bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydraulic Fracture Height Growth in San Juan Basin Coalbeds
Authors: Palmer I. D. , Kutas G. M.
Published: December 2007

Fracturing through perforations in the coal is often used in the San Juan Basin to stimulate production of natural gas from Fruitland coalbeds, which overlie the Pictured Cliffs (PC) sandstone. A data set of many fracturing treatments has been analyzed, including (a) pressure versus time profiles, and (b) wellbore gamma ray (GR) surveys of radioactive tracer added to proppant. First, factors that tend to confine a fracture's height growth are reviewed, and vertical stress profiles are discussed. Secondly, three classes of fractures are identified: When the PC sand is close (less than 20 ft) and the coal is deeper than 1800 ft, a fracture is likely to grow into the PC sand, accompanied by falling pressure.When the PC sand is more than 20 ft away, a fracture is largely confined by the shales and accompanied by rising or flat pressure, a proppant-induced pressure increase (PIPI), and ISIP > 1 psi/ft. There is likely to be a T-fracture. The limited (or zero) fracture height growth in bounding shales is explained.When the PC sand abuts one of the coal seams at shallower depths (<1800 ft), fracture growth appears to be limited by the PC sand, fracture pressure rises, and ISIP > 1 psi/ft. This may be due to factors which encourage interfacial slippage at shallower depths.

The rapid fall in tracer signal from a coal seam into bounding zones is interpreted by a discrepancy in fracture width, or due to zero fracture width in shale. Proppant tracer signals in shale-bounded coals are asymmetric: more peaks occur at or above the coal roof than at or below the coal floor. This may reflect a horizontal fracture component near the roof of the coal seam (i.e., a T-fracture), but more analysis is needed to confirm this. When several seams are stimulated simultaneously, if two coal seams are separated by more than 15 ft, they are unlikely to be linked by tracer, and fracture communication may not exist between the two seams. Although proppant appears to have access to every seam usually, this may not mean equal fracture lengths in these seams. Finally, an anti-correlation between 40/70 and 12/20 proppant tracer supports 40/70 proppant plugging smaller flow channels, thus diverting fluid to other channels which become wider, and can more easily transmit 12/20 proppant. This may explain success of "graduated proppant" fracture treatments.
Case History of Waterflood Infill Drilling in the Johnson J.L "AB" Unit
Authors: Yadavalli S. K. , Brimhall R. M. , Wu C. H.
Published: December 2007

This paper presents the results of a 3-D, 3-P reservoir simulation study of waterflood infill drilling in a study area of the Johnson J.L. "AB" unit, located in Ector county, West Texas. The primary objective was to evaluate the waterflood infill drilling performance in the study area. This was accomplished by simulating the waterflood infill drilling performance followed by simulation of an alternative infill scheme or targeted infill drilling, utilizing a detailed reservoir characterization model. An economic evaluation was carried out for both the actual and targeted infilling schemes. The targeted infill drilling scheme resulted in higher recovery and better economic returns as compared to the actual infill drilling scheme. The major inference of this study was that the optimal infill drilling pattern need not necessarily be a regular pattern.
Surge Test Simulation
Authors: Petak K. R. , Prasad R. K. , Coble L. E.
Published: December 2007

Post-perforation surge tests are frequently used in the oil industry. A surge test is normally conducted by flowing fluids into a closed chamber. This category of testing includes backsurge perforation washing, underbalanced perforating with subsequent flow, and closed chamber drillstem testing. Typically, downhole response is measured by a pressure/temperature gauge. This response may be analyzed for reservoir parameters by using existing techniques; however, variable wellbore conditions and rapidly changing rates make finding a solution difficult and sometimes impossible.

This paper presents a numeric simulator which is used to model surge behavior for various wellbore and reservoir conditions. Because variable wellbore conditions are considered, the resulting analysis is more reliable and often possible when other techniques fail.

Reservoir flow into the wellstring is controlled by the wellstorage coefficient and completion and reservoir parameters. At each time step the wellstorage coefficient is explicitly solved by performing a mass balance on the wellstring fluids. This calculation accounts for compression of air in the surge chamber, variable cushion pressure, displacement of rathole fluid into the wellstring, changing inside diameter in the wellstring, and volume of reservoir fluid produced into the wellstring.

