bluuebunny/crossref_metadata_2025 huggingface dataset:
Oil Recovery Simulation for Heterogeneous Reservoirs
Authors: Myerson A. S. , Izmailov A. F. , Kessel A. R.
Published: December 2007

Description of the oil recovery process implies creation of an adequate simulation model. One of the such models, the Dynamic Invasion Percolation with Trapping (DIPT) model, has been recently developed [1, 2]. This model is based on two independent steps.

The first step is to describe the oil reservoir saturated and/or unsaturated porous media in terms of the integer lattice models. In these models the lattice sites and bonds are identified with pores and capillary channels, respectively. It was suggested in [1,2] to describe n possible different states (empty, filled with displacing fluid or displaced one, etc.) of each lattice site j (j ⊆ [1, N]) in terms of the time-dependent n-component spinor functions χjm(j)(t), where N is the total number of lattice sites and m(j) ⊆ [l, n]. In such an approach the time-dependent state function ψ(t) of the entire lattice modelling oil reservoir porous medium can be introduced as the following direct product: (1)Ψ(t)=∏j=1N⊗χjm(j)(t).

The second step is to describe evolution of the oil reservoir subjected to the recovery process. It was done within the DIPT model. In this model it was suggested to describe evolution of the oil reservoir state function ψ(t) with the help of the following Schrodinger-like equation: (2)∂Ψ∂t=τH Ψ(t),
The Use of Optimal Control Technique To Validate Reservoir Simulation Results
Authors: Elemo R. O. , Lawal A. S.
Published: December 2007

The advent of fast digital computer has made numerical modeling of petroleum reservoirs very attractive, starting with a landmark paper published in 1953 by G.H. Bruce, et al. Reservoir simulation, a major numerical modeling technique, has now become an important tool used to study the performance of oil and gas reservoirs of various complexity where several variables are involved, and therefore, analytical solution may not be appropriate and/or closed form solution is not feasible. A number of sources of error in reservoir simulation application has been identified and documented in literature. One major source of error is frequent use of inaccurate reservoir description data. Therefore, model validation and calibration, meant to ascertain the correctness of the simulator and the applied description data, are essential parts of reservoir performance numerical modeling. Model validation and calibration are usually done by history matching of the field performance data and simulator calculated performance responses. In the last couple of decades, there has been considerable interest in the development of automatic history matching algorithms. Automatic history matching is preferred to the traditional trial-and-error approaches despite the fact that the automatic routines require some additional iterative optimization routines to the basic simulator because the investment of additional optimization code development time and computational CPU time is worth the effort.
Endurance Testing Begins Where API 6A 16th Edition Appendix F Ends
Authors: Dach A. J. , Nordeen Merle
Published: December 2007

AN OVERVIEW OF API SPEC 6A, APPENDIX F

API Spec 6A has undergone extensive revisions to become a more widely accepted specification worldwide. API 6A is no longer a dimensional specification. The 15th Edition of API 6A, which was effective 4/86, dealt in detail with quality levels of the iron used to manufacture API 6A components. The 16th Edition, which was effective 4/89, dealt in detail with quality and performance of API 6A metallic components, seals and sealing materials. The new API 6A will now make it possible for a user to spec in the cleanliness of the steel and the performance requirements of the seal required to meet the actual intended service conditions which include pressure (oil or gas), produced well fluids, actual well temperature and production variables such as inhibitors, acidizers, etc.

Performance testing for valves currently identified in API Spec 6A was developed by surveying users of API equipment A task team, consisted of 56 members, both users and manufacturers, was set up to analyze this data. These team members were mostly technical in background. After two years of technical discussions analyzing data and test programs, the team agreed to the performance testing shown in Appendix F of API 6A. The testing outlined for valves represents what the average product would endure in its field life. The three pressure temperature cycles outlined for wellhead seals, hangers, etc. represent a tortuous path that, if endured by a seal, it would continue to perform for its expected life.

DRIVING FORCES BEHIND ENDURANCE TESTING

Prior to the 15th Edition of API Spec 6A, many users of 6A products worldwide had identified weaknesses in Spec 6A. North Sea users were requiring equipment which basically met PSL 3 as now defined in Spec 6A. The MMS required SPPE surface safety valves be used on all wells drilled in Outer Continental Shelf waters. The requirements for this equipment exceeded PSL 2 and PR 1 as now defined in Spec 6A. Several major worldwide users of 6A equipment had developed internal specifications which outlined requirements for equipment which exceeded PSL4 and PR2 as now defined in Spec 6A.
Desktop Computer Application for Quantifying Cycle Wells Performance
Authors: Smith Matthew , Lawal A. S.
Published: December 2007

Synopsis

The expert system was developed for the Prudhoe Reservoir Engineering group to query the effectiveness of gas utilization on individual wells basis. It analyzes welltest and production data within the Production Database (PDB) to obtain an historical perspective of oil production and the decline parameter of a given well or group of wells in a pad/ or drill site. Historical production trends are monitored by well to identify candidates for well cycling, workover or shut-in. By specifying a date range for the required production data, an Excel-compatible spreadsheet and associated graphs are produced in real-time.

