bluuebunny/crossref_metadata_2025 huggingface dataset:
Geological Aspects Of The Drilling Of The Buchan Field
Authors: HILL P.J. , Smith G.
Published: December 2007

INTRODUCTION AND HISTORICAL BACKGROUND

The Buchan field, located some 150 km north east of Aberdeen in 120 m of water, is situated largely in the UK licence block 21/1 (P.241) that was granted to Transworld Petroleum (UK) Ltd. in July 1972. (Fig. 1) The discovery Petroleum (UK) Ltd. in July 1972. (Fig. 1) The discovery well 21/1-1 was drilled in June 1974, and was followed during 1975–76 by three appraisal wells, two of which eventually penetrated and tested the reservoir. However, the appraisal wells 21/1-2 and 21/1-4 experienced serious drilling problems at the top of the reservoir section and were eventually lost. These wells serve as illustrations of the extreme difficulties encountered in drilling this structure and proved the existence of a complex, fault-controlled structure with a maximum oil column of 582 m in overpressured, highly fractured, low porosity reservoir sandstone of Devonian-Lower Carboniferous porosity reservoir sandstone of Devonian-Lower Carboniferous age (Fig. 2).In July 1977 as a result of a farm-in agreement BP Petroleum Development Ltd., became the operator of Petroleum Development Ltd., became the operator of licence P.241 and took a 54 1/76 per cent interest in the Buchan field. In planning any development of the field it became evident that a conventional North Sea drilling production platform would be economically, a very high production platform would be economically, a very high risk proposition. The size and complicated nature of the structure and reservoir sandstones posed many questions regarding the reliable calculation of oil in place and recovery factor, and make the field worthy of the title marginal. As a result of feasibility studies it was decided to develop the field from eight wells producing to a converted semi-submersible platform. Transportation of the stabilized crude will be by a tanker shuttle service via an offshore loading buoy located close to the platform (Fig 3.). Production is planned to start in the autumn of 1979. In Production is planned to start in the autumn of 1979. In a time sensitive plan of this nature, and in view of the past drilling history, the successful completion of the past drilling history, the successful completion of the drilling phase was an important step in the development of the field. Development drilling commenced in September 1977 and was completed in early November 1978.
Drilling, Evaluation And Completing High Angled Wells In The North Sea
Authors: Woodall-Mason N.
Published: December 2007

Drilling, evaluating and completing two wells at angles in excess of 70 degrees required planning to account for the reduced along hole component of gravitational force. Drilling assemblies and their build up characteristics were affected and friction forces experienced by surveying and electic logging tools and perforating guns necessitated the use of the pump down technique. An S shaped hole allowed free fall below the shoe of the pump down string. The high angle adversely affected bore hole stability requiring higher mud weights to hold back the hole and hole condition was found to be more sensitive to changes in mud properties and to mud quality. A production test procedure and completion string were compiled and procedure and completion string were compiled and designed, neither of which made use of gravitational forces for wireline tool operation below 4,000 ft.

Introduction

In order to reach areas of the Aukfield not falling within the existing drainage pattern, Shell Expro embarked upon the drilling of 2 highly deviated offshore wells. A-03 and A-09, with a view to completion as single string oil producers. Auk-A is a small 12 slot steel platform located producers. Auk-A is a small 12 slot steel platform located in 280 ft of water in the central North Sea. Eight wells had then been drilled into various areas of the reservoir. The central North Sea Lithology is well known for its high content of both mud making and dispersible clays above 7,000 ft requiring a mud weight of some 12.5 pounds per gallon (ppg). Below 7,000 ft in the fractured pounds per gallon (ppg). Below 7,000 ft in the fractured Cretaceous and Permian evaporites (Fig. 1), losses had been experienced with mud weights in excess of 10.5 ppg necessitating the setting of a string of intermediate casing. In previous wells where the angles were less than 60 degrees it was possible to drill for and set 9 5/8 in. casing in the top chalk. However, with the long tangent sections in A-03/ A-09, the 9 5/8 in. was required higher necessitating a 7 in. liner in its place and a 4 1/2 in. liner across the reservoir section of Zechstein chalk and Rotliegend sandstone (Fig. 2).
Treatment Fluids To Improve Sea Water Injection
Authors: Davison P. , Hyatt J.P. , Grist D.M. , Gardiner D.C.
Published: December 2007

Introduction

Sea water injection to maintain reservoir pressure is currently practised in several North Sea reservoirs viz: Beryl, Forties, Montrose, Piper and Claymore. Injection wells may be completed wholly in an oil bearing zone (pattern flood case) or partly in an oil bearing or transition zone (peripheral flood case). In either case the rate of water injection is restricted by the presence of crude oil in the pores of the rock particularly in the region immediately around the well. This oil is immobile despite continued water injection. The injection rates can be raised, however, if the oil in this critical region is removed as the conductivity (permeability) of the formation will be increased. Very considerable increases in injection rates were reported by previous investigators who used micellar solutions (complex surfactant solutions) to stimulate wells by residual oil removal.
Corrosion Control For Fixed Production Platforms Subsea By Coatings And Cathodic Protection - A Review Of Recent Experience
Authors: Pursell M.J.
Published: December 2007

