bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Staged Mill and Mechanical Whipstock Saves Sidetrack Time and Cost by up to 50%
Authors: Kirkwood Y. S. , Pritchard M. D.
Published: December 2007

Due to the current marginal economic status of the petroleum industry, drilling a new well is more difficult to justify than ever before. Many Operators have adjusted by recompleting old wells whenever possible. While the use of old wells reduces up front capital investment and alleviates some environmental concerns, the risk to formation damage can be much higher than drilling a new well. Although there are many methods of recompleting old wells, the experience at Mt. Poso indicates that none can provide a cleaner wellbore than a sidetrack completion.

This paper discusses sidetrack operations using redesigned staged mill and mechanical whipstock. These sidetracks were performed in 1800’ wells located at the Mt. Poso field, CA. The staged mill and mechanical whipstock system, called the Sidewinder, and is jointly invented by B&G Machine & Welding shop and Shell Western E&P Inc. The Sidewinder is an enhanced version of the existing whipstock and staged mill technology that is currently overshadowed by the casing section mill. The initial result indicates the new method can reduce both time and cost by as much as 50% over the conventional casing section mill method. The margin of savings is even greater in wells with multiple casing strings.

Thus far, the Sidewinder has been used to sidetrack single and dual casing wells with standard casing sizes. The Sidewinder can be modified to accommodate any non-standard casing sizes also. The greatest benefit thus far has been superior economic success rate due to reduced number of tools and less milling time from sidetracking wells with multiple casing strings. The superior economics have also allowed wells to be recompleted that would have been uneconomic using the conventional casing section mill.
Stimulation Fluid Developement and Applied Fracturing Model Improves Results, Morrow Sandstone, Hutchison County, Texas
Authors: Lehman Lyle V. , Olson Robert , Kelley Charles C.
Published: December 2007

The Morrow formation in Hutchison County, Texas was long considered incapable of producing hydrocarbons at an economic rate. Most post-frac production rates were the same or less than pre-frac rates. Only high flow rate, non-stimulated completions were considered economic, but these completions were few in number. These facts lowered expectations for sufficient recovery of investment necessary to continue developmental drilling.

Utilization of modern fracture model techniques, core analysis, fluid testing and stress data lead to a system of stimulation techniques, fluids and proppants that has created a cost-effective stimulation system for the Morrow formation. Lithology studies showed that the frac fluid was primarily critical to success. These studies lead to an unorthodox fluid. It contained two elements that would not be considered practical in any other formations or circumstances in the Western Anadarko basin. Proppant placement was identified as the second most important issue. Fracture height was found to be controlled by permeability, not stress. This led to the discovery that proppant convection did not allow for good proppant placement. Proppant staging methods were augmented to combat excessive convection and then acquire advantageous proppant placement. Proppant selection was identified as the third most important criteria. Reservoir stresses and modeling showed that high cost, high stress proppants were not necessary. Lower cost, larger sized proppants yielded much higher conductivity than in previous completions.

These criteria were integrated into a solution which brought the post-frac production rate from a one fold to a ten fold increase.
Better Gas Identification in Southwestern Wyoming
Authors: Corbett Joe , Jardon Michael , Crary Steve
Published: December 2007

A new epithermal neutron tool, the Accelerator Porosity Sonde (APS), is being used for improved gas identification in Southwest Wyoming. The APS uses a high-yield electronic neutron source instead of the chemical source used in conventional neutron tools. It has five neutron detectors that provide both thermal and epithermal neutron detection, as well as borehole shielding, to obtain better porosity measurements. These improved measurements are not as sensitive to borehole environments and lithology effects and thus provide better gas determination. The tool has improved vertical resolution, which is helpful in the thin-bedded, shaly gas bearing sands of southwest Wyoming. This paper will discuss the tool features and compare examples of conventional neutron tools versus to this new technology and demonstrate improved identification of pay zones.
Tight Gas Sand Production from the Almond Formation, Washakie Basin, Wyoming
Authors: Iverson W. P. , Surdam R. C.
Published: December 2007

Gas production from the Almond Formation in the Standard Draw trend can only be accounted for by draining numerous layers of tight gas sands via the permeable upper bar sand. Discovery of this field originally focused upon production from this bar sand. But continued development cannot be explained simply by considering depletion of a 30 foot sand. Gas volumetrics verify the need to include lower sands in reservoir analysis. Core obtained from the Almond bar sand confirm petrophysical constants used in our models. Our results imply that economic levels of gas production should be possible wherever a similar horizontal conduit can be tied into gas saturated layers through massive hydraulic fracturing.
Investigations of Matrix-Fracture Transfer Flows in Dual Porosity Modeling of Naturally Fractured Reservoirs
Authors: Chen Jianping , Miller Mark A. , Sepehrnoori Kamy
Published: December 2007

In recent years many research results, both theoretical and experimental, have been published to improve the accuracy of dual porosity modeling. Most of these studies dealt with the accuracy of matrix-fracture transfer flow (MFTF) calculations (so-called transfer functions). Some studies concentrated on creating empirical transfer functions through single matrix block modeling, while others incorporated MFTF calculations in dual porosity model by using some type of sub-gridding or averaging technique. However, flow in fractures and its effects on MFTF have not been fully studied in the literature.

