bluuebunny/crossref_metadata_2025 huggingface dataset:
A Point Bar Facies Reservoir Model – Semi-Communicated Sandbody
Authors: Xue Peihua
Published: December 2007

It is indicated in the secondary recovery practices that in the course of development by waterflooding, the point bar reservoir of meandering channel deposition generally shows a complicated production performance, poor development results and low ultimate recovery, estimated as about 30%.

Furthermore, it shows that this type of reservoir has a great potential with the estimated remaining oil reserve of more than 50% based on the analysis of swept thickness and water displacement efficiency of the reservoir by an examination of the data from inspection wells. How to tap the potentialities and how to improve the ultimate recovery of this type of reservoir are the primary issues that are commonly concern personnel in the petroleum industry.

In this article, from a developmental, geological point of view, modern deposits study is used, combining some case histories to analyze the geological factors which affect the present development results in which heterogeneous characteristics of point bar reservoir were the main items studied. Results of some related numerical simulations have been used and the program of mixed injection water and gas which can possibly increase the recovery factor by 16% have also been discussed, in order to further establish, perfect and prove the practices and the theory of semi-continuum reservoir model for the point bar facies sand body.
Determination of Residual Oil Saturation in Place By Carbon/Oxygen (C/O) Logging in Daqing Oilfield
Authors: Yang Yinzu , Qu Xiancai , Yin Guocai
Published: December 2007

In this paper, the application of the c/o spectrum logging tool developed by the Geophysical Institute, Daqing Logging Company in Daqing Oilfield, is described. The expressions for interpretation of oil saturation in place by c/o logging which is suitable to the arenaceous and argillaceous section in Daqing area is proposed. Data analysis indicates that the average accuracy for determining oil saturation in place by c/o logging is 10.9%, and the degree of agreement of grade of flooding determined for an oil reservoir is 76.9%.
The Permian Massive Conglomeratic Reservoir in Karamay Oilfield
Authors: Liu Jingkui
Published: December 2007

This paper gives an analysis of Wuerhe oil reservoir in block-8 and discusses the effectsof Sedimentary facies, reservoir texture, diagenetic compaction and epigenesis on the petrophysical properties and the oil saturation of this low permeable reservoir. The alluvial-flood fan depositional facies and structural elements give controls on the oil and gas distribution; "multi-mixtures" texture makes the petrophysical properties worse; the diagenetic compaction and epigenesis cause authigenic minerals to be vertically distributed zones and horizontally in belts. A low permeability, fine throat and double-porosity reservoirdominated by secondary porosity is formed. Thedata of conventional core analysis, special core analysis, well-testing, and their isopack maps are used to evaluate the reservoir in eachzone and each belt. The development pattern ofthis type of oil reservoir is discussed with these parameters together with those data from the production tests.

The lower Wuerhe oil reservoir of upper Permian in block No. 8 of Karamay oilfield, is located on the monocline of K-W overthrust zone along the N-W margin of Zhunger Basin, it is bounded by No. 202 paleo-uplift in its west andby Mahu depression in its south, being a monocline controlled by "A" type faults formed by an intersection of the K-W fault and No. 202, No. 256 faults. It dips to the southeast at an angle of 3-14° with an average depth of burial of 2900 m, and is a conglomeratic reservoir of alluvial-talus mixed facies with a thickness of 111-815 meters. From the bottom to the top the seven members, U17-U11, are overlapped on Carboniferous-Permian andesite with a mean effective thickness of 58 m, an effective porosity of 9.0% and an effective permeability of 2.15 md.U13,U14,U15, are the major oil-bearing zones and the U16,U12, being the next. The reservoir pressure is 348.5 atm. and saturation pressure is 296 atm. The original GOR is158 m3/m3, and the formation temperature is 67°C. The reservoirviscosity of the oil is low, averaged 0.7 cp. Salinity of formation water is 30 g/l and is in the type of CaCI2, NaHCO3, or Na2SO4(see Tables).

Poor depositional facies, strong diagenic compaction, complicated reservoir matrix texture and intense epigenesis have resulted in the characteristics of a fine throat and low porosity, very low permeability double porosity conglomeratic reservoir which is dominated by secondary porosity.
An Equation of Formation Deviating Force and its Application
Authors: Yang Xunyao
Published: December 2007

An equation of formation deviating force has been developed based on drillability anisotropy of formation. It can be used to simplify the calculation of deviation control by a pendulum drill string, to determine the formation anisotropy index and to analyze quantitatively the total deviation force acting on the bit in combination with drill string mechanics. A sample calculation of deviation control by a pendulum drill string with a specified length is also presented. A number of field tests have demonstrated satisfactory results.
The Black Oil Model for a Heavy Oil Reservoir
Authors: Huan Guanren
Published: December 2007

In a real black oil reservoir, especially in a heavy oil reservoir, the density, viscosity and other fluid properties of the oil vary both horizontally and vertically from point to point in the formation. For example, formation oil viscosity may vary several times and even more from the top of the formation to the water-oil contact. This phenomenon is due to the variation of crude oil composition. In a heavy oil reservoir, due to the gravity segregation and the difference of the oxidation of water to oil, the asphaltine and gel content of the oil varies with depth and the distance to the water-oil contact. The above mentioned phenomenon and the behaviour of that type of reservoir can not be realistically simulated by the conventional black oil model with multipool approach.