Introduction

British Petroleum has tong had a different approach to the underwater protection of fixed structures from that of other oil companies. The major point of divergence is the use of paint coatings in conjunction with sacrificial cathodic protection. The technique has proved remarkably successful, especially for deep water structures. This paper reviews the history and development of the technique and it discusses in greater depth its application to the deep water Forties field structures. The author has insufficient knowledge of the particular applications of competitive techniques to make safe comparisons. Those with more intimate knowledge must judge.

HISTORY AND DEVELOPMENT

BP formed its ideas through the 1960s. which was a period when it was developing offshore oilfields for Abu period when it was developing offshore oilfields for Abu Dhabi Marine Areas (ADMA) and a gas field at the West Sole in the southern North Sea. Both had water depths in the order of 30 m. and were developed with a lumber of small structures. Some know-how was available in the late 1950s from mainly US sources but it was some of BP's own work on the protection of salt water fed cooling equipment that was found to be the most convincing. Particularly the work had shown the value of coatings for the improvement of the spread of protection and for the extension of anode life. If coal tar/epoxy paints had not been developed around the same time then the technique would probably not have been a success. The pure epoxies used for the cooling water work were too expensive and too difficult to apply for use on structures. The bituminous paints used for a few early ADMA structures suffered badly from attack by marine growth. Coal tar/epoxy has been proved to be cheap enough and sufficiently tolerant in application. Recent inspections on the West Sole have shown no coating degradation after ten years service. Minor mechanical damage has occurred due to abrasion by for instance, wire rope debris and during marine growth removal.
Pipeline Trenching In The Future
Authors: Erling Saebo , Andersen Terje
Published: December 2007

Like all other work related to offshore activities. trenching of pipelines seems to be more troublesome in the North Sea than in other parts of the world. This is either because more attention is paid to the results in this area, or because the environmental conditions make it more difficult to perform satisfactorily with the same equipment. The problem with conventional trenching equipment is that it does not perform well in clayey soils. and in several cases misoperation has resulted in damage to coating and pipeline (leading to rupture during pressure testing). This pipeline (leading to rupture during pressure testing). This possibility. taking into account the cost of trenching and possibility. taking into account the cost of trenching and pipeline repairs. should be weighed against the protection pipeline repairs. should be weighed against the protection provided by a trench towards natural and man-made provided by a trench towards natural and man-made hazards. This paper discusses the influence of trenching on pipeline safety for trunk lines with a diameter of more than pipeline safety for trunk lines with a diameter of more than 30 in. For smaller diameter pipelines the conditions may be different. Statistical analysis of pipeline failures show that the most important causes are corrosion and equipment fault. These types of failure can hardly be affected by trenching. Another important cause is anchor dragging, which also only to a limited extent can be protected for by trenching. For the major offshore pipelines constructed or planned in the North Sea over the last few years. great emphasis has been put on thorough investigation of the needs for protection of pipelines of the seabed. Based on our protection of pipelines of the seabed. Based on our knowledge of these investigations carried out by owners and operators of submarine pipelines. and on our experience as a certifying agency and consultants to oil companies. our evaluation of trenching as a safety pressure is given in this paper. A shore summary is given pressure is given in this paper. A shore summary is given below.
Operational Experiences With The Offshore Loading Units Auk-ELSBM And Brent-SPAR
Authors: Buyzen J.P.M.
Published: December 2007

Buyzen, J.P.M., Shell Expro UK Ltd. Scotland

Introduction

Shell Expro operates in the British sector of the North Sea on behalf of Shell and Exxon. The company has three operating locations: London, (Head Office), Lowesoft (Southern Gas fields) and Aberdeen (Middle and Northern North Sea). This paper deals with the operation of the Auk-ELSBM (Middle North Sea) and Brent-SPAR (Northern North Sea), activities which are controlled from Aberdeen (Fig. 1).

DESCRIPTION OF THE INSTALLATIONS

General

The hostile environment of the North Sea demands a major effort with respect to the design and effective operation of the offshore loading facilities. Although designs show significant differences, each of these installations is a variation of the Single Point Mooring theme, in that they all incorporate some form of mooring turntable and fluid swivel, which permits the tanker, while remaining moored, to weathervane around the SPM in response to the prevailing weather and sea conditions.