Description

Cycle Well program developed from expert system has recently been used in the Gravity Drainage regions and up-structure areas of the Prudhoe Bay Field (PBU) to optimize production strategy of high GOR wells (> 5000 scf/bbl). The program consists of strategies for intermittently producing high GOR wells by optimizing the flowing and shut-in schedules of the individual wells (details of the schedules are provided in SPE paper No. 26091 by Easley and Lawal). The program provides information for cutting gas allocation to the individual wells, thereby converting cycle wells into continuous producers. The use of the program with the historical performance of individual wells and available geologic data provides a means of enhancing oil production from high GOR wells.

Posters Display

The posters are developed from the reservoir mechanics of high GOR wells using integrated knowledge of Reservoir and Production Engineering coupled with expert system programmers from BP Computing community. The posters provide algorithms for displaying information about the performance of individual wells using the production database. The information display include oil rates, gas rates, GOR, cycle periods, measure of decline parameters, down time periods. The technique is applicable to the wells in a pad/ or drill site or the wells feeding into a gathering center or flow station; it can also be tailored to selected group of wells.
Petrographie Image Analysis: An Effective Technology for Delineating Reservoir Quality
Authors: Gies R. M. , McGovern Jon
Published: December 2007

Petrographie Image Analysis (PIA) is an emerging technology used to estimate the properties of pore systems that occur worldwide in sandstone, carbonate and conglomerate reservoir rock samples. It provides quantitative evaluations from standard core plugs as well as from material unsuitable for conventional core analysis such as core rubble and drill cuttings. PIA technology also supplements routine core analysis by estimating other parameters like the specific pore size interval that regulates fluid flow.

The method described here is based on a simulated capillary pressure curve. It has been used routinely to estimate pore and pore-throat size distributions, porosity, permeability, air-mercuiy capillary pressure, irreducible water saturation, effective porosity, microporosity, seal capacity, and the minimum saturation of the non-wetting phase at which it becomes mobile throughout the pore system. These and other new relationships being developed and tested can be mapped to help delineate trends in reservoir quality.

PIA procedures and relationships are discussed and illustrated with an example application from a large gas reservoir in the Western Canadian Sedimentary Basin.
New Insights in the Formulation of Porous Media Mass and Momentum Equations
Authors: Civan Faruk , Evans R. D.
Published: December 2007

New equations for porous media mass and momentum conservation for variable fluid and porous media properties are derived by representative volume averaging of the microscopic laws. The new mass conservation equation contains an extra term interpreted as mass transfer by spatial dispersion in porous media. The new momentum conservation equation contains only one empirical parameter, referred to as an apparent permeability. It is shown that the Klinkenberg and Forchheimer equations can be derived readily from the apparent permeability concept. Therefore, it is concluded that future research should be devoted to developing correlations for the apparent permeability rather than an absolute permeability, inertia resistance coefficient, and other parameters that the special equations Darcy, Forchheimer, and others may include. It is also shown that apparent permeability is a function of the porous media Reynolds number which implicitly includes the information about the fluid conditions through density, viscosity, and flow rate, and the information about the porous media properties through the use of an apparent pore size diameter concept. The present study, thus, leads to new insights into the mathematical description of the flow behavior in porous media.
CO2 Foam Slurry Friction Correlations
Authors: Kenyon D. E.
Published: December 2007

An analysis of turbulent fluid friction was made for data of vertical flow of C02-foam slurries. These data were obtained during a fracture stimulation in a uniquely-instrumented, 3.5-inch tubing string. Data were culled to steady state for each C02 cut, gel concentration, sand loading, and rate. Friction gradients were computed and a new friction correlation was developed. The correlation uses the friction factor concept for high speed, single phase flow by defining appropriate mixture density, viscosity, and Reynolds number from foam slurry properties.
Analysis of Abnormally High Fracture Treating Pressures Caused by Complex Fracture Growth
Authors: Davidson B. M. , Saunders B. F. , Robinson B. M. , Holditch S. A.
Published: December 2007

INTRODUCTION

The Gas Research Institute's (GRI) fourth Staged Field Experiment (SFE No. 4) well was drilled as part of a field-based research program that has been conducted in the Frontier formation of southwest Wyoming. During this experiment, data were collected from whole cores, multiple sets of openhole logs, in-situ stress measurements, microseismic surveys, and multiple injection (mini-frac) tests.1 These comprehensive data sets have been used to fully describe the Frontier sandstone. This paper summarizes the analysis of abnormally high fracture treating pressures that were observed on SFE No. 4.

