bluuebunny/crossref_metadata_2025 huggingface dataset:
The Sensitivity of U.S. Gas Supply Outlook to Changes in Price or Demand
Authors: Woods T. J.
Published: December 2007

Strategic planning of Gas Research Institute's R&D program requires an appreciation of the outlook for U.S. energy supply and demand and an estimate of the role that natural gas will play within that outlook. The development of a consistent framework that establishes a likely projection of future energy supply and demand is critical to this planning process. This framework is called the GRI Baseline Projection.

Overall, the 1988 GRI Baseline Projection indicates that U.S. gas production can be held stable over the next 25 years as a result of incremental production of gas in the lower-48 using new technologies and production practices and the introduction of Alaskan gas into lower-48 markets. In the 1988 GRI Baseline Projection, detailed sensitivity analyses were made of the effects on this gas supply outlook arising from significant changes in the outlook for oil prices or the demand for gas, such as might be expected should environmental policy decisions encourage gas consumption.

These sensitivity analyses lead to some interesting observations. The linkage between oil and gas prices may not be as strong as past experience has indicated. That is, while gas prices will follow oil prices down, they will not necessarily follow oil prices up. Return to gas demand levels comparable to the peak level of the early 1970s will require a substantial increase in gas imports. New gas supplies must be viewed from three perspectives: cost, location relative to gas demand, and the incremental unit size at which the new sources are introduced into the U.S. gas supply slate.
Independent Access to Institutional Capital
Authors: Vig P. R.
Published: December 2007

It is my pleasure to be with you. I am going to direct most of my comments today to investment in oil and gas by pension plans, including: the major participants in this market; the type of deal structures involved; and perhaps most important, how to position yourself to access this particular market.

First, I feel it's important to look back for a moment to the independents’ historical access to capital and how this market has changed in the 1980's, and, unfortunately, most of the changes have been to the independents’ disadvantage. The independents’ historical source of capital has essentially been three-fold: internal cash generation,bank borrowings, andindustry partners.
Utilization of the Personal Computer To Map Lineament Densities as a Tool for Fractured Reservoir Exploration
Authors: Walbe K. A.
Published: December 2007

Production of gas and oil from the fine grained, low permeability Upper Devonian rocks of the Appalachian Basin depends on connecting with natural fractures. In an attempt to correlate these productive zones with surface features a correlation has been observed between subsurface fracturing intensity, as observed from Borehole Television Camera surveys, and surface lineament density. The digitizing, calculating and density contouring of these surface lineaments can now be done with reasonably priced commercial software and a personal computer. The utile nature of this system is that it gives exploration departments a quick look at possible fracture-enhanced areas of production without the tedious and time consuming process of generating the statistics and maps by hand.
The Use of a Semianalytical Method for Matching Aquifer Influence Functions
Authors: Wattenbarger R. A. , Ding Sheng , Yang Weiping , Startzman R. A.
Published: December 2007

Aquifer performance can be modelled with an aquifer influence function (AIF). For a heterogeneous aquifer of unknown size and shape, the AIF can be calculated from field production and pressure data. The most successful method for doing this has used linear programming (LP) to compute the AIF. The current research introduces an alternate method to LP in an effort to improve computer storage and speed.

The new technique is based on the analytical solution form of a heterogeneous aquifer of any size and shape. The approximating AIF is a continuous function which is a truncated series of the analytical solution. This "semi-analytical function" is fit to field data by the use of nonlinear least squares fitting, using the Levenberg-Marquardt method. The advantages of this method, over the LP method, are that the new method (1) uses less computer storage, (2) is much faster, (3) does not require evenly spaced production periods, and (4) is more robust in use with actual field data.

The results of the new method are striking. Results show that the new method runs as much as 3,218 times as fast as LP and only uses a fraction of the computer storage. The previous implementation of the LP methods was limited to about 70 months of production history on a microcomputer, whereas the new method is virtually unlimited on the amount of production data it can handle.
Support of Drilling Operations Using a Central Computer and Communications Facility With Real-Time MWD Capability and Networked Personal Computers
Authors: Booth J. E. , Hebert J. W.
Published: December 2007

Mobil's Drilling Data Center system in Dallas gathers real-time data and manually entered reports for high cost drilling operations. The information is made available throughout the Drilling organization by means of a communications network which comprises a satellite earth station and high speed data links between major network nodes in Dallas, Houston, New Orleans and Denver. Some 200 users in these locations are directly connected to the network. Access via high speed modems is available to users not directly connected.