THE AUK-ELSBM (Exposed Location Single Buoy Mooring)

Location

The ELSBM is located 2,000 m from the Auk platform and moored to the seabed by 8 anchors, each weighing 15 tons, which are set around the buoy in a circle with a 460 m radius. Each anchor is attached to the ELSBM by a 3 in. diameter stud link chain and is pretensioned (Fig. 2). The water depth in the Auk field is 84 m.
The World Bank Program To Accelerate Oil And Gas Production In The Developing Countries
Authors: Friedmann Efrain , Elejalde Eduardo
Published: December 2007

Introduction

I would like to thank you for the opportunity to discuss with you the World Bank's Program to Accelerate Oil and Gas Production in the Developing Countries. Before discussing the program itself, and the role we see for the World Bank in assisting developing countries to manage their energy resources, I will say a few words about the World Bank.

The World Bank

The World Bank was established in 1945 following a United Nations Monetary and Financial Conference of 44 Governments at Bretton Woods, New Hampshire. The International Monetary Fund also was founded as a result of that conference. The World Bank is owned by the governments of 132 countries. It obtains its funds primarily from its own borrowings in the world capital markets, from its net earnings, the flow of repayments of its loans, and also from the paid in capital subscriptions of its member countries. The Bank's first loans were made for post-World War II reconstruction. However, by 1949, the emphasis had shifted to loans for the purpose of economic development. Loans are made directly to governments, to state enterprises, or to private companies, with a government guarantee. The bulk of the World Bank loans have been for specific projects in such sectors as agriculture and rural development, education, electric power, industry, population planning, telecommunications, tourism, urban development and water supply in developing countries.
Characterization and Mapping of Burrowed and Microporous Intervals in the Arab D Reservoir, Dukhan Field, Qatar
Authors: Trabelsi Ali , Beg Mirza Arshad
Published: December 2007

Several burrowed and microporous intervals occur throughout the Jurassic Arab D Reservoir of the Dukhan Field, Qatar. Burrowed intervals are characterized by variations in porosity and permeability values between the burrow structures and the surrounding rock matrix. Measured porosity and permeability of burrows in most instances is higher than the surrounding rock matrix. The burrows were selectively dolomitized, whereas the surrounding rock matrix remained unaffected.

Microporosity also occurs in several intervals of the Arab D Reservoir. Qualitative petrographic examination indicates that microporosity occurs within allochems (peloids, ooids and skeletal grains) and rock matrix. Thin section point counts and pore throat size distributions derived from capillary pressure data were used to estimate the amount of microporosity. Microporosity varies from sample to sample and can range from 5 % to about 90 % of the total measured porosity of a sample. Depositional texture, grain mineralogy and microstructure control variations in microporosity abundance and type. Microporosity resulted from dissolution and incomplete re-precipitation of metastable carbonate and boring of grains by fungi and endolithic algae.

We are documenting the abundance of microporosity and mapping the occurrence and distribution of the burrowed and intervals. This will lead to a better understanding of the properties of the fluid flow and the ultimate recovery of hydrocarbons in this giant field.
Towards Zero Flaring Emission
Authors: El Messiri Amir , Al Attas M.O. , Nashat Mohamed , Malash Karim
Published: December 2007

ADMA-OPCO Drilling Division took the initiative and formed a joint Task Force with ZADCO and put together, with the help of the contracted service providers, a plan to gradually achieve ADNOC's targets for Flaring Emission Reduction, categorized in Three stages as follows:- (see summary-Table-1)

Two pumping systems were introduced in May 1998, to serve the full range of the operating envelope of all ADMA and ZADCO wells. A third "Pumping System" was introduced in December 1999. This helped reduce oil flaring by 65% (200,000 bbls oil were re-injected).

ADMA-OPCO had successfully tried, via the Rigless well Invention Operations to re-inject the produced separated gas, together with the oil. ADMA-Drilling are currently studying this process with ADMA-Engineering Division, in order to Safely introduce this scenario to the eleven operating rigs. This step once implemented can reduce ±30% of gas flaring emission related to drilling operations.

Neutralization Systems neutralize the well's back flowed effluents allowing to flow immediately through the test separator, thus re-injecting the oil at the clean up phase. The 1st Neutralization trial job was carried out in February 2000 where zero oil flaring was achieved. It is expected that oilflaring reduction would reach 90%+ by the utilization of Neutralization Systems before end Year 2000. Currently only two neutralization units utilized. However, it is planned to have four units in operation before the end of year 2000.

The introduction of multi-Phase pumps, to replace the currently utilized single phase oil re-injection pumps will help achieve the re-injection of the gas, commingled with the oil (currently, this gas is being routed to the burners). It is targeted to have these pumps operational during 2001.

By the introduction of the Multiphase Pumps and with the aid of the neutralization systems, it is believed that we would achieve the Practical Zero Flaring Emission.