Over the past two decades, the analysis of the net or excess pressure has become an important diagnostic tool for the petroleum engineer to evaluate hydraulic fracture treatments. The technique was introduced to the industry by Nolte and Smith2 and has been used in many situations to diagnose fracture growth patterns. Net pressure analysis can also be used to categorize formation types based on their net pressure response.3 Abnormally high fracture pressures encountered in certain formations have also been evaluated with this method4

It was evident from the initial injection tests on SFE No. 4 that the injection pressure was noticeably higher than other wells in the area.5-9 Due to this high injection pressure, a series of diagnostic injection tests was developed to evaluate the cause of the high pressure. These tests indicated the high injection pressures were caused in part by high near wellbore friction. We also saw evidence of high net pressures in the fracture, indicating that multiple fractures were propagating simultaneously.
Electronic Gas Management: An Integrated Approach
Authors: Halliwell K. A.
Published: December 2007

To support the complex operation of a large gas transmission system, information must move rapidly and accurately within NOVA and between NOVA and its business partners. With the implementation and integration of systems to perform pipeline control (SCADA), commodity management, electronic flow measurement (EFM), and electronic data interchange (EDI), this goal is being achieved.

This paper will follow a typical process from a customer's electronic request for gas, through the commodity management system for contractual and operational checks, to the issue of a change in flow, the control and measurement of that flow through the SC AD A and EFM components, back through the commodity management system, and through to the communication of the transported commodity totals back to the customer.
Process Design Integration: A New Optimized Approach That Will Facilitate Gas Development Projects for Nigeria
Authors: Ofoh E. P.
Published: December 2007

Nigeria is blessed with Natural gas reserves whose abundance is estimated in the range 100-300 trillion cubic feet. It is, perhaps, the most wasted energy resource in Nigeria: In 1970, there was no gas processing plant in Nigeria and as such about 99 percent of all gas produced was flared. In 1979, the Nigerian government filed a directive that required the multinationals to find utilization for gas reserves and all gas produced. The goal was to reduce energy waste and environmental pollution. As an alternative to the above decree the multinationals were required to pay penalties for all gas wasted. Despite this decree, and encouraged by still lack of facilities, gas flaring continued with the Operators under great regulatory and economic pressures. A Joint Venture between government and the multinations agreed to finance gas projects which would be founded on sound engineering basis. An integrated process design is a cost-effective conceptual engineering in which process and utility systems are carried out in parallels and with the cooperation of all subgroups. This integrated technology is expected to put both the conceptual and the detailed designs of the fast lane and thus alleviate the fears of the Nigerian clients.

The other advantages of the integrated process design over the conventional design are:–Consistent optimization of the entire design is now possible and less complex.–Primary process and utility equipment set up which constitute about 90 percent of the total capital investment are now made early before final construction is embarked upon.–Work activities relating to subsystems can now be done cooperatively and in parallel by the use of softwares which can transfer final simulation output into subsystem spreadsheet programs for quick updates of results.–The integrated process, founded on sound engineering judgement and consistent with well defined energy efficiency has an advantage of reducing the overall construction schedule.

A detailed account of this new process and its future on worldwide projects will be outlined. The effect of reimbursable arrangement will be mentioned.
Risk-Based Considerations in Developing Optimum Hydrotest Strategies
Authors: Leis B. N. , Rahman Sharif
Published: December 2007

As pipelines age, a flaw population that varies initially along the pipeline can advance in size and number. Analysis of the serviceability of pipelines based on either in-line inspection or hydrotesting can lead to overly conservative decisions or an excessive risk of failure when the random nature of this population and the pipeline's properties are represented by a "typical" flaw and "average" properties. It follows that decisions on serviceability should reflect the random nature of the variables involved or be justified by demonstrating that the uncertainty in these parameters does not adversely effect cost and safety.

This paper explores the significance of the random variables related to serviceability in pipelines. This study is made under the assumption that continuing serviceability is based on the use of hydrotesting. Results generated via probabilistic analysis form the basis for the discussion of risk and safety and the significance of the random variables. This same technology could be used in (1) risk and safety assessments associated with pipeline operating decisions, (2) designing hydrotests and choosing their frequency to ensure continued safe operation of the line, and (3) assessing the operating and safety implications for flaw populations characterized by in-line inspection.
Identification and Potential Treatment of Near-Wellbore Formation Damage in a Horizontal Gas Well
Authors: Jamaluddin A. K. M. , Vandamme L. M. , McGuffin R. G.
Published: December 2007

This paper presents the results of a study carried out to identify near-wellbore formation damage in horizontal wells. Formation damage occurs when pore throats are constricted by clay swelling upon contact with incompatible fluids, by clay migration or by plugging with drill solids and mud products. Relative permeability effects can also cause water/condensate blocking and subsequent reduction in loadfluid recovery and productivity.