This paper suggests a black oil model with four components, which uses a two-pseudo-component-mixture concept to solve the above mentioned simulation problem. In this model, oil is considered as a mixture of two pseudo oil components with the different asphaltine and gel contents. In this case, the properties of the mixture will be dependent on, in addition to the pressure and temperature, the mass fraction of each pseudo component in the mixture.

The paper uses the 'flash' approach in paper(1)to solve this problem. In the model, the pressure and the four components (water, gas and two pseudo oil components) masses per unit formation volume are considered as basic unknowns to be solved. Though more complicated considerations are included, the model still uses the PVT data of conventional black oil, and the computer time would not be increased too much, as the Sequential Implicit method is applied for the numerical solution.
An Improved Model for Interfacial Activity of Acidic Oil/Caustic System for Alkaline Flooding
Authors: Tong Mingzhe , Liu Pu , Zhang Lufang , Zhu Yajie
Published: December 2007

In alkaline flooding, Interfaclal properties of acidic oil/aqueous caustic play an important role. Although lots of experimental results concerning the effect of various parameters upon interfacial tension and surface charge density have been reported, the mechanism is still not well clarified. C. J. Radke, T. F. Yen and D. T. Wasan have already presented their chemical models for interfacial phenomena of this system, but they all ignore the possibility of forming micelles in the aqueous phase.

This article deals with an improved equilibrium chemical model of acidic oil/caustic system. Taking the effect of NaOH-NaCI concentration on the micelles formation into consideration, an expression of interfacial activity is proposed on the basis of Davies theory of the ionic monolayer. Using kerosene containing oleic acid/aqueous solution of hydroxide-sodium containing sodium chloride as the model system, the data of interficial tension (7) and electrophoretic mobility (U) with various concentration of sodium hydroxide and sodium chloride in aqueous phase and acid value of oil phase are presented. The critical micelle concentration of sodium oleate under the various ionic strength is determined and the relation between the micelle concentration and ionic strength is employed in the simulation calculation. γmin and U max thus obtained from the model calculations agree well with the experimental results in regard to the varying trend of parameters used. The mechanisms for the presence of γ min are also suggested. This model may be used in practical numerical simulation for alkline flooding with reasonable option of physicochemical parameters.
Well Testing in the Annulus of Pumping Wells
Authors: Wang Qian , Fu Shenquan , Wang Zhuguo , Sun Yingche
Published: December 2007

Well testing technique in the annulus of a pumping well has been a subject on which great efforts have been made by petroleum scientists and engineers in recent years. Based on the practical situation in our country this paper analyzes and discusses in detail the features of such techniques developed in our country. The paper also describes some testing devices, instruments and equipment used for the well testing in cacing-tubing annulus and puts forward their opinions as to the interpretation of the data obtained from such instruments in the downhole annulus and its application. Thus a valuable basis for the development of well testing techniques in pumping wells in our country is provided.
Variable-Rate Reservoir Limits Testing
Authors: Blasingame T. A. , Lee W. J.
Published: December 2007

This paper presents a new method of estimating drainage area size and shape from production data (bottom-hole pressures and flowrates). The method is a rigorously derived approximation for variable-rate flow in. a closed reservoir. This method requires a graph of Δp/qm vs. the superposition plotting function (which is easily calculated by hand). The slope and intercept of the graph are used to provide the desired estimates of drainage area size and shape.

The method that we propose is an approximation, however it has been proved to be very accurate for the constant rate, constant pressure, exponential rate, logarithmic rate, hyperbolic rate, sinusoidal rate, and discrete rate cases. The method also gives acceptable results for square wave rate and random rate cases.

The new method is derived for the time after the initial pressure transient has reached the outer boundary. The changes in flowrate cause additional transients, but we assume that this effect is negligible when compared to the influence of the outer boundary. Therefore, if the change in flowrate does not dominate the influence of the outer boundary, the new method should give acceptable results. Also, at present, this method is only derived for single-phase flow of a liquid of small and constant compressibility.
Steamflood Surveillance Using Temperature Observation Wells
Authors: Wood S. G. , Dunham D. J.
Published: December 2007

Much has been written about screening criteria and design methods for steamflooding. However, equally important is surveillance of existing projects. Fields undergoing expensive supplemental recovery processes cannot be installed and then left unattended. Careful monitoring of a steamflood is needed to ensure that the operator is producing the most oil for the least steam, or in other words, is maximizing the project's profitability.