In this paper, we first compare methods for MFTF calculations under static fracture conditions, followed by results of numerically modeling fluid flow in matrix blocks with adjoining fractures undergoing dynamic conditions. The system studied is an oil-saturated matrix block surrounded by fractures in which water is injected to generate dynamic flow conditions. Hence, there are two dynamic flow systems. One is counter-current imbibition inside the matrix block, and the other is two-phase flow in the fractures.

Results show that MFTF can be characterized by three flow regimes. The first is before water breakthrough at the producing end of the fracture, during which little imbibition occurs inside of the matrix block depending on injection rates. The second is transient flow inside the matrix block. During this flow period the most injected water is imbibed into the block. The last flow regime occurs when flow in both systems approaches a pseudo-steady type behavior. Dimensional analysis shows that two parameters can be used to characterize these flow regimes. One is a global time scale ratio and the other is a storativity ratio. The use of proper boundary conditions imposed on both systems plays a vital role in accurately modeling MFTF. Results show that the usual assumption of phase saturation continuity between matrix block and fracture in a conventional dual porosity model generates erroneous results, especially breakthrough time at producers. Our approach is also successfully used to model published experimental data without any adjustment to measured rock and fluid data.
Simulation of Gas Cycling Using a Beta Model
Authors: Guehria F. M. , May R. S. , Baiar T. E.
Published: December 2007

In this work, we present a field study which indicates that if PVT properties are properly derived, we may be able to use a beta model to history match and predict performance for complex fluid systems. The specific example considered pertains to a field containing a gas condensate fluid column underlaid by a volatile oil leg. Residue gas and nitrogen are continuously injected into four wells completed in the gas condensate column, whereas, 29 wells produce from the oil zone. For this system, we were able to build a two-component beta model that accurately reproduced the same thirty years of reservoir performance as an eleven component compositional simulator originally formulated for history matching and performance prediction.

The intended major contributions of this work are as follows. First, we present a procedure which uses a calibrated equation of state combined with material balance techniques to generate appropriate PVT properties for the beta model. The PVT properties properly account for the variation in saturation pressure from one point to another in the reservoir. Second, we illustrate that a beta model can often be used for history matching and performance for cases where it is commonly believed that a multicomponent compositional model is needed.
Multi-Phase Flow Properties for Coalbed Methane Wells: A Laboratory and Field Study
Authors: Conway M. W. , Mavor M. J. , Saulsberry J. , Barree R. B. , Schraufnagel R. A.
Published: December 2007

The traditional concept of coalbed methane production is one where the coal natural fracture system is initially 100% saturated with water and that this water must be produced to initiate gas production. This paper summarizes an investigation designed to reconcile measured relative permeability data with well test analysis results obtained during single-phase and multi-phase tests, and with reservoir simulation projections of gas and water deliverability as a function of bottom-hole pressure. Improved well test and relative permeability measurement procedures are summarized so that projections of future fluid deliverability made during the dewatering and early multi-phase production stages are more accurate.

A variety of well tests were performed that included water slug tests, water injection tests, gas injection tests, and multi-phase production and shut-in tests. Estimates of absolute permeability obtained from these data were variable depending upon the test procedures. In addition, multi-phase and gas injection test analyses were strongly influenced by the relative permeability data used during the analysis. Based upon newly measured relative permeability data and by history matching multi-phase production data, it was possible to reconcile some of the differences in estimates of absolute permeability that were obtained from each of the test types. Finally, a new field procedure is proposed and demonstrated to measure permeability in wells producing both water and gas.
Determining the Effectiveness of Multi-Zone Completions and Stimulations in Low Permeability Formations with Production Logs
Authors: Mullen Mike , Frisch Gary , Johnson Jeff
Published: December 2007

The current economic structure of the petroleum industry often requires multiple completions with production from each zone co-mingled to reduce completion costs. However, these multiple completions require a different approach to analyze the effectiveness of both the original completion and possible later stimulation treatments of low permeability formations. To reduce the financial impact of individual zone testing it is desirable to run production logs to detect the contribution from each zone to the total production rate.