Simulated pressure profiles are presented for various reservoir and wellbore conditions. A simulated match of field test data is also given to illustrate the practicality of this work. The matching process yields permeability, skin, static formation pressure, and radius of investigation.
Scale Prediction During CO2 Huff 'n' Puff Enhanced Recovery, Crooks Gap Field, Wyoming
Authors: Smith L. K. , MacGowan D. B. , Surdam R. C.
Published: December 2007

Perturbation in the rock-water systems of petroleum reservoirs during CO2 enhanced recovery processes may cause precipitation of scale in production lines. Therefore, a prediction of the scale potential of a particular system is valuable in the design of the enhanced recovery treatments. On the basis of formation mineralogy, formation water chemistry, and estimated temperature and pressure conditions, scale build-up during a CO2 Huff ‘n’ Puff treatment in the Cretaceous Crooks Gap reservoir in Wyoming was predicted to be minimal. Carbonate mineral cements (mostly calcite) and plagioclase, both of which are sources of scale constituents, are present in the reservoir only in trace amounts. Also, the estimated pressures both in the formation and in the production lines were sufficient to keep most of the bicarbonate ions in solution. Finally, organic alkalinity was insufficient to buffer pH which otherwise might have stabilized carbonate minerals during the CO2 injection and cause them to precipitate within the reservoir.

Water chemistry was monitored during the production phase of the Huff ‘n’ Puff treatment to test the reliability of the predictions. Initial production showed an order of magnitude increase in the calcium concentration in the produced waters as well as a two-fold increase in the bicarbonate concentration. Calculations of mineral stabilities using the post-CO2-injection produced waters indicated a slight over-saturation with respect to calcite. However, further calculations done to determine the amount of scale precipitation needed to bring the system back to saturation demonstrate that the scaling potential was minimal. The concentrations of both constituents dropped back to pre-CO2-injection levels within thirty days after the production began, which further diminished the potential for scale problems.
A Review of Horizontal Methods and Drilling Technology
Authors: Leaf R. C. , Pittard F. J.
Published: December 2007

This paper covers the geology of the Rocky Mountains, low permeable hydrocarbon producing formations and the problems associated with horizontal drilling tools in these regions. The paper includes representative horizontal well data from the Rocky Mountain region and low permeable hydrocarbon producing formations outside the United States. Oil producing trends with respect to fracture and formation are described as they pertain to horizontal drilling tools. Where applicable emphasis is placed on solutions to problems associated with horizontal tools.
Fluid Loss During the Fracturing of Naturally Fractured Reservoirs
Authors: Stahl R. M. , Clark R. E.
Published: December 2007

There are several different types of reservoirs that have a high degree of natural fracturing. In these reservoirs, the fluid loss mechanisms are more complicated than those found in more coherent formations. The loss of fluid to intersecting fractures is especially important in the fracturing of coalbeds, Devonian type shales, limestones and naturally fractured sandstones. In many cases, the reservoir permeability is often such that the fluid loss to these fractures is the primary fluid-loss mechanism. Little is known about how to handle this type of fluid loss in fracture simulation calculations, or the effects of this fluid-loss mechanism on pressure drop in the fracture. While the loss of fluid to intersecting fractures is not the only fluid-loss mechanism in naturally fractured sandstone reservoirs, it can dominate the fluid loss to the reservoir under some conditions. Examination of the problem from both a computer based modeling and laboratory standpoint is clearly warranted.

Flow of fluid down a fracture in a sandstone reservoir is modified by the continual loss of fluid to the reservoir through the permeability of the rock. In a naturally fractured reservoir, fluid loss occurs mainly at points where the fracture intersects an existing fracture in the rock. This not only changes the nature of fluid loss in the fracture, but it also creates serious flow disturbances that can change the pressure drop in the fracture. It has been shown that flow into orifices placed perpendicular to the major axis of flow results in a highly extensional flow situation. Extensional flows have been shown to increase pressure drop in porous media using non-Newtonian fluids. In addition, it has been shown that two-phase fluids will separate to some extent when a branching of the flow path occurs. These factors have important implications in the flow of fracturing fluids in fracturing treatments in naturally fractured reservoirs.

To study the flow effects, a computer model of a small section of a fracture with one intersecting fracture was setup. A commercial finite element analysis program (FIDAP) is used for the fluid flow calculations. This program is optimized for power law type fluids. Computations for several different values of the power law parameters coupled with different intersecting fracture widths and fracture width ratios will be presented. Conclusions about the nature of the fluid loss in naturally fractured reservoirs will also be made.
Reservoir Characterization of the Frontier Tight Gas Sand, Green River Basin, Wyoming
Authors: Harrison C. W. , Dutton S. P.
Published: December 2007

A research study has been performed to improve the formation evaluation and reservoir description of the Frontier Formation located in the Green River Basin of southwestern Wyoming. Results of this study are presented which include the integration of data from an extensive wireline logging program, a comprehensive core analysis program, and well test production performance from two wells completed in the Frontier formation. Features of several core analysis techniques are reviewed which were used to determine more accurately the ¡η-situ porosity, water saturation, permeability and producibility from logs. This includes correcting core water saturation for mud filtrate invasion, correcting porosity and permeability to net overburden stress, and comparing core data and log responses to quality control the laboratory core analyses. Log derived lithology was calibrated to that determined from cores using thin section point count and x-ray diffraction analysis. The log evaluation model, which was calibrated to core porosity, uses porosity and saturation exponents derived from electrical property measurements on cores. A preliminary log derived permeability relationship has been developed and compared to that obtained from production well tests.
A Slimhole Coring System for the Deep Oceans
Authors: Storms M. A. , Howard S. P. , Reudelhuber D. H. , Holloway G. L. , Rabinowitz P. D. , Harding B. W.
Published: December 2007

