bluuebunny/crossref_metadata_2025 huggingface dataset:
Geotechnical Hazards Associated with Leg Penetration of Jack-Up Rigs
Authors: Kee Roger
Published: December 2007

In recent years there has been a large increase in offshore oil and gas exploration activities. A large proportion of the work is being performed with jack-up drilling rigs.

Jack-up rigs basically are of 2 types, depending on their foundation: Mat-supported orIndividual footings (spud cans).

Mat supported rigs have a large foundation bearing area and therefore impose relatively low bearing pressures on the seabed resulting in limited penetration. Mats are usually A-shaped and are suitable for use when the seabed comprises very soft clay soils. However, mat supported rigs require that the seabed is fairly level and their stability is sensitive to factors such as subsoil variability, cyclic and eccentric load effects, lateral sliding resistance and seabed instability. Rigs supported on individual footings are more numerous and much more widely used in South East Asia and this paper presents aspects of geotechnical hazards that may be encountered when their legs penetrate into the seabed.
Development and Design of two Series of Jack-Ups for Hostile Waters
Authors: Mommaas C. J. , Blankestijn E. P.
Published: December 2007

This paper describes the development of a jack-up design philosophy. An overview of design aspects in the various modes of operations is given.

As example the development of two series of jack-up designs for hostile waters is discussed.
The Design and Construction of Stabilization and Protection Works of Offshore Structures Placed on the Seabed
Authors: Groothuizen Albert G M , Lubbers A
Published: December 2007

This paper discusses several subjects with respect to the burial of pipelines and transmission lines in particular and the design and construction of bottom and scour protections for offshore structures in general.

Possible incidents with pipeline and cables during installation, burying, testing and operation are discussed as well as the environmental impact of these incidents and of burial operations. Alternative methods of protection cq. stabilization of pipelines, cables and offshore structures, using specially designed stone-dumping vessels and mattress-sinking techniques are presented.
Single and Dual Lift Analyses of Offshore Structures
Authors: Sekita Kinji , Kimura Hideo
Published: December 2007

At offshore job sites today, decks are lifted onto jacket structures in relatively large, heavy sections. Since lifting operations are greatly affected by the motions of the derrick barge or the crane ship, it is necessary to evaluate the sling system in consideration of vessel motions in order to regulate lifting operations at the job site.

This paper proposes a static analysis method for designing sling systems and describes the application of this method to dual-lift operations carried out by two derrick crane barges in Southeast Asian waters.

This paper also presents the methods of analyzing the motions of a hoisted load caused by wave-induced vessel motions and resulting dynamic sling tensions in single- and dual-lift operations.

Single-lift, unified analysis -- a method that considers the interaction between the barge and the hoisted load -- is discussed, and calculated results are compared with 1/75-scale model test results to clarify the conditions necessary for unified analysis. Finally, the results of transient motion analysis for a barge crawling while lifting a load are compared with model test results.
Simple Subsea Completions
Authors: Crossland Richard
Published: December 2007

This paper addresses the basic configuration of simple subsea completions.

In an attempt to present an overview of the options open to an operator, examples are taken from various systems which have been designed and/or installed. Features from more advanced designs have become available to upgrade the state of the art in this field.

It should be emphasised that like land and platform wellheads and trees, a vast array of options and customised designs are available to meet particular requirements in this environment, and it is difficult to propose a standard completion.

To encble a concise view of a subsea completion oil major areas have been touched, from the drilling equipment required, the interface equipment and finally the tree and control systems typically available.
Use of Preformed Stable Foam in Low Pressure Reservoir Wells
Authors: Anderson Glenn W
Published: December 2007

Preformed stable foam is a proven process that has an extensive successful track record. This paper emphasizes its use in several applications in low pressure reservoirs, such as: Sand cleanout, recompletion, new completions, and concentric tubing work.

New applications for stable foam; namely, gravel packing and balanced-pressure coring for insitu formation saturation, are discussed.

The use and importance of a foam circulation computer model is illustrated. This model has proven to be extremely accurate and valuable as a planning tool in establishing the liquid/volume ratio and annular back pressure requirements for balanced pressure operations.

Case histories and survey results are presented to illustrate the cost savings and production benefits of foam circulation.
Evolution Of The Tanker-Based Floating Production, Storage And Offloading Concept
Authors: Klein Pieter J. , Smulders Louis H.
Published: December 2007

Stationary offshore terminal facilities utilizing former trading tankers were employed by the oil industry as early as fifteen years ago.