Introduction

ADMA and ZADCO were burning oil, during drilling related clean-up and testing operations. Estimated quantities of oil and gas burned and re-injected from Jan. 1997 to May 2000 are summarized in Table-2. About 100,000 bbls of oil were reinjected during 1999. Clean up operations were conducted to achieve a zero BS&W in ZADCO wells while ADMA were accepting higher range of BS&W. ZADCO main reasons are to protect surface facilities and sea line from corrosion. It took approximately three hours to clean up the well from 5% BS&W until it was allowed to start re-injecting the oil into the production facility (See table 3). The Flaring Emission Reduction Task Force (FERTF) was convinced that a large quantity of oil is being flared unnecessarily, hence discussions within ZADCO lead to some flexibility without compromising the Production line integrity. ZADCO agreed that re-injection can commence once BS&W reaches a stable condition for three continuous hours, provided that Cl++ and Ca++ are within an acceptable range. This has saved three hours of oil flaring (±3,000 bbls of oil).
Ten Years Experience in Horizontal Application & Pushing The Limits Of Well Construction Approach In Upper Zakum Field (Offshore Abu Dhabi)
Authors: Ismail Gamal , Fada'q A. S. , Kikuchi S. , El Khatib H.
Published: December 2007

Over the past ten years, Zakum Development Company (ZADCO) Offshore Abu-Dhabi has drilled over 225 wells including 175 horizontal wells using different types of steerable drilling techniques.

Steerable drilling is a vital factor for horizontal drilling applications. Steerable drilling assembly selection is fundamental for wellbore quality improvement to minimise the pipe-sticking incidence and provide coiled tubing accessibility for barefoot horizontal completions. These lead to reducing overall drilling costs significantly.

Through ten years of steerable drilling experience, ZADCO recognise the following:

1) Drilling multilateral horizontal wells has created some economic risks and technical drawbacks: Well intervention requirements, accessibility and stimulation or cleaning individual lateral branches, reservoir monitoring or controlling production/injection profile. 2) There are still invisible operating loss times due to the lack of learning steerable drilling.

Pushing the limits of well construction performance and economics in the new millennium is the main target of ZADCO drilling team.

Engineering data base is the most effective tool to give clear ideas how to improve the performance and reduce the well construction cost. It identify the reasons behind the variation value of Non Productive Time (NPT) and invisible lost time in each phase and how to eliminate it

Engineered database gathering, historical problem experienced, well construction optimisation, integrated skilled teamwork spirits, and using the related new technology are the main key issue to apply Drilling The Limit (DTL) concept aiming to deliver quality well at less expenditure.

Well construction (performance) optimization and trouble free and high quality well delivery are considered essential issues for the economics of drilling wells and introducing new related technologies. Our approach is to identify the areas needed to be modified, for further improvement, through study and analysis of the previous wells drilled.
The vital importance of inter-discipline communication throughout reservoir model construction - case study
Authors: Parker A. R. , Shikama T.
Published: December 2007

Much has been written with respect to "multi-disciplinary" studies, however, in practice the disciplines still essentially operate independently, with only the input/outputs integrating together in the workflow. This paper outlines a case study, which demonstrates the success of a much closer working relationship across the Geologic/Engineering disciplines. In particular, emphasis is placed upon the benefits of reversible workflows between Geology and Engineering throughout the entire construction process.

The Field, which is the subject of the case study, is in the appraisal stage (6 well penetrations, no production) and is composed of a series of stacked Carbonate reservoirs located in shallow water offshore of the UAE. Main areas of challenge during construction of the models were; honouring observed multiple fluid contacts, lithofacies determination, 2D seismic uncertainties and non-intuitive production testing results. The vital key to resolving/matching these challenges was linking capillary pressure functions to lithofacies identifiers prior to model construction. Then throughout the construction process a series of forward/backward optimisations of geological parameters driven by both disciplines.

The resultant models are simpler than those produced in the past for similar fields. However, most importantly, a number of previously mysterious observed "problems" were resolved through the necessity of a truly integrated multidisciplinary approach. This resulted in a greater understanding of reservoir properties, allowing better matching of all observed data. This in turn gives greater confidence in the predictability of the models produced.
Vertical Transmissibility Assessment Across Stylolites in Stratified Carbonate Reservoir – A Field Experience
Authors: Al-Ansari Faisal , Konwar Lakshi Singha , Urasaki Daisuke , Parker Andrew , Hiraoka Takashi , Mitsuishi Hiroshi
Published: December 2007

One of the key uncertainties that impacts reservoir development and waterflood performance in a thick reservoir is vertical transmissibility across the stylolitic intervals. It is not clearly understood whether low vertical permeability or negative capillary pressure across stylolites holds the water from slumping, because both the realizations could achieve good history matches of observed well performances (water cut and pressure except MDT/RFT) in the simulation model. It is, therefore, crucial to calibrate the simulation model using field test results before it can be used to produce a reliable forecast. A comprehensive dualwell vertical interference testing program using a singleprobe formation tester was designed1 and implemented in a stratified carbonate reservoir in Upper Zakum Field. This paper presents the results of a time-lapsed dual-well vertical interference test that enabled assessment of the degree of vertical communication across various sub-zones and quantification of in-situ vertical permeability on a reservoir scale.

