bluuebunny/crossref_metadata_2025 huggingface dataset:
Hard or Soft Shut-In: Which Is the Best Approach?
Authors: Jardine S. I. , Johnson A. B. , White D. B. , Stibbs William
Published: December 2007

A concern relating to operational procedures following detection of a kick is whether closure of the blow-out preventer (BOP) with the choke valve shut, termed a "hard" shut-in, is likely to cause formation damage due to generation of a pressure pulse in the well-bore fluid. This has prompted some operators to opt for a "soft" shut-in whereby the choke valve is left open at closure of the BOP. The delay in closing the choke to obtain complete shut-in of the well, however, results in additional influx from the formation.

This paper describes a series of tests which have been conducted using a full-scale drilling rig and test well equipped with complete surface instrumentation and including downhole pressure measurements to resolve the hard or soft shut-in question. In this way quantitative downhole pressure measurements in a realistic well-bore environment were obtained for comparison with theoretical predictions made from analysis of the pressure wave propagation in the well.

Test results and theoretical analysis are presented to describe the issues relating to choice of shut-in procedure. Agreement between experiment and theory shows that the formation experiences negligible additional pressure when using a hard shut-in procedure and that the additional influx and well-bore pressures associated with the soft shut-in are avoided.
Reducing the Cost of Top-Drive Drilling System Installation: A Case History
Authors: Hock C. J.
Published: December 2007

Ways to reduce the installed cost of a top drive drilling system on a jack up rig are presented. The cost and time saving aspects used on the Offshore Mercury, i.e., not increasing the height of the derrick through the use of a power swivel drilling system and an electronic crown protection system are highlighted, as are the modifications to the DC-DC drilling power to enable it to emulate the control features of an SCR powers system. The major aspects of the installation are touched upon and the actual schedules followed and manning level used during the systems installation are presented as are the relative cost savings.
Lubricity and Wear of Shale: Effects of Drilling Fluids and Mechanical Parameters
Authors: Dzialowski Andrew , Hale Arthur , Mahajan Satish
Published: December 2007

The predominant limitation to directional and extended-reach drilling is excessive torque and drag. Although torque and drag data exist for sandstone and metal surfaces, over 70% of the formations drilled worldwide are classified as shales. Unfortunately, data on shales are limited because of practical restrictions.

Clearly, shales behave differently than metal and sandstone because of their chemical and physical properties. Chemical interaction between shale and the drilling fluid can change the mechanical properties of shale and significantly affect shale lubricity and wear characteristics.

The primary objective of this paper is to present for the first time a systematic study of the effects of various salts and other common water-based mud additives on the lubricity and mechanical wear of shale. Also provided are data on diesel-based inverts and synthetic-based drilling fluids. Tests were run on Pierre shale as well as Berea sandstone for comparison. The study was made possible by the recent development of a laboratory device specially designed to accommodate shale test blocks under heavy loads.
The Development of Improved Soft Formation Milled Tooth Bits
Authors: Liang D. B. , Keshavan M. K. , McDonough S. D.
Published: December 2007

The introduction of FDS+ bits in 1991 has significantly improved the performance of these types of soft formation milled tooth rock bits. Average bit life has been increased significantly, resulting in a substantial reduction in drilling cost. Tooth grading of the FDS+ bits also is much better than that of conventional milled tooth bits. In certain locations, the new FDS+ bits have approached the life of some soft formation tungsten carbide insert (TCI) rock bits.

This paper documents the successful development and application of these improved milled tooth bits, and briefly describes the following:

Design innovation of the newly-patented radiused crest tooth. Development of improved hardfacing materials and process. Field-test results.
An Interpretative Log Analysis Computer System
Authors: Breitenbach E.A. , Thurnau D.H. , Dougherty E.L.
Published: December 2007

This paper describes a computer software system recently developed for use of well logs in regional exploration and mapping. The system enables a log analyst to develop two-dimensional areal contour maps of requested exploration criteria from a file of digitized well log data.

The backbone of the system is an efficient computer procedure for recognizing and "compiling" the computations specified by the analyst. The desired computational processes are supplied as part of the input data in the form of algebraic or logical statements. The software system compiles the statements on data cards, translating them to psuedo-machine code. An efficient interpreter then is able to execute the analyst's statements. If an algorithm proves to be useful repetitively, means are available to include it within the permanent system. Thus a log analyst can use the permanent system. Thus a log analyst can use the system as a convenient laboratory to develop improved exploration techniques. Input from the analyst into the system could be of batch type or through time-sharing terminals. Output includes line printer tables, plots and contour maps.

The software system is described in detail and examples of its use are given.

