder aquifer gas storage project in Denmark. Two alternative strategies have been investigated, central or peripheral injection of the inert gas.

The 3-D studies were split into two 2-D stages, in order to reduce the simulation costs. In the first stage, the horizontal distribution of the natural gas and of the inert gas was computed on an XY model of the Tønder structure. For the second stage, that part of the model where most of the mixing occured was selected, and its parameters defined for the XZ simulation.

From this study, a strategy was defined for the following step of the project, involving technical choices. The paper concludes with a discussion of these next steps planned for implementing the inert gas technology at the Tønder storage.
Expansion of a Successful In-Situ Combustion Pilot in the Midway Sunset Field
Authors: Williams R. L. , Jones J. A. , Counihan T. M.
Published: December 2007

This study focuses on Santa Fe Energy's operating and monitoring experience of the expansion of a successful fireflood pilot in the Midway-Sunset Field1. The pilot had run for eight years, while the expanded project has been in various stages of operation since 1982. This study will review the rationale behind the facility installation and the various, unanticipated start-up problems that were encountered. A detailed discussion of the remedies for injector and producer damage, as well as our experience with bottomhole temperature, gas analysis, production and injection monitoring systems will be presented. The positive cash flow and project economics through 1986 are encouraging and effectively summarize Santa Fe Energy's efforts in fireflood technology to date.
Self-Powered Pumps for Watered-Out Trapped Gas
Authors: Elliott G. R. B. , Yates T. M. , Yates D. , McDaniel M. , Houseman B. L. , Elliott R. D.
Published: December 2007

The high-pressure gas in underground reservoirs can be used to provide the energy to pump brine underground and away from a well, thereby preventing premature watering out of water-drive gas wells. Use of such work has been demonstrated with modified 5-in turbine pumps acting as motors in an above-ground 500-gallon system. Such pumping work can also be used in secondary recovery of petroleum and in recovery of dissolved or hydrated natural gas.
A Novel Approach to Flow Control for Chemical Injection and Continuous Sampling
Authors: Shelton M. S.
Published: December 2007

Multilocation injection of a single chemical has historically been accomplished by the use of multihead or small, pneumatic positive displacement pumps. Certain expense-incurring problems exist with these systems. A new approach to chemical injection reduces the number of metering pumps required for multilocation injection and associated installation, operation and maintenance expenses.
Characteristics of Metal-Polymer Interactions in Fracturing Fluid Systems
Authors: Kramer J. , Prud'homme R. K. , Norman L. R. , Sandy J. M.
Published: December 2007

A series of model derivatized guar polymer samples were crosslinked with three different metal-ion crosslinkers in order to better understand the complex chemical reactions involved in producing fracturing fluid gels. The gels were studied using steady shear viscosity and dynamic oscillatory measurements. Dynamic oscillatory measurements are often more sensitive probes of the structure of crosslinked gels than are steady shear viscosity measurements and, therefore, both viscosity and dynamic oscillatory measurements are needed to fully characterize fracturing fluids. We present examples of fluids with nearly identical viscosities but different moduli-- indicating different network structures in the gel. The gels considered represent commonly used fracturing fluids such as titanate crosslinked hydroxypropyl guar (HPG), titanate crosslinked carboxymethyl hydroxypropyl guar (CMHPG), and aluminum crosslinked CMHPG. The effect of molar substitution of hydroxypropyl groups (MS level) on HPG crosslinked with two titanate crosslinkers is presented. The effects of MS and degree of substitution of carboxyl groups (DS level) changes for CMHPG gels crosslinked with titanates and aluminum ions are also presented.

An explanation of the mechanism involved in titanate crosslinking is offered from evidence gathered from NMR and dynamic light scattering experiments.
Recompletion Workover Program at the Kuparuk River Field
Authors: Woodling G. S.
Published: December 2007

An aggressive workover program was undertaken from 1984 to 1987 at the Kuparuk River field on the North Slope of Alaska to recomplete older single completions with the more versatile selective single design. The two oil producing horizons ("C" and "A" Sands) have contrasting reservoir properties which complicate reservoir management. The recompletion allowed fracture stimulation of the "A" Sand which was easily damaged during drilling. In addition, selective zone management in each production or injection well maximized reserves development under waterflood and gas reinjection.