This paper describes one of the current surveillance programs for the Tulare formation steamflood in the South Belridge field, in Kern County, California. The progress of this steamflood is difficult to determine from volumetrics because of simultaneously flooding multiple sands with commingled injection and production wells. A primary tool was therefore needed to directly measure areal and vertical sweep efficiencies in order to optimize drainage and injection.

This has been accomplished by the use of temperature observation wells in about one per every three five-acre patterns. The observers consist of wells converted to observation and newly drilled observation wells. Several logging techniques were evaluated to ensure accurate, economical and timely data.

These observation wells are logged semiannually to determine the temperature of each of seven producing sands. This information is then used to construct computerized temperature isotherm maps for each sand over the entire field. These maps show which areas are being adequately heated and which are either too hot or not hot enough. Steam injection profiles and rates can then be adjusted accordingly using analytical heat balance calculations or temperature based injection guidelines from thermal reservoir simulations. The maps also show where additional steam injection wells or producers may be required.
Conductivity Testing of Proppants at High Temperature and Stress
Authors: McDaniel B. W.
Published: December 2007

A non-commercial approach to measure fracture conductivity in the laboratory has been developed to assist operators in selection of proppants for high temperature and high stress hydraulic fracturing applications. Simple laboratory tests that would dictate proppant choice are no longer considered sufficient since test parameter choices affect the outcome so drastically. For example, extending the stress period from 1 hour to 18 hours can decrease the measured conductivity value by a factor of three. The added effects of brine flow at elevated temperature for extended time periods have been seen to result in even greater conductivity decreases.

Much conflicting conductivity data has been presented in our industry. Often, the choice of test parameters or the test cell design have been responsible for these discrepancies. Sometimes such data are used to select a certain product and may significantly disagree with other published test results which indicate the superiority of a different proppant.

In this work, several variables that can affect measured proppant conductivity were evaluated using five proppants of different composition.

The variables studied were: (1) Effects of extended time at different test conditions; (2) Variation between ambient and elevated temperature testing; and (3) Effects of brine flow at high, temperature and closure stress.
Subzero Hydraulic Fracturing: A Field Case Study, Lisburne Carbonate Reservoir, Prudhoe Bay Unit, North Slope, Alaska
Authors: Schumacher J. P. , Dickerman R. P.
Published: December 2007

A successful hydraulic fracture treatment was performed on a delineation well in the Lisburne naturally fractured reservoir, North Slope, Alaska during extremely severe weather conditions. The well performance information from this delineation well was of critical importance to the development and subsequent funding of the $2 billion Lisburne project. Logistical problems which developed prior to the fracture treatment required special design considerations usually taken for granted in many North American locations. Special considerations for economy, the environment and safety were integrated into a straightforward hydraulic fracture treatment performed at a wind chill temperature of −85°F (−51°F ambient).

This paper discusses the fracture design and February 11, 1984 field treatment which led to the successful stimulation of the South Bay State No. 1 delineation well. Also included is a discussion of the results obtained from the subzero hydraulic fracture treatment. A better understanding of equipment performance, fluid rheology, proppant mixing, logistic limitations and human elements under severe weather conditions was gained from the treatment.

In addition, this paper addresses the following cold weather concerns that arose prior to the implementation of the fracture treatment:

○ Use available equipment, successfully perform hydraulic fracture treatment. ○ Mix proppants and additives "on the fly". ○ Proper function of electronic, pneumatic and hydraulic systems as well as rubber conveyor belts. ○ Safe and proper seal of surface tubulars. ○ Rheological properties of gelled diesel. ○ Effects of the elements on human beings. ○ Pre-frac breakdown to gain more data. ○ Uncomplicated pump schedule.
A Study of Crude Oil Composition During CO2 Extraction Process
Authors: Wang G. C.
Published: December 2007

The extraction process of hydrocarbon from crude oil by CO2 and the development of miscibility were simulated in a high pressure visual cell. Samples of the extracted crude oil as well as the enriched CO2 vapor were withdrawn successively from the cell for composition analysis using a gas chromatograph.

Three natural crude oils with gravities ranging from 17° to 45° API (sp. gr. 0.80 to 0.90) were chosen for the study. The results indicate that the CO2-crude oil interactions can be divided into three stages: (a) CO2 condensation, (b) extraction-condensation and (c) extraction. It was found that the amount of hydrocarbon being extracted was proportional to pressure or CO2 density. Lighter components from C5 to C20 were comparably easy to be extracted, however, heavier components up to C36 may also be extracted though in a relatively smallquantity. For heavy crude oil containing low intermediates of C5 to C20, the extraction was inefficient at all conditions. Active and deep extraction may cause permeability damage due to excessive asphaltine deposition.