Introduction

Several papers have appeared in the literature during the past five years describing computer software systems for quantitative evaluation of well logs. The first systems to be developed were those that computed values for variables such as water saturation, porosity and shaliness for a single set of data from one zone. The data was manually selected from the analog print normally obtained at the well site. The second generation of systems were those that operated on a larger set of data—in general the digitized data from all traces throughout a large portion of the well were used.
Onsite Disposal of Rig-Generated Waste Via Slurrification and Annular Injection
Authors: Louviere R. J. , Reddoch J. A.
Published: December 2007

The technique of using on-site injection of oil base cuttings into a casing annulus is widely accepted as an environmentally attractive, cost-effective disposal alternative. A joint research project was undertaken by Conoco with a cuttings injection service company, Apollo Services, to pursue technological enhancements to the original technique. The result of the research initiative was development of a means to incorporate other non-hazardous wastes into the cuttings slurry. The slurrification and the disposal by injection of a wide variety of waste products is now potentially possible. The cuttings/waste injection process, nicknamed "CUTWIP", provides both a systematic design assessment for implementation and a mechanical means of accomplishing this task. Process utilization eliminates repeated handling and transport of waste products from the drilling rig to land disposal sites. The risk of accidentally discharging either solid or liquid waste into the Gulf of Mexico waters or any other environmentally sensitive area can now be minimized.

This paper addresses development of the CUTWIP process, equipment and operational requirements, well design, permitting, and project economics. Results of the initial field application undertaken while drilling the East Cameron 56 JB-3 well in the Gulf of Mexico are also reviewed.
High-Pressure, High-Temperature Drilling: Data Management and Interpretation
Authors: Buchan Robert
Published: December 2007

The acquisition and management of drilling data is of critical importance for high pressure, high temperature wells if well objectives are to be achieved and well control incidents avoided. Key decisions such as when to set casing or when to raise mud weight are often crucial. This paper presents a summary of BP Exploration's most recent high pressure, high temperature drilling experiences and concludes that the Success of any high pressure, high temperature drilling operation depends on pre-planning, training, communication and data management.
A Clarified Xanthan Drill-In Fluid for Prudhoe Bay Horizontal Wells
Authors: Beck F. E. , Powell J. W. , Zamora M.
Published: December 2007

A clarified xanthan drilling fluid was designed in order to replace the arctic diesel based drilling fluid conventionally used to drill horizontal wells in Prudhoe Bay. Use of this fluid in conjunction with well design changes has resulted in reduced drilling costs and increased well productivity. The fluid is designed to exhibit a true yield stress, which in conjunction with pipe rotation improves hole cleaning in high angle holes. The fluid is also non-damaging, provides shale inhibition, and is environmentally safe.
Recommended Practices for Heat Management of Steamflood Projects
Authors: Ziegler V. M. , Crookston R. B. , Sanford S. J. , Merrell J. M.
Published: December 2007

Recommended practices are given for the steamflood heat management process: data collection, data analysis and adjustments to steam injection. A generic monitoring data table is presented which can be tailored to an individual project. The various options for modeling steamfloods are contrasted. A set of metrics is proposed which allows monitoring progress toward optimal operation. Project teams are endorsed as a way of ensuring that the diverse disciplines required for effective heat management are properly focused. A case example is presented that illustrates the proposed methodology.
The Meaning of Reserves in Context of Global Economic Security and Survival
Authors: Bogart A. J. , Ebneyousef M. H.
Published: December 2007

The estimation of reserves is not based on a universally accepted standard method involving science and technology. In addition, the terms reserves, resources, deposits, and accumulations are often used interchangeably.

The reserves depend on the recovery efficiency and the availability of sustainable production capacity. The estimation of reserves also involves geological and engineering judgment affected by bias by companies and governments alike. Moreover, commercial reserves – the "real" reserves – will be produced with a reasonable degree of certitude, but technical reserves – the "paper" reserves – will not.

In the context of global economic security and survival, we are only interested in "real" reserves, not in the "paper" reserves claimed by companies and governments.

In the post-Cold War era, new industry standards need to be adopted worldwide and implemented by multilateral institutions upon which their assistance is contingent.
The Potential Role of Future Environmental Regulations on the Domestic Petroleum Industry
Authors: Godec M. L. , Kosowski Bundhrig , Haverkamp D. S. , Hochheiser Bill
Published: December 2007

Increased environmental compliance requirements could have a significant impact on future U.S. oil and gas supplies. This paper summarizes the results of a recently published National Petroleum Council (NPC) assessment of constraints on future North American natural gas production and use1, along with a concurrent study of future oil supplies by the U.S. Department of Energy (DOE). The paper identifies possible environmental and legislative initiatives affecting domestic exploration and production (E&P) operations, characterizes the potential impacts of these initiatives on future compliance costs, and estimates their potential impacts on future oil and gas supplies.

The assessment was performed for two potential future environmental regulatory scenarios: a "balanced" scenario, and a more stringent regulatory scenario. Each environmental compliance scenario was assessed under two "reference case" economic scenarios. The estimated impacts of potential increased environmental compliance requirements are presented in terms of the following: (1) unit compliance costs; (2) economically recoverable resources (reserves) and future production potential lost; and (3) incremental industry expenditures.