Initially, a tanker was simply connected to a single point mooring (CALM) by conventional hawsers where it served as a combination buffer storage vessel and mooring platform for shuttle tankers. Operational restrictions survival characteristics and high operating costs stimulated the development of the single buoy storage (SBS) and single anchor leg storage (SALS) systems employing rigid arms for permanently mooring the vessel to the SPM.

The first terminal of this type became operational in 1973 and it along with half a dozen similar terminals has served efficiently for many years.

In August 1977, a further step in the evolutionary process was taken with the startup of a tanker-based, rigid-arm-moored (SALS) floating production Facility. This system incorporates conventional separation equipment on the vessel for producing from a single subsea-completed well. A second similar facility also producing from a single well was installed in 1980.

Recognizing the need for testing and producing independently from two or more wells and injecting into wells, a program was instigated in 1978 to develop a high pressure, multiple flow path swivel to conduct fluids between the weathervaning vessel and the non-rotating buoy or riser. In August 1981, a facility went into operation using this new high-pressure, multiple flow path swivel producing from the subsea-completed wells in the Philippines. Philippines. More recently, a floating production, storage and offloading (FPSO) facility that can accommodate up to eight wells became operational in November, 1982.

The latter system, incorporating a 210 000 dwt vessel permanently moored in 140 metres, accommodated five production wells and three water injection wells by means of highly engineered riser, swiveling and manifolding techniques.

In the present paper, the author describes in detail four existing tanker-based floating production systems and traces their evolutionary development through stages of increasing capacities and complexity.

Also described is the progress made in perfecting vessel mooring and fluid transfer technologies which were critical pacing factors enabling realization of the tanker-based floating production concept.

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Design And Construction Examples Of Loading Terminals And Floating Production Systems
Authors: Koenig D. , Klante H. , Engelskirchen J.
Published: December 2007

This paper deals with two designs:–an articulated loading tower for the North Sea and;–a similar to the CALM type single buoy production and storage system for optimum application in South East Asian waters;and additionally with–the construction, assembly and inshore erection of the single pointmoored articulated loading tower for the STATFJORD 'B' field in the North Sea.

Areas of technical and/or economic interest are depicted and discussed in more detail.

Introduction

Offshore loading terminals and floating production platforms are commonly well-known, are used worldwide because of a variety of reasons, and play their role also in future developments.

This paper deals mainly with three examples, two designs and one construction work, based on experience and expertise of and depicted out of a number of development, design, engineering, construction and erection projects like: projects like: - single point mooring buoys;–articulated loading towers;–floating LNG systems inclusive LNG loading units and components;–tension leg platforms (Figures 1 and 2);–semi-submersible production platforms;–mooring systems.

Of course, this paper can only highlight some aspects, which are contributing to the economics of such systems.

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Conoco's New Approach to Drill Site Construction in Difficult, Remote, Swamp and Jungle Terrain Irian Jaya, Indonesia
Authors: Rodriguez Fernando H.
Published: December 2007

In October 1982, Conoco Irian Jaya as operator: and partners: Pertamina, Inpex Bintuni Limited, and Moeco Irian Jaya Company, mobilized construction equipment from Singapore to the KBS "A" contract area in Irian Jaya, Indonesia for the purpose of constructing a base camp and drill three exploratory sites.

What made this construction effort different from others previously used in Irian Jaya; was that it incorporated several new and unique features, namely: A turnkey approach to construction; that is Conoco providing complete set of specifications and conditions with contractor assuming risks for a lump sum payment.Special equipment designed by contractor for Irian Jaya operations.An incentive to соmpensate or penalize contractor for helicopter hours flown below or above a predetermined number.Structural steel pile platform designs for two swamp locations (Ayot and Aum), as opposed to the more conventional corduroy timber log-plank arrangement.Drilling rig pads designed for specific heli-rig with limited extra space.

All work was successfully completed within the time frame stipulated in the contract, that is five months from the time the contractor was notified to begin mobilization of equipment, materials and personnel.
Total Analysis Computer for a Semi-Submersible Offshore Unit
Authors: Katayama Susumu , Morishita Sumitada , Ogawa Yasuko
Published: December 2007

An application of a computer system is investigated for the purpose of the assistance in the operation of a semi-submersible drilling unit.

A conceptional design of application softwares and a configuration of hardwares are studied.

The required major functions, flow chart, input data and output data are presented for each program.

