bluuebunny/crossref_metadata_2025 huggingface dataset:
Computed Relative Permeability Drainage and Imbibition
Authors: Ashford Frank E.
Published: December 2007

A brief review of the historical developments of both drainage and imbibition relative permeability reveals shortcomings in previously permeability reveals shortcomings in previously applied mathematical models.

Recent investigations indicate justifiable bases for relating the Leverett "J" function directly to the relative permeabilities of both phases. Development of this procedure yields a phases. Development of this procedure yields a relationship describing the "J" function in terms of rock matrix properties, i.e.: k, krw, phi, Sw, the absolute permeability, the wetting phase relative permeability, the porosity, and wetting phase saturation, respectively.

(Equations) are the expressions for the drainage cycle, while

(Equations) are the expressions for the imbibition cycle.

The saturation exponent relates the relative permeabilities to pertinent matrix parameters. The result is considered an improvement parameters. The result is considered an improvement over previous models that assumed krw and krnw to be exclusive functions of the mobile wetting phase saturation. A method is also presented for phase saturation. A method is also presented for computing a pseudo irreducible water saturation, Swp, below which krw is assumed negligible. The application of this value to relative permeability calculations has been very successful.

Recent imbibition relative permeability studies have yielded a model that predicts imbibition parameters from drainage values. The model is an extension of the Naar-Henderson treatment.
Option Theory for Evaluation of Oil and Gas Assets: The Upsides and Downsides
Authors: Lohrenz John , Dickens R. N.
Published: December 2007

Assumptions encumbering option theory methods for valuation of oil and gas assets, unlike purely financial assets, are reviewed and shown to severely burden getting serviceable answers. In fact as a general rule, the further upstream the oil and gas asset valuated with option theory methods is, the more so the assumptions may be called into question.
A Comprehensive Model of Minifrac Pressure Behavior With Foam Fracturing Fluids
Authors: Zhu Ding , Hill A. D.
Published: December 2007

A comprehensive model of pressure behavior in a minifrac test with a compressible fluid (a fluid for which the density is a function of temperature and pressure) has been developed to simulate the pressure behavior more accurately and realistically. Since for minifrac tests, the fracture will more likely be radially expanding, Geertsma's penny-shaped fracture geometry model has been introduced to modify an existing linear fracture model. The new model handles a wide range of frac fluids using the proper equations of state to simulate slightly compressible fluids or highly compressible fluids such as high quality foams. In the case of surface shut-in, the effect of wellbore fluid warming due to the geothermal heating along the wellbore on the pressure decline is also examined.

Numerical solution of the model shows that the pressure decline after shut-in will be affected by the frac-fluid warming if the fluid is compressible. The higher the gas quality of a foam is, the more pronounced this effect will be. The leakoff coefficient evaluated frompressure decline using the Nolte model will be in error at early shut-in time. The wellbore fluid warming adds more inaccuracy to the leakoff estimation. The estimate error caused by the fluid warming in the fracture will decrease to zero as the fracture closure time fracture approaches.
A Computerized System for Planning Major Investment Decisions in Oil
Authors: Dougherty E.L. , Thurnau D.H.
Published: December 2007

A mathematical model, based on a systems approach, has been developed and is being used as a primary tool in planning investments in oil field production facilities. For a given set of assumptions the model determines magnitude and timing of investments in primary and secondary wells, surface-handling facilities and pipelines, and fixes production rates each time period to maximize present worth profit over a planning horizon. Engineering profit over a planning horizon. Engineering requirements, economic factors plus physical and regulatory limitations are simultaneously taken into account. The model

generates better plans than conventional procedures, helps systematize and document basic planning data for later reference or updating, and provides a unique common ground which provides a unique common ground which promotes understanding and communication promotes understanding and communication between engineers, planners and top management.

Introduction

In all business enterprises, some form of planning takes place, although the quantity and planning takes place, although the quantity and quality may vary widely depending upon the nature of the business and the attitude and level of sophistication of the management. Since the petroleum industry has long been a leader in petroleum industry has long been a leader in applying latest technology to improve operations it is no surprise that petroleum companies have been among the first to begin applying modern computer-based management methods to their critical planning problems.

The greatest advantage to be gained from applying the computer in a planning situation is to provide a mechanism by which data and assumptions can be easily and quickly converted into meaningful planning guidelines. With an efficient and flexible system, it is possible to feed in new data as soon as it becomes available to keep planning current.

From a technical standpoint, the oil business gives rise to some of the most difficult analytical planning problems encountered in business. As a result, progress toward development of improved computerized planning systems for the petroleum industry has come slowly. However, recent mathematical developments combined with the ability of modern day computers to process enormous quantities of data at fantastic speeds now makes it possible to consider all significant interactions in a complex oil system in generating the kind of information required by enlightened petroleum managements to make better decisions.