Extensive laboratory experiments were carried out on cores from wells offsetting four poorly producing horizontal wells in a gas-bearing formation. The results indicated that clay-related near-wellbore formation damage was the primary cause of the low productivity from these horizontal wells. Results from further laboratory investigation indicated that the formation damage could be remedied using an oxidizing material (e.g., hydrogen peroxide).

Based on these laboratory results, a field test was carried out to treat the near-wellbore formation damage using a mixture of oxidizing fluid and acid. The results of this field test are also presented in this paper.
Isotope Analyses of Gases in Gas Field and Gas Storage Operations
Authors: Schoell Martin , Jenden P. D. , Beeunas M. A. , Coleman D. D.
Published: December 2007

Natural gases vary in chemical and isotope composition as a function of their formation and migration history. Compositional and isotopic variations are often caused by mixing of two or more compositionally and isotopically different gases. Isotopic properties in gases can be used to determine the mixing ratio of the two endmembers and/or calculate the composition of the endmembers from different mixing ratios. The variations of isotopic properties of gases within a continuous reservoir are generally small but can be significant between fault blocks of one reservoir or between unconnected but closely stacked reservoirs. These inter-reservoir variations can be utilized to help solve many problems occurring during gas field development and operation:

Reservoir Identification:

Gases within a single reservoir are very similar, but non-communicating reservoirs can often be differentiated through isotopic differences in their gases. Isotope analyses of gases could be helpful in such cases to identify the production zone in new completions.

Reservoir Compartmentalhation and Fault Block Mapping:

Isotopic signatures of gases in faulted reservoirs with completions in different fault blocks can be used for better identification of sealing faults and subdivision of drainage compartments.

Reservoir Allocation:

Isotope analyses in commingled production could be used to allocate contributions from individual sands if isotopic differences exist between the gases from the contributing reservoirs.

Gas Storage:

Gas storage fields provide excellent "laboratories" for demonstrating the effects of mixing gases of different compositions. Examples are given which demonstrate the use of chemical and isotopic analyses to calculate mixing ratios of storage gas and native gas.

Identification of Gas Seeps:

Movement of natural gas from reservoirs to the surface may change the concentration of gas components, but the isotopic composition remains mostly unaltered (isotope changes through oxidation can be recognized through special isotopic anomalies in compound patterns). Isotope analyses can, therefore, help identify the source of surface gas leaks.
Buying Gas To Re-Sell Instead of Producing Gas To Sell
Authors: Williams H. D. , Lohrenz John
Published: December 2007

Since deregulation of natural gas prices in the U.S. became fact, not just intent, producers have had to reckon with the progeny of market supply and demand. Long-term speculations abound regarding improved gas prices in the future. Short-term speculative opportunities arise due to seasonal price peaks. One way of acting on these speculations is buying gas for re-sale instead of producing one's own gas; the decision algebra of such speculations is treated here.
Global Warming and the Emerging Importance of Natural Gas
Authors: Kamal W. A.
Published: December 2007

The paper examines the environmental crisis facing the planet in the coming decades due to an enhanced ’greenhouse effect’, its causes and impacts. It then discusses future energy demands of industrial and developing countries and shows that the latter will face a huge energy crisis with serious consequences on the environment – unless a move to cleaner fuels is adopted. It finally examines the future prospects of Natural Gas, an abundant and relatively cheap · at today's prices – primary energy source which is the most environmentally-benign of all fossil fuels. The study demonstrates why Natural Gas is regarded as the fuel of the 21" century, and our hedge against a looming environmental crisis.
Production Data Analysis for Wells That Have Been Subject to Periodic Curtailment
Authors: Spivey J. P. , Lee W. J.
Published: December 2007

Gas wells are often subject to periodic or cyclic curtailment. Currently available methods are poorly suited for analyzing production data from these wells. Using methods presented in this paper, an equivalent continuous flowing pressure can be calculated from pressures measured at the end of the flow and shutin periods during each cycle. This equivalent continuous flowing pressure is then used for production data analysis in conjunction with the average flow rate. This method is applicable for boundary dominated flow, transient radial flow, and transient linear flow of slightly compressible liquids in a homogeneous formation. The method may be applied to gas well production data through the use of pseudopressure or normalized pressure.
Correlation for Determining Gas Condensate Composition
Authors: Niemstschik G. E. , Poettmann F. H. , Thompson R. S.
Published: December 2007

A correlation was developed that relates the composition of the well stream effluent at any depleted state to the composition of the retrograde gas condensate at its initial dew point pressure as a function of the fraction that the reservoir pressure is depleted, reservoir temperature and specific gravity of the retrograde gas condensate at its initial dew point pressure. The correlation is based on the analysis of 131 constant volume laboratory depletion studies on gas-condensate systems for a total of 907 depletion steps.