The system seems effective for the calculations of loading, stability, mooring and riser analysis.
Offshore Pipeline Cathodic Protection Retrofit Project
Authors: Robb G. A.
Published: December 2007

The retrofit of cathodic protection facilities to two offshore pipelines is described. The reasons for the premature failure of the initial system, and for the selection of the retrofit method are discussed. The design of the retrofit facilities, comprising sleds bearing 1.8 tonnes of aluminium alloy, is described, and results of pre and post-installation potential surveys compared. A number of conclusions for future retrofit operations are drawn.
Design And Installation Of The North Rankin Trunkline And Slugcatcher
Authors: Seymour E.V. , Craze D.J. , Ruinen W.
Published: December 2007

Design studies for the offshore pipeline system for the North West Shelf project in Australia commenced in the early 1970's. Flow mode selection project in Australia commenced in the early 1970's. Flow mode selection resulting in a two-phase flow system for gas and condensate was completed in 1978. A diameter of 1016 mm was selected for the 134 km trunkline from the North Rankin platform to shore. During 1978 and 1979 detailed route surveys, oceanographic investigations and cyclone hindcast studies were completed, allowing detailed engineering to commence. Pipe was ordered from Japan in December 1980 and deliveries were made between April and August 1981. Pipe coating was carried out in Western Australia between August 1981 and March 1982. Pretrenching of portions of the pipeline route was completed between December 1981 and September 1982. Pipeline installation commenced in May 1982 and was completed, including post-trenching, by December 1982. Backfilling over the pipe was carried post-trenching, by December 1982. Backfilling over the pipe was carried out between August 1982 and June 1983. The tie-in to the platform and final hydrostatic test on the pipeline were completed by May 1983. Dewatering, drying and inerting is planned for October and November 1983. The slug catcher associated with the two-phase system will be completed by December 1983. The line is expected to be commissioned in June 1984.

Introduction

The trunkline from the North Rankin "A" platform to shore has recently been completed as the first part of the offshore pipeline system for the North West Shelf project. This pipeline originates from the platform in a water depth of 125 m, enters the mouth of Mermaid Sound, and terminates just south of Withnell Bay on the Burrup Peninsula, on the North West coastline of Western Australia (see Figure 1). The pipeline is 1016 mm (40 inches) in diameter and 134.2 km long. It will operate in two phase flow bringing both gas and condensate to the onshore plant near its landfall. A slugcatcher is under construction within the plant to receive liquid hydrocarbon slugs from the pipeline.

The trunkline to shore will initially serve only the one offshore platform and operate at about 25% of its capacity to supply the Western Australian domestic gas market. The domestic gas plant on the Burrup Peninsula is being constructed by Woodside to produce pipeline quality gas for delivery to the State Energy Commission and condensate for shipment by coastal tankers. A 1500 km long onshore pipeline from the Burrup Peninsula to Perth and other localities in the south west of the State of Western Perth and other localities in the south west of the State of Western Australia is being constructed by the State Energy Commission to supply local domestic and industrial users with up to 10.9 million m3/day of gas (385 MMSCFD).

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Leak Detection Survey of a 36 Inch Diameter 78 Mile Long Submarine Pipeline
Authors: van der Marel M , Sluyter E A
Published: December 2007

In the early part of 1982 a leak detection survey on the 36 inch diameter 78 miles (126 km) long E11 submarine pipeline was carried cut with optical and acoustical equipment during a period of 16 days. Two leaks were detected and identified as 0.5 inch (6 mm) cracks in two different circumferential welds.
Cementation of Intermediate Gas Sands in Central Luconia Province
Authors: Ratcliffe S H
Published: December 2007

This paper is a ‘case study’ of the techniques developed by Sarawak Shell Berhad (SSB) to successfully overcome problems encountered in primary cementing of shallow gas bearing intervals. During a recent gas development project, successful isolation from surface of three separate intermediate gas sands above the main reservoir was achieved by improved cement displacement efficiency and by improved pressure control of the gas sands during cement gellation. This was possible by drilling a smaller hole, minimising hole washouts, using fast setting cement, displacing the cement as fast as possible, reducing the length of cement columns by use of dual stage equipment and by applying backpressure above the cement columns immediately after displacement. The approach used can in principle be applied for the design of any cementation. The specific techniques developed will be applied in future gas developments to be undertaken by SSB, and may find applications with other operators facing similar problems.
Experience With Stratapax Drill Bits
Authors: Thant Myo
Published: December 2007

Polycrystalline Diamond Compact (PDC) bits have been extensively used in Polycrystalline Diamond Compact (PDC) bits have been extensively used in oil field drilling for sometime. Major performance gains have been reported for use of these bits in oil based drilling fluids, operating on mud motors.