Of course, the core of these planning problems is economic evaluation for problems is economic evaluation for decision-making.
Analysis of Coal Gas Reservoir Interference and Cavity Well Tests
Authors: Mavor M. J. , Robinson J. R.
Published: December 2007

This paper discusses the analyses of transient pressure data that has been measured during single well test and multi-well interference tests performed in wells producing gas and water from coal seams of the Fruitland Formation of the San Juan Basin of Colorado. The test procedures included open hole drill stem tests, cased hole water injection tests, open hole production tests, multi-well interference tests, and post-cavitation production and shut-in tests. Proper evaluation of the pressure behavior measured during each type of test resulted in similar estimates of the absolute permeability of the coal gas reservoir natural fracture system.

Evaluation of post-cavitation well test data has not been presented in the literature prior to this paper. The analysis results are shown to be accurate by agreement with reservoir simulation and multi-phase interference test analysis results.
Analysis of the Hydraulic Fracturing Behavior in the Bowen Basin
Authors: Morales R. H. , Davidson S. C.
Published: December 2007

This paper presents an analysis of the hydraulic-fracturing stimulations of the coalbed formations of the Bowen Basin of eastern Australia. In particular, two fracturing tests conducted in coal seam No. 4 (Well 3) are analyzed.

The analysis indicates that multiple fractures with horizontal and vertical components are created. A pressure-dependent fluid-loss formulation for naturally fractured reservoirs and a large apparent fracture toughness are necessary to match the observed pressures.

A calibration treatment to determine the fracturing regimes, pressure-dependent permeability, and apparent fracture toughness is proposed for the design and analysis of forthcoming fracturing stimulations. The formulations for these mechanisms are described.
Liner Cementing Across the Wasatch Formation in the Bluebell Altamont Field: A Case Study
Authors: Grubich J. M. , Morris B. V. , Gill P. J.
Published: December 2007

This paper describes work done in the Bluebell Altamont Field of Northeastern Utah (see fig. 1), with the objective of eliminating poor bonding on liners set in the Wasatch Formation. The Wasatch Formation has posed problems with cementing, as well as drilling, due to the frequency of natural fractures in the zone [2]. The use of Anionic Aromatic Polymers in cement systems has proven to exhibit superior fluid properties that enable the cementing of liners with low pipe to open hole tolerances. The cement systems have also provided improved cement bonding across the Wasatch Formation.
New Type Curves for Analyzing the Transition Time Data from Naturally Fractured Reservoirs
Authors: Onur Mustafa , Satman Abdurrahman , Reynolds A. C.
Published: December 2007

This work presents new type curves for the characterization of a naturally-fractured (dual-porosity) reservoir. These type curves were motivated by new approximate solutions for the pressure derivative which apply during the transitional flow period which exists between the two classical semilog straight lines. These approximate solutions suggest the appropriate pressure, pressure-derivative, integral-pressure-derivative and time groups necessary to prepare type curves. New type curves are presented for both the pseudosteady-state interporosity flow model of Warren and Root and the transient interporosity flow model of Kazemi and de Swaan.
Transient Finite Element Code: A Versatile Tool for Well Performance Analyses
Authors: Morita Nobuo
Published: December 2007

This paper describes a system of general transient finite element flow programs for analyzing complex flow problems. It emphasizes a structured system consisting of a set of mesh generators, a main program, and a post processor, allowing applications as a routine practical tool rather than a research tool for well performance analysis, completion design tool, and pressure transient analysis.
Using Polymer Injectivity Tests to Estimate Fracture Porosity in Naturally Fractured Reservoirs
Authors: Gilman J. R. , Hinchman S. B. , Svaldi M. A.
Published: December 2007

A new technique is presented to calculate fracture porosity in naturally fractured reservoirs using composite system analyses.

The concept outlined here is to inject a viscous solution (e.g. polymer) which will not invade the matrix rock, but remains in the fractures. Subsequent falloff tests can then be used to determine the bank radius of the polymer in the fractures and thus fracture porosity from material balance. In the early 1980's Marathon Oil Company performed a number of polymer injectivity tests in naturally fractured reservoirs. In several cases, apparent bank radius was much larger than anticipated. This observation lead to the technique proposed in this paper.
Three-Dimensional Analysis and Visualization of the Wellbore and the Fracturing Process in Inclined Wells
Authors: Morales R. H. , Brady B. H. , Ingraffea A. R.
Published: December 2007

This paper describes the three-dimensional analysis and visualization of an inclined wellbore during the early stages of the hydraulic fracturing process. The analysis indicates that two or more fractures are developed during the early stages of pumping. Depending on the well inclination, these fractures can be aliped with or intercept the wellbore axis. Further, the fractures interact, twist and turn to align parallel to the preferred fracture plane. Based on this analysis, guidelines for perforation completions are proposed.
Field Implementation of Proppant Slugs to Avoid Premature Screen-Out of Hydraulic Fractures with Adequate Proppant Concentration
Authors: Cleary M. P. , Johnson D. E. , Kogsbøll H-H. , Owens K. A. , Perry K. F. , de Pater C. J. , Stachel Alfred , Schmidt Holger , Tambini Mauro
Published: December 2007

Premature screen-outs and/or low proppant concentration are the most likely cause of failure in hydraulic fracturing treatments. Although commonly blamed on a variety of presumed problems—most typically the treating fluid, or large-scale reservoir conditions, such as permeability or stress profile—the true source of most problems has been uncovered only recently by careful analysis of treatment data. The source is referred to as near-wellbore tortuosity, but it can variously arise from deviatoric stress, natural fractures and/or perforation-dominated creation of complex fracture patterns in the wellbore vicinity.