Temperature has a great effect on CO2 extraction. The extraction efficiency could be improved with reduced temperature. Best extraction was obtained when CO2 was in liquid state.
Evaluation of the Performance of 13% Cr/4130 Bimetallic Tubing in CO2 Environment
Authors: Dávila A. , Newski M. , Zerpa G.
Published: December 2007

The corrosion behavior of 13%Cr/4130 bimetallic tubing produced by hot forging was evaluated under extreme CO2environment, i.e. well conditions. This investigation involves corrosion testing in static autoclaves and an additional full scale test, in order to evaluate the corrosion behavior of the pipe and its connection under different Venezuelan well-operational conditions. Furthermore chemical composition, mechanical testing and metallographic characterization were also carried out.

The study is relevant to the oil industry since it implies a cost reduction of about 30% compared with the use of conventional 13%Cr OCTG tubulars. Excellent resistance was achieved with mechanical properties of the pipe similar to the 4130 carbon steel and a corrosion resistance to the CO2 environment equivalent to that of the 13%Cr conventional pipe. However, the interfase shows depleted chrome regions, as a result of carbon diffusion for adequate metallurgical bonding during manufacture of the pipe, which makes it susceptible to galvanic corrosion. As a result of this investigation the bimetallic tubing will be tested under different field conditions.
A Color Borehole Television System for Developing Gas Production From Devonian Shales
Authors: Darilek G. T.
Published: December 2007

A specialized borehole television system has been developed to aid in the development of gas production from eastern Devonian gas shales and other tight formations. The borehole television has advanced capabilities that are useful for visually diagnosing geological and reservoir factors associated with gas production. These features include high resolution color video, compass for orientation determination, control of borehole debris to maintain an unobstructed view, and simultaneous forward and upright side view. The side view is provided by positioning a mirror in front of the camera lens. Upright orientation of the side view image is maintained by rotating the camera and mirror assembly as a unit within the camera housing. The forward view provides rapid reconnaissance and the side view is used for detailed inspection of features in the borehole. A compass placed beneath the side view mirror is used to determine the orientation of the viewed image.

Field applications in the Appalachian basin demonstrated the usefulness of the color borehole television system. Geologists visually examined the depths of the gas wells to identify the factors affecting gas production. Of particular utility was the ability to definitively identify areas of gas and oil entry. Gas condensate was observed to bubble and vaporize as it entered the boreholes. The locations of side wall core samples were verified and the orientation of these samples was determined. Geological strata, crude oil stains, condensate and crude oil in the bottom of the well, cavities, porous zones, fractures, and casing were inspected. The camera was also used to locate a stuck logging probe lodged between the casing and a washout behind the casing The system has been installed in a borehole television logging truck for use in Gas Research Institute Devonian shale research programs and other commercial applications in the Appalachian Basin.
Pressure Transient Analysis of Methane Production From Coal Beds: An Analytical Approach
Authors: Bayles G. A. , Reznik A. A.
Published: December 2007

Transient and semi-steady-state solutions of the radial diffusivity equation are presented for the case of well tests on coalbed-methane reservoirs.

An inverse diffusion term, which characterizes coupled matrix-fracture gas. transport, is defined from a Langmuir desorption term and the inverse hydraulic diffusivity. The ratio of this total or coupled diffusivity to the hydraulic diffusivity is identified as the time delay of the bottom-hole flowing pressure response of the coalbed vis-a-vis that of a conventional gas reservoir during a constant-rate pressure drawdown test.

The modified transient and semi-steady-state equations for pressure drawdown as functions of time are completely analogous to those for conventional gas reservoirs when the inverse hydraulic diffusivity of the latter is replaced by the inverse coupled diffusivity of the coalbed.

A numerical simulator is employed to solve the open forms of both the conventional and coalbed radial diffusivity equations. The usual straight-line trends for the transient and semi-steady-state periods are manifest from simulation of both cases. These were parallel for the transient time period and divergent for the semi-steady-state period.

Values of permeability, net skin factor, area of drainage and shape factor are obtained directly from the pressure-versus-time plots of the two time periods.

The present analysis is limited to the extreme matrix-to-fracture transport rates, namely, instantaneous and zero. Actual pressure-response data, however, can be analyzed for any implicit transport rate.

The present work is limited to single-phase gas flow without wellbore storage and to a single net skin effect.
Designing Hydraulic Fractures for Efficient Reserve Recovery
Authors: Elbel J. L.
Published: December 2007

In designing hydraulic fracturing treatments, the designed fracture length is often limited to a percent of the drainage distance. If the well spacing is based on a square pattern, the results may be that the designed fracture length is too small to achieve adequate production at an early time. If the fracture length is increased to provide adequate early-time production rates and the spacing is increased accordingly but still in a square pattern, the result may be that a large portion of the reserves will remain in place after a normal 20- or 30-year well life. A number of papers have been written concerning fracture optimization and well spacing indicating the need for a rectangular drainage shape. This paper shows how cumulative production type curves for hydraulically fractured wells can be used as guidelines in determining the combinations of fracture length, fracture conductivity, spacing and spacing geometry to provide an adequate early production (one to two years) and efficient reserve recovery (±90% in 20 to 30 years). The method presented can be performed in a matter of minutes. It can also provide a basis for a more thorough reservoir simulation if more detail or accuracy is required to overcome the limitations imposed by the use of type curves.
Effective Production Strategies for Coalbed Methane in the Warrior Basin
Authors: Wicks D. E. , Schwerer F. C. , Militzer M. R. , Zuber M. D.
Published: December 2007