Specialized drilling and coring techniques and equipment have been developed by the Ocean Drilling Program (ODP) to recover fractured basalt cores in deep water. Cores were successfully retrieved in 5900 feet (1800 m) water depth using the new equipment during seatrials in June and July 1990. This paper presents the history of the development and use of the Diamond Coring System (DCS) equipment, and includes information on planned future enhancements to the system to improve operational efficiency.
Side-Drive Drilling System: Description, Installation, and Field Data Performance
Authors: Renfro J. G. , Gaddy D. W. , Moses J. K.
Published: December 2007

In 1987, the Side Drive Drilling System was introduced and has proven to be another successful system for drilling from the top.

This paper describes a new approach to an already proven field. This is an overview of the Side Drive Drilling System concentrating primarily on the following three areas: What is the Side Drive and how does it differ from conventional Top Drives? This examines unique design aspects of the tool by major components.Installation requirements and how they impact rig modifications, cost and time.Actual performance data taken from several installations in various geographic locations. This is a compilation of new data and that which has been reported in various trade journals.
World Record in Extended Reach Drilling, Well 33/9-C10, Statfjord Field, Norway
Authors: Rasmussen B. , Sørheim J. O. , Seiffert E. , Angeltvadt O. , Gjedrem T.
Published: December 2007

This report is a case history of drilling well CIO in the Statfjord Field. The well is a world record in Extended Reach Drilling with a horizontal reach of5003 meters (16 414 ft). This report will mainly concentrate on planning and executing the work; how torque, drag, hole cleaning, welbore stability and surveying were handled through careful planning, follow-up and performance on the rig.
Features of Logging-While-Drilling (LWD) in Horizontal Wells
Authors: Hansen R. R. , White J.
Published: December 2007

Logging While Drilling (LWD)* tools are formation evaluation sensors engineered into drill collars. Using LWD in horizontal wells offers significant advantages over other logging systems for formation evaluation. When LWD is provided in real-time via mud pulse telemetry the system becomes a geological steering tool which can be used to accurately place the horizontal section with reference to formation features and/or fluid contacts. The combined benefits of formation evaluation and real-time geological steering make LWD an essential tool for many horizontal wells.

We will describe the benefits of LWD measurements and the improvements in both drilling and logging efficiency which LWD offers. These features are illustrated with practical examples of LWD from a number of horizontal wells in the North Sea. Although these examples are from horizontal wells in particular, the same benefits can be realized in directional wells in general.
Regulatory Processes for Mining on the Outer Continental Shelf
Authors: Monkelien K. E. , Conner-Hite T. A.
Published: December 2007

This paper describes the regulatory requirements and procedures which will govern Outer Continental Shelf (OCS) mining activities. The regulatory environment for OCS mining is in the early stages of implementation in the United States. Although seven lease offerings involving nonenergy-related materials have been held in the past, the OCS Mining Program, Norton Sound Lease Sale will be the first competitive lease sale (offering) for nonenergy minerals conducted under new regulations promulgated in 1989. These regulations cover leasing and operations for minerals other than oil, gas and sulphur (Code of Federal Regulations (CFR), Title 30, Parts 281, and 282). The regulations establish procedures for leasing and for postlease exploration and mining activities so that operations will be conducted in a safe and efficient manner which provides optimum protection for the environment and for human health and safety. This paper will be directed to the postlease processes.
Research on New Alaskan Mining Technology
Authors: Chamberlain P. G.
Published: December 2007

As readily accessible ore deposits in this country are mined to depletion, mining companies must turn to deposits in remote, environmentally sensitive regions. Alaskan deposits may well offer opportunities for new production of many important minerals. Bureau of Mines engineers and scientists have begun a research program that features new technology for mining in Alaska. The program emphasizes efficient extraction of the mineral value while minimizing environmental disruption. Projects on borehole slurry mining, underground placer mining, back - filling, rock mechanics/mine design, and mine closure practices are reviewed.
FEM Analysis of the Creep Behavior of a Spray Ice Island and Comparison with Actual Island Performance
Authors: Thiel D. T. , Reddy D. V.
Published: December 2007

Although the use of spray ice as a construction material in the Arctic has gained wide acceptance, little quantitative information has been published on the time dependent deformations experienced by spray ice structures due to internal and externally-applied loads. This paper describes a finite element analysis of the time dependent, viscoelastic (creep) behavior of Amoco's MARS spray ice island. Two dimensional, plane strain elements were utilized to model the island. Emphasis was on the deformation of the structure due to its self-weight and the weight of the drilling rig, as well as from lateral displacements occurring in the surrounding ice sheet. The analysis was limited to secondary (steady state) creep behavior. Required values for all physical parameters were obtained from actual island measurements, including those from in situ pressuremeter tests carried out at the island.