Numerous theories have been formulated to deal with near-wellbore screen-outs and, especially for oriented wellbores from Arctic or offshore platforms, various perforation strategies have been postulated and/or implemented. In contrast to the idealizations and costs associated with those theories and strategies, this paper presents simple cheap solutions that are less sensitive to the wellbore environment This novel strategy involves injection of proppant slugs into the near-wellbore region and, when necessary, immediate shut-ins upon small slugs, with three important results: the response of the near well-bore region can be measured and characterized; a large part of the near-wellbore tortuosity can be removed, by simplifying the near-wellbore fracture pattern; and the true nature of the large-scale reservoir response can be determined, e.g. from the greatly modified pressure fall-off obtained after placing slugs near the wellbore.

The paper reports the concept and implementation, in a number of commercial fracturing environments, in both gas and oil reservoirs, with both foam and liquid-gel jobs. These show the effective removal of tortuosity varying from 20 to 200 bars and associated elevation of allowable proppant concentrations.
Natural Fractures in Sonora Canyon Sandstones, Sonora and Sawyer Fields, Sutton County, Texas
Authors: Marin B. A. , Gift S. J. , Hamlin H. S. , Laubach S. E.
Published: December 2007

The Sonora Canyon is one of several "Canyon Sands" (Virgilian-Wolfcampian) intervals that exist in the Val Verde Basin of southwest Texas. This paper describes the presence and attributes of natural fractures in Sonora Canyon sandstones in Sutton County, Texas. Data obtained from three cored wells through a cooperative research program conducted by the Gas Research Institute and industry show that natural fractures are locally abundant. At least three distinct natural fracture classes coexist that have contrasting distributions, characteristic sizes, and/or mineral fills. The most abundant fracture class consists of clay- or clay- and carbonate-filled fractures existing only in siderite-cemented zones in sandstones. Owing to their clay content, these fractures locally may be barriers to fluid flow and their presence could cause reservoir heterogeneity and anisotropy. Calcite- and quartz-cemented fractures are less common fracture classes. These fractures are larger than those in siderite layers and are partly open as a result of propping by diagenetic minerals. Our results show that fractures in Sonora Canyon sandstones should be considered in completion and stimulation design. For example, high treatment pressures observed in some Canyon Sandstone stimulations may be due to natural fractures promoting propagation of multiple fracture strands near the wellbore. Inconsistencies between hydraulic fracture strike and maximum horizontal stress may be due to natural fractures guiding hydraulic fracture growth.
Fracture Identification and Characterization Using Cores, FMS, CAST, and Borehole Camera: Devonian Shale, Pike County, Kentucky
Authors: Kubik West , Lowry Patrick
Published: December 2007

An accurate characterization of natural fractures is an important part of reservoir exploitation in the gas-bearing Devonian shales of the Appalachian Basin. These reservoirs commonly have very low matrix permeabilities (10-9 to 10-7 md), and a well developed natural fracture system must be present to provide sufficient deliverability for economic production. A detailed fracture description is crucial to proper reservoir modeling and simulation.

Fractures have been identified and described in 440 feet of oriented whole core from two research wells in eastern Pike County, Kentucky. FMS, CAST, and Borehole Camera data have also been acquired, and the core data was used as a basis for the interpretation of these tools. Each tool has its own unique advantages and disadvantages, and guidelines have been established for the optimum use and interpretation of each.

The complex nature of the fracture systems in these reservoirs often pose special problems in fracture identification using these borehole imaging tools. The ability to properly characterize fractures in this reservoir is strongly influenced by the apparently very fine fracture apertures and limited fracture vertical extent.