As personal computers have replaced terminals as the primary end-user device, the role of the Data Center and the communications network has changed. Recent upgrades to the network permit high speed data transfer from the minicomputers at the Data Center, to personal computers. Text, numeric, and graphic data (including real-time MWD information) can be transferred to the personal computer, then edited or manipulated using standard software packages. This provides the user with much greater flexibility than was possible when using terminals and host computer software. The Apple Macintosh is the standard computer used within Mobil Drilling and the network has been configured to support Apple's Localtalk/Appletalk protocol. This provides users with Wide Area Network connectivity between Local Area Networks in division offices, while maintaining the graphical user interface with which they are familiar.
A Microcomputer-Aided Experimental Gas Reservoir Simulator for Well Control Operations
Authors: Santos O. L. A. , Bourgoyne A. T.
Published: December 2007

An experimental simulator has been designed and constructed to model a gas reservoir performance during well-control operations. The simulator has been installed in a full-scale well in which a gas kick is simulated by injecting natural gas through a tubing string into the bottom of the well.

Basically, the system consists of a pressure sensor installed at the bottom of the well, a gas flow controller valve placed on the surface injection lines and a microcomputer that stores a gas reservoir inflow performance curve (flowing pressure at producing formation face vs. gas producing rate). A variation of flowing bottomhole pressure is sensed and electrically transmitted to the surface where it enters the microcomputer that processes the corresponding gas flow rate based on the previously defined inflow performance curve. This information is sent to the gas flow controller device that adjusts by itself to deliver the new injection gas flow rate.

Including the data acquisition and the gas meter systems, the simulator employs as many as four microcomputers.

The simulator performance is evaluated through graphical comparison between the gas flow rates calculated from the inflow reservoir performance curve and the actual gas flow rates delivered by the system. These data were obtained during well unloading experiments.

The overall performance of the simulator was satisfactory for the range of gas flow rates used in the experiments. Operational factors have limited the range of gas flow rates to be delivered, however. These limitations are discussed and recommendations are made to widen the range of utilization of the simulator.
Intelligent Interfaces for Reservoir Simulators
Authors: Guerillot D. R. , Blanc G. A. , Madre V.
Published: December 2007

This article describes an interactive software called AIRS ™ (for Artificial Intelligence for Reservoir Simulators). This system helps the user build the input data file for reservoir numerical simulation software.

It uses Artificial Intelligence methods to create some ‘friendly intelligent interfaces’ used to input the large amount of data needed by the simulator1. In these interfaces, the user is guided through a set of screens automatically generated by a screen generator 2 according to his set of data.

Two operational applications were developed: one for a well-testing simulator3,the other for a 3-phase, n-components compositional thermal reservoir model4, 5.
An Expert System for Multiphase Measurement and Regime Identification
Authors: Darwich T. D. , Toral H. , Archer J. S.
Published: December 2007

ESMER is a novel PC based package which can measure individual flowrates of gas and liquid phases in multiphase flow by matching the hydrodynamic turbulence characteristics of the flow, represented by pressure and void fraction waveforms, to a calibration database. The method applies advanced random signal processing algorithms employed in voice recognition and seismic analysis. A "calibration feature vector database" is first constructed on the superficial liqud-gas velocity domain. Pattern recognition techniques can then be applied to match the "feature vector of measured samples" to the "calibration database".

ESMER is available as a turnkey multiphase flowrate measurement system consisting of sensor's of user's choice, an analog to digital converter and a personal computer. Existing absolute or differential pressure electronic transducers or a simple void fraction sensor, such as a capacitance sensor could be used. The software is menu driven and includes facilities for digital filtering of noisy signal, graphical presentation of results and the compilation of the rig dependent feature vector calibration database. Help menus are provided.

ESMER has yielded accuracies of ±5% in laboratory trials. Its principal advantages are ease of installation and maintenance.

ESMER poses no obstruction to the flow line and would not normally require any modification to the flow line.
A Multiple-Process Algorithm for Laboratory Automation Systems
Authors: Nelson H. C.
Published: December 2007

This paper describes a multiple-process algorithm for Hewlett-Packard computers controlling real-time laboratory automation systems. The algorithm, called the Multiplexer, allows the resident control software to automate several independent experiments concurrently on a time-sharing basis. The multiplexing mechanism is an automated context switching cycle that directs the control software sequentially to one laboratory process at a time. The software carries out scheduled data acquisition and control operations for that process, then switches to the next process until all have been serviced. The Multiplexer keeps track of each experiment by managing context tables stored in the computer's volatile memory. The context tables contain the process hardware driver commands, automation instructions, and run status variables that define each experiment. The Multiplexer also supports context switching from the keyboard. This enables the operator to bring one of the experiments into the foreground where it can be monitored and controlled directly from the keyboard.