The analytical results were compared to actual island performance characteristics, measured during its operating life over the winter and spring of 1985-86. The results show reasonably good agreement between modeled behavior and actual island performance. Observed discrepancies are discussed in the paper.
The Cuttings Grinder
Authors: Smith R. I.
Published: December 2007

The Cuttings Grinder was built as an innovative method to dispose of drilled cuttings, providing an alternative to placement of drilled cuttings in reserve pits. The Cuttings Grinder reduces drilled cuttings into a slurry, which is then pumped down a disposal well into the Tertiary sandstone. This paper explains why the Cuttings Grinder was built and describes how it works, together with the modifications that have been made since it has been in operation.
Full-Signature Multiple-Channel Vertilog
Authors: Adams G. W. , Moffat W. D.
Published: December 2007

A new version of the Vertilog flux leakage (DC Magnetic Inspection) pipe evaluation tool has been developed. This new system is called the Digital Vertilog (DV). This paper presents an explanation of the DV tool theory, operating system and its working components. The sensor system of the standard Vertilog has been provided with an updated data gathering system in order to increase the information available to the log analyst. This new system transmits true bi-polar representations of each flux leakage sensor and a number of eddy current sensors to the surface recorder. The multiple bi-polar flux leakage (FL) channels allow easier interpretation by contrasting changes due to hardware and corrosion. Some of the features more easily determined include pitting, perforation (including the phase of gun used), scratchers, and centralizers. Log examples generated in the lab and their interpretation will be presented. These examples successfully demonstrate the advantage of recording full signature wave response and accurately differentiating pipe hardware from corrosion.
A New, Low-Cost, Ice- and Wave-Resistant Port Facility at Nome, Alaska
Authors: Swigart W. S. , Nottingham D.
Published: December 2007

This paper describes the design and construction of an ocean dock that will be built in Spring 1991 in Nome, Alaska. The dock will be constructed near the offshore end of a rock causeway that extends about 2,700 feet (823 m) into the ocean. The project features the opencell dock concept, which was developed by the writers in 1981 and used on about 40 docks and bridge abutments since that time. The open-cell dock will consist of interlocking sheet pile cells filled with granular fill, heavy-duty energy-absorbing fenders on the dock face, and pipe bollards to secure vessels.

The open-cell dock concept is particularly suited for use in Nome and other Arctic locations because it is inexpensive, relatively simple and fast to construct, makes use of locally available fill materials, and is highly resistant to ice forces. The Nome dock will be constructed through a large hole in the approximate four-foot-thick arctic pack ice which should provide total protection against storm waves during construction. Some other logical uses for the open-cell concept in the arctic include drilling islands, bridge piers and abutments, erosion control structures, retaining walls, marine breasting dolphins, and harbor entrance channels.
Gas Handling Expansion Facilities at Prudhoe Bay, Alaska
Authors: Metz W. P. , Elliott R. A.
Published: December 2007

The Prudhoe Bay Unit Owners are completing installation of the first major phase of Gas Handling Expansion (GHX) facilities at Prudhoe Bay. GHX will add significant crude oil reserves as well as slow oil production decline by allowing production of higher gas/oil ratio wells. The GHX facilities include several large components which are being used to increase field gas offtake (FGO) rates. The first phase of GHX (GHX-1) will increase FGO from a nominal 3.6 billion standard cubic feet per day (BSCFD) to about 5.1 BSCFD; the second phase (GHX-2) will increase FGO to about 7.5 BSCFD. As is with most major projects, aggressive schedule targets were established for GHX-1 to optimize project economics. Preliminary Engineering was initiated in June 1988, with major facility modules sealifted in summer of 1990. The fabrication and construction effort involved work in Portland, Oregon and Prudhoe Bay, Alaska. All GHX-1 facilities should be in place and operating in early 1992. Current forecast cost for the overall project is approximately $450 million.
Watchdog: An Anti-Collision Wellhead Monitoring System
Authors: Stagg T. O. , Reiley R. H.
Published: December 2007

BP Exploration undertook the development of a new rig safety system to provide an increased level of protection against sub-surface well collisions. The Watchdog system is an acoustic wellhead monitoring system designed to warn the driller when a collision with an existing well is imminent. Monitors are placed on the wellhead of each well considered an intersection risk to detect vibrations created by an approaching drill bit. This data is processed in real time and plotted versus measured depth of the well being drilled. By this means the approach of a drill bit can be detected before impact occurs and correctional action may be taken to avoid collision.
Drilling Smaller Surface Holes Results in Substantial Cost Savings
Authors: Krawietz T. E. , Gremley R. B.
Published: December 2007

This paper addresses ARCO Alaska's successful program of drilling smaller holes for 13.375 inch [339.73 mm] surface casing strings. Data is presented from wells drilled by Arco Alaska Inc. on the Alaska North Slope along with a detailed breakdown of cost reductions in cement, rig, bit and mud costs.
Applicability of Soviet Arctic Mining Technology to Northern America
Authors: Skudrzyk F. J.
Published: December 2007

The author has visited the northern part of the Soviet Union several times in recent years and has had the opportunity to acquaint himself with Soviet arctic mining technology through visits to mines, discussions with Soviet mining professionals and extensive studies of available Soviet mining literature.