Some wells encounter multiple low permeability pay zones that are uneconomical to complete and stimulate individually. If the well does not do as expected or has a problem producing, the problems may not be recognized by conventional testing. If multiple zones are stimulated simultaneously there may be a concern whether each zone was responding to the stimulation treatment. Radioactive isotopes are used as a tag during the stimulation process to measure completion and/or placement effectiveness. Other methods for evaluating stimulation treatments include well testing, using pressure drawdown, and/or buildup analysis. However conventional analysis’ techniques are complicated to interpret with multiple completion intervals and may not yield information on the flow capacity of each zone.

With production logs it is possible to detect the type and rate of the fluids being produced from each individual zone in a timely manner. By comparing the open hole log analysis to a production log after stimulation it is possible to determine the effectiveness of the stimulation. This information could serve as a knowledge base for future stimulation design and improved well performance. Further computer analysis of the openhole logs, production logging data, and stimulation information could provide additional insight to enhance the economics of the reservoir development and to help understand wells that are producing below their expectations.

This paper will suggest guidelines for running production logs and show the usefulness of using these tools when evaluating multi-zone completions in tight gas sands. A three well example from the Rocky Mountain area is used to highlight the use of production logs to analyze multi-zone completions.
A Semi-Empirical Model of the In-Situ Stress Distribution for a Strike-Slip Regime: the Long Beach Unit, California
Authors: Katahara K. W , Lynch K. W. , Keck R. G.
Published: December 2007

The Long Beach Unit (East Wilmington Field, California) consists of nearly a thousand active wells and currently produces about 47,500 BOPD. Values of the in-situ stresses are needed for designing hydraulic fracture stimulation treatments. Estimation of the stresses is complicated by the fact that the field is in an active strike-slip tectonic regime where the vertical stress magnitude is intermediate between the minimum and maximum horizontal stresses. Stress magnitudes from casing-leakoff tests and density log calculations are consistent with this structural interpretation,

Stresses were directly measured in several casing-leakoff tests, micro-fracs, and mini-fracs performed in various sands and shales in the field. The minimum horizontal stress in the shales is roughly linear with depth, while in the sandstones it increases more rapidly, and is more variable than in the shales.

This paper presents a semi-empirical model for calculation of in-situ stresses from logs. It assumes that the stresses are determined by a mechanical stability criterion, and that the ratio of the mean horizontal effective stress to the vertical effective stress is constant from one formation to another. This ratio can be determined from casing-leakoff tests. The new model matches the observed stress contrasts better than conventional elastic models.
A Practical Approach For Predicting Casing Running Speed From Couette Flow Of Non-Newtonian Power-Law Fluids
Authors: Chukwu Godwin A.
Published: December 2007

Godwin A. Chukwu*

The displacement of drilling fluid by the movement of the drill string or casing pipes produces pressure variations in the borehole. The velocity of this displacement governs the magnitude of the pressure change which can add or subtract to the hydrostatic pressure of the mud to produce surge or swab pressure, respectively.

The surge or swab pressure computation techniques presented in this paper are based on sound, easy to follow, step-by-step analysis of steady laminar couette flow of non-Newtonian power-law fluids through a concentric annular wellbore. The annular geometry is made of a stationary outer pipe and a steady axial motion of an inner pipe.

By employing the computed surge pressures, in combination with family of curves, the maximum velocities at which the casing pipes can be run in the hole without the danger of fracturing the formation are obtained. The results obtained from these analysis will aid in proper design and optimization of drilling programs.

Introduction

Couette flow phenomenon occurs when two co-axial cylinders are placed such that one of which is stationary and the other is moving at a specified velocity. This flow characteristic is representative of flow in the borehole annulus where the wall of the wellbore is represented by the stationary cylinder, and the drill string or casing is represented by the moving cylinder. The fluid local velocity is dependent on the velocity of the moving cylinder. The geometric representation of a concentric annulus is as shown in Figure 1.

In drilling operations, the displacement of fluid encountered when running or pulling the drill string or casing in the annulus produces momentary variations in fluid pressure. This pressure change is known as surge or swab pressure, the magnitude of which is governed by the movement of the inner pipe, the annular geometry, and the drilling fluid properties.

Surge or swab pressure evaluation is important in the general planning of drilling a well. Excessive surge or swab pressure can lead to formation fluid invading the well annulus, causing a threatened blowout. High surge pressure can lead to loss of mud, either suddenly by fracturing the formation or slowly by continuous efflux to permeable formation, The drilling fluid enters the fractures and this produces a drop in the fluid level, causing a reduction in mud hydrostatic pressure in the borehole. The reduction in mud hydrostatic pressure allows formation fluids to enter the wellbore, which may result to blowout.

