bluuebunny/crossref_metadata_2025 huggingface dataset:
Faja Case Study Results on a Single Well, MFM-7S
Authors: Everett R. V. , Herron M. , Pirie G. , Schweitzer J. , Edmundson H.
Published: December 2007

Factors expected to be of importance in understanding a deltaic environment are grain size and sorting, cementation, compaction, and diagenesis. In an attempt to isolate two of these variables, sorting and grain size, a well was selected where these parameters could be related to logging measurements.

Here, the Oficina formation is a complex series of stacked, river-derived, heavy-oil-saturated, sand-dominated sediments overlain, in turn, in the upper section by shale-dominated estuarine (brackish) sediments. We identified zones that have potential water production on primary recovery even though the oil saturation is close to 90%. Studies of lithology, mineralogy, texture, and porosity from extensive log and core data with novel interpretation methods resulted in a detailed geologic description of the reservoir.
Multivariate Statistical Analysis of Stuck Drillpipe Situations
Authors: Hempkins W. B. , Kingsborough R. H. , Lohec W. E. , Nini C. J.
Published: December 2007

Stuck drillpipe accounts for losses of millions of dollars each year in the petroleum industry. Major efforts have been made to determine the causes of stuck pipe and to outline operating practices that will minimize the occurrence of the problem. No previously published efforts, however, have attempted to predict the chances of the pipe sticking on the basis of existing conditions. An analytic technique was therefore developed that evaluates 20 common drilling parameters to determine the probability of the pipe sticking in a particular well.
An Analytic Model for Electromagnetic Wireline Tools
Authors: Durgapal Prabha
Published: December 2007

A mathematical model for electromagnetic tools is presented that accounts for the finite size of the transmitter and receiver coils, tool mandrel, a shielding conductor internal to the tool, and the concentrically stratified media surrounding the tool. The model is applied to various tools in the 20 × 103 to 1 × 109 -cycle/sec [20-kHz to 1-GHz] frequency range, and results indicate that this model will be useful in designing future tools.
Future Development of Water Control Methods in Air Drilling Operations
Authors: Roberts Alan P.
Published: December 2007

In certain cases, the advantages of air drilling are very great. The economic incentives can be high, for we hear of operators who have saved more than $100,000 on one well through the use of air drilling. However, in the great majority of drilling situations, air cannot be used because of the water influx problem.

A number of techniques are available to fight water influx. Some have been successful under certain conditions. However, nearly all need considerable further testing and development before they can be considered as routine operations. In short, we are a long way from being over the hump with respect to water control. Now it often costs us considerable money before we even can determine the extent of our problem.

Water Control Methods Now Available

The best water control method now available is, of course, to drill our wells where we know water will not be encountered. Although this sounds facetious, we should certainly make a thorough study of a prospective air drilling location to determine the possibilities that water will be encountered and to make an estimate of the probable locations and number of water-bearing zones which must be penetrated. An idea of the quantity of water influx would be very helpful.

Unfortunately, unless previous air drilling has been done in the immediate area, we normally cannot predict with any high degree of certainty where water will be located. Logs from previous wells in the area are of some value, but apparently do not provide the entire answer. A study by a joint API-AAODC committee indicated that logs are effective in approximately 50 per cent of the cases in locating water-bearing zones.

In any case, it behooves us to obtain the best information available in order to intelligently make the decision as to whether or not air drilling should be contemplated. In some cases, planning the casing program with water zones in mind may make the difference between an economic air drilling operation or a series of expensive water shut-off operations.
Interpretation of Flowing Well Response in Gas-Condensate Wells
Authors: Jones J. R. , Raghavan R.
Published: December 2007

A fully implicit compositional model is used to simulate the well response in a gas-condensate system. The objective of this work is to examine the flowing well response in a condensate reservoir and to examine the effect of liquid condensation on the well response as the pressure drops below the dewpoint.

A theoretical foundation for the analysis of well test data in gas-condensate systems is presented. The concept of pseudopressure integrals is introduced and the utility of these integrals—the reservoir and the sandface integrals—to analyze well test data is presented. Short-time performance for both constant-(molar)-rate and constant-pressure production is examined. A pseudopressure transformation is used to incorporate the effects of multiphase flow and changes in fluid composition. We show that the pseudopressures may be used to determine formation flow capacity and skin factor. Estimates of skin factor, however, are approximate for production at a constant rate. Long-time performance is examined in detail for the constant-terminal-pressure case. These solutions should be useful in anticipating the problems involved in conducting production forecasts. An inflow equation for both modes of production is presented. The influence of important variables of interest, such as composition, relative permeability characteristics, mode of production, dewpoint pressure, and initial pressure level, is examined. Long-term performance appears to be particularly sensitive to the difference between the initial pressure and the flowing pressure, but the individual differences between initial and dewpoint pressures and between dewpoint and flowing pressures also have some influence on long-term rates. The consequences of neglecting the appearance of a second phase are documented.