If the initial specific gravity of the gas condensate is not available, a second correlation was developed to predict the initial specific gravity.
Improved Acid Fracturing Treatment Designs Based on In-Situ Temperature Calculations
Authors: Roodhart L. P. , Kamphuis Harry , Davies D. R.
Published: December 2007

Successful acid-fracturing treatment requires the creation of etched channels of sufficient width and length. This paper shows how the channel shape can be calculated using knowledge of the acid/rock reaction process, in-situ temperature and hydraulic profile. A simulator has been developed for this purpose, on the basis of an implicit finite-difference scheme permitting rigorous treatment of all relevant processes, such as the cooling of the rock adjacent to the fracture and the heat transfer between fracture and wall during and after pumping, is employed. Detailed knowledge of the temperatures of both the fracture fluid and the rock face allows quantitative description of the progress of the acid/rock reaction. Model calculations show that the channels etched in calcitic rock may be very wide near the wellbore because of turbulence effects. On the other hand, the etched channels may be too narrow in dolomitic rock, or rock with a low fracture toughness. This will impair well productivity, and should be avoided by modifying the pumping scheme. Two field examples of treatment design and evaluation using the new simulator are discussed.
A Comparison of Short-Core and Long-Core Acid Flow Testing for Matrix Acidizing Design
Authors: Fambrough J. D. , Newhouse D. P.
Published: December 2007

Most acid core flow testing utilizes short (<3") core plugs. In this study flow tests were run using both short core plugs and long(>8") core plugs. All plugs were from a producing formation in the Gulf of Mexico. Both long and short cores were damaged with a fluid loss control pill and then treated with various acid systems. When treated with HC1 or HC1:HF the short core plugs showed an increase in permeability over the length of the core. Long cores treated with HC1:HF showed an increase in permeability in the first 2 inches of the plug but a decrease in permeability farther down the plug. Analysis of the spent HC1:HF indicated that the loss of permeability was caused by precipitation products from the HF/clay reaction. Observations made during these tests indicate that relying on short core flow tests for selection of a matrix treatment fluid can result in a damaging treatment. Long core tests provide a better tool for selection matrix treatment fluids.
Using an Expert System To Select the Optimal Fracturing Fluid and Treatment Volume
Authors: Holditch S. A. , Xiong Hongjie , Rueda Jose , Rahim Zillur
Published: December 2007

Many wells drilled and completed to produce oil and gas must be stimulated to increase flow rates and ultimate recovery. In low permeability reservoirs, long hydraulic fractures are required to optimize the depletion of the reservoir. In high permeability reservoirs, formation damage during drilling must be overcome using short, highly conductive hydraulic fractures.1 Most recently, in ultra-high permeability, poorly consolidated formations, a new stimulation method that combines both hydraulic fracturing and gravel packing principles (the FRACPAQ has been successfully used to stimulate oil and gas production.

To optimize production, one must optimize the fracture fluid properties, the treatment volume, and the fracture conductivity. Choosing the correct fluid and additives is extremely important to be sure the proppant is placed successfully. We also want to use a fluid that breaks and cleans up properly. Ideally, every fracture treatment should be designed by an expert with adequate data available. However, most fracture treatments are not designed by experts; instead, most stimulation treatments are designed by inexperienced engineers without all data they need.

We have developed a PC-based interactive computer model to help an engineer choose the best fluid, additives, and propping agent for a given set of reservoir properties.2,3 The computer model also optimizes the treatment volume based upon reservoir performance and economics. To select the fluids, additives, and propping agents, the expert system uses rules developed by surveying stimulation experts from different companies, reviewing the literature, then incorporating the knowledge into rules using an expert system shell. Our design expert queries the user for necessary reservoir data, then using the knowledge base, the expert system recommends the best materials for the treatment.
Reservoir Characterization of an Eastern Kentucky Devonian Shales Well Using a Naturally Fractured, Layered Description
Authors: Jochen J. E. , Lancaster D. E. , Holditch S. A.
Published: December 2007

This paper presents a summary of the complete integration of geological, geophysical, geochemical, and reservoir engineering analyses into a single reservoir model that accurately simulates observed production and pressure transient data fa-a gas well completed in the Devonian Shales of the Appalachian Basin in Pike Co., KY. This well was part of a three-well research program sponsored by the Gas Research Institute (GRI). Data collected and evaluated include a detailed openhole logging suite (including the formation microscanner), 240 ft of oriented whole core, open- and cased-hole stress tests, nitrogen slug tests, fracture treatment pressure data, and pre- and post-fracture pressure buildup tests. The purpose of this paper is to discuss the data collected on the well, to present the data analyses, and to demonstrate how the various analyses are being integrated to form a better understanding of the physical properties controlling well performance in the Devonian Shales. This paper also provides intrinsic reservoir properties, such as matrix permeability, desorption isotherms, and natural fracture spacings from the Devonian Shales that were measured in this well.
Cost Reduction of Injection Tests for Under-Pressured Reservoirs
Authors: Saulsberry J. L.
Published: December 2007