Whole core represents the best source of data for a detailed, accurate fractured reservoir interpretation. The FMS and CAST are good fracture detection tools, but should be tied to whole core data. The borehole camera, though less quantitative than other tools, represents a reliable source of fracture data, and is inexpensive to acquire and interpret.
Perforation Design Models for Heterogeneous, Multiphase Flow
Authors: Behie Alda , Settari Antonin
Published: December 2007

Design of perforating for optimal productivity is currently based on semi-analytical techniques or charts developed with the use of finite element models. Both methods are severely restricted by their limiting assumptions, while the direct use of finite element models is impractical for field design work. This paper describes the development and application of two new, practical finite difference models for the determination of the productivity of single perforation and multi-perforation systems in single phase as well as multiphase flow. The first models flow through laboratory cores. The second models multiple perforations in a field context. The latter allows any arbitrary perforation geometry, including irregular spacing; gun eccentricity; gravel packed completions; drilling damage; and complex reservoir heterogeneity. In addition, the field model can be applied to vertical or horizontal wells, and can be also used for analyzing RFT pressure tests. The models have been tested and validated against published results including laboratory cores and perforated completions. The validation and application work has yielded a number of interesting findings and some important practical implications for perforating design.
A Study of the Damage Zone Created by Shaped-Charge Perforating
Authors: Yew C. H. , Zhang Xichang
Published: December 2007

A high amplitude pressure pulse was produced by the shaped charge during perforation. The method of characteristics was applied to study the damaged zone created around the perforating tunnel. The analytical results offered an analytical explanation to the experimental observations made by Pucknell and Behrmann1. It was demonstrated that the pore fluid played a major role for the damage surrounding the perforated hole.
Prediction and Analysis of Performance of Gas Wells Producing from Reservoirs Containing Several Noncommunicating Layers
Authors: Dougherty Elmer L. , Juber Fahmi , Chang Jincai
Published: December 2007

This paper studies performance of gas wells producing from a reservoir containing several noncommunicating layers. Predictions were made with a newly developed simulator that performs a complete "nodal analysis" on each time step to determine flow capacity. The four categories of results given are; (1) the excellent correlation of predicted performance of 1- & 2-layer reservoirs with published data validates the novel mathematical approach used in our simulator, (2) for a 5-layer system comparison of simulated results to published values obtained with an analytical solution finds only partial agreement, (3) predicted recoveries after aggregating layers of differing permeability show that layer combinations must be chosen carefully to avoid large errors in predicted recovery and (4) the turbulence coefficient must be defined on a unit thickness basis to obtain correct results for layered systems.
Log-Based Gas Content and Resource Estimates for the Antrim Shale, Michigan Basin
Authors: Decker A. D. , Hill D. G. , Wicks D. E.
Published: December 2007

Antrim Shale multicomponent gas storage mechanisms of adsorption, porosity and solution in bitumen preclude the use of conventional gas-in-place volumetric calculations. Total in-situ gas content has been measured using canister degassing techniques adapted from coalbed methane technologies. Gas measurements ranged from approximately 5 scf/t to 166 scf/t. Gas contents exceed apparent gas-filled porosity by 6 to 8 times where organic content is high. Cross plots of gas content to companion TOC and density measurement resulted in a direct correlation between increasing gas content corresponding to progressive increases in organic matter and an inverse relationship between increasing gas content and decreasing density. The linear function relating density and gas content can be used in conjunction with open-hole log bulk density measurements to calculate gas-in-place.

A side-by-side comparison of gas content measurements from rotary sidewall core and whole core demonstrated that the measurements from both core sampling types are of equal accuracy. From the standpoint of cost, sample homogeniety and sampling selection, rotary sidewall cores are preferred over whole core. The total gas contained in the shale can be completely released as a single measurement by crushing the core upon retrieval. Utilizing the on-site gas content measurements, density/gas content relationship and density log it is possible for the first time to locate and quantify gas bearing Antrim shale intervals from well logs.
A Quick Technique To Define Compressibility Characteristics of Hydrocarbon Reservoir
Authors: Unalmiser Servet , Swalwell T. J.
Published: December 2007

During the production of reservoir fluids, the pore fluid pressure decreases as the overburden pressure remains constant Consequently, pore compression occurs as the disparity between external and internal pressure increases. The technique developed in this study has a different approach to the conventional method resulting in a procedure which is both highly efficient and cost effective. This is achieved by neglecting the cr, which is typically an order of ten less than the cb, thus permitting the almost routine determination of cp. A microcomputer controlled porosimeter has been utilized to carry out compressibility studies to obtain rapid reliable results in a highly cost effective manner. The compressibility characteristics of twelve samples, 2 inches in length and 1.5 inch in diameter, can be determined to a maximum frame stress of 10,000 psi in a matter of hours. The applied technique assumes that: (a) pore compressibility behavior depends only on the effective frame stress based on the theory of poroelasticity; (b) irreducible brine and rock matrix expansion due to reduction in pore pressure are negligible; (c) hydrostatic pore volume compressibility can be converted to uniaxial strain condition based on constant Poisson's ratio for all loading conditions.