In this paper Soviet mining technology for arctic/subarctic regions is reviewed and critical assessment is offered from a perspective of its applications to northern climates in Alaska and Canada. Several specific examples of the Soviet mining technologies are given indicating that the mines and equipment can successfully function at prolonged periods of temperatures down to −60 °F.
Arctic and Offshore Research Information System
Authors: Shoemaker H. D , Chiang D. L.
Published: December 2007

The unique Arctic environment effects significant technological and economic barriers to developing the Alaskan oil and gas resources. Therefore, the U.S. Department of Energy has established a computerized information system to assist industry and government in the development of these Arctic resources. This paper describes the DOE Arctic and Offshore Research Information System (AORIS), its development and public assessment, which sources were accessed for inventory, examples of contents, how it can be queried, and potential uses. The AORIS has an on-line thesaurus and other personal computer, user-friendly aids to assist in querying the AORIS. There are three principal components:a directory that lists 85 data bases containing Arctic energy-related information and how to access them; a bibliographic information system containing over 8,000 references and abstracts on energy-related research (sea ice, ice gouging, seafloor soils, subsea permafrost, seismic activity, and offshore structures); and a scientific and engineering information system (or data component) containing over 800 data sets, extracted from the cited material, in both tabular and graphical formats, on sea ice characteristics (morphological, mechanical, and physical properties) and ice-structure interaction. This unique data component provides preliminary information useful in the design of Arctic offshore oil and gas development structures. The AORIS, its operational software, and users' manual are contained on Compact Disk—Read-Only Memory (CD-ROM) media. The AORIS is available through the DOE National Energy Software Center, Argonne National Laboratory.
Environmental Compliance Assessment Review
Authors: Holliday G. H.
Published: December 2007

During the period 1972-1991, The United States Congress passed stringent environmental statutes which the Environment Protection Agency implemented via regulations. The statutes and regulations contain severe civil and criminal penalties. Civil violations resulted in fines, typically payable by the company. The act of willfully and knowingly violating the permit conditions or regulations can result in criminal charges being imposed upon the responsible part, i.e., either the company or individual. Criminal charges can include fines, lawyer fees, court costs and incarceration.

Traditionally, there has been a clear demarcation between civil and criminal sanctions. Recently, the two sanctions have overlapped so that what a few years ago would clearly have been a civil charge may now be classed as a criminal charge. Criminal charges have been extended to include Senior Management who fail to initiate and monitor an environmental program designed to assure environmental compliance. Accordingly, most large and many small operators have initiated audit programs.

Such a compliance review program provides protection from criminal charges for Senior Management but makes Middle Management and first line supervisors more vulnerable unless management provides them with environmental training and monitoring of the effectiveness of the environmental program. Although this paper concentrates on Environmental Compliance Assessment Review [CAR] programs, other types of environmental audits exist. The most important being the Preacquisition/ Predivestiture Audit. This is an audit of a facility prior to purchase or sale with emphasis on recognizing liabilities which might be transferred as the result of the purchase or sale of the facility. Preacquisition/Predivestiture audits are beyond the scope of this paper.

This paper describes steps necessary to (1) form an effective Environmental Compliance Assessment Review [CAR] program, (2) train field and engineering personnel and (3) perform a CAR audit. Additionally, the paper discusses the findings of a number of Exploration and Production [E&P] field audits.
Surface Area Measurements on Sedimentary Rocks
Authors: Brooks C.S. , Purcell W.R.
Published: December 2007

Published in Petroleum Transactions, AIME, Volume 195, 1952, pages 289–296.

The internal surfaces of rocks which are in contact with interstitial fluids are known to influence in some degree the recovery of hydrocarbons from pay zones. Despite the admitted importance of the influence of solid surfaces on hydrocarbon recovery, little information is available concerning the extent of surface of reservoir rocks. In this paper a description is given of the apparatus and procedure employed in the determination of the surface areas of sedimentary rocks, and values are reported for a variety of sandstone and limestone cores. In addition, consideration is given to the Kozeny equation, which relates surface area to porosity and permeability. A comparison is made between the surface areas as calculated from this equation and the geometrical areas of a series of packs of spherical glass beads. Also, for a group of sandstone cores, Kozeny areas are compared with surface areas as determined by the gas adsorption method employed in this investigation.