The testing procedure involves a partial penetration well test followed by the generation of a pressure wave by a partially penetrating well which is monitored in an offset, fully penetrating well via time lapse MDT measurements. Upon completion of the inter-well interference test, a vertical interference test is conducted in the observer well by using a dual-packer, dual-probe MDT tool.

Analytic methods were initially utilized followed by construction of a 3D numerical sector model to match the observed data in order to estimate vertical permeability. Results indicate that there are no vertical permeability barriers present except in the bottom part of the reservoir that could account for the water over-ride of oil seen in the test well. Thus, low vertical permeability is discounted and presumably, capillary pressure barriers may be responsible for preventing slumping of injected water within the reservoir. This finding will have a significant impact upon future field development planning particularly with regard to well design (orientation, location and benefit of lateralisation). More importantly, the results can be utilized to calibrate the full field model culminating in a credible dynamic simulation model to produce accurate future prediction cases.
A Basic Scanning Electron Microscope Study of Drilling Fluids
Authors: Porter Kenneth E.
Published: December 2007

The Field Emission Scanning Electron Microscope allows a different approach to understanding the structure and concepts behind the design of drilling fluids.

Information obtained from the preliminary studies indicates changes may be required in our thinking on what are acceptable fluid parameters, such as fluid loss and how to control this effectively.
A Plastic Pre-Coated Gravel for Controlling Formation Sand
Authors: Underdown David R. , Day Jon C. , Sparlin Derry D.
Published: December 2007

Results of field tests and laboratory evaluation have shown that a plastic pre-coated gravel system is a successful method of sand control for both non-thermal and thermal wells. Significant improvements in this process have been made which provide higher compressive strengths, increased quality of coating, greater chemical and thermal stability and higher permeability of the consolidated gravel. These results have been obtained by using higher quality gravel, an improved coating process and improved placement techniques.

Full scale pumping tests and actual field results indicate that this system provides a consolidated gravel pack capable of controlling sand production without impairing fluid production. The use of this type of material even prior to the improvements has provided good sand control in both injection and production wells in the offshore Gulf Coast region for over a year. Field results in the San Joaquin Valley, California have demonstrated that it is also well suited for sand control in moderate temperature thermal wells. Wells using both steam drive and huff-and-puff methods of stimulation which have employed this improved plastic coated gravel have increased production and virtually eliminated bailing of sand.
Federal Government Role in Enhanced Oil Recovery
Authors: Adams Martin
Published: December 2007

Good Morning, Mr. Chairman, members of the Society of Petroleum Engineers, distinguished guests including our many visitors from other countries, and all of you who are interested in Enhanced Oil Recovery. I am pleased to be here on the occasion of the first Joint SPE-DOE Symposium on Enhanced Oil Recovery. This is the sixth in a series of biennial meetings sponsored by the Mid-Continent Section of the SPE and also is the sixth annual meeting sponsored by the DOE and our predecessor agencies. This particular meeting is an excellent way to determine if the respective aims of our two organizations can be adequately served by such a joint meeting. Based upon the excellent program that is in store over the next three days and the fine attendance, I am very encouraged about the future prospects of joint meetings such as this one.

I am here today in the place of Secretary Duncan who unfortunately could not arrange this meeting into his schedule. My responsibility as Deputy Assistant Secretary for Oil, Gas and Shale Technology includes DOE's program for research on enhanced oil recovery. I regard this as an extremely high priority area because of the potential of EOR to make significant contributions to domestic supplies of liquid fuels in the decade of the 80's and beyond.

The translation of potential to crude oil to the tank will happen only if industry decides to do it. And this must take place within the framework created by our laws and Government policy.
Examination of Techniques for Thermally Efficient Delivery of Steam to Deep Reservoirs
Authors: Johnson Donald R. , Fox Ronald L.
Published: December 2007

The major objective of Project DEEP STEAM is to develop the technology required to economically recover heavy oil from deep reservoirs. One approach to achieve this objective involves the evaluation and modification to improve the thermal efficiency of the delivery processes for surface generated steam.

A full-scale test facility for evaluation of well completion components has been constructed. The testing of insulated injection strings and high temperature packers utilizes a seventy-foot above-ground tower capable of operation to 700°F and 3000 psi steam injection pressure; most of the testing has been carried out at 640°F and 2100 psi injection pressure. The tower is instrumented for measurement of parameters required to evaluate performance of individual completion components. The measured parameters are analyzed through computational programs to predict the comparative economics of the well completion in a specific recovery project. Various approaches to insulation of injection strings have been investigated. Insulation materials tested include calcium silicate, mineral wool, and multi-layered radiation barriers and insulating fibers. High temperature packers from various manufacturers have also been examined. All the commercial packers tested utilized non-elastomeric sealing materials consisting of combinations of asbestos with stainless steel and carbon fibers.