The Multiplexer is part of a proprietary process control and scheduling software system that automates laboratory displacement experiments such as core floods, slim tubes, permeameters, and capillary tube viscometers. Scheduled operations include data capture from various analog and digital devices, control of pumps and valves, fluid sample collection, automated gas chromatography, and on-line graphics data processing. The software also permits experiments to be monitored and controlled indirectly over telephone lines from a remote computer.
Evolution of a Network System in a Geologic Research Organization
Authors: Duncan K. M. , Orr E. D.
Published: December 2007

The Bureau of Economic Geology has successfully integrated DEC minicomputers, Apple Macintosh and IBM-compatible PC's, IBM and CDC mainframes, and a CRAY supercomputer in a flexible network that allows geologists as well as support staff to use a wide variety of software and output devices.
Petroleum Engineering Studies Educational Model
Authors: Daltaban T. S. , Archer J. S. , Toral H.
Published: December 2007

PRESEM is a computer aided field development training system used in the Petroleum Enginering postgraduate and final year undergraduate courses at Imperial College.

PRESEM provides an integration of many of the activities which go into field development from drilling to the design of surface facilities, economic forecasting of pre performance and application to regulatory authorities.

The core of the PRESEM system consists of a data base which is generated by the system supervisor through a menu driven suite of programs simulating the properties of a given or hypothetical oil field. The data base contains the geological description of the reservoir, rock and fluid properties, presented as mud and electrical logs, RFT and production test data, core and PVT analyses. These vary in accordance with the depth and location of the exploration wells chosen by the user with reference to the formation top surface map.

PRESEM also contains many auxilary programs including Schlumberger type log plotting, log-interpretation, pressure analysis, phase package for separator design, reserves estimates by Monte-Carlo analysis and economic feasibility analysis.

The paper describes the basic features of PRESEM and presents a case study.
Automatic Crude Oil Handling Through a Pressurized System from the Wellhead to the Refinery
Authors: Davis William B. , Truman Paul W. , Groeneman Austin R.
Published: December 2007

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

Production from 51 wells completed in the three unitized formations of the Lost Soldier Field, Sweetwater County, Wyoming, is brought to a central point through individual flow lines. Here the fluids are directed through separate automatic well testing and oil treating facilities, one for each formation. After separation of oil, gas and water, the oil goes to pressurized surge tanks and then to lease automatic custody transfer units. There is one surge tank and one LACT unit for each formation. The oil is automatically transferred to the Sinclair Pipe Line Company for delivery to Sinclair's refinery at Sinclair, Wyoming, through a closed pipe line systems.

A central console provides:

supervisory control from the wellheads through the LACT units, well test and production data logging, and monitoring by activating alarms for abnormal conditions of flow, liquid levels, temperatures and pressures.

Fifteen months experience with automatic handling of crude oil through a pressurized system from the wellheads to the refinery at a rate exceeding 12,000 barrels per day of pipe line oil has revealed many advantages to all parties concerned. The advantages include:

Increased recovery of produced hydrocarbons and boosted gravities by the elimination of oil storage in atmospheric tanks both in production and pipe line facilities.

Early detection of pumping wellmal functions enabling repairs to be made before daily production is substantially decreased.

Quick and definite alarm reporting resulting in immediate repairs.

Reduced manpower requirements for gathering field data and operating valves, pumps, etc.

Provides printed well test and production data records.
Use of Mud Logging Data in Drilling Performance Analysis
Authors: Aarrestad T. V. , Tapper R
Published: December 2007

For a long time the mud-logging companies have provided the driller and drilling engineers with rather sophisticated computer systems for data presentation and some minor data processing, while drilling a well. The computer systems have also been available for office use both with a link to the on-site computers and as a post-processing data system.

Several systems are also available for well planning, ie well trajectory planning with or without a torque and drag model connected to the computer programme.

Each mud-logging company delivers its own special system for recording and analysing the data. In order to evaluate data from the different service companies and extracting more information about the drilling process there is a need for a general system. A main-frame database system with additional software packages for statistical analysis and torque/drag calculations has been developed. The data from the mud-logging companies may then be read from the received tapes/diskettes and put into the multiwell database structure.
The Osprey Development - The Use of the Cluster and LBM Concept for Marginal Field Development
Authors: Wilson R. , Oakes N. E. D.
Published: December 2007

Having enjoyed considerable sucess with its high technology Central Cormorant Underwater Manifold Centre, Shell Expro has directed its attention towards simpler, low technical cost systems which can be applied to ‘fast track’ development of marginal prospects. One method of achieving these objectives is to utilise Xmas tree manufacturing techniques and resources, to provide solid block forged manifolds with suitable bores and end outlets to facilitate connection of cluster wells and transport pipelines. This Shell Expro concept, involving assembly, rather than fabrication processes, to construct the manifold and requiring minimal land testing, was developed by Cameron Offshore Engineering, and has been adopted as the basis for the eleven Well Osprey Development.