Steady flow in gas-condensate systems is also examined. These solutions are important in their own right and provide important insights into the performance of condensate systems (e.g., cycling). Of importance to this work, the steady-flow solution enables us to verify the accuracy of the numerical solutions and to evaluate the pseudopressure transformation used in this paper.
Effect of Turbulence on Transient Flow of Real Gas Through Porous Media
Authors: Lee R. L. , Logan R. W. , Tek M. R.
Published: December 2007

This paper represents the first effort in quantifying the "turbulence intensity" as related to deliverability front gas wells. A new dimensionless number called the Forchheimer number, NFo, has been proposed along with a generalized expression of turbulence coefficient. Applications include a new concept called "inverse productivity index, JI," proposed as an alternative to classical backpressure plots for characterizing gas well performance.
The Effect of an Immobile Liquid Saturation on the Non-Darcy Flow Coefficient in Porous Media
Authors: Evans R. D. , Hudson C. S. , Greenlee J. E.
Published: December 2007

The results of an experimental research program to investigate the effects of immobile liquid saturations on the non-Darcy flow coefficient are presented. Sandstone cores of absolute permeabilities ranging from 50 to 800 md were used to investigate non-Darcy flow phenomena under multiphase conditions. Immobile liquid saturations were varied from 8 to 30% PV. The multiphase experiments were conducted with N2 gas as the flowing phase and glycerin as the immobile liquid phase. It was found that the non-Darcy flow coefficient for the multiphase case may be estimated with a dry-core non-Darcy-flow-coefficient/permeability relationship developed for the rock in question and the effective gas permeability at a given saturation.

For the immobile multiphase cases, the non-Darcy flow coefficient consistently increased with increased saturation. The experimental data obtained from this research were compared with the limited multiphase data in the literature. Where comparisons could be made, the data reported in this paper agreed favorably with the existing published data.

An analysis of the experimental data revealed that a unique relationship existed between the non-Darcy flow coefficient and the effective gas permeability, porosity, liquid saturation, and effective overburden pressure at a given temperature.

Correlations were developed from this analysis to predict the non-Darcy flow coefficient as a function of rock and fluid properties. Where possible, the correlations were used to predict the non-Darcy coefficient measured by other researchers and were compared with the dry-core correlations developed by Janicek and Katz and with a theoretical equation developed by Geertsma.
Prediction of Reservoir Compaction and Surface Subsidence: Field Application of a New Model
Authors: de Waal J. A. , Smits R. M. M.
Published: December 2007

A new loading-rate-dependent compaction model for unconsolidated clastic reservoirs is presented that considerably improves the accuracy of predicting reservoir rock compaction and surface subsidence resulting from pressure depletion in oil and gas fields. The model has been developed on the basis of extensive laboratory studies and can be derived from a theory relating compaction to time-dependent intergranular friction.

The procedure for calculating reservoir compaction from laboratory measurements with the new model is outlined. Both field and laboratory compaction behaviors appear to be described by one single normalized, nonlinear compaction curve. With the new model, the large discrepancies usually observed between predictions based on linear compaction models and actual (nonlinear) field behavior can be explained.
An Analytic Model for Analyzing the Effects of Dissociation of Hydrates on the Thermal Recovery of Heavy Oils
Authors: Kamath Vidyadhar A. , Godbole Sanjay P.
Published: December 2007

This paper presents an analytic model that includes the effects of the presence of hydrates in a thermal recovery process. The model considers continuous injection of steam into a reservoir containing an oil zone overlain by a hydrate zone. The model results indicate that, although part of the steam is consumed in dissociation of hydrates to gas and water and the dissociated hydrate zone acts as a thief zone for steam, there is a reduction in heat losses to the overburden because of the "insulation" effect of overlying hydrates. Thus, the net reservoir heat efficiency is not significantly affected by the presence of hydrates. Although the model does not address the effect of gas generated from hydrate dissociation, it is speculated that the dissolution of the gas will cause oil swelling, oil-viscosity reduction, and improved steamflood performance.
Graded-Viscosity-Bank Design With Pseudoplastic Fluids
Authors: Stoneberger M. W. , Clarldge E. L.
Published: December 2007

A method for the design of graded viscosity banks of pseudoplastic fluids in five-spot patterns of a single homogeneous layer is presented. This method is based on the extension of Koval’s work on unstable miscible displacements to multiple slugs in radial systems and then to five-spots, with corrections made for pseudoplastic viscous-fingering behavior. Experiments were performed in a Hele-Shaw model to determine the qualitative nature of the various displacements that occur and to determine the parameters used in the equations.
Experimental and Theoretical Study of Polymer Flow in Porous Media
Authors: Sorbie K. S. , Parker A. , Clifford P. J.
Published: December 2007