This paper describes the experience in Sarowak and Sabah Shell Operations with PDC bits in water based drilling fluids and with rotary drilling. It represents the results of over 80 individual PDC bit runs incorporating over 30,000' of 8 1/2" hole drilled with 4 types of PDC bits from 3 manufacturers, and over 14,000' of 12 1/4" hole with 8 bit types from 4 manufacturers.

The paper discusses the PDC bit runs made, the performance in relation to conventional tri-cone bits, the effects of conventional hydraulics on PDC bit performance and the design of the PDC bits in terms of cutter density and placement, number of nozzles and their placement, and construction methods.

The outlook for future designs of PDC bit with respect to use in water base drilling fluids and on rotary drilling is presented.

The experience presented con be applied to drilling operations in a wide variety of areas to optimise usage of PDC bits in water based drilling fluids and on rotary drilling.

As a result of extensive testing within Sarawak and Sabah Shell operations, the use of 8 1/2" PDC bits in water based drilling fluids on rotary drilling con now be considered a proven application when drilling both clastics and carbonates. Only modest success has been achieved in 12 1/2" hole where tri-cone bit performance (Cost/ft) in generally softer clastic formations has proven more difficult to match with PDC bits.

Introduction

PDC (Stratapax) bit trials were initiated in Sarawak Shell Berhad/Sabah PDC (Stratapax) bit trials were initiated in Sarawak Shell Berhad/Sabah Shell Petroleum Company (SSB/SSPC) operations in July 1981. 30 runs in 12 1/4" size, 55 runs in 8 1/2" size and 4 runs in 6" size have been made. These trials involved a total of 57 bits of 14 different designs from 5 suppliers (Table 1). Bit prices range from US$15,000 to US$34,000 for 12 1/4" size and from US$10,000 to US$19,000 for 8 1/2" size.

All bit runs are judged in terms of profitability (cost per foot comparison against rock bits). Smaller diameter bits have been more successful with 70% success rate in 8 1/2" size (all 6" bit runs are also successful). Cost per foot (standard cost per boot equation using bit cost and cost of rig time) reductions vary from 19% to 250% in 8 1/2" bit runs (See Figures 1 and 2).

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Liquid Mud Plant Use and Benefit in the Arun Field
Authors: Soepardi Mulya , Kimiadi Irwanto
Published: December 2007

This paper briefly discusses the abnormally high temperature and pressure conditions in the Arun Gas Field and examines the special mud requirements caused by these extreme conditions.

The next section focuses on the Liquid Mud Plant (LMP) which has been developed for use in the Arun Fieid to meet these special drilling fluid requirements.

The paper's conclusion points out the particular benefits of the LMP which produce cost savings in terms of both time and materials.
Geothermal Well Cementing Technology
Authors: Shryock S H
Published: December 2007

The success or failure of drilling and completing Geothermal Wells depends reatly on available cementing technology. This requires not only having the knowledge of temperature stable competent materials but also a complete understanding of hole preparation, casing running procedures, mud displacement, lost circulation and the mixing-placing of the cement slurry.

Many steam fields are located where the formation contains poorly consolidated sedimentary deposits, rubblized shales and fractured volcanic rock. These formations are fragile in that some upheaval may have occurred disrupting the structural stability, and with low reservoir pressures, make them prime candidates for lost circulation problems. Many of the geothermal wells have to be drilled through and/or into these fractured formations. Loss of drilling mud or any other fluid put into the hole usually occurs creating problems which are expensive to eliminate. This paper offers methods which have proven successful in combating lost circulation during the drilling and casing cementing operations on geothermal wells located in fields all over the world.
Wareships Provide Economical Supply Base Alternative For Remote Area Drilling
Authors: Williams L.M. , Harrington J.P.
Published: December 2007

This paper discusses the three basic support-supply systems available to an operator when drilling offshore in remote, undeveloped areas of the world. These areoperate from a far distant port;construct one's own share base;use a wareship.

Each of these alternatives are discussed in detail, reviewing the various facets of support logistics for various cases. A cost comparison of the three alternatives for a typical one well and two well program are given. Some examples of Amoco Production Company's experience using wareships are discussed and advantages, other than cost, are listed.