In its original form, the concept was a stack up of solid block forgings serving as production, injection and pigging manifolds, mounted on a single base. However as Shell Expro developed this approach, it was realised that significant operational advantages could be gained by separating the oil and water systems into two separate clusters, located within the span of a drilling / installation vessel's anchor pattern, but allowing (through repositioning of the rig within the same anchor pattern) concurrent sea bed operations to be carried out at each cluster.

Detailed design and manufacture of this system is now being undertaken by Cameron Iron Works for Shell Expro, with installation planned for spring and summer 1990.
Practical Problems in Well Testing Devonian Shale Gas Wells
Authors: Murtha J. A. , Lancaster D. E.
Published: December 2007

This paper itemizes several problems that can occur when conducting pressure buildup tests on Devonian Shale gas wells. Although buildup tests conducted on Shale wells have the same objectives and use the same procedures as buildup tests run on other formations, certain characteristics of Shale reservoirs and their well completion methods make well testing complicated. Specific problems include not running the test long enough, encountering liquid in the wellbore, mechanical failures, communication failures, cleanup behavior following stimulation treatments, and surprises. We provide field examples and suggest remedies and means of avoiding some of the common problems.
Correlations of Interference/Pulse-Test Results With Tiltmeter Studies of Fractures Induced in the Chattanooga Shale
Authors: Locke C. D. , Salamy S. P. , Overbey W. K. , Yost A. B.
Published: December 2007

Natural/induced fracture orientation and permeability anisotropy (Kx:Ky) are two critical parameters required for understanding highly fractured anisotropic reservoirs such as the case in the Devonian shales.

A detailed geologic/engineering test was performed on the Chattanooga shale in eastern and southeastern Kentucky. Early results of tiltmeter responses were correlated with pre- and post-stimulation interference and pulse test results. Tiltmeter responses were corrected for uplifts induced by pressure transient during the frac treatment. In addition, corrections were applied to pulse test results for skin and wellbore storage.

Early studies of the pre- and post-stimulation interference tests indicated major permeability trends of N18°E and N32°W, respectively. In addition, a post-stimulation permeability anisotropy of 20:1 was calculated. Results of initial tiltmeter pressure response analyses indicated an induced fracture orientation of N30°E and a possible second orientation of N30°W.
CO2 Mobility Control by Carbonate Precipitation: A Modeling Study
Authors: Aminian K. , Ameri S. , Cunningham L. E. , Watts R. J.
Published: December 2007

CO2 flooding is the most promising enhanced oil recovery method. However, the CO2 tends to bypass a high percentage of the oil in the flood pattern causing early breakthrough and low recovery efficiency. An unconventional approach for CO2 mobility control is to modify the reservoir permeability profile by chemical precipitation. This method employs water soluble salts of earth alkali group that react with CO2 to form carbonate precipitate. Chemical precipitation occurs in the high permeability zones and the subsequent fluid flow will be diverted to unswept portion of the flood pattern. The overall objective of this study has been to evaluate the feasibility of carbonate precipitation to improve the recovery efficiency by reducing CO2 mobility. The earlier experimental studies have shown that carbonate precipitation can alter the core permeability under reservoir conditions. In addition, the relative permeability measurements have revealed that precipitation reduces the gas permeability in favor of liquid permeability. This paper reports the preliminary results of modeling of the process for field application. A numerical reservoir model has been utilized to study the effect of precipitation on sweep efficiency and oil recovery.
Effect of Various Additives on the Properties of the Clarified XC Polymer System
Authors: Nguyen H. T. , LaFontaine J. M.
Published: December 2007