In this paper, an extensive study is presented on the single-phase flow of xanthan/tracer slugs in a consolidated sandstone. The phenomena studied include polymer/tracer dispersion, excluded/inaccessible-volume effects, polymer adsorption, and viscous fingering. In some floods, there is also evidence of nonequilibrium effects. Macroscopic flow equations are derived that include terms to model all the behaviors listed above. A microscopic approach is also developed that describes certain features of polymer flow in porous media semiquantitatively.
Development and Evaluation of EOR Polymers Suitable for Hostile Environments—Part 1: Copolymers of Vinylpyrrolidone and Acrylamide
Authors: Doe Peter H. , Moradi-Araghi Ahmad , Shaw James E. , Stahl G. Allan
Published: December 2007

This paper describes the properties of synthetic water-soluble polymers that are stable for extended periods of time in hard brines at very high temperatures. Several copolymers of vinylpyrrolidone (VP) and acrylamide (AM) were prepared and evaluated in our laboratories for EOR application in hostile environments. VP in the copolymer composition protects AM against extensive thermal hydrolysis, which otherwise will result in loss of viscosity and precipitation. A range of VP/AM copolymer compositions was found to tolerate the harsh conditions of 250°F [121 °C] in seawater for extended periods of time and to be suitable for EOR application under these conditions. The performance of these polymers in porous media was evaluated by extensive coreflood experiments in Berea sandstone at 250°F [121 °C] with synthetic seawater. The results indicate that these copolymers can easily be injected into porous media and that they can be effective polymers for EOR application in hostile environments.
Protective Colloid Muds Provide Cost-Effective Prevention of Wellbore Enlargement in the Gulf of Mexico
Authors: Chaney P. , Sargent T. L.
Published: December 2007

Protective colloid muds prevented severe hole enlargement, even in "gumbo" shales and poorly consolidated sands. Improved hole size and excellent primary cement bond logs (CBL's) were achieved. Compared with five offset wells drilled with lignosulfonate muds, combined intangible drilling and cement costs were reduced by more than $35/ft [$115/m], a savings of more than 30%.
How To Improve Your Waterflood Brinkmanship
Authors: White Wilbur R.
Published: December 2007

This paper recognizes that most North Texas operators practice a certain amount of "brinkmanship" every time they start a new waterflood, even though good reservoir engineering is used. Eight possible methods of improving the brinkmanship are discussed and some examples are given. The eight methods are:

apply multi-zone floods, where possible; acquire larger holdings in the reservoir through favorable lease purchase arrangements; co-ordinate the proposed waterflood with development of water drive reservoirs; merge the proposed waterflood with any existing saltwater disposal problems; reduce investment by purchasing injection water; consolidate leases where possible; incorporate certain "poor boy" features based on judgment gained from local experience; and arrange joint expenditures with other operators in the area. The author concedes that these eight considerations will not insure success, but concludes that a reasonable economic venture may be created where none existed before.

Introduction

Our politicians and diplomats seem to think that they have a monopoly on "brinkmanship". This is not true. Waterflood operators in North Texas practice this dubious feat regularly. On almost every project, the operator must walk the brink between a reasonable profit and an unsatisfactory return on his investment. Too often the first economic projection on a proposed project shows the venture to be unfavorable or perhaps a borderline case. This paper deals with methods that might change the economic outlook from unfavorable to favorable. The obvious waterflood precautions, such as having cores checked and reservoir calculations made, will not be repeated here. Good engineering is even more important when second and third class reservoirs are being considered. Also, it is assumed that nobody would start a secondary project without some sort of economic analysis. This analysis may be a highly sophisticated projection, run on the latest million dollar computer and presented in great detail on rolls of perforated paper. Or, it may be a "cash register" estimate of future income and outgo carried only in the head of the intrepid operator. In either case, having made an accurate appraisal. the operator usually finds himself still on the brink. What then can he do to improve the economic outlook?

Apply Multi-Zone Waterfloods

Check the multi-zone prospects. Quite often a North Texas lease will have one blanket zone and perhaps two or three secondary stringers at various locations and depths. A paper by Moyer* estimated dual zone investment to be 32 per cent less than for separate facilities (Fig. 1).

JPT

P. 915ˆ
Pressure Drawdown and Buildup Analysis of Horizontal Wells in Anisotropic Media
Authors: Goode P. A. , Thambynayagam R. K. M.
Published: December 2007

An analytic solution is presented for the pressure response during drawdown and buildup of a horizontal well. This method results from solving the three-dimensional diffusion equation with successive integral transforms. Simplified solutions for short, intermediate, and long times that exhibit straight-line sections when pressure is plotted vs. time are presented. The validity of the method is demonstrated by comparing with results generated numerically by a reservoir simulator and with an analogous analytic solution. Methods for analyzing pressure drawdown and buildup data are presented with examples. The method allows reservoir characteristics, including permeability, skin, and distance to boundaries to be determined. The early-time effects, where the well behaves as if it were in an infinite reservoir, are also discussed. Expressions to determine times to critical events, which are important for well test design, are presented.
A Statistical Study of Reservoir Permeability: Distributions, Correlations, and Averages
Authors: Jensen Jerry L. , Hinkley David V. , Lake Larry W.
Published: December 2007

We propose that reservoir permeability may be statistically distributed in a variety of ways. Two hypothetical cases of reservoir layering are statistically analyzed. This analysis suggests that a restricted family of functions—all related to the normal distribution—can be used to represent permeability distributions. The log-normal distribution is one member of the family.