PREVIOUS WORK

Several investigators have developed methods for predicting pressure surges in drilling wells.

P. 263
Design Of A Storage Field For A Variable Hourly Market
Authors: Farris Clifford B.
Published: December 2007

The design of a gas storage field and associated dehydration plant for transient hourly flow is more complex than for steady-state flow. The major difference is that a transient gas flow facility requires 30 to 100 percent more capacity than a steady flow for the same daily gas rate. Further, water in the gas withdrawn from storage is not a problem under steady-state conditions but causes many operating and processing problems under transients. Low ground temperatures cause the formation of gas hydrates and free liquids in the gathering systems and plant.

The effect of these liquids is minimized, but not eliminated, by removing the free water at the wellhead and heating the gas to 125 degrees F. Careful operation is still required on startup to avoid freeze-ups and to deliver pipeline quality gas into the transmission system. pipeline quality gas into the transmission system. The water problems are analyzed qualitatively for the effect on the final design.

Introduction

A. BACKGROUND:

Colorado Interstate Gas Company (CIG) operates a natural gas storage field near Denver, its major market. A map of CIG's main transmission system and storage field is shown in Figure 1. Gas supplies are located far from Denver in Kansas, Oklahoma, Texas, and Wyoming. The Fort Morgan storage reservoir, when it is filled during the summer, supplies gas to Denver on cold days throughout the winter.

Clean, dry gas is used to fill the reservoir. However, water in the reservoir is picked up and carried back out when the stored gas is withdrawn. A dehydration plant is required at the field site to remove the water before the gas reenters the transmission system for sale to Denver.

This same site also houses injection compressors to pump the gas into the ground during the summer.

Since the Fort Morgan storage field and plant are located only 60 miles from Denver, plant are located only 60 miles from Denver, they undergo quite variable gas flow rates and pressures. The unusual features of the design to handle the transient operations are the main topic of this paper.
A Method for Optimizing the Design of Gas Storage Systems
Authors: Van Horn H. Glen , Wienecke Donald R.
Published: December 2007

The design of underground gas storage systems requires the selection of optimal values for several interacting variables. Some of these variables are related by nonlinear functions so that frequently used optimization techniques, such as linear programming, are less than precise and cumbersome to apply. precise and cumbersome to apply. A method of optimizing the variables, subject to the operating and physical constraints, has been developed and programmed for solution by digital computer. A Fibonacci Search routine is used for efficient convergence on the optimal solution. The relationships between the variables are preserved in original form, nonlinear where this is the case.

The storage system includes the underground storage reservoir, the wells, the gathering system, the purification facilities, and the compressor station. purification facilities, and the compressor station. Because the gathering system is analyzed separately, only the average pressure loss from wellhead to compressor suction is entered into this system. The solution selects optimum horsepower for the withdrawal cycle. The reservoir is represented by the pressure-withdrawal relationship, and the producing ability of the wells by the back-pressure relationship.

The variables subject to optimization are the volume of in storage, the producing rate of the wells, the number of wells, the size of the casing, the size of the purification system, and the size of the compression equipment used for withdrawal. The optimal solution is the set of values for the variables that will minimize investment.

When the purification equipment is sized for the peak day volume, and the number and casing sizes of the peak day volume, and the number and casing sizes of the wells are temporarily considered fixed, the optimum-seeking computer program can be formulated as a two-variable, unimodal function that lends itself to efficient solution by the Fibonacci Search convergence technique. The program is designed to evaluate several casing sizes for any number of wells. By using the Fibonacci Search, the original range of uncertainty can be reduced to less than one percent in ten iterations. A tolerance of .001 percent can be achieved in 25 iterations.

Introduction

Variation in rates of gas consumption requires the use of some form of gas storage in conjunction with transmission and distribution facilities. Storage is used to supply additional volumes on peak demand days. it also permits the more efficient use of facilities during summer permits the more efficient use of facilities during summer months. Usually underground storage is the most practical means of gaining seasonal gas storage. An underground storage system contains several subsystems: the well casing, gathering, purification and compression facilities and the reservoir. The optimum design is the best combination of these subsystems.

Gas transmission facilities should be operated at a high load factor. Interruptible sales are one method of accomplishing higher load factors.
A New Model to Predict Steam Override and Viscous Fingering in Heterogeneous Oil Reservoirs
Authors: Godderij R. R. , Bruining Johannes
Published: December 2007

Early steam breakthrough, often observed in practice, is usually attributed to steam override. In the paper we address the question whether viscous fingering and/or channelling have an additional effect on the time of steam breakthrough. We have developed a pseudo 3-D mathematical model for steam drives that can handle steam override, viscous fingering and channelling in 3-D heterogeneous reservoirs.1

The model incorporates gravity and viscous forces as well as heat losses to the cap and base rock. Capillary forces are not included. We use an interface approach where we decouple heat and mass transfer. We simplify by the vertical equilibrium approximation and reduce the model equations to 2-D.