A new method for performing reduced cost injection/falloff tests in under-pressured reservoirs has been developed at the GRI sponsored Rock Creek research site. The new method referred to as the "Tank Test" uses gravity drainage from a water storage tank to inject water into the reservoir. The primary advantages of Tank Test over the traditional injection/falloff tests are reduced costs and improved test results. The tank test eliminates the need for expensive pumping equipment and the manpower required for manual pump rate adjustments. Further cost savings can also be made by using gauges intended for ground water monitoring in place of oil field gauges when downhole shutin is not required. The low cost of the Tank Test allows longer duration tests to be economically performed so that the radius of investigation of a test is extended. The Tank Test also reduces the possibility of fracturing the reservoir during the injection portion of the test which is a common problem when testing shallow low permeability reservoirs. This paper describes the circumstances under which the Tank Test is most applicable, the equipment that is required and how to perform the test. The paper presents results of field tests performed on coal seams and a test performed on an Antrim Shale well. A simple Tank Test design procedure is also provided.
Economic Evaluation of Nitrogen Injection for Coalseam Gas Recovery
Authors: Stevenson M. D. , Pinczewski W. V. , Downey R. A.
Published: December 2007

This paper presents a scoping study to investigate the economic viability of nitrogen injection to improve the recovery of coalbed gas. The sensitivity of the analysis to key reservoir parameters is also presented.

The results of the study suggest that nitrogen injection may be more attractive than conventional pressure depletion for lower permeability formations where the loss in permeability with pressure decline is significant. Nitrogen injection economics are shown to be very sensitive to the costs associated with injection and separation and are adversely affected by reservoir heterogeneity.
Liquid Fuels and Petrochemicals From Natural Gas: A Canadian Perspective
Authors: Fouda S. A. , Galuszka Jan , Sekhar M.
Published: December 2007

Canada is blessed with vast reserves of natural gas. A large portion of the reserves is in the frontiers and remains unexploited due to the prohibitive cost of transporting the low energy density gas. Moreover, only a small portion of Canada's consumption of natural gas is used as a chemical feedstock. Current conversion technologies involve an initial steam reforming step to produce synthesis gas which is then converted to methanol, gasoline or other products. These indirect routes are energy intensive and costly. Enormous market opportunities can be created especially for remote natural gas by developing new direct conversion technologies.

The development of direct conversion routes is at an early stage. Oxidative coupling of methane to ethylene and partial oxidation to methanol are the two routes most investigated. Engineering and economic evaluations indicate, for both routes, that the product selectivities are less than desirable due to the deep oxidation of the reaction intermediates or products to form carbon oxides.

Aggressive R&D is needed in catalyst design, reactor design and process design to overcome these chemical and engineering challenges and speed the development of direct conversion routes to commercial viability.
Case Study: HPHT Casing Design Achieved with Multistring Analysis
Authors: Goodman M. A. , Halal A. S.
Published: December 2007

Conventional casing design is based on single-string analysis which ignores annulus fluid heat-up loads and composite cemented string effects. This paper presents the design of a 7" production casing and 10-3/4" × 9-5/8" protective casing under high burst/collapse conditions. Uniaxial and triaxial safety factors are computed and compared for single-string versus multi-string analysis with and without temperature loads. In the multi-string analysis, casing stresses are calculated for the radially composite structure assuming the elastic properties of casing, cement, and formation. Results demonstrate a significant increase in burst safety factor for cemented casing and show that burst/collapse tendency for HPHT wells is strongly dependent on multi-string top-of-cement locations. For this HPHT application, reliable triaxial design is achieved with multi-string analysis using standard weights and grades of casing, which otherwise is not possible with single-string uniaxial analysis.
Integrated Approach to Bit Programming Improves Drilling Efficiency of Offshore Mobile Wells
Authors: Spaar J. R. , Brown L. A. , Goodman H. E. , Bomar B. B.
Published: December 2007

Historically, the development of a bit program for a proposed well merely involved the optimization of bit designs that have proven successful in the targeted area. While this approach appears to optimize bit performance, it does not take advantage of rock strength information that is now available.

This paper describes a new approach to bit programming and its impact on a challenging multi-well program in Mobile federal waters. The bit program, which employed rolling cone and fixed cutter bits, incorporated a new revolutionary Rock Mechanics Algorithm (RMA) that is based on lithology and sonic log intrepretation. Central to the success of the program was a thorough understanding of both fixed cutter and rolling cone bits in different drilling conditions. The evolution of bit programming for the Norphlet in the Mobile area offshore Mississippi will be detailed.