Recently, a clarified XC polymer has been introduced to the petroleum industry and extensive studies have been performed to determine the effectiveness of this polymer as a viscosifier for gravel packing fluids. A good gravel packing fluid must have good gravel carrying capacity, good fluid loss or leakoff, controllable viscosity reduction, and minimal damage to the formation. XC polymer was evaluated to have good gravel carrying capability at lower polymer loadings, 36 - 48 pptg (pounds per thousand gallons), than the standard HEC polymer, 65 90 pptg. The XC polymer also displays good leakoff characteristics which are essential to gravel placement in perforations. However, XC is an anionic polymer, it is sensitive to chemical additives. Therefore, this study includes the effect of various common oilfield additives on the properties of the clarified XC polymer system. Common oilfield additives are salts, sequestering agents, surfactants, clay stabilizers, acids, bases, biocides, defoamers, etc. The results showed that the leakoff characteristics, the effectiveness of gel breaker and the formation damage potential of the XC polymer system were greatly affected by these chemical additives. Applications of any chemical additives to the XC polymer system without testing could result in severe damage to the formation. This paper discusses and presents data that shows the effect of various chemical additives on the performance of the clarified XC polymer system as a gravel packing fluid. Comparison between the XC polymer system and the conventional HEC polymer system will also be presented in the process.
Completion Fluid Invasion Simulation and Permeability Restoration by Sodium- and Potassium-Based Brines
Authors: Azari M. , Leimkuhler J.
Published: December 2007

A laboratory study was performed to simulate completion fluid invasions into large Berea and Casper sandstone cores. Permeability was initially stabilized with a 4% NaCl reference brine, then flow direction was reversed through each core with sodium and potassium completion brines. After a stabilized permeability was obtained under invasion conditions, the reference brine was flowed again through the cores to simulate production after completion.

In Casper sandstone the permeability stabilized 5% higher than the originally established level for the KCl completion fluid, while it only increased 2% with NaCl brine. No increase in permeability was obtained in Berea cores with either KCl or NaCl completion fluids.

Experiments were also performed to determine the effects of completion fluid and flow reversal on stabilizing the permeability of a formation with clay dispersion damage. Results of these studies indicate that for each sandstone a threshold KCl brine saturation exists (10% in Berea and 5% in Casper) above which the illite clay lattices collapse around the exchanged K+. Once a formation is exposed to a KCl brine saturation higher than the threshold saturation, the excessive clay dispersion and swelling damage of the rock is inhibited even after the formation is exposed to much lower salinity levels.
The Comparative Effect of Petroleum Taxation on Field Development
Authors: Allinson W. G. , Williamson M.
Published: December 2007

Petroleum royalty, tax, State participation and production sharing regimes have a significant effect on field development economics and the decision to explore for and develop oil and gas discoveries.

The paper examines and compares the effect of taxation/production sharing regimes on hypothetical but representative field developments in Australia, Papua New Guinea and Indonesia with the aim of demonstrating how these regimes affect the investment decision and corporate strategy.

The paper covers the following:-

A description is given on the petroleum royalty, income tax, surplus profits, State participation and production sharing regimes for petroleum developments in Australia, Papua New Guinea and Indonesia.

The results of economics analyses of the same hypothetical field development with the application of the different regimes are presented and discussed. These isolate the economic effects of the major differences in the taxation/production sharing regimes in the different countries without regard to the different hydrocarbon potential or field characteristics appropriate to each country. The assumption of a common environment and prospectivity is then relaxed in a discussion of the effects of tax in the context of exploration and field development in the specific geological, economic and political conditions of the countries in question.

Broad conclusions are made of the effects of taxation/production sharing regime on oil company profitability in the countries selected and how they affect company strategy and Government policy as part of a range of factors influencing their determination.
Uncertainty and Risk in Petroleum Exploration and Development: The Expectation Curve Method
Authors: Behrenbruch P. , Azinger K. L. , Foley M. V.
Published: December 2007

Hydrocarbons are being recovered from ever greater depth and offshore in deeper waters. More marginal (offshore) projects are often only viable due to the use of new and innovative engineering solutions. Furthermore, these technically more advanced projects are being planned in today's volatile, economic climate where oil prices are relatively low and uncertain. It is therefore not surprising that project feasibility and economic analysis methods are becoming more elaborate, methods that take proper account of uncertainties and risks in all aspects of a project.

Statistical distribution methods have been in use since the early 1900's, but Monte Carlo methods were generally not applied until the 1940's, methods that were based on game theory of von Neumann and Ulam. While those early applications were mainly in science and some selective engineering areas as for example defence, wider technological use1 and business applications2 were not prevalent until the fifty's and early sixty's. Simple statistical methods used in petroleum engineering, in common use since the early sixty's, were generally replaced by full Monte Carlo methods in the seventy's, with recent, more elaborate calculation methods requiring considerable computer power, as for example in reserves calculations of the North West Shelf Gas Development3.

The expectation curve, also known as cumulative frequency distribution, S-curve or exceedance chart, may be the result of simple statistical frequency analysis or more comprehensive probabilistic (Monte Carlo) modelling. As will be described, the use of the expectation curve is a universal and powerful technique which allows for a quantitative appreciation of data in all areas of exploration and production, situations where variation and uncertainties in variables are of importance.