The results of this assessment show that increased environmental compliance requirements could have a significant impact on the U.S. oil and gas industry and future U.S. oil and gas supplies. Depending on the level of future economic growth, the industry could incur an additional $70 to $86 billion in increased environmental compliance expenditures over the 1992 to 2010 time period. Under a high (stringent) regulatory scenario, a substantial portion of otherwise economic oil and gas resources could become uneconomic to develop and produce. Stringent environmental compliance requirements could result in 26% higher initial costs for new gas wells, and 32% higher costs for new oil wells. Annual operating costs could increase by 59% for gas wells and 43% for oil wells. Crude oil production in the U.S. could decrease by 290,000 to 620,000 B/D by 2010 under a high regulatory scenario, depending on the level of future economic growth. Under this stringent environmental regulatory scenario, U.S. gas production could decrease 2.0 to 2.3 Tcf/year.
Site Assessment Methods in Determination of Liability in Oil and Gas Property Acquisition and Divestiture
Authors: Wilson M. J. , Kiser S. C.
Published: December 2007

This paper will identify oil and gas property due diligence auditing procedures for quantification of environmental liabilities and assets for both acquisitions and divestitures.

There are many site assessment guidance manuals and auditing programs, brief as well as very detailed, available to direct the general business of liability determination in site assessment. These guidance manuals and auditing software provide an excellent regulatory checklist to organize a site assessment but are lacking in guidance on how best to focus a site assessment on oil and gas producing properties. The most effective site assessment and audits are performed by professionals who know both how the oil business operates in the specific area and what the relevant environmental regulations are.

Efforts in a site assessment for acquisition and divestiture of oil and gas operations can be focussed by: Preparing an inventory of permits necessary for operation, reviewing their compliance conditions, and field verification of compliance.Reviewing all operations where non-hazardous and hazardous chemicals are used and hazardous waste streams are generated with the idea of identifying physical non-compliance rather than documentation violations.

A comprehensive review of regulatory compliance is still necessary but major areas of liability and assets can be identified early in the site assessment process. Many environmental problems which are identified on a property would not be classified as a "deal killer". But, quantification of identified problems in terms of the cost to remedy the problem can significantly reduce the value of the property. Environmental assets can significantly add to the value of the property. In addition, environmental permitting can impact the scheduling of new projects. Delays in project scheduling will in turn affect the property's fair market value.
Slaying the Capital Budget Constraint
Authors: Schuyler J. R.
Published: December 2007

There is an unresolved, fundamental issue in capital budgeting. Companies that plan against a capital constraint are usually rejecting some projects which appear profitable. This discussion reasons that a capital constraint is inconsistent with knowing a company's Marginal Cost of Capital (MCoC). The incongruity arises because MCoC represents that additional funds are available at this rate, even if the full budget has been committed already. Thus, an extra project that would provide a return greater than MCoC should be funded, because it would contribute net value to stockholders. Companies accepting this reasoning can greatly simplify their project decisions. In particular, the widespread practice of ranking projects under an arbitrary capital budget ceiling is unnecessary.

The most fundamental and least assailable corporate decision policy is: Choose the alternative providing the greatest contribution to stockholder value. Although theoretically sub-optimal, there may be situations that preclude this decision policy in favor of project ranking. Also discussed are issues with valuing projects from a stockholder perspective and with implementing a value-driven decision policy.
An Integrated Approach To Characterize Low-Permeability Reservoir Connectivity for Optimal Waterflood Infill Drilling
Authors: Malik Z. A. , Silva B. A. , Brimhall R. M. , Wu C. H.
Published: December 2007

This study defines and investigates the Hydraulic Interwell Connectivity (HIC) concept to characterize and estimate the reservoir connectivity. This approach is an integrated study of reservoir characterization, geostatistics, production performance and reservoir engineering. In this study HIC is quantitatively defined as the ratio of observed fluid flow rate to a maximum possible (ideal) flow rate between any combination of any two wells in the producing unit. The spatial distribution of HIC was determined for the net pay of a reservoir by geostatistics. It was used as a guide for selecting infill well locations to optimize waterflood infill drilling. A low permeability carbonate reservoir producing unit, J.L. Johnson "AB" was used to illustrate the application of HIC. In simulation study, three production wells 27, 107 and 109 were realigned according to HIC distribution which resulted in an additional 10% (10,000 STB) of waterflood oil recovery.
Case History of Reservoir Simulation and Resulting Development of an Enhanced Oil Recovery Project, Henry Enhanced Recovery Unit, Unita County, Wyoming
Authors: Warren J. B. , Mullarkey J. C. , Grass V. J. , Breit V. S.
Published: December 2007

A detailed geological and compositional simulation study of the 4A Dakota Sand in the Henry Field, Uinta County, Wyoming was authorized by the Henry Field Technical Committee in April, 1991. The 4A Sand is a retrograde gas condensate reservoir. In April 1991, ownership of the reservoir involved three separate sets of working interests; the Henry Unit Participating Area (PA), South Henry Unit PA, and the Marathon Federal #16-1 well. The Henry Unit PA initiated an ongoing pilot injection program in December, 1985. The study was undertaken to determine the economic feasibility of further developing the 4A Sand in the Field by expanding the pilot injection to increase recovery of liquids in the 4A Sand.