Demonstrative studies were applied to core samples from limestone and sandstone reservoirs. A total of 714 carbonate plugs were tested at five different frame stresses between 500 and 3,500 psi. A further 32 sandstone samples were tested, primarily at four different pressures ranging from 500 psi to 3,500 psi. Of these six samples were tested at pressures from 4,000 psi to 9,500 psi at 500 psi increments. An exponential relationship in the form of: Eq. (1)cp=−mP

was found to give excellent correlation with an R2> 97% for all cases. The slope of the exponential line allows one to determine the pore volume compressibility, porosity at stress, and relative porosity change of each core plug at any pressure corresponding to the relevant depth.
Reservoir Quality and Well Response to Stimulation in Frontier Sandstones, Moxa Arch, Southwest Wyoming
Authors: LaFollette R. F. , Davis B. J.
Published: December 2007

Reservoir quality and response to stimulation vary significantly in the Frontier Formation. Available geological and engineering data have been integrated with a core study to better understand Frontier reservoir properties and stimulation response.

Second Frontier reservoir quality is best developed in marine upper shoreface/bar and fluvial channel depositional systems. Lower shoreface sandstones are generally non-reservoir-quality material. Flow study results support the use of crosslinked gelled-water frac fluids from pH 4.0 to pH 10.5. The major potential completion problem identified in the Frontier is fines migration of mixed-layer illite/smectite clay. Analysis of production and stimulation data from the Church Buttes/Bruff area indicates that foam fracs may yield higher initial flow rates, but crosslinked gelled-water treatments result in higher ultimate recoveries.
Characterization of Oilfield Waters by pH and Oxidation-Reduction Potential
Authors: Shafer R.V. , Pirson Sylvain J.
Published: December 2007

Approximately 50 connote water samples were collected from various oilfields in East Central Texas. These water samples were subjected to tests to determine their pH, oxidation-reduction potential and conductivity values. It was found that values for these three variables tend to cluster, suggesting that they might help identify the specific formations involved and contribute to an understanding of the geological structure.

It is tentatively concluded that the combination of oxidation-reduction potential, pH and conductivity values may help indicate the pH and conductivity values may help indicate the depositional environment and classification of hydrocarbon present, and that certain negative values of oxidation-reduction potential may indicate the presence of hydrogen sulfide.

Introduction

In recent years there has been increasing interest in geochemical processes associated with the relative stability of minerals found in the earth. Study of the chemical forces and conditions necessary for various chemical equilibria has brought new understanding and insight into how minerals are formed and where mineral deposits of economic importance might be found.

Of predominant importance in the formation of sedimentary rocks and associated minerals are processes involving aqueous media, for water permeates everywhere the upper porous portion of the earth's crust. Two portion of the earth's crust. Two characteristics of these aqueous media can be measured which are functionally related to the chemical activities of various substances dissolved in or in contact with the aqueous media. These two characteristics are the acid-base relation or pH, and the oxidation-reduction potential or Eh.

In spite of many recent papers and books, treating the relationship of oxidation-reduction potential and pH to the formation of minerals in sediments, little has been published on the question as it relates to the formation and stability of petroleum in sedimentary basins.

This study reports an investigation of the oxidation-reduction potentials and pH found in formation waters from various oilfields in the vicinity of Austin, Tex., and discusses possible relationships between these characteristics possible relationships between these characteristics and the formation mineral content, the type of hydrocarbon present and the amount and type of substances in solution. This is intended as a preliminary investigation to which subsequent preliminary investigation to which subsequent work may be added.
Real-Data On-Site Analysis of Hydraulic Fracturing Generates Optimum Procedures for Job Design and Execution
Authors: Johnson D. E. , Wright T. B. , Tambini Mauro , Maroli Renato , Cleary M. P.
Published: December 2007

This paper demonstrates our methodology and capabilities for effective on-site real-time analysis, re-design and execution of hydraulic fracturing treatments. This unique technology has been developed over many years of research and development, sponsored primarily by the Gas Research Institute (GRI). Ten years of field implementation in the stimulation of gas- and oil-well production have led to conclusions and recommendations which involve major changes from conventional concepts about hydraulic fracturing. Most of our recommendations are relatively simple, low-cost procedures for adequate data collection, such as the use of flow-rate changes and/or multiple injection/shut-in cycles for stringent model evaluation of recorded data. Proper implementation of our recommendations is demonstrated by a case study in a commercial field situation, where the fracture treatment was drastically redesigned as a result of on-site analysis, and executed on the same day. This job showed that treatment cost/benefit optimization can be achieved by careful on-site analysis and more flexible field execution schedules.
Large-Volume, High-Rate Stimulation Treatments in Horizontal Wells in the Niobrara Formation, Silo Field, Laramie County, Wyoming
Authors: Johnson R. L. , Brown T. D.
Published: December 2007

In 1991, Union Pacific Resources Company (UPRC) stimulated four horizontal wells in the Niobrara Formation in the Silo field, Laramie County, Wyoming. Stimulation treatments were required due to the rapid production declines seen early in the life of these wells, which were completed in 1990 and 1991. Horizontal and vertical wells in the Austin Chalk formation have been stimulated by injecting large volumes of water (10,000–30,000 bbls) at high rates (50-220 bbl/min) to improve productivity. This stimulation technique was applied in the Silo field because the Austin Chalk and Niobrara reservoirs have similar features; the most important similarity is that productivity requires connection to an adequate natural fracture system. These Niobrara stimulation treatments consisted of 30,000 bbls of water pumped at rates up to 150 bbl/min with wax beads as diverting material.