Several sets of field data are analyzed. The analyses show that (1) permeability data are not necessarily log-normally distributed, (2) all the permeability distributions considered are closely approximated by members of the proposed family of functions, and (3) improved porosity/permeability relationships result when the permeability distribution is known.
Reservoir Characterization of Tuscaloosa Sand by Mineralogical and Petrophysical Data
Authors: Hosseini Masood S. , Hayatdavoudi A.
Published: December 2007

A laboratory investigation has been made of the relationship between mineralogical and petrophysical properties of Tuscaloosa sandstone with a combination of petrographic analyses, formation-resistivity-factor measurements, and rock failure analyses. Petrographic analyses revealed that on the basis of the mineralogy of pore-filling and pore-lining cements, Tuscaloosa sandstones can be divided into two distinct types: those with authigenic quartz-overgrowth cement blocking the pore throats and those with authigenic chlorite cement coating the sand grains and preserving the pore system. For each type of sandstone, a well-defined relationship exists between the cementation factor m and other physical properties of the rock, such as porosity, type of cement, compressive strength, cohesive strength, failure angle, angle of internal friction, Young's modulus, Poisson's ratio, and drilling strength. Furthermore, we found that the fracture mechanism is grain fracturing in a fairly brittle mode for silica-cemented sandstone, while the fracture mechanism is grain sliding and pore closure or expansion for chlorite-cemented sandstones.
Design, Installation, and Early Operation of the Timbalier Bay S-2B(RA)SU Gravity-Stable, Miscible CO2-Injection Project
Authors: Moore J. S.
Published: December 2007

This paper reviews the design, installation, and early operation of a gravity-stable, miscible CO2-injection project initiated in April 1984. The purpose of the project is to determine process economics, recoverable reserves, and operational difficulties to evaluate better the potential for fieldwide large-scale CO2 flooding. The results will also help to justify the major investments required to provide pipeline CO2 to the gulf coast oil fields.
Measurement of CO2 Flow in its Supercritical and Gaseous Phases
Authors: Oakes F. G. , White J. T.
Published: December 2007

Production of CO2 and its injection for tertiary recovery of hydrocarbons has produced a need for an accurate method, adaptable to microcomputer technology, for orifice measurement of CO2 fluid flow. A method meeting that need has been developed and successfully implemented. The accuracy of the method for orifice measurement of both gaseous and supercritical CO2 has been verified at the temperature and pressure conditions experienced in field operations. Details of the measurement method and its verification are presented.

The flow rate of any single-phase fluid through an orifice is proportional to the density (and related to the viscosity and ratio of specific heats) of the flawing fluid and the pressure differential across the orifice plate. Mathematical methods are available and applicable for calculation of all three of these physical properties as a function of pressure and temperature. While the work presented here is directed to the measurement of pure CO2, the method is applicable to measurement of any single-phase fluid, provided suitable models are available for calculation of the values of the three physical properties.
Study of Equilibrium Properties of Cr(III)/Polyacrylamide Gels by Swelling Measurement and Equilibrium Dialysis
Authors: Young T. S. , Hunt J. A. , Green D. W. , Willhite G. P.
Published: December 2007

In observations of the long-term properties of a series of Cr(III)/polyacrylamide (PAAM) gels, the gels either underwent syneresis upon aging or swelled in contact with excess brine. Both syneresis and swelling can substantially change the volume and properties of a gel placed in a formation and therefore influence the effectiveness of a crosslinked-polymer treatment. Efforts were made to develop an understanding of these phenomena and to describe them in terms of the gel's physical and chemical states. A long-term gel's physical and chemical states are characterized by two parameters, effective crosslinking density and chromium density, determined by equilibrium swelling and equilibrium dialysis, respectively. Swelling and syneresis properties were correlated to the effective cross-linking density described in polymer network theory. A model based on Flory and Hermans' swelling equations was developed to calculate the effective crosslinking densities of gels prepared from solution. Attempts were made to relate the swelling and syneresis properties to the compositions of gel systems to allow prediction of long-term stability of a gel based on its composition.