Following a geological study of the structure, thickness and continuity of the 4A Dakota Sand in the Field, a compositional simulation model was used to obtain a match to the Field's 3 years of primary and 6 years of cycling history. This model was then used to study alternate producing schemes, ranging from continuation of historical practices to expansion of the dry gas cycling project by the addition of three injectors, to accelerated expansion of the project by adding injectors and producers and hydraulically fracturing all new wells and the lowest productivity existing wells.

The compositional model predicts that 16% of the original 13,880,000 barrels of condensate in place in the 4A Dakota Sand would have been recovered if gas injection had never been initiated. The FULL EXPANSION CASE predicts recoveries as high as 64.6% of the maximum possible oil recovery.

Prior to initiation of the accelerated expansion project, a Henry Field Enhanced Recovery Unit (HERU) was formed from existing working interest tracts based on participation parameters approved by the Technical Committee and approved by the Working Interest Owners. At the end of 1992, injection well drilling, compression installation, and gas plant construction were in progress at the HERU with an expanded project start up date of early 1993.
Perforation Friction Pressure of Fracturing Fluid Slurries
Authors: Willingham J. D. , Tan H. C. , Norman L. R.
Published: December 2007

Even though pressure drop across perforations for clean fracturing fluids can generally be accurately predicted, it is not well understood for fracturing slurries. In this paper, two wellbore models-one transparent and one high pressure-were used to study the perforation friction pressure behavior of sand laden fluids. The transparent model constructed with cast acrylic allowed visual observation of fluid exchange in the "rat-hole" and flow patterns of the slurries in the wellbore and through the perforations. Critical velocity at which sand begins to screenout at the perforations was also determined. Tests were performed in the high pressure model varying gel concentration, sand concentration, proppant size, and perforation diameter to gather pressure drop data. The effect of the ratio of perforation diameter to the average proppant size on the sand screenout tendency at the perforation was also investigated.

A correlation to predict the change of perforation coefficient due to proppant erosion was developed from the laboratory data. This paper presents a field procedure to better estimate the change of perforation coefficient during proppant stages for calculating the change of perforation friction.

Incorporating this change of perforation pressure drop during proppant stages in the real-time bottomhole treating pressure calculation will enhance interpretation of the treatment analysis.
Reservoir and Stimulation Evaluation of the Berea Sandstone Formation in Pike County, Kentucky
Authors: Frantz J. H. , Hopkins C. W. , Lancaster D. E. , Jochen J. E.
Published: December 2007

The Gas Research Institute (GRI) has been sponsoring a three-well cooperative program with Ashland Exploration, Inc. (ΑΕΙ) during the past two years evaluating the Devonian Shale and Berea sandstone formations in Pike County of eastern Kentucky. The COOP 2 was targeted to evaluate the Berea and was GRI's first comprehensive tight gas sand research project in the Appalachian Basin. The objective of the research was to use and apply technologies developed previously in other GRI research. This paper will summarize the integrated reservoir and hydraulic fracture descriptions determined from analyzing the data collected in this project. The results presented can be applied by operators to better understand the productive mechanisms in the Berea reservoir, to predict well performance, and to design completion procedures and stimulation treatments. The methodology can also be applied to other tight gas sand formations.
The Measurement of Matrix and Fracture Properties in Naturally Fractured Cores
Authors: Ning Xiuxu , Fan Jin , Holditch S. A. , Lee W. J.
Published: December 2007

This paper describes a new laboratory technique to evaluate the properties of a naturally fractured, low permeability core sample. We specifically determine (1) the porosity of the matrix, (2) the permeability of the matrix, (3) the effective width of the fractures, and (4) the permeability of the fractures.

New laboratory equipment has been designed and constructed to conduct pressure pulse tests in either a homogeneous or a fractured core sample. Analytical solutions have been developed to model gas flow in a fractured core sample during a pressure pulse test. An automatic history matching program has been developed to analyze the laboratory measured pressure transient data using the analytical solutions. The new technique has been used to measure the matrix and fracture properties in twelve naturally fractured, Devonian Shale cores.