The ensuing model equations are solved by the probabilistic method proposed by King which is designed to model viscous fingering. The method allows 3-D evaluation of steam drive projects in heterogeneous reservoirs without the necessity for expensive fine grid three dimensional simulations,

Example calculations for a thin medium-viscosity oil field show that heat losses have a stabilizing effect on the displacement process. They completely suppress viscous fingering and reduce steam override. For the homogeneous cases, poor steam drive recoveries occur due to strong override and cusping towards the production well, as a result of the pattern geometry. For the heterogeneous cases, the additional effect of channelling through high permeable zones occurs.
Creating 3-D Reservoir Models Using Areal Geostatistical Techniques Combined with Vertical Well Data
Authors: Gorell Sheldon B.
Published: December 2007

Advances in geostatistics, seismic processing and interpretation are now providing capabilities for improved reservoir characterization by allowing integration of seismic and well data. In certain situations where correlations can be established between seismic and well attributes, the seismic data can be used to bias the interpolation of well attributes away from the wells using techniques such as co-kriging (or variants thereof). Traditionally, this approach has been applied in situations where areal seismic attributes over a reservoir interval are correlated with zone-averaged petrophysical attributes. These techniques result in improved zone-averaged petrophysical maps. However, for certain applications, particularly dynamic reservoir simulation of fluid flow, zone-averaged properties may be inappropriate. In such situations, it is necessary to somehow "unaverage" the zone-averaged maps to produce vertically heterogeneous maps. Since the scales of seismic resolution are still generally much coarser than those needed for simulation models, seismic data often does not provide much, if any, information which can be used to infer details about internal reservoir heterogeneities. This paper discusses a technique for creating 3-D reservoir models based on underlying seismic maps and some measures of vertical heterogeneities at the wells. What results are 3-D reservoir models which honor both the vertical variations at the well locations and the geostatistically created zone-average petrophysical maps. Some examples are presented which demonstrate the applicability and limitations of this technique. In addition to visual inspection of the models, reservoir injection and production is simulated and used to illustrate the importance of various modeling assumptions.
An Experimental Study of Foam Flow Through Berea Sandstone With Applications to Foam Diversion in Matrix Acidizing
Authors: Parlar Mehmet , Parris M. D. , Jasinski R. J. , Robert J. A.
Published: December 2007

The results of a series of dual (diversion) and single core foam experiments followed by liquid injection in unfired Berea sandstone cores are reported at high rates relevant to matrix acidizing. The sensitivity of the results to surfactant type and concentration, foam and post-foam liquid injection rates, permeability, temperature and presence of oil are discussed. Surfactant type, preflush and foam slug sizes are identified as critical parameters for subsequent liquid diversion into low-permeability regions. In contrast to EOR processes, surfactant adsorption is shown to be beneficial for diversion. At low liquid rates and high foam qualities relevant to EOR, foam at steady-state is found to behave as a Newtonian fluid with respect to liquid rate provided that the gas rate is above a critical rate. At high liquid rates and low qualities a shear-thinning behavior is observed. Pressure gradient during post-foam liquid injection is found to be independent of both foam and subsequent liquid rates, and to depend only on permeability for fixed surfactant chemistry. The entrance effects noted in foam literature are found to be more pronounced at high permeabilities and intermediate injection rates. Potential mechanisms as to why foam diversion in matrix acidizing works in the field are also discussed.
Technical Basis for Establishing Environmentally Acceptable Endpoints in Contaminated Soils
Authors: Nakles D. V. , Linz D. G.
Published: December 2007

There is a growing body of evidence that soils that contain residual concentrations of contaminants above background or pristine conditions may not pose unacceptable risk to the environment and human health. The initial results of a research program sponsored by the Gas Research Institute support this contention. The GRI research program has reviewed the existing soil literature: (1) to obtain a better understanding of the physical and chemical interactions that bind contaminants within the soil matrix and that govern their rate of release into the environment and to living organisms and (2) to examine and/or develop correlations between soil treatment and the resulting toxicity and mobility of contaminants in the soil matrix. This paper presents a sample of the supporting data which have been found regarding the persistence of contaminants in soil with time; the effects of aging of contaminants on their availability to microorganisms, the extractability of contaminants from the soil and the release of contaminants from the soil into the environment; the effects of the sorption of contaminants on soil on their effective toxicity; and the results of biological treatment on the concentration, toxicity, and mobility of PAHs in soil. The implications of these findings on the determination of environmentally acceptable endpoints in contaminated soils and the management of contaminated sites are also discussed.
Simultaneous Solution Of Oil-In-Place And Water-Influx Parameters For Partial Water Drive Reservoirs With Initial Gas Cap
Authors: Tehrani D.H.
Published: December 2007