Risk can be considered to fall into two categories: situations which give rise to equipment failure or human error leading to a major accident, as for example the recent Piper Alpha platform disaster, and those situations which are related to uncertainty, the subject of this paper. A number of Australian examples are presented.
A Prediction Method for Conduction Heating of Reservoirs by Steam Injection
Authors: Satter Abdus
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

A method of reservoir heating involving heat conduction from a thin steam channel within the pay has been investigated. Solutions using a simplified heat flow model are provided to estimate steam injection rate, growth of steam zone and temperature distribution as a result of injecting steam into either a fracture or a thin section of the pay. Equations are also presented to obtain temperature distribution after termination of steam injection. Calculated results show the effects of injection rate, temperature, pay thickness, and well spacing.

The conduction heating process can be applicable for raising the entire reservoir to a moderate temperature in a relatively short time. Other advantages over the conventional steam drive are also discussed. It has been shown that a direct steam drive operation which degenerates into steam channeling through a thin section of the pay can be carried on as a conduction heating process.

Introduction

A direct steam drive process which requires that steam flows through the entire vertical section of the pay suffers from a number of disadvantages. A large quantity of heat is needed to move the steam front through a reservoir, especially with thick pay and high steam temperature. Heat losses into the under and overburden formation also retard the movement of the steam zone. Unless the well spacing is close and/or a very high steam injection rate is used, the project can be too long to be economic. In addition, many heavy oil reservoirs are unsuitable for the direct steam drive process because the oil viscosity is too high. While the oil viscosity in the hot water bank ahead of the steam zone is reduced, the interwell area or the region around the producing wells remains at the original reservoir temperature with no reduction in oil viscosity. Therefore, the oil production rate remains relatively low for a good portion of the project life.

A thermal recovery technique called conduction heating may overcome these disadvantages by providing a rapid means of heating a reservoir.
Cased-Hole Hydrocarbon Detection in the Permian Basin Using the Full-Wave Sonic Tool
Authors: Kessler C. , Sanders L.
Published: December 2007

The detection of hydrocarbons through casing in low porosity formations is extremely difficult using traditional log analysis techniques. Pulsed neutron logs are usually ineffective for saturation determination in this environment. At low porosities, the thermal neutron capture cross section, Σ, is dominated by the large volumetric effects of the matrix; therefore, the Σ-contrast between hydrocarbon- bearing and brine-bearing formations is generally small and virtually undetectable. Location of hydrocarbons through casing with dual-detector neutron tools is also difficult. Such tools respond primarily to formation hydrogen (which is found mainly in the pore fluids), and the effects of gas and low porosity on tool response are very similar. Sonic tools with conventional transmitter-to-receiver offsets are routinely run in cased holes in hard rock areas and can yield valid formation interval transit time (Δt) measurements when there is excellent cement bond. Under these conditions, cased hole Δt and neutron porosity measurements can be crossplotted for lithology identification and gas detection.

The Full Wave Sonic tool has been used successfully to detect hydrocarbons behind casing. In cased hole applications, this tool is free of many of the problems that plague sonic logging tools with conventional offsets. In other than perfect bonding situations, its longer offsets allow ample time for the casing and formation signals to separate, thereby permitting accurate determination of Δt. This is verified by comparisons of open and cased hole compressive and shear Δt measurements, Δtc and Δts. Additional test well data from an ultra-long- offset Full Wave Sonic tool that has an 18- foot (5.49-m) transmitter-to-first-receiver offset are presented to show this effect. To further expand the application of cased hole Full Wave Sonic data analysis to other than perfect bonding conditions, enhanced processing techniques employing time windowing and frequency filtering are available to reduce the effects of the casing signal.

This paper emphasizes field examples in which hydrocarbons were successfully detected using Full Wave Sonic data. The presence of a compressible pore fluid, such as gas or oil with dissolved gas, causes a reduction in an acoustic velocity ratio and an increase in the attenuation of the acoustic signal. The reduction in the velocity ratio is significantly greater than variations that may arise from slight lithology changes. Successful production of light hydrocarbons has resulted when zones were selected for completion based upon velocity ratio reductions and acoustic signal attenuation over intervals of sufficient length.
Network Modeling of Xanthan Rheology in Porous Media in the Presence of Depleted Layer Effects
Authors: Sorbie K. S.
Published: December 2007