The technique we developed in this research is new to the petroleum industry. Our laboratory equipment is unique, and the analytical solutions have not been published in the literature. With this technique, we can measure matrix properties as low as 10−9 md. This is a significant step forward in permeability measurement because the lowest permeability that most existing laboratories can measure is about 10−6 millidarcies.
Tracer Flow in Naturally Fractured Reservoirs
Authors: Jetzabeth Ramírez S. , Fernando Samaniego V. , Jesús Rivera R. , Fernando Rodríguez de la G.
Published: December 2007

This paper presents solutions for the continuous, finite step and spike injection of radioactive tracers in naturally fractured reservoirs. Solutions are presented for linear flow-vertical fractures, and for the radial flow cases of horizontal fractures and cubic block matrix-fracture geometry. The three derived solutions consider as particular cases the flow of a chemical tracer. The reservoir is treated as being composed of two regions: a mobile (fractures) where dispersion and convection take place and a. stagnant (matrix) where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The solution that considers vertical fractures is analytical, thus avoiding the double Laplace space numerical inversion used in previous studies. Another main advantage is that the important numerical dispersion reported by previous investigators when using the Stehfest Laplace transform inversion algorithm is avoided. The radial coupled matrix to fracture solutions are presented in Laplace space, and are accurately inverted by means of the Crump algorithm. The influence of the main dimensionless parameters that enter into the solutions was carefully investigated. A comparison of results for the three different naturally fractured systems investigated, indicates that a uniqueness problem may arise in the interpretation of a test, especially to distinguish between the radial cases. As expected, this problem alleviates for the finite step injection cases. The results of this study can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix practical parameters of interest.
Field Tests of Downhole Extensometer Used To Obtain Formation In-Situ Stress Data
Authors: Kuhlman R. D. , Heemstra T. R. , Ray T. G. , Lin Peng , Charlez P. A.
Published: December 2007

Knowledge of formation rock properties, in-situ stress direction, and stress magnitudes are valuable aids to the successful drilling, completion and stimulation of oil and gas wells. These factors are of even greater importance for horizontal or highly deviated wells. Problems such as wellbore collapse, breakout, and breakdown during drilling and completion can be minimized by using knowledge of in-situ stress direction and magnitude to optimize wellbore direction and/or mud weight. Knowing the azimuth of hydraulic fractures will be of great benefit on any producing or injection well. For horizontal or highly deviated boreholes, this information may be required to avoid premature screenout and unexpectedly high treating pressures if the well is fracture stimulated. These problems can be addressed with improved mud weight control during drilling and stimulation treatment designs based on knowledge of the stress magnitudes, the direction of the principal stresses, and the formation's mechanical properties.

A downhole extensometer tool has been developed (jointly by TOTAL and Halliburton) and field tested that will monitor borehole deformation responses to pressuring before, during, and after a microfracture stress test.

The borehole strain measurements before and after fracture initiation are used to determine the following parameters: Minimum in-situ stress magnitude (closure pressure)Fracture directionWidth of induced fractureIn-situ shear modulus
Field Application of Real-Time Hydraulic Fracturing Analysis
Authors: Martinez A. D. , Wright C. A. , Wright T. B.
Published: December 2007

It has long been the goal of the petroleum industry to use a hydraulic fracture simulator to provide on-site real-time hydraulic fracturing analysis. Now with the development of real-time fracture simulators and the power of portable computers this is a reality. This paper describes the use of a computer modeling system to accomplish this goal. A brief background of the theory behind real-data real-time fracture modeling as well as a description of the computer interfaces, data acquisition, and overall hardware requirements are presented. Case examples are included which show the benefits as well as the limitations of real-time fracture monitoring and analysis. Some suggestions on valuable data collection procedures are also discussed.
Zero Generator Status
Authors: Anderson N. K. , Hall P. M.
Published: December 2007

Fundamentally the goal of becoming a "zero generator" of waste – hazardous, industrial, or household – is a term coined to focus the efforts of all work endeavors toward a common goal. The goal was made attainable through a series of endeavors that could succeed only through the cooperation of everyone involved in the process of offshore drilling – operator, contractor, individual crew members and subcontractors.
Vapor Jet System: An Alternative Vapor Recovery Method
Authors: Webb W. G.
Published: December 2007

The patented Vapor Jet System is an alternative to conventional vapor recovery technology for the recovery of low volumes of hydrocarbon vapors from oil production facilities' crude oil and produced water storage tanks. The Vapor Jet System utilizes a pressurized stream of produced water to serve as the operating medium for a jet pump (also known as a venturi, eductor or ejector). The potential energy (pressure) of the produced water stream is converted to kinetic energy (velocity) in the jet pump. The high velocity water stream entrains the near atmospheric pressured vapors and returns them to the facility's low pressure system for separation and sale. The water is returned to the water tankage for further degassing and reuse, disposal or waterflood injection purposes.