This paper describes the job designs, bottom-hole treating pressure (BHTP) trends observed during the job, and post-treatment well production. Early BHTP responses and post-treatment production are related to the extent of natural fracturing exposed within the horizontal (lateral) sections. The lack of sustained productivity after the treatments indicates that Niobrara wells respond differently than Austin Chalk wells after large-volume, high-rate treatments. The most likely explanation for this difference is that fractures opened during Niobrara large-volume, high-rate treatments either close during production or do not provide sustainable connectivity to high-conductivity fractures. Future treatment strategies are discussed concerning fluid selection and the use of diverting materials and proppants.
State of Texas Jurisdiction and Response to Inland Oil Spills
Authors: Tintera J. J.
Published: December 2007

The array of regulations of various state, federal, and local governmental entities can appear bewildering to those involved in responding to a major inland crude oil spill in Texas. The Brazos River crude oil spill of 1991 presents an example of a coordinated state response to an inland spill. The following review of the incident is intended to provide guidance to those who may be required to respond to a spill in the future.

When 6,200 barrels of oil spilled from a ruptured pipeline into a flooding Brazos River, the operator assumed responsibility. Since crude oil spills from a pipeline fall under Railroad Commission of Texas jurisdiction, the agency acted as lead state agency coordinating the state response to the Brazos River spill.

The lead state agency responding to a spill for the State of Texas coordinates activities by and between the federal, state, and local governmental authorities as well as the responsible party. This coordination involves all spill response activities, including safety measures, and environmental damage assessments.

As the operator attempted to place booms to contain crude oil spilling into the swollen Brazos River, federal, state and local authorities arrived on scene. These authorities represented the U.S. Environmental Protection Agency, U.S. Coast Guard, Texas Water Commission, Texas Parks and Wildlife Department, Railroad Commission, Texas Department of Public Safety, Governor's Division of Emergency Management, Texas Forest Service, and Brazos River Authority. Boom failure due to high water and rapid currents forced final boom placement 180 miles down stream at Possum Kingdom Lake, a major drinking water resource.

A command center was established by the Forest Service. The Railroad Commission used this command center to coordinate the state's response. With an active and organized responsible party, state coordination consisted of monitoring response activities, permitting waste disposal, and conducting environmental damage assessments.

As spill response activities evolved from the containment phase to the clean-up phase, state agency response action shifted toward environmental damage assessment as non-lead agencies carried out their regulatory responsibilities. The lead agency retained the coordination, financial reimbursement, and report writing responsibility for the state.

After lengthy clean-up efforts and site-by-site environmental damage assessment, the responsible party provided the lead state agency the final report outlining containment and clean-up efforts.
Meeting the Training Challenge
Authors: Accardo A. J.
Published: December 2007

An increasing number of regulations address the control of hazardous materials and the protection of the environment. In order to protect the health and safety of employees working with hazardous materials, the Occupational Safety and Health Administration (OSHA) has issued standards on communicating the hazards of chemicals in the workplace. This law is known as the Hazard Communication Standard (HAZCOM) or employee "Right-to-Know." In addition, OSHA and the Environmental Protection Agency (EPA) have collaborated to issue standards to protect employees during emergency response to chemical spills and hazardous waste cleanup operations. These standards are known as Hazardous Waste Operations and Emergency Response (HAZWOPER).

In order to meet these standards, businesses must develop programs to communicate to employees hazards in the workplace, how to protect themselves from these hazards, and how to react in emergency situations. These programs can be developed in house or contracted through training consultants, or both. This paper reviews the HAZCOM and HAZWOPER regulations and describes their application to the oil and gas industry. This customized communication and training program which meets the requirements of OSHA and EPA describes incident prevention, emergency response, and crisis management.
Slag Mix Mud Conversion Cementing Technology: Reduction of Mud Disposal Volumes and Management of Rig-Site Drilling Wastes
Authors: Nahm J. J. , Javanmardi Kazem , Cowan K. M. , Hale A. H.
Published: December 2007

ABSTRACT*

Blast furnace slag is a unique hydraulic material which is a by-product of the steel-making process. A new method of mud to cement conversion technology utilizing slag as the hydraulic material has been developed, and the technical merits of this slag mix are briefly reviewed. This slag mix technology is economically, technically, and environmentally superior to conventional Portland cements and has been used in many fields.

The major environmental benefit is the reduction of mud disposal volume. Since the application of slag mix at Prospect Auger in the Gulf of Mexico, excess whole mud discharge has been reduced by about 70% (4,530 barrels per well). Approximately 15,000 barrels of excess drilling mud was recycled into slag mix at Auger.