Introduction

It has long been recognized that many processes which are of importance to hydrocarbon production are controlled in some degree by the extent of the surface of the reservoir rock through which the hydrocarbons move. For example, the recovery efficiency that is obtained in a given reservoir is certainly determined in part by the action of interfacial forces between the reservoir fluids and rock, and this action is influenced in turn by the extent of solid surface. Despite the admitted importance of surface effects to problems of petroleum recovery, little information is available concerning the extent of surface of reservoir rocks. A recent paper by Kulp and Carr reports surface areas of deep-sea sediments. Their values are in general much higher than those reported herein for reservoir rocks probably because of the high clay and silt content of the sediments. It is the purpose of this paper to describe an apparatus which has been employed for the measurement of the surface areas of rock samples and to present the values which have been obtained for a variety of sandstone and limestone cores. In addition, the relationship of surface area to permeability and porosity, as given by the Kozeny equation, will be discussed.
Oilfield Percussion Drilling
Authors: Smith F.W. , Kopczynski Wink
Published: December 2007

Advancements in tools and technology for air drilling have been quite numerous. One of the more publicized tools in recent years has been the air-rotary-percussion drill. This paper is prepared to evaluate the tool performance and to indicate problem areas where the tool may be used to the greatest economical advantage.

Continued improvement of the tool, along with improved bit design, will extend the application of air-rotary-percussion techniques to greater hole intervals in oil and gas wells.

Introduction

Percussion drilling, as used in the oil field today, is a combined action in which positive rotation of the tool together with a high static thrust on it has been superimposed on the basic percussive action. The percussive action is a process of rock drilling in which repeated blows are applied to the surface of a rock through a pointed bit as used in cable tool drilling. One of the most successful ways of drilling a hardrock formation, this method has been improved recently by the percussive rotary technique. The tool is installed next to the bit and is actuated by air the circulating media. The volume of air and the pressure requirements of the percussion tool are designed to be compatible with air drilling equipment currently being used Due to the greater penetration rate of the down-hole machine, the volume of air required to remove all the cuttings from the annulus is sometimes 20 per cent greater than conventional rotary air drilling.

Air not consumed in the operation of the machine is directed through the bit for bottom-hole cleaning while the used air is discharged at or near the bit, thus giving total hole-cleaning capacity.

The pressure required to operate a percussion tool varies with the individual tool. Some tools operate with as little as 50 psi, while others require as much as 200 psi, with their maximum efficiency at 400 psi.

The percussion tool advances by punching rather than by boring under pressures; therefore, its progress is more nearly vertical while drilling in hard, slanting formations. The tool also maintains a higher penetration rate without the excessive hole deviation sometimes encountered in conventional air drilling. Some percussion tools with heavy impacts have a tendency to destroy the standard-type bits; therefore, this requires that the manufacturers "beef-up" their bits with reinforced seam welds to withstand the excessive blows.
Parameterizing Environmental Assessments for Oil and Gas Facility Construction
Authors: Semenov L. P.
Published: December 2007

This paper reviews several issues concerning the possibility of setting quantitative norms for individual natural parameters and for technogenic loads on the environment resulting from oil and gas facility construction. Such standards are set with the object of effectively planning environmental assessments for projects and forecasts of changes over long periods (up to 50 years) in natural-technical complexes or in individual sites. The determination of certain complex or simple inter-relationships involving the oil and gas facility system permits quantitative determination of system stability at both regional and local levels.
Methods of Engineer-Ecological Identification of Designs of Oil and Gas Facilities
Authors: Moldananov O. I.
Published: December 2007

This paper describes the criteria and methods of objective estimation of designs at the stage of designing and construction of oil and gas facilities from the point of view of the minimum ecological damage. The paper also presents the principles of quantitative analysis of comparable processes and construction objects. Presented as the most preferable are the criteria of ecologically rational limitations and ecologic equivalence.
Biological Rehabilitation of Disturbed Lands in the Arctic Gas-Producing Regions
Authors: Masalkin S. D.
Published: December 2007

This paper presents the results of a number of research projects on rehabilitation of disturbed (being disturbed) Arctic territories during the development of gascondensor fields in the North of Tumen Region, and describes some techniques and methods of rehabilitation. Soil-vegetation cover characteristice as well as physical characteristics of tundra soils are given, the rates of mineral fertilizer application for different revegetation plants, rates, terms and techniques of seeding are defined.Our experience in shrub planting as means of technical and biological rehabilitation of slopes subject to erosion is presented. The stationary test plots are situated on the Tazovsky peninsula (68 degrees North) and the Yamal peninsula (70 degrees North).
Foundation Rehabilitation at ADOT/PF Jim River Maintenance Camp
Authors: Rooney J. W. , Riddle C. H. , Scher R. L.
Published: December 2007

The vehicle maintenance shop at the Jim River highway camp experienced severe total and differential settlement following original construction in 1977. Although the exact original grade could not be precisely determined, the lowest depth of building settlement was believed to be 3 to 4 feet (. 91 to 1.2 m) below the finish floor grade while slab diffential settlement of up to 2.5 feet (.76 m) occurred inside the building.