Utilization of the aforementioned analytical tools in formulating a bit program for a Mobile program resulted in a 22,489-ft. exploratory well being drilled 32 days ahead of schedule. This resulted in a substantial reduction in the cost per foot drilled as compared to the previous wells drilled in this five-well campaign.
Unique Rock Bit Cutter Fabrication Technology Provides Bit Design, Performance, and Reliability Breakthroughs
Authors: Nixon M. S. , Walter J. C.
Published: December 2007

The development of a patented powder metal forging technology for making rockbit cutters is the first major innovation in rockbit manufacturing technology since the development of the insert bit. Rapid, solid state densification of a net shape cutter eliminates many conventional cutter design constraints and provides advanced materials options that significantly improve cutting structure integrity.

A review of the new manufacturing process and comparison with conventional methods will highlight the design and materials capability and reliability improvements intrinsic to this solid state densification process.

Prototype bits made using this technology duplicated the cutting structure and materials used in standard IADC Type 11 roller cone bits. These bits demonstrated the process capability and potential, and provided insights into design and process improvements used in second generation bits. Field test results from the second generation bits that employed more advanced profile designs and cutting element materials demonstrated the potential impact of this new class of rockbit on drilling cost.

Powder metal cutter (PMC) bits from the prototype program and phase one of the project have been successfully run in typical Type 11 bit applications. The materials and design options available indicate the capability to address a wide range of soft and medium soft drilling applications economically by linking PMC with state of the art bearing and hydraulic design technologies.
Offshore Drilling in the North Sea
Authors: Belknap William B.
Published: December 2007

Introduction

Much has been learned during the first 3 years of drilling in the U.K. sector of the North Sea. Generally, conditions have been difficult. Although few conditions can be pointed out as being the worst known, many of pointed out as being the worst known, many of the conditions are among the worst and require considerable attention to engineering and plannings. plannings. This paper discusses various aspects of planning and drilling exploratory and planning and drilling exploratory and development wells in the North Sea. It covers the initial planning of equipment to drill exploratory wells; some of the problems encountered in drilling these wells; Phillips' solution to these problems, and finally the planning of a directional drilling program for shallow gas production from a fixed platform of limited production from a fixed platform of limited area.

Prior to selecting drilling equipment for a project like this, consideration must be given to the weather conditions, water depths, drilling depths, rig mobility, availability and logistics of moving materials and supplies, means of transportation and numerous lesser considerations.

This paper presents one major operator's solution to the many problems and considerations. There are other ways of doing many of these things and reaching the same end point. There are other problems which we did not encounter. We believe that, in general, we have used a practical and economical approach to drilling in the North Sea.

EXPLORATORY DRILLING EQUIPMENT

Since most of the Phillips group's concessions were in water of less than 200-ft depth, a self-elevating platform-type rig was selected rather than a floater or semisubmersible. The self-elevating rig was preferred to a fixed platform-type for exploratory operations because platform-type for exploratory operations because of mobility and to a semisubmersible because of fixed position and increased efficiency by eliminating wave motion. Because of severe weather in the North Sea and availability of rigs for deep water operation, it was decided to contract The Offshore Co. to build a new rig for this operation. Consequently arrangements were made to construct the North Star drilling rig at John Brown shipyard in Clydebank, Scotland.

As originally equipped, the North Star rig is capable of drilling in 150-ft water depths in the North Sea. Additional leg sections can be installed to increase the water depth capability to 200 ft. We did not find this necessary in our exploration program. The general appearance of the platform can be seen in Fig, 1. The dimensions and capacities of the barge hull equipment are as follows.
Integrated Design by Design: Educating for Multidisciplinary Teamwork
Authors: Thompson R. S.
Published: December 2007

This paper addresses the multi-disciplinary educational needs of the petroleum engineer. Petroleum engineers, as multi-disciplinary team leaders, will continue to play key roles in the future of the petroleum industry. Working and functioning in a multi-discipline team of geologists, geophysicists, and petroleum engineers is especially difficult since each team member brings a different perspective to the team. It is this same difference in perspective that makes multi-disciplinary teams an economic and effective approach to problem solving. The key to educating for multi-disciplinary teams is to recognize important behavioral issues and to incorporate these into the curriculum. This paper addresses these issues and demonstrates how they can be incorporated into the petroleum engineering curriculum.
Drill Cuttings Reinjection for Heidrun: A Study
Authors: Crawford H. R. , Lescarboura J. A.
Published: December 2007

Drilling of 56 wells from the Heidrun Platform in the Norwegian North Sea may generate about 150 million pounds of drill cuttings. If oil-based mud (OBM) is used on any of the wells these oily cuttings will need to be disposed of in an environmentally sound manner. This study was to assess the feasibility of disposing of these oily cuttings by reinjection into a fracture, initiated from a purpose-drilled reinjection well. A slurry was prepared from OBM drill cuttings from the Norwegian North Sea using a commercial cuttings slurrying system. Laboratory and pilot-plant tests of this slurry were conducted to measure: composition, rheology, laminar and turbulent friction loss, and leak-off coefficient. Laboratory tests were performed simulating the flow of the slurry along a fracture in a permeable formation with leak-off occurring from one side of the fracture. The paper describes the results of the tests. It concludes that it is feasible to dispose of the cuttings by reinjection into a fracture created in an impermeable formation. A procedure is suggested. It theorizes that permeable formations can act as barriers to the vertical growth of the fracture.
The Delineation and Development of the Gas Council/Amoco Group North Sea Leman Field
Authors: Cole Ronald J. , Marshall Charles R.
Published: December 2007