Introduction

One of the major considerations, and often the most difficult, in mobilizing to drill an offshore exploratory well in a remote area is how to support and supply the drill rig. A remote area is one which is undeveloped or lacks adequate port and dock facilities and local infrastructure to provide a shore base. It is generally more than 150 nautical miles (278 km) distance from suitable port facilities. In these circumstances there are basically three alternative supply systems available to the operator:operate from the far distant port;build his own shore base;use a wareship.

This paper will examine each of these alternatives in detail and compare the overall costs for each. Amoco Production Company has used up to two wareships to support remote area operations in various regions of the world since 1974. Amoco's experience with their use is discussed later in the paper. Wareships provide advantages other than lower cost which will paper. Wareships provide advantages other than lower cost which will become evident within the paper.

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The Use of a Real-Time Wave and Weather Measurement Program to Assist in Offshore Operations and Tropical Cyclone Forecasting
Authors: Peters David J H
Published: December 2007

This paper describes a program set up by Conoco to improve weather forecasts in the Gulf of Mexico and minimize the risk to the safety of offshore personnel during severe tropical cyclone events.

A series of automated wind, wave and weather stations have been deployed in the Gulf to improve the real-time data base available for forecasting.

This data is used in support of a hurricane alert program that utilizes the latest state-of-the-art techniques in oceanography and meteorology. Conoco has seen benefits in safer and more efficient evacuations during severe tropical cyclone events, timely return offshore, and a large increase in the amount of real-time information available on these storms.
Hydraulic Fracturing Design and Evaluation: A Case History
Authors: Al-Khatib A. M. , King A. R. , Wilson M. S.
Published: December 2007

A unique method utilizing fluid entry surveys has been developed to improve fracture treatment designs at the Lost Hills Oil Field. Fluid entry surveys were conducted on thirty-two hydraulicly fractured wells in three different sections of the Lost Hills Oil Field. The surveys were analyzed to identify intervals of the completed zone contributing to flow (Contribution Ratio, CR) and to determine intervals of high water production.

Data from this type of analysis were then used to develop a correlation between the total thickness of the perforated/fractured zone and the fraction of that zone contributing to fluid flow (CR).

Considering this relationship as a potential design criteria, many fracture treatments were logged and evaluated. In conjunction with the aforementioned relationship, empirical correlations relating to perforation size and density, friction pressure losses and surface treatment rates were then used to modify the fracture treatment designs.
Foamed Cement: A Second Generation
Authors: Loeffler N. R.
Published: December 2007

Advanced technology in design and implementation of stable foamed cement systems now offers new solutions to critical oil-field cementing problems well beyond the original utility of lightweight slurries in reducing hydrostatic pressure across fracture-sensitive zones. Implications of new high-performance foamed cement capabilities are discussed for specialized applications such as thermal recovery, deep cementing in a narrow annular gap, lost-circulation control and stimulation across fractured or washed-out zones, as well as other unique advantages in primary cementing.

Specialized foamed cement studies reveal improved prevention of strength and permeability retrogression and enhanced thermal isolation for steamflood applications, all at significantly reduced fracture stress as compared to conventional extended systems. Because of their unique rheology, high-performance foam slurries can be designed to exhibit moderate thixotropy but maintain excellent fluidity at extremely low shear. Cement foams further aid zonal isolation due to improved shear bonding and enhanced pipe/cement/formation contact as a result of the expansive nature of the slurry during setting.

A number of successful jobs are documented in which lightweight nitrified systems placed across weak and washed-out zones have been successfully perforated and fractured. Several new potential applications for moderate to high-density, stable, nitrified slurries are also discussed based on their unique performance.
Regional Models of Drilling Activity: Forecasting Rig Count in The Permian Basin
Authors: Dollens K. B. , Williams J. L.
Published: December 2007

Ordinary least squares regression analysis is used to develop a model to forecast the Permian Basin rig count. Comparative analyses of various independent variables in linear, logarithmic and rate-of-change form indicate that approximately ninety percent of the variation in rig count can be explained using four independent variables. These variables represent Windfall Profits Tax, the maximum marginal personal income tax rate, crude oil price, and hourly wages of production workers in oil and gas extraction.
Optimizing Diamond Bit/Turbine Drilling Performance
Authors: Mason C. M.
Published: December 2007