The Vapor Jet System is simple, cost effective and virtually maintenance free when compared to the small conventional vapor recovery units (VRU's) in use in the industry today. The Vapor Jet System is ideally suited for facilities with hydrocarbon vapor volumes too small to economically justify conventional vapor recovery systems. The Vapor Jet System will operate at whatever minimum volume level emission control is desired. The Vapor Jet System can be installed for 50% of the cost of the small conventional VRU and realize significant savings in operating expenses over the conventional VRU.
Proposed Changes to EPA Class II Well Construction Standards and Area of Review Procedures
Authors: Smith J. B. , Browning L. A.
Published: December 2007

The Environmental Protection Agency (EPA) is proposing amendments to its Underground Injection Control (UIC) program regulations (40 CFR parts 144 and 146) as they pertain to Class II (oil and gas-related) wells. The proposed amendments revise current provisions relating to construction standards and apply the "area of review" and corrective action requirements to previously exempt wells "authorized by rule."

The proposed modifications build upon recommendations made by a Federally-chartered Advisory Committee pursuant to the findings of an internal Mid-Course Evaluation effort and a General Accounting Office Report.

Under the provisions of Section 1425 of the Safe Drinking Water Act (SDWA), these amended regulations would not need to be adopted verbatim by the States; however, EPA will require that "primacy" States demonstrate that their programs are still effective in light of these new Federal requirements.
A Survey of Regulatory Approaches to Cleanup Standards for Soil Contaminated by Spills of Crude Oil or Salt Water
Authors: Hoffman Jane
Published: December 2007

How do regulatory agencies determine how clean is clean? In the absence of federal directives, states have developed a variety of approaches to cleanup standards for soil contaminated by spills from exploration and production facilities. A few states have established cleanup standards through general guidelines or by rule, while other states set cleanup standards on a case-by-case basis. The survey covers: the status of regulatory cleanup standards and trends; the economic concept of beneficial use as a cleanup standard; pit closure standards used as a cleanup standard for crude oil spills; and cleanup standards designed for crude oil spills.
Bioremediation of Hydrocarbon-Contaminated Soils at Crude Oil Production Sites in West Texas and New Mexico
Authors: Scott T. W. , Barker G. W. , Cook R. C.
Published: December 2007

A pilot scale field study was initiated to evaluate the feasibility of bioremediating hydrocarbon-contaminated soils at production sites in the southern Permian Basin in West Texas and New Mexico. Soils were contaminated with crude oil which had leaked into the soils from tank batteries and wellheads during production operations. Soils were characterized as fine to medium sands and loamy fine sands, well drained, low water holding capacity, and alkaline. Native soils at the sites contained an indigenous microbial population capable of degrading hydrocarbon contaminants. It was not necessary to add commercial bacteria to achieve acceptable biodegradation rates. Bioremediation is a viable technology to remediate hydrocarbon contaminated soils at production sites in the Permian Basin.
Conversion of Oilfield Produced Water Into an Irrigation/Drinking Quality Water
Authors: Tao F. T. , Curtice Stanley , Hobbs R. D. , Sides J. L. , Wieser J. D. , Dyke C. A. , Tuohey David , Pilger P. F.
Published: December 2007

A process has been developed for converting oilfield produced water into irrigation/drinking quality water. The process consists of air flotation, clarification, softening, filtration, reverse osmosis and water reconditioning. A pilot plant was successfully operated for a extended period of time for handling water with approximately 7,000 mg/L of total dissolved solids, 250 mg/L silica and 170 mg/L soluble oil at a wide range of pH (7-11). The quality of treated water met the stringent California Title 22 Drinking Water Maximum Contaminant Levels.
Salinity/Toxicity Relationships to Predict the Acute Toxicity of Produced Waters to Freshwater Organisms
Authors: Mount D. R. , Gulley D. D. , Evans J. M.
Published: December 2007

As part of previous research, the Gas Research Institute, ENSR, and the University of Wyoming developed a series of multi-variate logistic regression equations (called Salinity/Toxicity Relationships or STRs) that predict acute toxicity to three freshwater organisms based on major ion composition. While these equations did an excellent job of representing responses in the laboratory data set on which they were based, their validity and usefulness lay in their-ability to make accurate predictions for independent data sets and real-world samples. Accordingly, the STR equations were applied to a series of data sets from different sources. This exercise shows that the equations generally provide accurate predictions of toxicity, even across waters with very different ionic compositions. STR equations were also able to detect the presence of toxicants other than major ions in the samples. These results indicate that the STR approach will provide a valuable tool for assessing and managing produced waters and other waters with elevated concentrations of dissolved ions.
A Successful Public Consultation Program for Drilling Near-Urban Sour Gas Wells
Authors: O’Byrne Dan , Tamasi Rick , Kruk G. E.
Published: December 2007