Eighty-six (86) of the field's 529 wells (16%) have been recompleted since 1984 at a total cost of $68 million (1987 dollars). This case history summarizes oil rate benefits and workover cost trends for use in future evaluation of remaining Kuparuk workovers. An economic evaluation approach for justifying injection workovers in a limited-capital environment is also included.
A Combination Gas Field Development Model Evaluated with Field Data
Authors: El-Feky S. A.
Published: December 2007

For a gas field a close relationship exists between the production and marketing phases. Accordingly, the design of an optimum development plan for a natural gas field always depends on the field parameters, such as total natural gas reserves, the individual well productivity, the dependence of production rates on the equipment capacity and the state of depletion of the reservoir, and the gas sales contract. To maintain total field output at the required gas sales contract level, additional infill wells are drilled.

This paper presents a model for abnormally pressured gas-condensate reservoirs that can predict the delivery rates from individual wells to meet a gas sales contract, set the completion schedule for additional infill wells, and determine the requirements for compression facilities.

The model combines certain facets of previously published ones in a manner that required development and use of some new and some little-known relationships. Analytical methods for calculating gas compressibility factor, dew-point pressure, volume percent liquid formed during retrograde condensation, and other gas properties have been included.

The volumetrically calculated original gas-in-place was allocated between wells based on their production histories. Individual well deliverability was evaluated using a semi-steady state quadratic flow equation with the real gas pseudopressure function. The loss in productivity sustained by producing wells due to condensate accumulation around the well-bore, change of permeability with pressure, and the effect of pressure on formation compressibility have been considered.

Performance matching for individual wells in one of the Middle East gas fields has demonstrated that the resulting approach, which was designed for computer solution, is as accurate as the necessary available data will permit.
Laboratory Measurements Relevant to Two-Phase Flow in a Tight Gas Sand Matrix
Authors: Chowdiah P.
Published: December 2007

True drainage measurements of specific water permeability, gas entry pressure, critical gas saturation and effective gas permeability at in-situ stress conditions have been conducted on several tight sandstones, mostly from the Mesaverde formation. The results have been used to develop some general rules useful in making meaningful estimates of both drainage and imbibition relative permeability curves for use in reservoir simulation.
A Correlation for the Increase in Gas Gravity During Pressure Depletion of a Dissolved Gas/Oil Reservoir
Authors: Ostermann R. D. , Qadeer S. , Dehshani K.
Published: December 2007

A correlation is presented to predict the increase in solution gas gravity experienced during pressure depletion in solution gas drive reservoirs. Correlations are also presented for predicting the change in CO2 and N2 content of dissolved gas during depletion. The application of these correlations to standard PVT correlations is demonstrated.
Modeling the Performance of Fractured Wells in Pattern Floods Using Orthogonal, Curvilinear Grids
Authors: Fleming G. C.
Published: December 2007

Previous investigators have used orthogonal, curvilinear grids to simulate oil recovery processes in repeated well patterns. These grids are radial in the vicinity of the wells, allowing accurate resolution of the near well region. This paper extends the applicability of curvilinear grids to include patterns with vertically fractured wells, where elliptical coordinates provide better representation of fluid flow near the fracture. Appropriate curvilinear coordinate systems are obtained from an analytic solution for steady, unit mobility displacements. This solution encompasses a variety of pattern geometries, including fractured five and nine spots, line drives, staggered line drives and single wells. The analytic potential for unfractured wells in these patterns is available in the literature, while the extension to fractured wells is developed in this work. Unit mobility flow rates and areal sweep out in fractured well patterns can be easily obtained from the analytic solution. Examples are given for line drives and staggered line drives, for different fracture lengths and pattern aspect ratios.

Pore volumes and transmissibilities are calculated from the analytic potential, and are incorporated into a thermal reservoir simulator. Excellent agreement is demonstrated in comparing the curvilinear formulation with Cartesian grids for a miscible displacement at a mobility ratio of 40 in a five spot pattern, and a steamflood in an inverted nine spot pattern. The fracture formulation is verified against published numerical solutions for the performance of finite conductivity, vertically fractured wells in single-layer reservoirs. Fewer grid blocks are required by the curvilinear grid to obtain the same accuracy as a Cartesian grid.