The results of tests for a variety of insulation and packer combinations reveal that casing temperatures and tubing heat losses can be successfully reduced by currently available components, but that most of the systems evaluated are not likely to survive long term or repeated use in their present form. Recommendations for further development of the hardware components required for improved, thermally efficient delivery systems are presented.
A Check on Numerical Thermal Simulation
Authors: Myhill Norton A.
Published: December 2007

This paper describes a test of thermal numerical simulation. A three phase, three dimensional, numerical simulator duplicates reasonably well a complex laboratory steam drive. The laboratory steam drive was in a glass bead pack and was conducted at subatmospheric pressures. Since the matched steam drive was a laboratory one, much of the basic input data to the simulator was measured. The simulator used injection rate and reservoir pressure as input variables and calculated gross production, oil production, injection pressure and steam zone position as output variables. There is a close match between the simulator output and the experimental results.
Single Well Cyclic Method for Determining in Situ Chemical Retention
Authors: Satter Abdus , Shum Yick-Mow , Widmyer Richard H.
Published: December 2007

Reliable data on chemical retention in the reservoir is vital for designing chemical floods. A multiwell pilot can provide the needed information; however, such a project is expensive and time-consuming. Experience has shown that a chemical flood pilot can fall short of the predicted performance using the laboratory data and mathematical model studies. An alternative approach for obtaining retention under the reservoir condition is from a short duration, low cost field test using only a single well.

The proposed technique entails multiple cycles of injection of a tertiary chemical solution containing a non-adsorbing tracer, soaking and production from the same well. The concept initially was verified by tests conducted in laboratory core cells. A mathematical model also was developed for simulating the cyclic test. Finally, a field test was carried out in a well in the Manvel Field, Brazoria County, Texas, where a pilot chemical flood was underway.

This paper presents the results of the aforementioned investigation. It is concluded that the single well cyclic test is a potentially viable, short term, low cost technique for determining chemical retention in situ. The test may bridge the gap between the laboratory and pilot floods. Data obtained from such a test could yield scale-up criteria for designing and implementing a full scale pilot, or in determining the feasibility of even undertaking a project.
Rock Structure and Transport Therein: Unifying with Voroni Models and Percolation Concepts
Authors: Pathak Prabodh , Winterfeld Phillip H. , Davis H. Ted , Scriven L. E.
Published: December 2007

Matrix and pores of rock form irregular, interpenetrating, networK-like structures with interrelated shapes and connectivities that are statistical variables resulting from the nature of the original sediments and the diagenetic processes they have suffered. Transport properties of either network depend on geometry, i.e. size and shape distributions; transport depends equally on the number of transport paths, or distribution of connectivity, i.e. topology. Thus different structural properties and transport processes in rock matrix and in pore space are interrelated.

This theoretical prediction is studied by means of the Voronoi construction for subdividing space, which provides precisely defined, realistically irregular models of rock and of distributions therein of fluids, conductivity, permeability, strength, etc. Geometry and topology of the models are coded into matrices that are useful for thinking about structure and transport, and which become factors in illustrative calculations of electrical conductivity, Young's modulus, and fracture strength as functions of, for example, porosity. The results show percolation thresholds: cessation (or onset) of transport when a critical fraction of paths is randomly blocked (or created). Statistical features of structure and transport are the subject of percolation theory.

The results help focus experimental studies and point to a unified picture of structure, strength, and transport.
Salt Water Disposal
Authors: Ellison W.F.
Published: December 2007

This paper begins with a short review of current state legislation directed toward the satisfactory disposal of salt water. An example is cited of the progress the oil industry has made in meeting the problems involved in disposing of salt water in the most economic manner while complying with certain state regulations.

Methods of disposal, types of disposal systems, and the considerations involved in selecting the best method to use under given conditions are discussed. The paper enumerates the various components of a disposal system and discusses the selection of materials used in the construction of a salt water disposal system. A few paragraphs are devoted to the problems encountered during construction. The paper contains the writer's interpretation of the importance and reasons for a concentrated effort toward properly maintaining such systems after installation.

Conclusions provide a few basic concepts that should be considered in the evaluation, design, construction, and maintenance of salt water disposal systems:During the past few years, there has been a sharp increase in the demand and a decrease in the availability of fresh water for residential and commercial uses. A definite need, therefore, exists for a continued concentration of efforts toward the elimination of pollution of the nation's fresh water resources. Proper disposal of waste brine is the oil industry's contribution to the solution of this problem.The importance of an economical solution to the problem of disposing of salt water is illustrated by the fact that on a national scale approximately three barrels of waste fluids are produced for each barrel of commercial crude.From an economical and operational standpoint, the use of semi-closed systems has proven to be successful in most instances.Experience has shown that with the proper emphasis on economics, a selection of the best corrosion-resistant materials would be advisable for use in salt water disposal systems.Good planning and close inspection of construction on salt water disposal projects has been beneficial in lowering future maintenance costs.Provision for periodic cleaning of gathering and injection facilities has proven to be profitable from an operational standpoint.