This paper describes a proactive public consultation process conducted for a sour gas development project on the outskirts of Calgary, Alberta. After substantial delays in obtaining regulatory approval to drill development wells containing up to 35% hydrogen sulphide, Canadian Occidental Petroleum Ltd. participated in a formal, mediated consultation process involving affected stakeholders and regulatory agencies. The public perceptions of safety, land use conflicts and communication were significant issues dealt with by the consultation process. In June of 1992 the Northeast Calgary Application Consultation Committee, which included community representatives and government agencies, forwarded reports to the Energy Resources Conservation Board approving the proposed wells and suggesting some modifications to the project design. The consultation process provided the opportunity to identify and address stakeholder issues before the final project design was submitted to regulatory agencies for consideration. Communication with the stakeholders was improved and an opportunity for ongoing dialogue with interested parties was identified.
Effect of Water Spray on the Combustion of Crude Oil on a Water Surface
Authors: Nelson W. G. , McKenzie Bruce
Published: December 2007

Mesoscale test burns were conducted to determine the effect of water spray on the combustion characteristics of crude oil on a water surface. Data obtained during these burns suggest that the water spray increased the surface regression rate, decreased the smoke production, and did not reduce the fraction of oil consumed. Such information could be applied to in-situ burning of oil on water as an oil spill response technique.
Evaluation of Acid Stimulation Treatment of Horizontal Wells
Authors: Malekzadeh D. , Azari M. , Day J. J.
Published: December 2007

The potential for severe formation damage around horizontal wells exists due to the increased time of formation exposure to the drilling fluids as compared to the time that a vertical well is exposed to these fluids. This paper explains that the combined effect of the formation damage and the presence of impermeable barriers and low permeability regions in the vicinity of some sections of the horizontal wellbore will manifest itself as skin factor in well test analysis if the total drilled length of the horizontal section is used in the calculations. The purpose of this paper is to present practical new equations, based on a recently introduced concept in well performance analysis, for evaluating the actual length of the horizontal well contributing to production. It is determined that the performance of a horizontal well with mechanical skin and of length Xf1 can be substituted by the performance of a horizontal well of length Xf2 with no skin. Xf2 is smaller than Xf1 for a damaged well and is greater than for a stimulated well. By combining the concepts of equivalent horizontal well length and equivalent wellbore radius, one will be able to evaluate the performance of a horizontal well in comparison to its expected performance and to subsequently relate it to an equivalent stimulated vertical well. The new equations and guidelines can be used to determine the magnitude of formation damage around horizontal wells and to evaluate the success of a stimulation treatment.
The Quantification and Management of Uncertainty in Reserves
Authors: Smith P. J. , Hendry D. J. , Crowther A. R.
Published: December 2007

This paper gives a method for estimating reserves uncertainty for oil and gas fields. The parametric method is a long-established statistical technique, yet has seldom been applied in the oil and gas industry. The power of the method lies in its simplicity, for this gives access to a ranking of uncertain variables in terms of importance in affecting reserves. Once the key uncertainties have been identified, attention can be focussed on appropriate contingency plans to reduce their impact. By planning for potential downsides and upsides in advance, project econonics become more robust. The technique is extended to production profile predictions.

The paper describes the statistics of the method, and then illustrates its application through a case example, the Forth Field, which lies in the northern North Sea and is due for development approval in the first half of 1993.
Development of Team Approach for Identifying and Drilling Horizontal Wells Will Improve Success Rate and Quality Control
Authors: Crouse P. C.
Published: December 2007

Horizontal well technology has advanced over a rapid pace in the last seven years. With its development, the need for improved communication and a team approach insuring the best drilled and completed well has become increasingly important to a quality producing well. This paper identifies a process to help component groups to manage and monitor more effectively the project implementation of a horizontal well. The project management technique, CPM/PERT or Critical Path Method, Program Evaluation and Review Technique is a natural management technique which could be used to save both time and money, and could be used as a quality control tool.
Gas Channeling and Micro-Fractures in Cemented Annulus
Authors: Talabani Soran , Chukwu G. A. , Hatzignatiou D. G.
Published: December 2007

Gas leakage through a cemented wellbore annuli is a major problem in many oil wells in the world, and specifically in the United States. Enormous amounts of money are spent on squeeze cementing these affected wells often without effecting a permanent solution. This problem is not only expensive to control, but also a menace to the environment. Gas leakage occurs as a result of bad cement-formation bonding caused by incompatible contraction-expansion mechanism during cement setting.

This work proposes the use of new cementing additives which can reduce the effect of the expansion-contraction mechanism during the cement slurry setting. These additives fill contraction induced voids within the cement structure and between the pipe and cement, which leads to an impermeable cement, thus eliminating the existence of micro-fractures and micro-annulus. These materials are economic to use and are readily available. It is proposed that the cement bond index should be estimated in the laboratory using Ultra-Sonic test prior to the cement job.
Static and Dynamic Fluid-Loss Characteristics of Drilling Fluids in a Full-Scale Wellbore
Authors: Warren B. K. , Smith T. R. , Ravi K. M.
Published: December 2007

This paper describes the dynamic and static filtration characteristics of four different drilling fluids under downhole conditions. Filtration rates were measured over two-, four- or five-day periods in a simulated sandstone formation. The drilling fluids studied had a wide range of API fluid loss and rheological characteristics.