This paper explains the basic concepts and techniques necessary in optimizing and improving a turbine/diamond bit drilling application. Recent turbine/diamond bit drilling experience in the Morrow Formation of the Anadarko Basin indicates that a linear relationship exists between penetration rate and turbine output power available at the bit. Turbine output power is a linear function of the mud weight but more importantly, it is a function of the flow rate raised to the third power; therefore, slight increases in flow rate will yield significant increases in turbine output power. The increased turbine output power allows a higher bit weight which normally results in an increased penetration rate. Actual field data is presented which supports these relationships. Since fluid flow rate is of primary importance this paper describes techniques for maximizing flow rate. The importance of lithology is also presented. Finally, turbine/ diamond bit drilling economic evaluation is described.
Drilling in the Fletcher Area of the Deep Anadarko Basin
Authors: Humphrey D. R.
Published: December 2007

Drilling 20,000'+ high-pressure gas wells in southeastern Oklahoma (figure 1) presented numerous organizational, operational, and technological problems. Long open-hole sections between surface problems. Long open-hole sections between surface pipe shoe and intermediate pipe setting depth pipe shoe and intermediate pipe setting depth presented a number of problems. Among them were presented a number of problems. Among them were hole stability, corrosive gas influxes, over- and under-pressured formations and drill string fatigue. Deep high pressure sections below intermediate casing required high-strength tubulars and wellhead equipment. Industry shortages of materials and equipment plus inexperienced personnel compounded the difficulties. personnel compounded the difficulties.
Techniques for Successful Liner Cementing in the Anadarko Basin
Authors: Muncrief R. E. , LaFollette R. E. , Rainbolt C. G.
Published: December 2007

By planning in advance and following proven techniques, many of the problems associated with the running and cementing of deep liners can be alleviated. Detailed considerations of casing designs, drilling fluid properties, cement designs, and special techniques are discussed.

Due to the nature of wells drilled in the Anadarko Basin, as with any area where abnormally high formation pressures are encountered, it has been noted that poor primary cementing jobs can often plague a well throughout its productive life. This paper deals with procedures which can be followed that should assist in planning and performing the job. Shown will be four separate tubular configurations dealing with three typical Anadarko Basin productive objectives.
Field Experience With Floodwater Diversion by Complexed Biopolymers
Authors: Abdo M. K. , Chung H. S. , Phelps C. H. , Klaric T. M.
Published: December 2007

Due to preferential flow of the injected water through the most permeable zones, waterflooding of stratified reservoirs is generally inefficient. A process for improving the performance of waterfloods in such reservoirs has been developed; it is based on complexing biopolymers with multivalent cations to form gels for selective blocking of water-thief zones, thereby diverting the trailing floodwater to previously under-invaded reservoir regions to recover by-passed oil. This polymeric modification of stratification and of water injection profile leads to increased volumetric sweep of the reservoir by the floodwater and, in turn, to improved oil production. This paper summarizes Mobil's experience in its first seven field projects in Oklahoma using this process. A total of two hundred and five injection wells were treated with complexed biopolymers, resulting in substantial alteration of water flow patterns and in significant incremental oil recovery.
A Laboratory Study of CO2 Foam Properties and Displacement Mechanism
Authors: Wang G. C.
Published: December 2007

This paper presents the results of a comprehensive study of CO2-foam physical properties and a series of displacement tests using a high pressure glass-lined flow-tube. The foam properties were studied in terms of foam quality, quantity and stability as functions of temperature, pressure surfactant concentration and surfactant mixing ratio. The CO2-foam displacement tests were performed using SACROC and Rock Creek crude oils, and the oil recovery efficiency was visually investigated tor both secondary and tertiary modes with varying CO2 slug injection sequence and surfactant concentration.

The results indicate that the increase of pressure promotes foam stability whereas the increase of temperature does the contrary. It was found that CO2-foam generated either externally or internally is susceptible to quick disintegration on contact with crude oil. Therefore, the control of CO2 mobility using a foaming agent could be effective only within a short distance from the injection well. Any improvement on oil recovery or gas-oil ratio is probably obtained as a result of foam blockage of the permeable streaks or channels in the injection formation. It was found that excessively high concentrations of surfactant (foaming agent) may cause "foam barrier" to decrease sweep efficiency.
Handling Water Treating Problems In Steam Injection Projects
Authors: Fincher D.R. , Hagist F.C. , Gallagher D.L.
Published: December 2007

Publication Rights Reserved

This paper was to be presented at the 40th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colorado, October 3–6, 1965, and is considered to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such abstract elsewhere after publication in the Journal of Petroleum Technology or Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation of the paper.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Water to be used for steam injection projects must contain a very small amount of hardness ions and oxygen. corrosion should be monitored at several locations. Methods used to accomplish these objectives are described.