SIMULTANEOUS SOLUTION OF OIL-IN-PLACE AND WATER-INFLUX PARAMETERS FOR PARTIAL WATER DRIVE PARAMETERS FOR PARTIAL WATER DRIVE RESERVOIRS WITH INITIAL GAS CAP

The application of Newton Optimization technique to volumetric balance equation is introduced. This is to determine, simultaneously, the original oil-in-place and water influx, using historical performance data of a petroleum reservoir. Equations are presented in a general manner so that the reader, familiar with matrix calculations, can easily apply them to any aquifer model. As a field example, an unsteady-state exponential form of water influx has been used to describe the aquifer performance of Haft Kel Field of Iran. performance of Haft Kel Field of Iran. The limitation of sum square deviations of oil-in-place as a basis for optimization has been described. Instead, the sum square deviations of cumulative reservoir withdrawals has been used for optimization which has accomplished satisfactory results.

The limitations of the method and the effect of its underlying assumptions have been discussed.
Seafloor Monitoring for Synthetic-Based Mud Discharged in the Western Gulf of Mexico
Authors: Candler John E. , Hoskin Sam , Churan Marc , Lai Cui Wei , Freeman Michael
Published: December 2007

Synthetic-based muds have been used to simultaneously improve drilling and environmental performance. The fate and effects of synthetic-based mud discharges in the marine environment have been issues of concern with the drilling industry and governmental agencies. Most of the environmental data on synthetic-based muds have been generated under laboratory conditions. This study uses field-collected data to investigate the fate and effects of a polyalphaolefin synthetic-based drilling fluid.

The first well drilled in the Gulf of Mexico using synthetic-based mud was completed in June 1992. Approximately 441 bbl of cuttings and 354 bbl of synthetic-based mud were discharged over a 9-day period. Three sampling trips have been made to the discharge location to collect sediment samples for chemical and biological analysis over a 2-year period. The sediment samples were analyzed for content of organic compounds and barium. On the third trip, infaunal samples were also taken.

Information collected from the chemical and biological analysis is documented and compared to similar field studies performed on oil-based and water-based muds. Sampling techniques and analytical protocols are described to facilitate future studies.

Two years after discharges of synthetic-based cuttings were completed, an area within 50 m of the discharge point continued to exhibit alterations in the benthic community not normally associated with water-based mud discharges. However, the study indicates that polyalphaolefin synthetic-based mud exhibits significant improvements over oil-based mud in terms of removal of organic contamination and minimization of adverse effects on the benthic community.
Characterizing Costs and Benefits of Uncertain Future Regulatory Requirements on the U.S. Natural Gas Industry
Authors: Godec M. L. , Smith G. E. , Fitzgibbon Timothy , Linz David , Pauling Gene
Published: December 2007

Environmental regulatory requirements at both the state and federal level are constantly changing, making it difficult for industry and R&D program managers to project future compliance requirements and costs. Even if a company is trying to keep abreast of various proposed regulatory initiatives, the number of possible combinations of initiatives that could occur in the future seems virtually limitless. Uncertainty associated with potential future environmental compliance requirements makes the identification and evaluation of future investment and R&D opportunities exceedingly difficult, and makes the process of systematic strategic planning increasingly complex.

This paper describes a methodology for accounting for uncertain future environmental compliance costs in a systematic, comprehensive manner. Through analysis of proposed initiatives for making future environmental requirements more stringent, forecasting the likelihood of occurrence and potential timing of each initiative, and estimating potential future compliance costs associated with each initiative, a thorough process for incorporating regulatory uncertainty into strategic planning and project evaluation is described. This approach can be used for evaluating R&D opportunities to determine where development of new technologies or assessment of risks posed by industry operations may have the greatest impact on future industry costs of compliance. This approach could also be used to account for the uncertainty of future environmental costs in corporate strategic planning or for factoring future compliance costs into project evaluation. This approach could also be enhanced through use in conjunction with other modeling and forecasting systems that could consider a broad range of impacts, including impacts on gas production, industry activity levels, and tax revenues.
Environmental Compliance Management System
Authors: Cason A. , Larrinaga L.
Published: December 2007