Introduction

The Leman field was discovered by the Shell/Esso group in March, 1966, when they drilled their initial exploratory well in the British North Sea approximately 60 miles NNE of Great Yarmouth, England. This discovery well found 900 ft of Rotliegendes sandstone at a depth of approximately 5,900 ft subsea. The well was initially tested at a flow rate of 25 MMcf/D in June of 1966. Daring June, 1966, the Gas Council/Amoco Group moved a jack-up type drill barge into U.K. North Sea Block 49/27 and spudded a field confirmation well 5.5 miles ESE of the Shell/Esso discovery well. This well was ultimately completed in Sept., 1966, and tested at a rate of approximately 25 MMcf/D.

Subsequent delineation drilling by the Shell/Esso Group, Mobil, Arpet Group, Phillips, Signal and the Gas Council/Amoco Group has now established that the Leman field is just over 20 miles long and 8 miles wide at its center covering an area of about 65,400 acres or 102 sq miles as shown in Fig. 1. The Rotliegendes sandstone which makes up the pay interval in the Leman field is of Early Permian age and is encountered at a subsea depth of approximately 6,000 ft. This sandstone is thought to have been originally deposited by swift flowing streams on alluvial desert plains and later reworked by wind into dunal-type deposits.

The Leman field structure is basically a faulted anticline with a gross Rotliegendes sandstone thickness of 800 to 1,000 ft. The faulting apparent in the Leman field is of a tensional nature, but because of the great thickness of the reservoir zone, the faults do not appear to be sealing. The complete Rotliegendes sandstone appears to be composed entirely of sand with a great variation in grain size distribution. No continuous impermeable layers or shale breaks are apparent in the Rotliegendes section, and the net gas productive sand section is normally the gross sand productive sand section is normally the gross sand section found above the water level.

The wide variation in porosity found in the Rotliegendes sandstone is attributed to the dunal-type deposition of the sand. The dunal working of the sand leads to the creation of areas where very fine grained sand has accumulated, thus creating areas of very low porosity and permeability. As a general trend, it has been noted that normally the highest porosity within the Rotliegendes pay section occurs at the crest of the Leman field structure. Also a porosity trend is noted along the major axis of porosity trend is noted along the major axis of the field with lower porosity and permeability being found in the northwest sector of the field.
Biodegradation Studies of Saudi Arabian Crude Oil
Authors: Whiteside S. E.
Published: December 2007

A bench-scale aerobic microbial degradation study of soil contaminated with Saudi Arabian crude oil was conducted. The effects of nutrient additions and seeding with naturally-occurring microorganisms were evaluated, through comparison of results from a control reactor, a second reactor with nutrients, and a third reactor with nutrients and seed microorganisms. A separate weathering experiment was conducted under identical environmental conditions for evaluation of abiotic weathering losses of crude oil.

The total petroleum hydrocarbon (TPH) content of soil contaminated with crude oil was measured as a function of time. During the five-week evaluation period, a TPH reduction of 60 to 70% was observed for the nutrient evaluation. Based on the weathering tests, approximately 17% of the TPH loss was attributed to abiotic losses.

For the specific environmental conditions, crude oil, seawater, and soil evaluated, the addition of nutrients stimulated the biodegradation of crude oil over the test period. Due to the availability of indigenous bacteria, seeding with naturally-occurring bacteria did not improve the rate of TPH loss.
Total Quality Management for the Oil and Gas Industry
Authors: Kessler F. A.
Published: December 2007

Total Quality Management (TQM) is applicable to all oil and gas companies, including majors, independents, and service companies. Presented here are an overview of TQM, a brief history of TQM in Japan and in our industry, a report on Japan’s oil and gas industry plans and progress, a discussion of the benefits of adopting this new management system, and a description of what is required to implement it. Examples of productivity and profitability improvements, as well as additional opportunities for improvement, are used to demonstrate the applicability of TQM to our industry. Calculation of potential profit improvements averaging three times current profit levels are used to illustrate the potential financial impact of this new management system to our industry.
Pitfalls in the Fractal Analysis of Reservoir Property Data
Authors: Gray T. A. , Chork C. Y. , Taggart I. J.
Published: December 2007

This study finds that three commonly used techniques for estimating the fractal dimension of one-dimensional records are not reliable when the underlying fGn signal is either limited, non-Gaussian or non-stationary. The three techniques are the rescaled range (R/S), variogram and spectral methods. Techniques which transform raw data into Gaussian and stationary data sets for more reliable parameter estimates are presented and illustrated with log data.