Introduction

Steam has been used to transfer energy for many years. In the oil field, steam has been used to heat oil for demulsification and viscosity-reduction purposes, as well as used as a source of power to drill oil wells. During the past few years, much emphasis has been placed on thermal recovery of low-gravity viscous crude by the injection of steam into the reservoir. This use of steam was tried in the 1930s, but it has reached real prominence in the oil industry only during the past five to ten years. Today, much interest exists in the generation of steam for injection into oil bearing strata, and many approaches are offered to the handling of this fluid.

Steam Generator Equipment and Water Sources

Many authors describe the qualities of the waters that are necessary for steam generation. The pitfalls of poor handling of boiler feed water are well known, and they have been made the subject of books and other literature. This paper deals with water treatment and handling designed for a steam product of approximately 80 per cent quality. The equipment referred to includes only the once-through steam generator where there is neither recirculation of the water phase nor blowdown of concentrated, soluble or insoluble, salts from the steam generator.
A Model for Calculating Polymer Injectivity Including the Effects of Shear Degradation
Authors: Sorbie K. S. , Roberts L. J.
Published: December 2007

Polymers are frequently injected into oil reservoirs in order to improve recovery. As they reduce the in-situ mobility of the aqueous phase (either by viscosity increase or permeability reduction), the fluid injectivity generally drops. It is very useful to be able to estimate in advance from a few laboratory measured quantities (a) the injectivity of the polymer and (b) whether the polymer is likely to be seriously degraded by the high shear experienced in the near-wellbore region. It is difficult to calculate the injectivity of the polymer solutions due to their complex rheological behaviour within porous media, especially when the polymer mechanically degrades.

In this paper, we investigate one approach to calculating the injectivity of polymers in the general case where mechanical degradation occurs. A kinetic model for polymer degradation is proposed which is used to obtain the radial viscosity profile of the degrading polymer. This may in turn be used to calculate the steady-state pressure drops associated with the degrading polymer. The model is based on a discrete multicomponent representation of the polymer molecular weight distribution (MWD). During mechanical degradation, the MWD changes as higher components degrade into lower molecular weight fragments. The degradation rate of a given component of the MWD is related to the local shear/elongational stress within the porous medium and the concentration of the component (Ci).

The model is used to match the results of experiments studying the shear degradation of polyacrylamide (PAM) in radial sandstone cores. The quantitative predictions of the model are very satisfactory. In addition, the model gives insight into the mechanism of shear degradation of polymers in porous media.
Analysis of the Performance of the M-6 Area of the Tia Juana Field, Venezuela, under Primary, Steam-Soak, and Steamdrive Conditions
Authors: Puig Fernando , Schenk Leendert
Published: December 2007

This paper deals with the reservoir performance of the M-6 Project Area in the south-east of the Tia Juana field. The field is one of the four heavy oil fields located along the eastern shore of Lake Maracaibo in Venezuela, collectively known as the Bolivar Coast fields. Since the early 1930's the area covered by these fields suhsides, an observation which one could not fail to make in this swampy coastal area. The subsidence prompted the construction of coastal dykes for protection against flooding and also the installation of a network of benchmarks which are surveyed biannually, to monitor ground level changes in detail. It soon became apparent that there was a direct correlation between subsidence and oil withdrawal, implying that the compaction phenomenon acts as an oil production mechanism. This established a cause/effect chain of oil production/pressure decline/formation compaction/surface subsidence which has since been a fertile field for investigation.

The application of thermal recovery methods in these fields has been geared to make full use of the compaction pheonmenon. First steam soak is applied to accelerate oil production, bringing down the reservoir pressure to the lowest possible level. This maximises the oil recovery contribution by compaction, which is as high as 15% STOIIP. The resulting low reservoir pressure level is favourable for steam drive as follow-up phase.

Because subsidence is measured on a routine basis in the fields and compaction is not, an important aspect of the study is the subsidence/compaction relationship. There are theoretical considerations which indicate that compaction approximately equals subsidence volumetrically for reservoirs which are large in relation to depth. This is supported for the M-6 area by the results of the reservoir performance analysis. The compaction of the area has been compared with theoretical values based on formation compressibilities measured on Tia Juana core samples, petrophysical data and the reservoir pressure performance. To obtain a match the pressure data had to be adjusted for vertical heterogeneity of the oil sands and time delay in the pressure decline of shales caused by their extremely low permeability. The calculation procedure developed to describe the reservoir behaviour of Bolivar Coast type heavy oil fields during depletion enhanced by steam soak, is considered satisfactory for practical considerations (oil production forecasts, dyke design).