A cross-functional team of environmental regulatory experts, plant managers, and plant engineers have been working since 1991 on the development, implementation and maintenance of the Environmental Compliance Management System. The Environmental Compliance Management System is a practical and accurate method of determining the applicability of the state and federal environmental regulations and of establishing standard and straightforward procedures to meet these requirements. The Environmental Compliance Management System allows individual manufacturing facilities to avoid the additional manpower that would be required to read, digest and decide on the applicability and plan of action to meet the requirements of all the environmental regulations.
Environmental Issues and Solutions for Exploratory Drilling in Sensitive Areas
Authors: Smith Robin M.
Published: December 2007

A multi-disciplinary team approach was successfully employed to design and implement innovative environmental solutions to drill the 8000 foot deep Hunter Creek exploratory well, less than 20 miles from Grand Teton National Park, Wyoming. Acquiring permission from the FS, the BLM, and ultimately, the public to drill the Hunter Creek well involved substantial teamwork in identifying and resolving many potential, environmental pitfalls. Creative, workable and cost-effective mitigation measures employed at Hunter Creek included: utilizing a helicopter and limiting vehicle use of an existing road, conducting environmental and safety training, careful project planning, an erosion control and reclamation plan, designing an environmentally friendly, near-zero-discharge drilling location, initiating a water quality monitoring program, designing a waste minimization plan, identifying threatened and endangered and special status species possibly affected by project activities, and ensuring compliance with all mitigation measures and Federal and State regulations.
EPA'S Natural Gas Star Program
Authors: Resch Rhone A.
Published: December 2007

Rhone A. Resch

The Natural Gas STAR Program is a voluntary partnership between industry and government, designed to reduce emissions of methane. The program uses market forces to save industry money while achieving the objectives of the Climate Change Action Plan.

This paper describes the development of the Natural Gas STAR Program, including sources of emissions, cost-effective solutions, and program benefits. Specifically, in the production sector the replacement of high-bleed pneumatics with low or no-bleed devices, and adding flash tank separators to dehydrators are two cost-effective methods that reduce emissions. Although the paper focuses on the production sector of the industry it is important to note that a program for transmission and distribution is already in place. Participation in the Natural Gas STAR Programs can provide each company with valuable information on updating systems and saving money

Introduction

In 1992, in response to global concern on greenhouse gases emissions, the U.S. developed the first Climate Change Action Plan. A section of the plan is dedicated to the reduction of methane, a potent greenhouse gas, and required EPA to create the Natural Gas STAR Program. The Natural Gas STAR Program is a cooperative, voluntary program between the Natural Gas Industry and the U.S. Environmental Protection Agency (EPA) to implement pollution prevention techniques in a cost effective manner. The initial program focused on transmission and distribution companies, and in the first full year of the program (1993) methane emissions were reduced by l,340,000 Mcf. This year, EPA has expanded the program to include the production sector of the industry.

P. 403
Oil & Gas E & P Field Personnel Pollution Prevention Training Project
Authors: Megna A. T. , Kinias C. J. , Souders Steve
Published: December 2007

The National Environmental Training Association (NETA) with a grant from the U.S. Environmental Protection Agency (EPA) has developed a comprehensive pollution prevention training program for oil and gas exploration and production field personnel. The program, developed by an interdisciplinary committee of industry, industry association, regulatory agencies, and environmental groups, provides the knowledge, tools, and instructional techniques to transfer a pollution prevention mind-set and cost-effective methodologies to field personnel.
Reuse of Spent Natural Gas Liquid Sweetening Solutions
Authors: Hahn Warren J. , McKim Mark N. , Smith Lynn S.
Published: December 2007

Partially spent caustic solutions from natural gas liquids (NGL) sweetening processes can be used as reagent for sulfur dioxide (SO2) scrubbing facilities, reducing the costs for purchasing scrubber reagent and eliminating the costs and liabilities associated with waste disposal.

This paper discusses: 1) the characteristics of typical spent NGL sweetening solutions, 2) State and Federal regulations governing the disposal of these solutions as wastes, 3) the operational variables affecting reuse of these solutions in SO2 scrubbers, 4) field and laboratory analytical data from a pilot project conducted to evaluate the reuse of a partially spent NGL sweetening solution as SO2 scrubber reagent, and 5) economic data from the pilot project.