An analysis of the amount of chromium that reacted with the PAAM was made by successive equilibrium dialyses of the gel followed by chromium analyses of dialysates by atomic and visible absorptions. The overall fractional conversion of chromium in the gelation was between 0.39 and 0.70. The equilibrium conversion of Cr(VI) to Cr(IH) ranged from 0.65 to 0.85. The effective crosslinking density obtained from the swelling experiment was <5 % of the chromium density for all samples studied. A substantial fraction of reacted chromium is suspected to be present in the gel matrix either in the form of intramolecular crosslinks or attached to only one polymer segment.
Mechanical Performance of Fiberglass Sucker-Rod Strings
Authors: Tripp Harley A.
Published: December 2007

The natural frequencies of fiberglass sucker-rod strings can be calculated by treating the rod strings as modified spring/mass vibration systems. The ratio of the pumping-unit operating speed to the rod-string natural frequency can then be used as a basis for understanding fiberglass-rod-string performance and for predicting downhole pump stroke lengths.
High-Pressure Gas Lift for Deep, Sour Production
Authors: Dickens R. J.
Published: December 2007

An innovative high-pressure N2 gas-lift design has been used to return several wells to production in the Jay/Little Escambia Creek (LEC) field of northwest Florida. The N2 was available from a field tertiary injection project and provided the means for the first continuous N2 lift system, and some of the deepest gas-lifted wells in operation.

The design accommodates the unique demands of gas-lifting a deep, sour oil well with high water cuts through the operation of a continuous N2 lift system. Because the project design was not limited to conventional artificial lift techniques, a solution was achieved with the resources available. The high-pressure N2 lift enabled wells to return to production that would not have been economically attractive or mechanically feasible with a standard hydrocarbon gas lift or submersible pump design.
Dynamic Performance Testing of Single-Element Unbalanced Gas-Lift Valves
Authors: Winkler H. W. , Camp G. F.
Published: December 2007

Reliable predictions of injection gas passage through gas-lift valves are important for unloading and lifting high-capacity wells. This paper outlines the procedure for conducting static and dynamic tests required to evaluate gas-lift valve performance. Limited test results are presented for the 1- and 1½in. [25.4-and 38.1-mm] unbalanced bellows-charged gas-lift valves with three-ply monel bellows.
Effects of Speed Variation on the Performance and Longevity of Electric Submersible Pumps
Authors: Powers Maston L.
Published: December 2007

The expanding usage of variable-speed drives (VSD's) indicates that their effects on electrical submersible pump (ESP) performance and longevity merit investigation. This paper demonstrates that speed variation makes ESP equipment selection more complex and critical if maximum pump life is to be achieved. Thrust wear can dramatically affect pump longevity. A common conception is that the rates identifying acceptable thrust limits for any pump speed would be the affinity-law projections of the defining rates at 60 cycles/sec [60 Hz]. This would result in a diverging thrust range as speed increases. This paper (1) shows the fallacy of this concept; (2) demonstrates mathematically and graphically that as speed increases, the thrust range converges; (3) expresses the need for verification of the calculated data with actual measurements; and (4) discusses potential pump damage caused by internal recirculation cavitation at high pumping speeds and the increased exposure’ to vibration damage resulting from speed variation.

The benefits of speed variation are summarized. A specific ESP was selected as a typical pump for illustration. Data were normalized by dividing all characteristics by those occurring at the peak efficiency point. The pump performance data thus obtained are used to illustrate techniques for designing a pump to be driven at variable or nonstandard speeds. An operating window is presented that is bounded by the thrust range limits and by the head-vs.-rate curves that correspond to the maximum and minimum driving frequencies to be considered. This is used in the discussion of VSD applications relative to wells of improving productivity and well testing. Also, the pump/motor mismatch inherent in wide-speed-range applications and resultant low motor efficiency are demonstrated.
Investigations on Viscous Fingering by Linear and Weakly Nonlinear Stability Analysis
Authors: Chikhliwala E. D. , Yortsos Y. C.
Published: December 2007

In this paper we examine the growth of unstable disturbances (viscous fingers) in a water/oil displacement process with a mobile interstitial water saturation. Both linear and weakly nonlinear methods of analysis that include continuously changing mobility and capillary effects are presented. The fingers are assumed to develop as a result of perturbations of a steady displacement.

After a brief review of the linear stability results, we implement a weakly nonlinear stability analysis for flow processes near the onset of instability (finite wave-number cutoff). Our numerical results indicate that disturbances near the critical point of the linear theory become stabilized to an equilibrium value, which is a function of the mobility ratio and the capillary number. This behavior suggests supercritical stability, in contrast to the instability predictions of the linear theory.

The results of the linear theory are subsequently used to investigate the mechanism of finger growth at the wavelength of the fastest-growing disturbance. Saturation contours and the water flow field are numerically computed as a function of time. The local mechanism for finger growth is shown to be the continuous transfer of water (oil) from oil (water)-rich to water (oil)-rich regions. Although the linear analysis predicts constant increase in the size of the regions, the weakly nonlinear theory shows that fingers eventually stabilize to a configuration of a fixed amplitude. Typical finger growth processes are numerically illustrated.
Mechanical Design Considerations for Fracture-Treating Down Casing Strings
Authors: Clark H. Craig
Published: December 2007