This paper discusses the economics of coal-bed methane production in the Warrior Basin under a variety of production strategies. Traditional development practices in the basin have used such techniques as hydraulic fracture stimulation in the single major coal seam, with wells spaced relatively close together on a square shaped pattern. This paper examines the enhancement of production using larger stimulations along with the corresponding economic impacts. Also examined are the effects of using multiple completions on several coal seams in the Pratt, Mary Lee, and Black Creek coal groups to further increase production from a single well. Finally, the impacts on production of drilling on various sized spacings and drilling on elongated pattern shapes to take advantage of permeability anisotropy are simulated. The production streams are then utilized in a detailed cost and economics model to determine the minimum gas price required for various rates of return on investment.

The effects of technology and production strategies for coalbed methane are forecast using a detailed two-phase, dual-porosity finite-difference simulator to predict both gas and water production rates. These rates are then used in the cost and economics model to determine equipment size and compression costs as well as generating revenue streams on which to calculate discounted cash flow. Costs are also determined by the depth of the seams, and in the case of stimulation, the thickness of the treated interval. The majority of the detailed reservoir data required to run the simulator were determined through field and labora tory tests at the Gas Research Institute's Rock Creek Multi-Seam site.
Coalbed Hydraulic Fracture Treatment Empirical Relationships and Computer Simulation
Authors: Jones A. H. , Bell G. J. , Morales R. H.
Published: December 2007

The stimulation of gas flow from coal seams by hydraulic fracturing has been pursued in the U.S. for more than ten years. However, there currently is no concensus among the industry as to the best approach for coalbed stimulation design; there are many different fracturing techniques used by operators.

Under sponsorship of the Gas Research Institute, data on more than 130 separate hydraulic fracture treatments in coal were acquired from the industry. An empirical study of fracture treatments in coalbeds of the Black Warrior Basin in Alabama reveals a trend for the maximum treatment pressures observed during hydraulic fracture treatments in coal to approach twice the values of the minimum horizontal stresses. This trend far exceeds the observed maximum treatment pressures in conventional sandstones at equivalent depths.

To enable simulation of such high treatment pressures, several physical mechanisms were investigated, including pressure buildup due to fluid leakoff, multiple fracture propagation, high viscosity fluid due to coal fines generation, and fracture-tip plugging. A 3-D hydraulic fracture computer code was modified to account for an incomplete fracture-tip screenout due to coal fines plugging within the fluid pad. The ensuing fracture treatment predictions more closely reproduce field results and provide better insight to the proper design of fracture treatments in coal deposits.
A Leading Index of Drilling Activity: Update and Improvements
Authors: Buell R. S. , Maurer R. A.
Published: December 2007

A five-component composite leading index of United States rotary rig drilling activity is updated. The index is presented for 1949 through April 1986 and is shown to consistently lead turning points in drilling activity. Seven new leading indices based on some new components are also presented. A forecast of drilling activity is made for the remainder of 1986 based on the leading index and the current economic condition of the petroleum industry. The methods used to prepare time series and construct indices are reviewed.
Drilling a 26-in. Diameter Hole to 12,550 ft: A Case History
Authors: Fontenot E. P.
Published: December 2007

Standard Oil Production Company (SOPC) drilled a 26" diameter hole to a world record depth of 12,550'. Although a number of holes of this diameter had been drilled to depths on the order of 7000' to 9000', most had not been drilled through geologic formations as old with rock as competent as encountered in this well. This paper discusses the drilling challenges encountered during the course of this drilling operation. Through planning, careful detailed research into equipment design, and close field observation, solutions to problems encountered under relatively severe, drilling conditions were developed. The successful drilling of this portion of the well allowed SOPC to set a world record string of 20" casing and ultimately led to the programmed objective of reaching a total depth of 25,015' in a hole size of 8-1/2".
Advanced Field Automation in the Tuscaloosa Trend
Authors: MacDonald T. E.
Published: December 2007

The Tuscaloosa Automated Production System (TAPS) was developed in response to the difficult producing environment of the Tuscaloosa deep gas trend. It has subsequently been expanded to include a waterflood project in a shallow oil field. This paper illustrates how TAPS transforms field automation into a simple tool that the entire staff can use to optimize and analyze field conditions.