Introduction

Salt water is a by-product obtained from the production of oil for which there is no apparent economic value except in its use as a reservoir repressuring or flooding agent. It is a waste product that is often produced in large quantities with the recovery of crude from an underground reservoir. Salt water is an expensive item to the oil producer.
A Unique Insulation System for Steam Injection Enhanced Recovery and Geothermal Wells
Authors: Brown Victor R. R. , Lorenz Alan A. , Prevost William M.
Published: December 2007

Wellbore heat loss and steam quality downhole, at the sandface, are primary factors affecting the performance of steam injection wells used in enhanced oil recovery. Secondary factors critical to steam injection operations are casing thermal stress and packer seal integrity. A practical, durable, and economical insulated downhole steam tubular system has been developed by the General Electric Company, Advanced Energy Department, Thermal Systems, in Tacoma, Washington. This insulated tubular is the latest product in the General Electric patented "ThermoCase" line of insulated downhole oilfield products and is designated "ThermoCase III".

The new insulated tubing allows deeper wells, protects old wells, improves steam quality, oil production, and simplifies completion design. A.P.I. standard tubulars, installation procedures, and rig equipment are used. Evolved from successful deployment at Prudhoe Bay, the welded double tube construction with expansion bellows, hermetically sealed, provides high performance insulation, protects tubular threads, and maintains low casing temperature when flowing 635°F (335°C), 2000 psi (141 kg/cm2), steam. Initial applications of ThermoCase III in Canadian heavy oil, and tar sands in California and Venezuela are now underway.

A thermal description of the product along with a discussion of a number of verification test results will be given. In addition, thermal/structural and financial/economic computerized analysis results will be given for a typical steam injection field application with 635°F (335°C) saturated steam at 2000 psia (141 kg/cm2) flowing down a 2300 ft. (701 m) well. In summary, "ThermoCase III" has been designed to give outstanding thermal performance with a nominal overall K-factor of 0.20 Btu-in/ft2-hr-°F (0.028 W/m°K). Typical significant reductions in casing temperature with ThermoCase III versus standard uninsulated steam tubing were determined to be approximately 431 percent. A similar reduction in relative packer axial movement of approximately 734 percent was also realized in the above mentioned example.
Predicting the In-Situ Stress for Deep Wells Using Differential Strain Curve Analysis
Authors: Strickland Frank G. , Ren Nae-Kan
Published: December 2007

Recent developments in energy exploration at depths of 5000 to 25,000 feet have made it necessary to quickly and reliably determine the in-situ stresses acting on the wellbore.

Differential Strain Analysis (DSA) is being investigated as a technique applied to core samples to indirectly determine the in-situ stress state.

Testing is being pursued in three steps. First, field measurements of strain are made in-situ as the core is pulled out of the well. Second, the cores are brought to the lab and DSA is performed under in-situ hydrostatic conditions. Third, the rock is examined microscopically.

These tests have been performed on both oriented and non-oriented cores from Texas, Louisiana and Fennsylvania.

At this point in the investigation, it appears very favorable that a reasonably accurate estimate of the 3-dimensional stress state can be obtained using the strain curve analysis method. It has been demonstrated mathematically that not only the ratio of the stresses can be derived but also the orientation of the stresses in free space. The application of these equations to the data from the latest high quality runs yields result well within the reproducible tolerance of other methods.
Polymers For Enhanced Oil Recovery In Reservoirs Of Extremely High Salinities And High Temperatures
Authors: Akstinat Manfred H.
Published: December 2007

Polymers for low salinity reservoirs and low viscosity crude oils are well known. For sandstone reservoirs with highly concentrated brines of low pH-values, reservoir temperatures up to 80 °C and crude oil viscosities of 20 to 200 mPa⋅s suitable polymers have hitherto not been available. Under consideration of these conditions rapid selection methods for polymers (biopolymers, HEC, PAA/HPAA etc.) were developed. By application of these novel test procedures to about 340 different products several promising polymers, as well as general correlations could be ascertained.

Test results concerning the shear stability, filtration, adsorption/retention and flow of polymer solutions in porous media allow reliable predictions about the efficiency of viscous flooding media.

Moreover quality and application values of suitable polymers for enhanced oil recovery are critically compared. Preselected polymers were tested in laboratory flooding experiments and have shown substantial increases in oil recovery of up to 24% OOIP.
Wettability Of Reservoir Minerals By Flotation And Correlation With Surfactant Adsorption
Authors: Celik Mehmet S. , Somasundaran P.
Published: December 2007

Minerals can undergo significant alterations in wettability upon adsorption of surfactants on them. A method that appears promising for measuring wettability is flotation using air or oil extraction. Unlike contact angle, it does not require such drastic treatments as polishing. Good correlation was obtained in the present study between wettability as determined by flotation and adsorption density. Both air flotation and adsorption exhibit maxima in the same concentration range. Zeta potential of particles measured under the same conditions, however, shows a continuous increase in its negative value with sulfonate concentration. Correlation of these data suggests that sulfonate monomers adsorb in increasing amounts below as well as above the critical micelle concentration but with a reverse orientation. There is however a decrease in measured surface excess, possibly due to such factors as precipitate redissolution and micellar exclusion.