This paper deals with the design, handling, and cementing of a casing string that will ultimately encounter a fracture treatment. Various wellhead configurations are suggested that provide safe installations while allowing downhole treating-pressure monitoring and easy flowback operations. Solutions to logistical and operational problems faced with a casing treatment are recommended. A comparison of tubing vs. casing as the fracture-treating medium is also provided to show the substantial cost differences.
Evaluation of Fracturing Results in Deviated Wellbores Through On-Site Measurements
Authors: Kim Chin Man , Champion John H. , Cooper Gary D.
Published: December 2007

Four adjacent oil wells in the Kuparuk River oil field, with deviated angles of 6°5′, 24°6′, 27°, and 36°7′ from the vertical at the perforations, were analyzed with prefracturing tests. The total fluid volume for these tests varied from 645 to 840 bbl [103 to 134 m3] of either clean lease oil or water-based fracturing fluid at low to intermediate rates (up to 15 bbl/min [2.4 m3/min]). These wells Were subsequently fractured with proppant-laden fluid. A series of instantaneous shut-in pressures (ISIP's) was obtained for each well. ISIP's and fracturing pressures decreased with time in two of the four wells with a relatively high friction pressure at the end of the pumping. A radially propagating fracture from a point source of pressure explains this decreasing pressure with time. The elasticity theory predicts that a fracture in a deviated, cased wellbore should intersect the wellbore at one location. Only when the deviated wellbore azimuth is near that of the fracture orientation does the fracture sweep the entire perforated zone. This observation of the fracture orientation relative to the wellbore azimuth based on the pressure analysis is enhanced further by postfracture temperature surveys. It appears that only a relatively small volume of proppant could be displaced in a deviated wellbore. The degree of deviation, however, did not appear to be a major concern in the treatment size.
A Model Case History of Infield Drilling and Completion in South Texas
Authors: Barnett K. L. , Jeansonne J. P. , Mitchell R. K.
Published: December 2007

This group project presented an opportunity to improve overall operations from title clearance to on-stream producing. Changes and improvements in virtually every area of drilling and completion contributed to substantial savings in time and money. These savings resulted in the drilling of twice as many wells as originally proposed, and all improvements are supported by actual field tests. This paper deals primarily with drilling and completion operations in the Laredo, TX, area.
Evaluation of Devonian Shale Gas Reservoirs
Authors: Vanorsdale Charles R.
Published: December 2007

The evaluation of predominantly shale reservoirs presents a problem for engineers traditionally educated either to correct for or to ignore such lithologic zones. Currently accepted evaluation techniques and their applicability are discussed to determine the best way to forecast remaining recoverable gas reserves from the Devonian shales of the Appalachian basin. This study indicates that rate/time decline-curve analysis is the most reliable technique and presents typical decline curves based on production data gathered from 508 shale wells in a three-state study area. The resultant type curves illustrate a dual- (or multiple-) porosity mechanism that violates standard decline-curve analysis guidelines. The results, however, are typical not only for the Devonian shales but for all naturally fractured, multilayered, or similar shale reservoirs.
Well Test Analysis of Data Dominated by Storage and Skin: Non-Newtonian Power-Law Fluids
Authors: Vongvuthipornchai S. , Raghavan Rajagopal
Published: December 2007

We examine pressure falloff behavior dominated by storage and skin subsequent to the injection of a non-Newtonian power-law fluid. New solutions to analyze falloff tests are presented in a form suitable for analyzing field data. The effective wellbore concept is used to combine the wellbore storage constant and skin factor. This phase of our work required extensions to the effective wellbore radius concept (for power-law fluids) given in the literature. To improve analysis procedures, we examine the use of the pressure-derivative technique. We discuss the advantages of this method for the problem under consideration.
The Role of the Independent in the U.S. Oil Industry
Authors: Heyser Estill S.
Published: December 2007

"Independent" Difficult to Define

A precise definition of an "independent" oil producer is difficult because he actually defies description. The usual measurement is that he is a non-major, which then brings up the problem of where "majorhood" sets in on a scale of barrelage, income, degree of integration, etc.

The literature and legend of the industry abound with fabulous stories of a daring, colorful, venturesome breed of American businessman known as the oil independent and wildcatter. A number started enterprises which today are known as major companies.

One of the Society's great patron saints and now elder statesman, John Suman, used to say that when he started out before World War 1, "The mark of a real independent that did a good job was one who had an automobile about a block long, a diamond stick pin, a big bull-dog and a kept woman". Unfortunately, except for a change in some of the status symbols, this type of mythical character still persists in the folklore of our industry and in that of the general public.

One economics professor has said of independents, "The independent, as the non-integrated producer is called, developed into a veritable institution - a typically American phenomenon. The blinding success of the lucky ones hides the tragedy of many losers and large losses".