Examples of features such as the annunciator, schematic diagrams, and process control demonstrate the system's ability to aid in field operations. Other options including online history, real time data graphs, and automatic reporting show how automation is used to analyze field conditions. Four years of experience have proven these features enable both field and office staffs, that have no "computer" training, to use the system as an integral part of the daily producing routine.
Polymer Mud vs. CLS-Lig in Normal Pressure Applications: South Texas
Authors: Koenig R. L.
Published: December 2007

Exxon Company, U.S.A., South Texas, has recently employed the use of a polymer drilling fluid system in 68 drill wells with encouraging results. Both drilling and production related benefits have been observed on many of the wells using the polymer system when compared to those drilled with conventional chrome lignosulfonate mud. These benefits include: 1) increased ROP, 2) improved bit life, 3) better solids control, 4) reduced hole enlargements, and 5) improved completion success. Additionally, these benefits have been achieved at lower overall intangible costs than comparable wells drilled with chrome lignosulfonate mud.

This paper summarizes some of the advantages of the polymer system relative to chrome lignosulfonate mud as observed from actual field comparisons. It includes a thorough discussion of the polymer system and the various products used in make up of the mud. Factors that contributed to the improved performance are discussed in detail. Problems experienced in the use of the system with possible explanations are also provided.
A Comparison of New Ultrasonic Cement and Casing Evaluation Logs With Standard Cement Bond Logs
Authors: Sheives T. C. , Tello L. N. , Maki V. E. , Standley T. E. , Blankinship T. J.
Published: December 2007

New ultrasonic inspection techniques have been implemented to evaluate cement bond and casing conditions. These techniques, relying on state of the art downhole, high-speed waveform digitization, can successfully determine cement voids and channels and also provide accurate bond information in the presence of a microannulus. The downhole microprocessor controlled electronics transmits the digitized waveforms to the surface for computations and display. The downhole waveforms are then viewed by the operator in real time to insure proper log quality. Numerous log examples showing comparisons with the standard Cement Bond Log (CBL) demonstrate that the accuracy and resolution of the new approach provide much more information.

Casing conditions are determined using both acoustic caliper measurements and a new casing thickness measurement technique. The acoustic caliper measurement not only determines accurately the casing inside diameter, but also detects the pipe gap at casing collars. The new measurement determines actual casing thickness variations due to internal or external pipe wear or corrosion. Experimental results along with log examples show the effectiveness and accuracy of measuring the actual casing thickness at the well site in real time.
A New TFL Test Centre in Norway
Authors: Tailby R. J. , Christensen O. S. , Aarrestad S. , Maddux G. D.
Published: December 2007

A TFL test centre has recently been built in Stavanger, Norway, with the aim of qualifying TFL equipment and techniques for use in subsea wells.

This equipment is presently being testing in a 660 ft (200 m) horizontal loop, to which a 5000 ft (1500 m) flowline has recently been added. A well is planned for 1987. All surface facilities are indoors, and all-weather capability has been achieved.

Problems have occurred with the test equipment and the facilities which have provided inexperienced personnel with valuable and relevant on-the-job training. After one year's operation, the test centre is rapidly proving its worth and generating a better understanding of TFL in Norway.
Successful Salvage and Tie-Back Operations for a Hurricane-Damaged Satellite Well in the Gulf of Mexico
Authors: McCutcheon J. B. , Payne M. L.
Published: December 2007

The Eugene Island Block 174 Well No. 3 was producing 1000 B0PD before it was blown over by Hurricane Danny in August, 1985. The well was located offshore Louisiana in 80′ of water. The 60″ OD x 1.75″ wall caisson which supported the satellite well was sheared in two at four feet below the mudline, while the upper portion of the well was bent 85 degrees from vertical. Taking into account the severe bending of the tubing and casing, reduced pressure ratings were calculated and the well was killed. Successive windows were cut in the casing by divers to evaluate the inner pipe strings for salvageability. The tubing strings were plugged with cement and the well was severed at the bend area with high explosive shape charges. The casing stubs were dressed off and the well tied back. The successful salvage operation achieved a two million dollar cost savings when compared to drilling a replacement well.
Discussion of 1986 SPE Manpower Survey
Authors: Calhoun J. C.
Published: December 2007

1.) Twenty nine companies responded to the survey in 1986. Data covering all aspects of the survey were available in 22 of the replies, but for some aspects of the analysis as many as 27 replies were usable. In terms of numbers of engineers employed at the end of 1985, the distribution of company sizes for the 27 companies was:

2.) Year-end employment of engineers for 27 companies is shown in Figure 1. Year-end employment figures for those with petroleum engineering degrees were available only for 25 companies, and this is also shown in Figure 1 and tabulated in Table I. These companies, over the five years, reported 25% of their engineering work force to be petroleum engineers, although the percentage rose continuously from 21.9% in 1981 to 29.6% in 1985. The total engineering work force showed its lowest point in 1983. The petroleum engineering work force on the other hand showed a continuing increase over the entire five years.