The mathematical description of the rheology of xanthan biopolymer within a porous medium - referred to as in situ rheology - is important if we wish to model oil displacement processes using this polymer. Most workers find that the in situ behaviour of xanthan is qualitatively quite similar to that of the bulk fluid. However, in recent years, others have found clear evidence for a slip-like effect on the in situ apparent viscosity of xanthan. The main finding of this latter body of work is that, in the lower pseudo-Newtonian flow regime, the in situ apparent viscosity is lower than that of the bulk viscosity. This has been interpreted as being due to a layer close to the pore wall from which polymer macromolecules are excluded. This boundary layer is depleted in polymer and therefore has a lower viscosity than the injected fluid which leads to the slip effect. This surface exclusion effect is also thought to be responsible for the velocity enhancement of the polymer molecules relative to tracer species which is sometimes attributed to the alternative mechanism of inaccessible pore volume.

Previous work on the mathematical analysis of the depleted layer effect has used very simple models for single capillary flow which only apply in the low flow pseudo-Newtonian regime. In this paper, we present an extension of this previous work in which we first solve the full hydrodynamic problem within a single capillary including depleted layer and shear effects. The results from the single tube case are then used within a network model of the porous medium. These network calculations allow us to make certain predictions on the macroscopic consequences of the depleted layer on the experimentally observed apparent viscosity behaviour. A number of specific findings are presented but the main two predictions from the network calculations are that (i) the drop in apparent viscosity is significant even for fairly modest depleted layer thicknesses and (ii) the slope of the apparent viscosity vs flow (shear) rate curve in the shear-thinning region is less steep (apparent power law index is higher) in the presence of the depleted layer than in its absence. In both cases, the predicted magnitude of the effect is such that it should be clearly observable experimentally.
Phase Change in Binary Systems in Porous Media: Application to Solution-Gas Drive
Authors: Yortsos Y. C. , Parlar M.
Published: December 2007

In this paper, a study of the liquid-to-vapor phase change by pressure decline in porous media is presented. A simplified solution gas drive system is taken as a representative example. The issues of nucleation, critical supersaturation, and vapor phase growth in porous media are critically examined. At low supersaturations a percolation approach is proposed that allows for the estimation of critical gas saturation and relative permeabilities from nucleation and pore structure characteristics.
Horizontal Wellbore Stability for Openhole Completions
Authors: Fuh G-F. , Loose P. K.
Published: December 2007

Horizontal well drilling and production have been increasingly important to the oil industry in recent years. The potential of significant increase in oil or gas production from a horizontal well will be very attractive as drilling and completion costs diminish and new technologies are developed to address problems concerning wellbore stability and formation damage. This paper presents a successful case analysis on borehole stability conducted before an openhole recompletion was performed in an existing cased hole for increased oil production.

The North Sunshine May No. 4 well located in the Big Horn Basin of Wyoming, was originally completed as a vertical well in 1977. In late 1987, the well was sidetracked and laterally extended to a nearly horizontal wellbore. The 1000-ft lateral extension exposed 850 ft of the reservoir sands for production. The pay zone was cased with 4-1/2" liner. However, the production rate was not as high as originally anticipated. A decision was made to explore the possibility of pulling the slotted liner from the well and leave as an openhole completion after cleaning the reservoir portion of the hole. Based on rock mechanics principles, we conducted openhole stability analysis using high-angle drilling and core recovery data from the well. The analysis also considered the effect of reservoir depletion on openhole stability. The results predicted that the rock strength for the reservoir sands was great enough to keep the horizontal section open with little or no formation support during oil production, following the openhole recompletion operation. Field results after removal of the slotted liner have confirmed this finding. Some detail about the completion for oil production is also described herein.
Gravel Pack Quality Control by Neutron Activation Logging
Authors: Olesen J.-R. , Hudson T. E. , Carpenter W. W.
Published: December 2007

A successful gravel-pack is hard to achieve in wells that have highly deviated boreholes and long completion intervals. The primary difficulty in such wells is placing the pack material in the screen/casing annulus and in the perforations without leaving void areas. Using a low-density particle for packing will help prevent void area in allowing the use of the matched-density concept, where the particle density equals the density of the carrier fluid.

Since most gravel pack quality control devices rely on the usually sizable difference of density between borehole fluid and packing material, they may not be suitable for gravel-pack operations involving high-density borehole fluids and/or low-density gravel packing material.

This paper introduces a new application of existing logging devices to provide a quantitative evaluation of the packing quality. The method is based on neutron activation of particular elements contained in the gravel pack material and applies to standard gravel as well as to new low-density materials. The technique is relatively insensitive to formation characteristics because the depth of penetration of the activation neutrons is shallow. A base pulsed neutron capture log can be recorded simultaneously with log for gravel-pack quality control. The lack of sensitivity of the formation capture cross-section measurement to the presence of the gravel material, whether conventional or lightweight, has been demonstrated.