A combined approach using adsorption, wettability, zeta potential and surface tension shows promise as a valuable method for the study of mechanisms of interaction of surface active agents with minerals.
Operating Practices in Carthage Field
Authors: Rockwell Don E. , Coe Raymond H.
Published: December 2007

Through the cooperative participation of operators in the Carthage Field, a summarization of field completion practices has been prepared. This paper presents the results of an SPE questionnaire to determine operator preferences in tubular sizes, cementing practices, electric log interpretation, perforating techniques, fracture design and implementation, pre-frac and post-frac surveys, well clean-up procedures, and operational methods in the Carthage (Cotton Valley) Field. This summarization makes no attempt to identify particular operators with specific techniques, but endeavors to present an overview of the various field procedures being employed.
Fundamentals of Fracturing
Authors: Daniel Gene , White Jerry
Published: December 2007

The basic theory of massive hydraulic fracturing as it relates to rock mechanics and rock properties will be reviewed with particular emphasis on the Cotton Valley Formation. The assumptions and basic concepts in frac geometry and orientation will be discussed. The parameters required for design will be identified and their effect delineated. Although this paper will be geared for a general understanding of fracturing, recent findings in rock mechanics and key areas requiring further definition will be presented.
The Effect of Microscopic Core Heterogeneity on Miscible Flood Residual Oil Saturation
Authors: Spence Andrew P. , Watkins Robert W.
Published: December 2007

Much effort has been devoted to understanding the mechanisms responsible for the variation of CO2 flood residual oil saturations found both in the laboratory and in the field-Some of the many possible explanations are the detailed nature of CO2/oil phase behavior, trapping of oil by mobile water, viscous fingering, and bypassing of oil due to the micro-pore structure of a given porous medium. The purpose of this study was to investigate the influence of rock characteristics alone on misciblє displacement behavior through a combination of displacement testing and modeling. Modeling was used to characterize the displacements and to extrapolate the observed phenomena to untestable conditions. The displacement tests were used to calibrate the model and to test the model's predictive capabilities.

A number of stabilized CO2 displacements and xylene displacing iso-octane tests were conducted in both outcrop sandstones and San Andres reservoir carbonate core samples. By flooding with xylene displacing iso-octane, phase behavior complications and viscous fingering were avoided. Such an idealized displacement represented the "best case" laboratory miscible displacement. Effluent concentration profiles for the xylene displacing iso-octane floods were matched to the capacitance-dispersion model of Coats and Smith1 to estimate the magnitude of axial dispersion and so-called "dead-end" pore volume or capacitance.

The latter quantity was found to be essentially zero in outcrop sandstones but quite variable in the highly heterogeneous San Andres carbonates, attaining values as high as 50%. Axial dispersion followed similar trends. The carbonates displayed more variable and larger axial dispersion than the sandstones.

First contact and CO2 miscible flooding residual oil saturations were compared in the same core samples. Both measures of residual oil saturation were in agreement and depended on the particular sample. These data suggest microscopic heterogeneity is a primary determinant of residual oil saturation to miscible flooding when viscous fingering is controlled. Microscopic heterogeneity resulting from a non-uniform pore structure was characterized by the level of dispersion and capacitance in the rock sample. In addition, both laboratory data and model prediction showed that the effect of dispersion and capacitance on residual oil saturation decreased as the displacement was extrapolated to reservoir rates and system lengths of a few feet. This implies that microscopic heterogeneity is more important in laboratory systems than in field displacements.
High-Strength Nickel-Alloy Tubulars for Deep, Sour Gas Well Application
Authors: Vaughn Glen A. , Greer James B.
Published: December 2007

There is considerable interest in producing deep, high-pressure reservoirs that contain substantial amounts of sour gas. Because of the great depths and pressures involved, it is necessary to use high-strength tubular materials if safety features such as a downhole packer are to be incorporated into the completion design. It is known that sour production from these wells is severe from the standpoint of corrosion and sulfide-stress cracking of high-strength steels. Recent work has also identified two potential problems with high-strength, nickel-alloy tubulars. These problems are related to environmental embrittlement: (1) hydrogen-embrittlement cracking, which is a concern in the cooler, upper portion of the well during extended periods of shut-in and (2) stress-corrosion cracking, which is a concern at elevated temperatures downhole. This paper describes these problems and discusses the major environmental and metallurgical variables in terms of the conditions present in a deep, sour-gas-well completion. In addition, the progression from laboratory testing to full-scale high-alloy tubular manufacture, including specifications, is reviewed.