He said also, "The unique feature of the American petroleum industry is the existence of the thousands of independent producers of crude oil, large and small. These represent a basic element of the industry nowhere except in the United States and in Canada. They not only constitute a unique feature of the petroleum industry in North America but materially affect the position and policies of the large integrated companies. Their mere presence indicates that integration in the petroleum industry of North America is decidedly limited. The more or less complete self-sufficiency in basic raw materials which is typical in other basic mineral industries simply does not exist in the mineral petroleum industry of North America."
A New Algorithm for Estimating Relative Permeabilities From Displacement Experiments
Authors: Kerig P. D. , Watson A. T.
Published: December 2007

The process of estimating relative permeability curves from two-phase displacement experiments is considered. A parameter estimation approach overcomes significant limitations of the classic calculation procedure. In this approach, functional representations are chosen for the relative permeability curves. Adjustable coefficients (or parameters) in the functional representations are then chosen to minimize a least-squares objective function. Previous applications of this approach have used exponential functional representations with a single adjustable coefficient (the exponent) for each curve. However, significant errors in the relative permeability estimates may be encountered when this function is used.

It has been determined, in principle, that cubic spline functional representations may be used to obtain accurate estimates of relative permeability curves. The process of obtaining the least-squares estimates for the parameters is more difficult, however, because a significantly greater number of parameters are to be determined. No algorithm has been reported for this purpose. We present an algorithm for estimating relative permeability curves that uses cubic spline functional representations. A unique and essential feature of the algorithm is that it incorporates inequality constraints that ensure that physically realistic relative permeability curves are maintained throughout the iterative minimization process. The performance of the algorithm is demonstrated with data from hypothetical and laboratory coreflood displacement experiments.
Use of Simultaneous Flow-Rate and Pressure Measurements to Replace Isochronal Gas Well Tests
Authors: Horne Roland N. , Kuchuk Fikrl
Published: December 2007

The interpretation of gas well pressure-transient tests differs from that of oilwell tests in two important respects: the nonlinearity of the governing equations and the presence of a rate-dependent (non-Darcy) skin. The nonlinearities are commonly avoided by use of pseudofunctions, and the non-Darcy skin effect is handled by use of flow-after-flow, isochronal, or modified isochronal tests. Recent investigations have shown that the simultaneous measurement of well flow rate with well pressure can significantly shorten the test duration required for accurate interpretation. These methods rely on use of the straight-line approach, however, and in some cases on trial and error. This paper describes a computer-automated interpretation approach that can be applied generally for any type curve without trial and error. The use of this interpretation technique can reduce the test duration to only that required for a standard drawdown or buildup test, and will allow the estimation of the stabilized deliverability potential without flowing the well until stabilization is reached. Examples of use of the method on both simulated and real data demonstrate its effectiveness.
Fracture Geometry and Proppant-Transport Computation for Multiple-Fluid Treatment
Authors: Lee W. S. , Daneshy A. A.
Published: December 2007

This paper incorporates expressions for changing the flow-behavior index, n′, and the flow-consistency index, K′, of fracturing fluids used in any treatment into a dynamic procedure for fracture design to determine simultaneously the temperature profile, viscosity profile, location of each fluid, and location of each proppant in the fracture, together with the resulting geometry. After pumping ceases, the effect of temperature recovery on proppant deposition and fracture closure is also considered.

Several examples demonstrate the effective use of this new procedure for better fracture design. These examples will show the effect of temperature on fluid behavior and its influence on proppant deposition in the fracture.
A Thermodynamic Correlation for the Minimum Miscibility Pressure in CO2 Flooding of Petroleum Reservoirs
Authors: Enick Robert M. , Holder Gerald D. , Morsi Badie I.
Published: December 2007

A graphic equation-of-state (EOS)-generated correlation for the minimum miscibility pressure (MMP) of CO2/crude-oil displacements is presented, along with a brief review of 17 other MMP correlations.

The MMP is estimated as the cricondenbar or first-contact miscibility pressure of the pure or impure CO2/crude-oil system in which the C5+ oil fraction is modeled as a single normal alkane of equivalent molecular weight. The correlation accounts for all the experimentally observed trends in MMP in a consistent manner and is independent of any CO2/crude-oil data base. A correction is introduced, however, to prevent a predicted increase in the MMP with decreasing temperature at low temperatures for high-molecular-weight oils. The average predicted-MMP/experimental-MMP ratio for 157 CO2/crude-oil MMP values is 1.09, with a standard deviation of 0.19. Unlike other correlations, specifically those relating MMP with CO2 density, a decrease in MMP with temperature at elevated temperatures (> 120°C [> 248°F]) is predicted.
An Overview of Gravel-Packed Completions
Authors: Heng H. B.
Published: December 2007

Sarawak Shell Bhd./Sabah Shell Petroleum Co. (SSB/SSPC) experience with gravel-packed completions covers some 12 years. During that period, some 290 gravel-packed zones have been completed, and about 400×106 bbl [64×106 m3] of oil have been produced through gravel packs in 13 offshore fields.