3.) Employment and projection estimates were available for only 25 of the responding companies. Some respondents felt the current situation to be too unstable to permit any kind of projections. Figure 2 and Table II shows the projections to vary from an increase of 17.5% over the next five years to a decrease of 10.1%, but both high and low projections show a lesser total employment of engineers for both 1986 and 1987 than in 1985. The drop projected from 1985 to 1986 is not so large as would be expected from recent reports of retirements and layoffs that have been circulating, although the low projection for 1986 shows 15.4% less than 1985.
Basic Concepts in Static BHA Analysis for Directional Drilling
Authors: Chandra U.
Published: December 2007

Basic concepts related to the static analysis of two-and three-dimensional bottomhole assemblies are discussed. Beginning with a straight one stabilizer assembly, the effects of multiple stabilizers, borehole curvature, torque, wall contact, etc. are introduced in steps. The criteria for defining the build, hold, drop and walk trends is clarified. Two methods for computing bending stiffness and equivalent outer diameter of MWD collars with nonuniform cross-sectional properties are proposed. Also, simple methods of estimating buckling loads for one and two span assemblies are presented.
Design and Implementation of Immiscible Carbon Dioxide Displacement Projects (CO2 Huff-Puff) in South Louisiana
Authors: Palmer F. S. , Landry R. W. , Bou-Mikael S.
Published: December 2007

The CO2 Huff-Puff (Immiscible Carbon Dioxide Displacement) process is described including reservoir mechanics. The planning, design, and implementation of the projects including the equipment specifically designed and constructed for these projects are discussed. Case histories of selected projects are included. The paper contains field operations detailing the problems encountered and subsequentially corrected.
Techniques for Planning and Execution To Improve Foam Cement Job Performance
Authors: Kulakofsky D. S. , Creel P. G. , Kellum D. L.
Published: December 2007

A study of foam cement job results and laboratory data shows improved bond log performance, reduced planning time, and significant cost savings from using computer modelling and refined job procedures.

The computer model considers the most complex well conditions while still accounting for the continuously changing friction factors and density of an expanding or compressing foam. Elements of information predicted by the model are (1) pump rates, (2) surface pressure, and (3) nitrogen concentration. The model also gives an indication of the need to foam mud and/or spacers. These elements are based on predicted downhole circulating density, which is the prime factor determining the ultimate success of a foam cement job. A comparison of predictions to actual job results is presented.

When running a foam cement job, operators have historically attempted to either (1) maintain constant nitrogen levels, or (2) maintain constant density. Subject paper compares the two philosophies and recommends, based on analysis of six years of field results, what the authors consider the optimum approach. Aspects of the two philosophies selected for comparison are (1) circulatability of the cement throughout the job, (2) competency of the cement, (3) ease of job design, (4) ease of operation, and (5) feasibility.

Field results, laboratory data, and bond logs are presented which demonstrate (1) substantial reduction in cost per cement job, (2) elimination of surface water flow, and (3) probable long term production increases brought about by reduction of cement invasion into weak, producing formations.
A Second Look at the Chapman, Deep (Fusselman) Field
Authors: Prentice R. S.
Published: December 2007

A case history of a deep gas reservoir in the Delaware Basin of west Texas in which the water table acted erratically is presented. Gas wells in the Chapman, Deep (Fusselman) Field in Reeves County were watered out unpredictably by a strong edge or bottom water drive. Water coning, a process in which the water table selectively sought out low pressure sinks at producing well bores, was postulated.

Unswept pockets of gas in between the cones were also postulated. ARCO Oil and Gas Company tested the theory by recompleting an existing well on their Agnes Beckham "26" lease and found commercial quantities of gas. Under favorable economic and operating conditions, development of these unswept pockets may be feasible in this and other deep gas reservoirs.
A Laboratory Study of the Use of Subsurface Hydraulic Mining of Tar Sands
Authors: Marsden S. S. , Walter J.
Published: December 2007

We have experimentally studied subsurface hydraulic mining of tar sands which involves drilling a borehole into the sand; casing it; pumping aqueous solution down tubing with horizontal nozzles near the bottom, to use the erosive action of jets for pulverizing the tar-sand mixture and finally returning the slurry to the ground's surface for future processing.
Stratigraphic Interpretation Using Formation Imaging and Dipmeter Analyses
Authors: Grace L. M. , Luthi S. M. , Pirie R. G.
Published: December 2007

Successful stratigraphic interpretation depends on the analysis of several parameters. For many years, the dipmeter has been the key logging tool in stratigraphic interpretation. However, the nature of the measurement (four to eight microresistivity curves from four pads) placed some limits on a detailed interpretation beyond the wellbore. The recent development of 54 clustered microresistivity curves from two of the four dipmeter pads now provides two continuous side-by-side images oriented at 90° to each other. In an 8-in. hole, for example, the images cover 22% of the sedimentary formation exposed in the wellbore. The images characterize stratigraphic discontinuities (unconformities, erosional contacts), bedding thickness (thick bedded to laminated) and types (flaser, graded), sedimentary structures (crossbedding, bioturbation, deformational), and rock textures (conglomerates, breccias, shaly sandstones). Images of these oriented sedimentary features, in combination with conventional dipmeter interpretation, define the stratigraphic units and the reservoir geometry beyond the wellbore. Two case studies, including whole core analyses, are used to demonstrate the synergism between formation imaging and dipmeter interpretation.
Derivative of Pressure: Application to Bounded Reservoir Interpretation
Authors: Proano E. A. , Lilley I. J.
Published: December 2007