In addition, a new drilling waste management method to reduce or eliminate drilling waste at the rig-site has been developed. A new type of slag-supplemented drilling fluid containing 40 to 60 lb/bbl slag can produce slag-laden cuttings which are self-setting with time. The in-situ solidification method seems to be environmentally acceptable and potentially cost-effective.
Using Innovative Sample Collection and Field Analytical Techniques to Rapidly Characterize Multiple Petroleum Hydrocarbon Sites
Authors: Petersen F. S. , Francoeur T. L. , Kasper K. D. , Strutynsky A. I.
Published: December 2007

Innovative exploration methods and advanced on-site field analytical techniques identified the presence or absence of petroleum hydrocarbon constituents (PHCs) in the soil and groundwater at multiple sites, quickly and effectively. Where present, the vertical and horizontal extent of PHCs was identified. The field program was performed using a cone penetrometer unit, two geoprobe systems, and two mobile laboratories, and was completed in four weeks.

Piezometric Cone Penetrometer Tests with soil Electrical Conductivity (CPTU-EC) measurements were used to rapidly assess site hydrostratigraphy. Three CPTU-EC soundings were typically performed at each site. Soil and electrical conductivity measurements were used to identify aquifer and aquitard units in real time and evaluate whether free-phase products were present at each site. Small diameter piezometers were installed in each CPTU-EC exploration to identify the direction of groundwater flow and to allow for sampling of ground water. In addition, penetrometer soil and ground water sampling were performed when it was anticipated that the lighter weight geoprobes would not be able penetrate to desired depths. The penetrometer truck was able to complete exploration work at one and one-half sites per day, on average.

Using a phased approach, soil and ground water samples were analyzed for PHCs in the field, providing quality real-time data. During Phase I, all soil samples were analyzed for total petroleum hydrocarbons (TPH) by infrared (IR) spectroscopy, using a modification of USEPA Method 418.1. Data from these initial locations directed subsequent soil and ground water sampling, both horizontally and vertically. Approximately 30 percent of the samples underwent subsequent analysis (Phase II) using a gas chromatograph (GC) for the specific analyte determination of benzene, toluene, ethylbenzene, and xylenes (BTEX), and fuel fingerprint identification.
A Single Treatment Controls Scale, Emulsions, and Corrosion From the Producing Formation to the Disposal Sand
Authors: Park Ben D. , Elkins J.G. , Finklea S.R.
Published: December 2007

A blend of an organic phosphate, a wetting agent, and a corrosion inhibitor has been successfully squeezed into producing oil and gas wells to control scale and corrosion throughout the production and disposal systems. Both barium sulfate and calcium carbonate deposition have been reduced. Unusually good corrosion inhibition results in extremely low concentrations of iron in the water. Plugging by iron compounds is thereby considerable Plugging by iron compounds is thereby considerable reduced. The single treatment precludes the use of surface injection facilities for chemicals and the attendant maintenance costs of chemical pumps. Cleaner oil and cleaner water have resulted because of the detergent action of the wetting agent used to couple the scale and corrosion inhibitors. Productivity increases have been achieved in Productivity increases have been achieved in several wells. Service operations on producing and disposal wells have been reduced; injection rates have been maintained for longer periods.

Introduction

The concept of squeeze treatment with a combination chemical, soluble in brine, grew in stages. The chemical was developed first to improve salt water quality for subsurface injection. The water was extremely corrosive (up to 100 MPY), had high scaling tendencies (CaCO3), and was loaded with oil-wet solids and entrained oil. Mechanical separation was not achieving the desired quality although some improvements were obtained. An organic phosphate, a wetting agent, and a cation corrosion inhibitor were found which achieved the desired water quality and which reduced the scale and corrosion problems sharply.

Three chemical injectors were required at each of several locations. These injectors required careful supervision since the varying dosage resulted in different refill frequencies for each injector. The loss of several hours to several days of treatment could nullify the effect of prior treatment and reduce the effect of subsequent treatment for some time. It was decided that a blend of the three compounds would reduce mechanical, labor, and supervisory problems by two-thirds. The blend worked well, but surface chemical injection was still fraught with the usual maladies such as inoperative pumps and empty chemical reservoirs.

It was then decided that if the chemical could be squeezed into the producing formation, that it would return a period of several days to several weeks. At first, the thought of squeezing with water into an oil-producing formation was disturbing, but further evaluation indicated that a squeeze treatment could be safely performed.

The additional benefits gained from the squeeze treatment were varied and numerous.
Pollution Prevention at an Arctic Oil Field and Camp
Authors: Lettow J. H.
Published: December 2007

Pollution Prevention (referred to as "P2" by EPA) focuses heavily on source reduction and is viewed as the preferred approach for minimizing waste now and into the future. Minimizing waste through source reduction, product substitution, and product reuse, is a "proactive" approach "upstream" of what classically has been handled "downstream" as waste disposal challenges. Establishing open working relationships between various departments within a business unit is time and money well spent when compared to that involved with waste characterization and disposal in a more "reactive" mode.