The API fluid-loss for all drilling fluids tested were generally higher than the filtrate loss observed in the sandstone formation. The largest static and dynamic filtration rates were seen in drilling fluids having uncontrolled fluid-loss properties.

A large spurt loss volume, varying in duration from 30 seconds to five minutes occurred upon initial contact of the drilling fluid with the formation. A steady state filtration rate was quickly reached following the initial spurt loss. Dynamic filtration rates and the percentage of circulatable hole varied as a function of the drilling fluid flow rate in the annulus. Increased annular flow rates produced higher dynamic filtration rates. The dynamic filtration rates decreased prior to day four of the tests, afterwhich no significant changes were observed. Removal of the external wellbore filter cake using mechanical scrapers did not significantly change the dynamic filtration rate.

The results presented can be used to estimate the effect of flow rates, fluid loss, and rheology of the drilling fluid on the amount of drilling fluid filtrate lost to the formation and on the percentage of the annulus that is circulating.
Comparison of Stochastic and Deterministic Geologic Models Used in Reservoir Simulations for the Endicott Field, Alaska
Authors: Shaw A. L. , Cunningham A. B. , Johnson S. R. , Pearce A. J. , Adamson G. R.
Published: December 2007

Simulation models of the low net to gross zones of the Kekiktuk Formation have, historically, been difficult to history match. Traditional mapping of the zones, e.g., isopach, netto gross ratio, and porosity, tended to oversimplify the internal heterogeneities within the reservoir sandstones and the spatial distribution of sand bodies. Current reservoir simulations address this problem through the use of deterministic and stochastic fine-scale geological models. Fluid movement is appropriately modeled and history matched in both simulations without significant pore volume modifications. Contrary to previous simulations, current simulation data shows that up dip gas injection combined with down dip water injection increases ultimate recovery of Zone 3 oil. Results from both types of simulations can be used in synergy or separately to address global reservoir and well specific issues to optimize ultimate recovery.
Gravity Methods: Useful Techniques for Reservoir Surveillance
Authors: Brady J. L. , Wolcott D. S. , Aiken C. L. V.
Published: December 2007

Understanding the movement of gas in oil reservoirs is important because premature breakthrough or high gas-oil ratios significantly increase costs and can reduce ultimate recovery. The Prudhoe Bay and Kuparuk River oil fields, located on the North Slope of Alaska, have an expanding gas cap and a gas storage area, respectively. Significant gas movement in both reservoirs has occurred, since discovery, and the vertical and areal extent are not as well defined as desired. The current methods of monitoring are expensive and increasingly less reliable because of well conditions.

In a search for better methods to monitor gas movement, borehole and surface gravity techniques were identified. The Borehole Gravity Meter (BHGM), because of its large radius of investigation, can predict the true gas-oil contact, irrespective of a localized gas cone and other near wellbore completion problems. Bypassed lenses of oil and intervals of gas under running oil can be identified. The data from the BHGM can provide the vertical distribution of gas and oil at a well. To better understand the areal distribution of gas, high resolution surface gravity data can potentially be used. As the gas cap propagates outward and/or downward, a negative gravity anomaly is created due to the displacement of oil by gas.

The results show that significant gravity anomalies have occurred in the Prudhoe Bay and Kuparuk River oil fields due to gas replacing oil. The gravity anomalies can be measured with the borehole gravity and in certain situations with surface gravity instruments. New surveying techniques are needed to obtain increased vertical and lateral resolution for reservoirs buried as deep as the North Slope fields. Global Positioning Systems (GPS) is an economically viable method for obtaining accurate surface positions for locating surface gravity stations. Surface gravity data resolution can be improved further by stripping and downward continuation. The newly developed elevator sonde for the borehole gravity meter, may significantly improve the vertical resolution of the tool in deep deviated wells.

Additional developments to improve deviation and size limitations of the BHGM, data acquisition and processing of surface gravity, and testing of GPS in Arctic latitudes are required. Plans to field test these techniques and provide data to design new techniques and tools are on going.
Program for Improving Multiphase Flow Slug Force Resistance at Kuparuk River Unit Processing Facilities
Authors: Santana B. W. , Fetzner D. J. , Edwards N. W. , Haupt R. W.
Published: December 2007

Multi-phase slug flow forces in pipelines at the Kuparuk production facilities have caused fatigue damage to piping components and vessel nozzles. A program was implemented to modify the existing inlet systems to accommodate slug forces for current and forecast flow conditions. Data acquisition systems were installed to quantify the effect of modifications on vessel stresses. The systems are also providing justification to avoid more costly modifications while allowing continuous improvement of operating parameters in the field.