This paper presents the application of the derivative of pressure technique, through a process of pattern recognition, to identify bounded reservoir behaviour under both drawdown and build up conditions. During a well test, the flow and shut in sequence should be carefully selected to optimise the response which will, in turn, enable easier recognition of the outer boundary configuration and reduce the problems of non-uniqueness. With the evolution of high resolution and accuracy pressure gauges, and the introduction of simultaneous downhole flowrate and pressure measurement, convolution techniques should also be utilised to enable the analysis of previously uninterpretable drawdown data.

The pressure derivative technique provides a systematic and global approach to describe the late time features. With this technique, there is no need to resort to specialized analysis methods or correlations for well behaviour in bounded reservoirs, which are available for limited geometries and can yield erroneous results.

Due to the unusual outer boundary features now exhibited by a large number of current well tests, there is a growing need to develop better models to describe their effects. There is an even greater need to incorporate these findings with other sources of data for appropriate dynamic bounded reservoir description.

Three field examples are presented which illustrate the problems associated with interpretation of buildup data when drawdown analysis has not been possible.
North Sea Field Development: Historic Costs and Future Trends
Authors: Thomas W. A.
Published: December 2007

This paper reviews United Kingdom Continental Shelf (UKCS) field developments to date for technical features, development timescales and economics. Current UKCS field development trends are identified, including use of subsea completions and floating production platforms for development of small deep-water fields.

Economic comparisons are presented for a range of field developments under existing UK tax and fiscal regimes. The effects of unstable oil prices on rates of return are discussed, together with the effect of tax changes on field economics.
Reperforating Depleted Gas Wells in the Southern North Sea
Authors: Potts M.
Published: December 2007

Reperforating is an accepted method for reducing near wellbore pressure drop. This paper details an evaluation of the effects of reperforating upon reservoir parameters and flow profiles in depleted gas wells; the basis for the evaluation was a programme of reperforating carried out during 1985 by Amoco (UK) Exploration Company in the Indefatigable gas field in the Southern North Sea. In addition to increasing well deliverability, the aim of the programme was to use testing and production logging both before and after reperforating to evaluate its effectiveness. Two new techniques which were used are also described. These are the use of a pressure gauge in combination with a strip perforating gun, and a new design of overboard boom as part of the surface equipment.
Will Very Large Modules Reduce the Cost of Offshore Platforms?
Authors: Plowden D. , Allen R. E.
Published: December 2007

The new generation of heavy lift vessels has stimulated the design of offshore platform topsides using modules up to 7000 metric tons (or more). These very large modules will reduce the cost of offshore hook-up. However, the hook-up cost reduction may not be as great as expected and other costs should be offset against these savings.
Field Development Planning for the Heidrun Field
Authors: Till M. V. , Sauer C. W. , Smith J. E.
Published: December 2007

The Heidrun Field was discovered in March, 1985 in Block 6507/7 of the Norwegian sector of the North Sea. Partners in the block are Conoco Norway Inc., Operator (30%), Den norske stats oljeselskap a.s, (50%), Arco Norway Inc., (10%), and Tenneco Oil Company Norsk A/S, (10%). Reservoir delineation has begun with three additional wells drilled to date.

The Heidrun Field lies under 350 m (1150 ft) of water in Blocks 6507/7 and 6507/8. The average reservoir depth is 2375 m (7800 ft) subsea. The hydrocarbon bearing strata are predominantly unconsolidated sands which exhibit varied sedimentology, mineralogy and permeability through the section.

A variety of drilling and completion challenges will arise in order to fully exploit the reserves. Due to the relatively shallow depth of the reservoir and the areal extent of the sands. These include the following: High angle drillingPossible sand control measures over long sectionsHigh production rate completion practices

This paper deals with preliminary drilling and completion considerations. Items covered include reservoir modelling for well requirements; well flow analysis for well capability; structure requirements to meet various alternatives; subsea well alternatives; and sand production prediction studies to help determine completion techniques.
A Computer Monitoring System for Reservoir Management in Southern North Sea Gas Fields
Authors: Edwards P. J. , Hughes T.
Published: December 2007

Amoco (U.K.) Exploration Company, as operators in the Leman and Indefatigable Fields in the southern North Sea, have developed a computer monitoring system to facilitate reservoir management of the 118 producing wells.

The main database for the system is provided by a daily record of the individual well flowrates and pressures. The principle function of the system is to compare these values with those predicted by well test data. The results are stored and in time the history of a well's production is established.

These comparisons enable both short-term and long-term well problems to be identified and action appropriately directed to remedy them.