Working in remote industrial settings with optimized staffing levels, such as the oilfields located along the Arctic Ocean (the "North Slope"), "P2" challenges business units to further develop and foster integrated methods and systems for recognition and management of waste reduction opportunities.
Waste Minimizing Processing Technique for Solids Laden Biopolymer Gels
Authors: Haagensen R. V. , Blount C. G.
Published: December 2007

High viscosity biopolymer gels such as Welan and Xanthan gums are routinely used in Coiled Tubing (CT) operations. These operations range from common fill cleanouts to removing excess cement during CT squeeze jobs and for other applications such as CT underreaming of cement or other tenacious fills. These gels were chosen because of their highly desirable rheology characteristics and the their extremely low biological risks1. However, biopolymer gels have proven to be very difficult to break and process for solids removal and under some circumstances, can wreak havoc in oil processing operations.

This paper documents a test program that culminated in the identification of a process that effectively breaks these gels allowing higher solid removal efficiency and produces a liquid phase that has been shown to be compatible with oil processing.

The processing technique described in the paper has been field tested to quickly and effectively break back the difficult to clean, high viscosity biopolymers. Prior testing identified only a few chemicals such as ferric chloride and potassium permanganate that would rapidly flocculate high pH biopolymers. Unlike the aforementioned chemicals, the organic, cationic poly-electrolyte used in the process posses an extremely low health hazard and is "of low toxicity." Thus the process described is the paper is aligned with the goals of operations that pose minimal impact to the workplace and environment.
Permeability Estimation From Fracture Calibration Treatments
Authors: Mayerhofer M. J. , Economides M. J.
Published: December 2007

For data from fracture calibration treatments a methodology is introduced for the determination of the reservoir permeability as an addition to the usual variables of leakoff coefficient and closure pressure. The technique derives from the solution of the diffusivity equation for a well with an infinite-conductivity vertical fracture (as a multi-rate injection) with a superimposed varying filtercake skin effect. The transient reservoir response, which is found to be the essential feature, is then decoupled and used to determine the reservoir permeability.
Effect of Asphaltene Deposition on Dynamic Displacements of Oil by Water
Authors: Kamath V. A. , Yang Jiede , Sharma G. D.
Published: December 2007

The flocculation and deposition of asphaltenes in porous media and their interactions with rock and fluids represent complex phenomena which need to be investigated under dynamic flowing conditions. In this paper, experimental results are provided to determine the effect of asphaltene deposition on the dynamic displacements of heavy oil by water in consolidated as well as unconsolidated porous media. Dynamic method was used for in-situ asphaltene precipitation in the porous media. Several dynamic displacement experiments were conducted to understand the displacement of heavy oil by water at various degrees of asphaltene deposition.

The results show that, while the increase in asphaltene deposition increased pore plugging and reduced the absolute permeability of the porous media, it also improved the displacement performance and oil recovery by water flooding. It is believed that the improvement in displacement performance may be partly due to improvement in the relative oil permeability caused by end point saturation and wettability changes and partly also due to the flow diversion effect of asphaltene deposition.
An Analytical Pressure-Transient Model for Multilayered, Composite Reservoirs With Pseudosteady-State Formation Crossflow
Authors: Gomes Edmond , Ambastha A. K.
Published: December 2007

Reservoir deposition occurs over geologic periods of time. Although reservoirs are assumed homogeneous for simplicity of analysis, most reservoirs are heterogeneous in nature. Some common forms of heterogeneity are the presence of layers and the presence of different zones of fluids and/or rocks in the formation.

In this study, a new analytical solution for multi-layered composite reservoirs with pseudosteady state interlayer crossflow has been developed. Fluid flow in the reservoir has been treated as a generalized eigenvalue problem. The developed analytical solution for an n-layered composite reservoir is applicable for any irregularly-shaped discontinuity boundary, and for closed, constant-pressure and infinite outer boundary conditions. This new solution is computationally very efficient. Using eigenvalues and eigenvectors of the system, this method requires solution of an order of magnitude fewer simultaneous equations as compared to other methods proposed in the literature. This method is also very versatile and can handle multiple composite regions (more than two), and partially-penetrating wells subject to bottom-water and/or gas-cap drives for well testing purposes. This analytical model has been validated by comparing the results with those of some simple, well-known models in the well testing literature. Solution methodology and future possibilities of the new solution have also been discussed.
Optimization of Wellbore Placement Using 2 MHz Resistivity Technology in the Cook Inlet, Alaska
Authors: Stewart R. L. , Logan R. B.
Published: December 2007

Granite Point field is located 50 miles southwest of Anchorage. A redevelopment program on the southernmost platform included two high-angle single zone wells. Use of computer-modeled responses in conjunction with 2 MHz resistivity technology assisted in placing the two wellbores accurately in the reservoir.