This paper presents an overview of the development of gravel-packing methods, with special reference to the new gravel-packing technique developed in early 1984 for the Bay an field gravel-packed completions. Productivity reduction resulting from gravel packing and the long-term performance of the packs are discussed briefly.
Depositional Systems and Diagenesis of Travis Peak Tight Gas Sandstone Reservoirs, Sabine Uplift Area, Texas
Authors: Fracasso Michael A. , Dutton Shirley R. , Finley Robert J.
Published: December 2007

The Travis Peak formation (Lower Cretaceous) in the eastern East Texas basin is a fluvio-deltaic depositional system divided into large-scale facies packages: a middle sandstone-rich fluvial and delta-plain sequence that is gradationally overlain and underlain by a marine-influenced delta-fringe zone with a higher mudstone content. Domes and structural terraces on the west flank of the Sabine Uplift influenced deposition of Travis Peak sediments, and most Travis Peak gas production in this area is from thin sandstones (<25 ft [< 7.6 m] thick) in the upper delta-fringe facies. The trapping mechanism is stratigraphic pinch-out of sandstones or porosity zones within sandstones, or both, on the flanks of structures.

Detailed mapping of producing sandstone sequences in the uppermost upper delta-fringe on the western flank of the Bethany structure has delineated fluvial channelways, distributary or tidal channels, and barrier or distributary-mouth bars. Most Travis Peak gas production in the Bethany West area is from the bases of channel sandstones in a marine-influenced facies belt.

Travis Peak sandstones in the eastern East Texas basin have undergone a complex series of diagenetic modifications. Precipitation of authigenic quartz, ankerite, dolomite, illite, and chlorite and the introduction of reservoir bitumen were the most important causes of occlusion of primary porosity and reduction of permeability. Permeability decreases with depth in the Travis Peak, which suggests that the diagenetic processes that caused extensive cementation and resultant low permeability throughout most of the formation operated less completely on sediments deposited near the top of the succession.
Viscosity Measurements in the Presence of Wall Slip in Capillary, Couette, And Parallei-Disk Geometries
Authors: Yoshlmura Ann S. , Prud'homme Robert K.
Published: December 2007

Measurements of viscosities for slurries, cements, gels, foams, and emulsions are often confounded by the presence of slip at solid boundaries. Slip arises from thin regions of low-viscosity fluid at the boundary that result in large velocity gradients near the solid surface. Unless the measurements are corrected for slip, the calculated viscosities will be smaller than the true fluid viscosities. We review available techniques for determining wall slip velocities and viscosities in standard geometries. The earlier techniques of Mooney for capillaries and Couette geometries are presented. In addition, new analyses are presented for Couette and parallel-disk geometries. The new Couette analysis requires only two measurements rather than the three required in Mooney's analysis. Examples showing the application of these techniques are given for the capillary, Couette, and parallel-plate geometries. Experimental techniques to eliminate wall slip by use of rough surfaces are described.
Laboratory Study of Lost Circulation Materials for Use in Both Oil-Based and Water-Based Drilling Muds
Authors: Nayberg T. M.
Published: December 2007

Lost circulation is one of the most troublesome and costly problems encountered in drilling. This problem is magnified when expensive oil-based muds are used. There are many lost circulation materials (LCM's) that perform effectively in water-based muds but very few that work well in oil-based muds. Those that do work well are effective in controlling seepage loss only.

This paper presents laboratory test results that compare the performance of conventional LCM's with a new high-performance material, composed of thermoset rubber, in controlling mud loss to simulated fractured formations in both oil- and water-based muds. Field case histories describe the effectiveness of the thermoset rubber in fractured formations with severe lost circulation problems.
Analysis of Helical Buckling
Authors: Kwon Young W.
Published: December 2007

A new solution to helical buckling is presented yielding real helical shapes of buckled pipes with a varying helix pitch. This solution has been developed with the beam/column equation. The change in length and the bending stress can be computed from the helical-buckling solution. In addition, a new equation for tool clearance in helically buckled pipes is provided.
Openhole Packer for High-Temperature Service in a 500°F Precambrian Wellbore
Authors: Dreesen Donald S. , Miller James R. , Halbardier Floyd A. , Nicholson Robert W.
Published: December 2007

An openhole packer system has been designed, fabricated, and tested. The system has been used to isolate zones, to conduct injection tests, and to stimulate a 500°F [260°C] hot dry rock (HDR) geothermal reservoir. After exposure to temperatures of 460°F [238°C], the packer has functioned at differential pressures up to 5,500 psi [38 MPa]. Three high-pressure, massive hydraulic fracturing operations, each injecting more than 1 million gal [3800 m3] of water, have been conducted with the packer system.
Design Considerations for an Inhibitive, Stable Water-Based Mud System
Authors: Chesser B. G.
Published: December 2007

This paper discusses the technique of using high-molecular-weight organic polymers to stabilize troublesome shales through the adsorption of a protective polymer layer. It specifically covers the performance of a partially hydrolyzed Polyacrylamide (PHPA) in respect to shale preservation and in the retardation of cuttings dispersion. Other design factors—e.g., pH control, rheological stability, and lubricity—are also covered.