Previous exploratory work completed at the site indicated that settlement was most likely caused by thawing of ice-rich permafrost below the building. The original foundation design included 4 inches (101.6 mm) of insulation which was not adequate to counteract thermal degradation below the building. A sandy gravel material with cobbles extended beneath the floor slab to depths ranging from 10 to 14 feet (3 to 4.3 m). This coarse granular layer was underlain by a glaciofluvial deposit of frozen mixed fine and coarse-grained material having high ice content.

Rehabilitation of the building structure included short-term stabilization over a two to three month period that was accomplished using a mechanical refrigeration system. The "active" system was required because of the necessity for achieving shortterm stabilization of the building foundation. Following near total freezeback by the "active" system, it was planned to install permanent "passive" heat pipes to maintain the integrity of the frozen foundation soils on a long-term basis. Because of inadequate casing installation, the contractor was allowed to substitute a liquid-forced convection system.

The "active" mechanical refrigeration system began operating at the site on June 28, 1986, and was removed after 75 days of operation, when the degree of freezeback below the building was considered to be adequate. This paper presents design and construction considerations and provides information on the changing thermal regime beneath the building as revealed by thermistor readings versus the heat extraction calculated from temperature and flow measurement of the circulating coolant. Slab displacements are also described.
Comparison of Geostatistical Characterization Methods for the Kern River Field
Authors: Vogt J. P.
Published: December 2007

In recent years, three dimensional conditional simulation (3DCS) has become a popular technique to interpolate reservoir characteristics such as porosity, permeability, and facies between wells. 3DCS is usually thought to be the best characterization method for flow studies. However, this technique is also quite CPU intensive. Other geostatistical methods, such as pseudo 3D conditional simulation (P3DCS), 3D kriging (3DK), and pseudo 3D kriging (P3DK) are less CPU intensive. Therefore it is important to know how much less intensive these methods are and when they can be substituted for 3DCS.

In this paper, we will compare results from the above methods using actual resistivity data from the Kern River Field in California as input. We will also compare the output from two different 3D graphics packages.
3D Connectivity and Architecture in Sandstone Reservoirs
Authors: Budding M. C. , Paardekam A. H. M. , van Rossem S. J.
Published: December 2007

Conventional geological modelling of oil and gas fields has in practice been restricted to illustrations on paper. Complex spatial configurations are usually represented as a limited number of 2D maps and cross-sections, perhaps complemented by a conceptual reservoir model in a block diagram. This approach precludes a quantitative assessment of essentially 3D characteristics such as reservoir connectivity and effective permeability or transmissibility of reservoir intervals.

The computer modelling package Monarch, developed in Shell Research, enables the user to overcome this problem by subdividing the reservoir volume into a 3D grid of discrete volume cells (voxels) which can be used as a data base to integrate all available information. A set of modelling tools is provided to assign properties to groups of voxels, according to predefined geological rules.

For this purpose, well data are related to geological information via a genetic classification scheme. Monarch first models the distribution of geologically meaningful objects, such as genetic sand-body types or lithofacies units within an undeformed stratigraphic framework. If sufficient information is available, these objects are mapped directly in three dimensions, using any information available on their expected geometry. If insufficient information is available, their distribution is modelled by means of stochastic techniques, honouring established stratification patterns and architectural trends. Subsequently the structural configuration is restored, and the effects of through-fault communication are established. In a last step, the distribution of reservoir properties within the genetic elements is included.

By evaluating the resulting models statistically, probable hydrocarbon volumes connected to existing or planned wells can be calculated and optimal well locations selected. The method has been used over the last five years to assist in the development planning of oil and gas fields in the appraisal stage, to delineate optimal infill locations in producing fields and to locate remaining oil in a mature field.
Induction, Resistivity, and MWD Tools in Horizontal Wells
Authors: Gianzero S. C. , Chemali R. E. , Su S-M.
Published: December 2007

We shall investigate the applicability of induction and resistivity devices to horizontal wells, where the borehole runs parallel to the bed boundaries.

The presence of the borehole may be simply ignored for induction sondes and log response is computed analytically for entire trajectories for the more common radii of curvature used in the drilling process.

Since the borehole is an essential part of the problem for focused resistivity devices, the tool response must be evaluated numerically.