The main advantage of using a curvilinear model lies in the ability to accurately describe flow around the well, while simultaneously modeling the flow at a distance. Several applications have been chosen to demonstrate this capability. An adverse mobility, miscible line drive between fractured wells demonstrates that the large fluid flux near the injection well fracture tip has a strong influence on areal sweep. This is also shown in a steamflood between horizontal wells, where curvilinear and Cartesian grids predict significantly different recoveries. Finally, a waterflood in an inverted nine spot pattern, shows the importance of accurately modeling fractured injection wells.
Selection of a Hospital Cogeneration System
Authors: Miller G. S. , Branson M. W.
Published: December 2007

Stable natural gas prices and increasing power costs are making gas fired cogeneration systems economically attractive to hospitals. This paper presents analytical methods for preliminary evaluation of the economic feasibility of a proposed cogeneration plant. Equations are developed which permit rapid estimation of: generator size, cogenerated power cost, economic payback, additional hospital gas consumption due to cogeneration, and cogeneration cycle efficiency.
The Effect of Changes in Pricing and Other Economic Factors on Estimates of Gross Reserves
Authors: Letendre S. B. , Wright D. R.
Published: December 2007

Oil and gas reserves are projected based upon a number of fluctuating variables such as operating conditions (including curtailments), product prices, operating costs, and production trends. Most of these factors have a direct relationship to the future net revenues and payout times. However, the corresponding effect of changes in these parameters on the gross reserves is quite often buried beneath the surface of associated changes in future revenues. Even though the estimates of gross reserves that could be recovered may not change for a particular well, the economic gross reserves and associated future revenues could change dramatically due to economic and/or operating conditions. An increase, or decrease, in pricing and/or operating costs can alter the volume of oil or gas reserves which are reported. When reserves reports are prepared, it is necessary that the oil and gas producer understands the relationship between gross reserves and economic gross reserves as presented herein. The purpose of this paper is to further investigate and define the effect that changes in economic factors, especially pricing, have on the calculation of economic gross reserves. Three typical Appalachian Basin reservoirs (Clinton, Big Lime, and shallow oil productive sand) are used in this paper to depict the effects of changes in economic conditions. Variations in operating conditions such as curtailments are also briefly addressed to examine associated changes in future revenues and payout times.
Application of Nodal Analysis in Appalachian Gas Wells
Authors: Frear R. M. , Yu J. P. , Blair J. R.
Published: December 2007

Many small independent operators are currently using a cookbook style of production operation and performance evaluation. The result reduces the opportunity of producing at the well's top performance which will curtail the current revenues. A promising innovative Nodal analysis technique is being applied to two Appalachian gas wells using a microcomputer. The objective of this paper is to present the optimization studies and their effects on production operations.

Wade #2 well was drilled and completed in 1985 in Harrison County, West Virginia. The well was hydraulically fractured in 3 zones, Benson, Balltown, and Speechley and the stimulation seems to be working well. A 2-3/8 inch tubing string was run to a depth of 4774 feet. The well was loading with fluid and producing at a diminishing rate. It is suspected that oil is being produced in the upper zone which causes damage in the lower zones (gas zones). If the oil is isolated from the other zones, the gas will not have enough pressure to produce by itself. The Nodal analysis suggests that the well's production will be improved if an intermittent gas lift "rabbit" is installed for the production stream. The well will then be producing efficiently in different zones.

Pratt #1 well was drilled and completed in late 1985 in Lewis County, West Virginia. The well was stimulated in two zones, Balltown and Speechley, with hydraulic fracturing. Since the engineer believed the well could be a better well from the logging data, a deep penetration stimulation was conducted on this well. Unfortunately, the well started producing water, and the oil and gas rates dropped because the fracture had gone into the water zone in the neighboring area. If a casing log is run in order to find out the exact location of the water zone, the well needs to be cement squeezed, reperforated and re-stimulated in the new zone. However, this method would be very costly. The Nodal analysis was applied for this well. Clean-up and stimulation will be necessary to remove the wax and formation damage. Again, an intermittent gas lift is recommended to replace the sucker-rod pump. With all these recommended changes, the well will be producing at its optimized rate. In addition, both wells' new designs will have an economic advantage over the old design without excessive extra cost.