The logging procedure was developed using a series of laboratory measurements in formations with a simulated gravel-pack completion. Field results obtained with different types of gravel-pack material are compared to a density-based log when the density contrast of the packing material and completion fluid permits the use of the latter logging technique.
Fluid-Loss Control Using Crosslinkable HEC in High-Permeability Offshore Flexure Trend Completions
Authors: Blauch M. E. , Broussard G. J. , Sanclemente L. W. , Weaver J. D. , Pace J. R.
Published: December 2007

An alternative system to conventional HEC (hydroxyethylcellulose) and particulate fluid loss materials has been developed for fluid loss control in high permeability Gulf of Mexico Flexure trend completions. In offshore operations, the problem of controlling fluid loss to the formation is critical in achieving successful gravel pack completions. The problem is magnified in this environment because of the use of expensive high density brine, lost rig time, and increased standards for well control and safety. A newly developed fluid loss system which consists of a crosslinkable, derivatized HEC incorporating a branched functional group oh an HEC backbone has been evolving in the industry. The functional group provides a nonionic reaction site which allows the polymer to be crosslinked at a low pH, and broken in a controlled manner using a newly developed breaker.

Other fluid loss control systems used in Flexure trend completions exhibit specific problems which can be attributed to (1) physical properties of the particular material, and (2) the method of application. For instance, in many high permeability wells, noncrosslinkable HEC pills have proven inadequate for controlling fluid loss to an acceptable level, and in some cases have allowed significant invasion of HEC, thus potentially resulting in permeability impairment. Particulate fluid loss materials present other problems in that they can be difficult to remove from perforations.

Laboratory and field tests demonstrate efficient fluid loss control and potential for reduced formation damage with this new crosslinkable HEC (CLHEC). Internally broken crosslinked gel has shown more favorable return permeability in core tests than regular HEC polymer commonly used in the industry. The CLHEC system deposits a thin, crosslinked polymer filter cake which helps prevent fluid loss, but which can be removed by means of an internal breaker, an acid wash, or both. Subject paper presents laboratory and field data illustrating properties of the new fluid loss control system in high density brine applications.
Improved Methods for the Modeling and Conduct of Vertical Interference Tests Across a Tight Zone
Authors: Stewart G. , Jaafar M. D. , Du Kui Fu
Published: December 2007

Vertical interference testing to determine the effective vertical permeability of tight zones is an important part of reservoir characterisation. The analytical model of Bremer has been extended to include the effect of wellbore storage and skin using a real time convolution formula. This appraoch has been validated by comparison with the results of the dual permeability model in Laplace space proposed by Economides. Practical considerations relating to the effective conduct of such tests are given. In particular procedures for pressure testing of packers and eliding sleeve doors are recommended along with good cement bond logs. Reciprocal testing of both layers as active and observation layers gives much improved results. Several field examples have been analysed with success. The depth of investigation of such vertical interference tests is related to the gauge resolution. The effect of wellbore storage on observation layer response can be predicted by analysing the active layer response in the conventional manner. This reduces uncertainty in the determination of vertical permeability. Large negative skin factors due to acid stimulation lead to problems with the Laplace space method. Analytical results have been complemented by numerical simulation to characterise for example the effect of tight zone capacity and extension. Numerical simulation was also used to show up the effect of leaks behind casing on the observation layer response. A distinct change in the character of its signal occurs with a casing leak.
A Fractured Reservoir Simulator Capable of Modeling Block-Block Interaction
Authors: Por G. J. , Boerrigter P. , Maas J. G. , de Vries A.
Published: December 2007

A new simulator has been developed to model displacement processes in fractured reservoirs, in particular the block-block interaction in gravity drainage processes. This block-block interaction forces oil draining from a matrix block into the fracture system to be absorbed by the underlying matrix block whenever this is possible. Otherwise the oil flows through the fracture network. Block-block interaction influences both the initial production rates and the resulting hydrocarbon distribution in the reservoir.

Simulation of fractured reservoirs with this type of interaction between matrix blocks makes high demands upon the simulator, both in terms of memory requirements and speed. The simulator hence uses dynamic memory management and an efficient grid-block partitioning scheme that reduces the memory requirements significantly. In addition, this scheme enables a high degree of vectorisation on a Cray computer.

The simulator can be used for a variety of reservoir geometries: dual porosity, dual porosity/ permeability, reservoirs with block-block interaction and unfractured reservoirs.