The modeling results for the resistivity devices indicate that the measurement is more sensitive to conductive than to resistive shoulder beds, whereas, the reverse physical situation is evidenced with induction devices.
Reservoir Simulation Facilitates Synergism in Management of the Attaka Field
Authors: Zagalai B. M. , Houtzager J. F. , Mahadi S. , Partono Y. , Goodwin B.
Published: December 2007

The Attaka field, located northeast of the Mahakam delta, offshore East Kalimantan, Indonesia, consists of complex arrangements of distributary/tidal channels and tidal/barrier bars. Over the last 18 years, the field has produced about 460 million STB of oil and 700 billion SCF of gas. Despite the mature status of the field, lateral correlation of the various sand bodies is uncertain. This paper describes how reservoir simulation is helping to characterize the field architecture. Matching the production history with simple reservoir models is providing a means for combining geological and engineering data and is serving as a catalyst for synergism.

A simple approach is described for constructing a large multilayered model in a complex geological setting. Models of single reservoirs are developed and a preliminary history match is obtained by use of pseudo functions. Because most completions involve commingled production from two or more reservoirs, several reservoir models are combined to refine the history match. Finally, all reservoir models are stacked to form a large-scale field model.

The approach may be classified as adaptive deterministic. As more history matching studies are completed, a more unified set of generic pseudo functions which describe the various reservoir facies is obtained. Classification of rock types and facies is based on gamma ray logs. History matching is guided by descriptive use of gamma ray log fence diagrams and by analogy to the modern Mahakam delta. The history matching process is directed to define facies distributions and reservoir connectivity.
Integrating Transient Well Test Data with Field-Wide Simulation of Fluid Flow in Heterogeneous Reservoirs
Authors: Ehlig-Economides C. A.
Published: December 2007

When derived from adequate geophysical, geological, petrophysical, and dynamic data, numerical simulation of reservoir fluid flow provides a means for forecasting production under various scenarios of interest in a decisionmaking process. Routine pressure buildup tests provide flowing well and static reservoir pressure data which can be used for material balance computations and production history matching. Analytical models provided for buildup test interpretation permit estimation or characterization of wellbore damage or simulation, reservoir permeability or dual porosity parameters, and boundary effects such as faults or fluid contacts at or near the tested well. In multiwell reservoir models, features quantified by an analytical model interpretation appear to be more complex and variable. At the same time, field-wide simulations are designed to model a much larger volume of reservoir over a much longer span of time than a well test. Hence, the trends observed in the pressure buildup data are not readily usable in this context. This paper explains how to simulate pressure transient tests in a field-wide simulation model, and how a match with the test data can be used to improve the reservoir model, thereby enhancing its value as a predictive tool.
Dynamics of Jackup Structures
Authors: Liu Ping , Massie W. W. , Wolters J. G. , Blaauwnendraad J.
Published: December 2007

This paper summarizes the more salient results of an experimental and numerical study on jack-up dynamic behavior. The laboratory studies of three principle jack-up platform models were carried out in both regular and irregular waves. The data from irregular wave tests were analyzed in both the probability domain and frequency domain supported by a careful error analysis.

Computer simulations were carried out in the time domain using a nonlinear, dynamic, multiple degree of freedom software which includes various hydrodynamic interaction options.

The experimental results and associated computer simulations demonstrate that nonlinearities are important even with the present simplified model testing and different nonlinearities have different (sometimes compensating) influences on the structure's dynamic behavior. Some more specific results include: (1) Relative motions from structural compliance are such that they cannot be neglected in the hydrodynamic computation; (2) the stiffness obtained from static tests can be significantly lower than that inferred from dynamic vibration tests and (3) inclusion of the P-δ effect in the structural schematization is essential for the jack-up simulations.
Unique Characteristics of Mixed Metal Hydroxide Fluids Provide Gauge Hole in Diverse Types of Formation
Authors: Fraser L. J.
Published: December 2007

The recent introduction to the drilling industry, of magnesium aluminum hydroxide compounds represents a departure from traditional drilling fluid technology. The unique rheological performance of the fluids (which has been described in earlier publications) and their apparent inhibitive behavior are both considered as potential contributing factors in provision of gauge holes. Field and laboratory data are presented to support the validity of the dual contributions which appear to be derived from a single mechanism.
Pore Fluid and Wellbore Stabilities
Authors: Yew C. H. , Liu Gefei
Published: December 2007

A method for estimating the borehole pressure or mud weight, required for maintaining the stability of a deviated wellbore, is presented in this paper. The critical borehole pressure is calculated by incorporating elastic stresses on the hole surface into a failure criterion of the rock. The Drucker-Prager criterion together with an experimentally obtained Mohr-Coulomb (p - q) curve is used to estimate the condition for plastic flow on the hole surface, and the maximum tensile stress failure criterion is applied to calculate the breakdown pressure of the hole. Both the flow induced stresses and the effect of pore pressure on failure of rock are taken into consideration. It is demonstrated that the plastic failure of borehole is very sensitive to the pore pressure, and that the range of safe borehole pressures (or mud weights) decreases with the increase of the borehole inclination angle.