For the pilot project, a partially spent caustic NGL sweetening solution was used in place of soda ash solution as reagent in a SO2 scrubber serving two steam generators burning sour gas. Emissions testing of the scrubber demonstrated that the solution provided effective removal of oxides of sulfur (SOx) in both gaseous and particulate phases to meet permitted limits. Data from the pilot project is used in the paper to: 1) quantify SO2 scrubber performance with partially spent caustic solutions in terms of SOx removal efficiency, 2) identify the necessary modifications in scrubber operation (reagent feed rate, scrubber liquor pH and specific gravity, blowdown rate) to achieve acceptable performance using partially spent caustic solutions, and 3) describe the effect that the use of partially spent caustic solutions has on physical and chemical properties of scrubber liquor.
Biocide and Corrosion Inhibition Use in the Oil and Gas Industry: Effectiveness and Potential Environmental Impacts
Authors: Brandon D. M. , Fillo J. P. , Morris A. E. , Evans J. M.
Published: December 2007

Treatment chemicals are used in all facets of the natural gas industry (NGI) from well development through transmission and storage of natural gas. The multitude of chemicals used, combined with the dozens of chemical manufacturers and/or suppliers has lead to the availability of hundreds of possible chemical products. Because of the widespread use of chemical products and their numerous sources, the NGI needs access to consistent data regarding their effectiveness and potential environmental impacts.

The objective of this work was to evaluate the effectiveness and potential environmental impacts of chemical products used in the NGI. This assessment was initially focused on biocides and corrosion inhibitors and their use in the gas production, storage and transmission facilities, The overall approach was to obtain the necessary data on chemical use and effectiveness directly from the oil and gas industry, supplemented with data/information obtained from the published literature. Five case histories of chemical use were documented and evaluated to assess the effectiveness of these chemicals. Potential environmental impacts were addressed by performing a screening environmental assessment on the use of glutaraldehyde, a widely used biocide. Prototype discharge scenarios were formulated and modeled to evaluate potential impacts to groundwater and surface water.

The paper describes the basis for the study, provides an overview of chemical use with a focus on biocides and corrosion inhibitors, describes and assesses the specific uses of chemicals, and presents the results of the environmental assessment. It was found that various chemicals can be effective in treating microbiologically influenced corrosion and souring, but that the effectiveness of specific chemicals is dependent on the operational scenario and the site-specific conditions. Results of the screening environmental assessment indicated that surface and groundwater impacts were not significant for the scenarios evaluated.
Environmental Impact of a Flocculant Used to Enhance Solids Transport During Well Bore Clean-Up Operations
Authors: Yunus M. Nassir Moho , Procyk Alexander D. , Malbrel Christophe A. , Ling Kenny L. C.
Published: December 2007

This paper investigates particle flocculation as a mechanism to remove residual contaminants in well bores during completion operations. Laboratory tests and field trials were conducted demonstrating the ability of flocculating polymer sweeps to improve well bore cleaning efficiency. This process reduces the volume of fluid accumulated in the well bore that is discharged to the environment and minimizes the risk of formation damage by residuals left in the well bore. In addition, a comprehensive environmental impact study was performed on the flocculating polymers which included 72 hrs-EC50, 48 hrs-LC50, 10 day- LC50 tests on a variety of marine organisms, and bioaccumulation and biodegradability tests. In all cases, the flocculating polymers were shown to be environmentally safe at the recommended concentrations.
Synthetic Drilling Muds: Environmental Gain Deserves Regulatory Confirmation
Authors: Burke C. J. , Veil J. A.
Published: December 2007

Efficient drilling technology is essential to meet the needs of the oil industry. Both the challenges of new oil provinces, especially in offshore waters, and the demands for efficient environmental protection have driven the development of new technology. Drilling mud is a key factor influencing drilling technology used in modern drilling operations. New oil industry developments involve directional and horizontal drilling as well as drilling in frontier areas at greater and greater depths. Such capabilities and conditions demand careful attention to the selection and engineering of efficient mud systems.

Spent drilling fluids and drill cuttings are among the most significant waste streams from exploration and development activities in the oil and gas industry; they pose a serious and costly disposal problem for offshore operators who must barge spent mud and cuttings to shore for land disposal if they do not meet U.S. Environmental Protection Agency (EPA) discharge limitations or permit requirements. Suppliers of mud systems have responded to this problem. Since 1990, several non-toxic, biodegradable synthetic-based muds (SBMs) with desirable performance and environmental characteristics have entered the market.

However, EPA regulations apply mud technology that was available when the regulations were developed, namely water- and oil-based muds (WBMs and OBMs). While EPA requirements appear to have been a major driver behind the development of SBM, now concern is focused on the inhibiting effect of discharge limitations on use of alternative mud technologies.

This paper examines and describes SBM systems recently developed as substitutes for conventional drilling muds. Initially, background information on drilling mud is presented to provide an overview. The paper identifies the advantages and disadvantages of alternative drilling muds and assesses their comparative environmental impact and cost/benefit. The paper also characterizes the regulatory factors which affect the introduction and widespread use of innovative alternative mud technology. Finally, the paper asssesses the approach of EPA in administering effluent limitations guidelines (ELGs) and its impact on innovative technology development. It recommends areas of further study and suggests regulatory process improvements to enacourage the development and use of alternative mud technologies.