During the steam drive phase of M-6 the relative importance of compaction has strongly decreased. Additional performance is required, however, to enable definitive conclusions on the effect of steam drive on compaction.
An Automated Method for Predicting Full-Scale CO2 Flood Performance Based on Detailed Pattern Flood Simulations
Authors: Rester Stephen , Todd M. R.
Published: December 2007

A procedure is described for estimating the response of a field scale CO2 flood from a limited number of simulations of pattern flood symmetry elements. This procedure accounts for areally varying reservoir properties, areally varying conditions when CO2 injection is initiated, phased conversion of injectors to CO2, and shutin criteria for producers. Examples of the use of this procedure are given.
Progress Report: Big Muddy Field Low-Tension Flood Demonstration Project with Emphasis on Injectivity and Mobility
Authors: Ferrell H. H. , Gregory M. D. , Borah M. T.
Published: December 2007

A Demonstration Project for the low tension flood process was initiated in the Big Muddy Field in 1980. This paper introduces the concept of optimum slug mobility for maximum oil recovery and injectivity in the Second Wall Creek reservoir. A procedure to determine the optimum mobility for a low tension flood is described, and the early field performance data is compared to the laboratory design.
Statistical Network Theory of Three-Phase Relative Permeabilities
Authors: Heiba A. A. , Davis H. T. , Scriven L. E.
Published: December 2007

The statistical network model and percolation theory of capillary pressure and relative permeabilities in low capillary number displacements account for much of the behavior of two fluid phases under the gamut of wetting conditions encountered in reservoir rocks (SPE 11015, SPE 12172). The model and theory are here extended to three fluid phases, viz. gas, oil, and water. For convenience in illustrating the theory the gas is taken as everywhere nonwetting against the oil and water, and the oil as everywhere nonwetting against the water.

The starting point is the representation of the chaotic connectivity of porespace by a bond-disordered Bethe tree; also as before, the bonds are characterized by a single statistically distributed parameter, porethroat radius, with which other pore dimensions are regarded as completely correlated. The distribution of the three phases among the poresegments, or bonds, is taken as controlled by capillary pressure, wettability, and prior occupancy criteria of allowability to a locally invading phase: the complication is the competition among three phases. These criteria and accessibilities evaluated with percolation theory in turn define the pore filling sequence in terms of phase-occupancy-conditioned poresize distributions. From this follow occupancy-conditioned distributions of segment volumes, and thus saturations; and occupancy-conditioned distributions of hydraulic conductance, from which relative permeabilities are again calculated using Stinchcombe's method from percolation theory.

Examples include simultaneous displacement of oil by gas and water, and waterflooding in the presence of an evolved gas saturation. Effects of oil wettability and of phase swelling by mass transfer are touched on. The predictions of relative permeabilities and saturation states accessible by a given process from a given initial state highlight the sensitivity of displacements to the history of the process, or to the details of a laboratory experiment, when three phases are present. Limited comparisons are made with the few published data.
A Group Contribution Activity Coefficient Model for Enhanced Oil Recovery Process Involving Electrolyte Solutions: Part II—Solutions in the Presence of Partial Molecular Association
Authors: Chien M. C. H. , Lee Sheng-Tai
Published: December 2007

In Part I of this series, a group contribution activity coefficient model for electrolyte solutions was developed based on Debye-Hückel theory, solvation theory and local composition theory. It was demonstrated that the model can satisfactorily correlate the complex thermodynamic properties of electrolyte solutions in the absence of partial molecular association. In this work, the above described model is extended to electrolyte solutions which exhibit partial molecular association.

In addition to the thermodynamic theories introduced in the preceding paper, the present model further includes the chemical equilibrium theory to represent chemical association between molecular species in the solution. The equilibrium thermodynamic properties are then solved by invoking a recently developed simultaneous phase and chemical equilibrium calculation scheme.

The reliability of the proposed model is tested for two important thermodynamic behaviors occurring in related solutions, namely, micellization and the phase transition upon salt addition.

First, experimental mean ionic activity coefficients of the homologous sodium carboxylates in aqueous solutions are compared with the correlation. Chemical equilibria are introduced to account for the micellization of sodium carboxylates. The chemical equilibrium constant and aggregation number are found to increase with the length of hydrocarbon tail in the ampliphile. The sudden drop in the mean ionic activity coefficient caused by micellization is correctly predicted. The average deviations between the predicted mean ionic activity coefficients and experimental-data are generally less than 5%.

Second, published experimental phase behavior data of water-NaCl-t-butanol-n-paraffin mixtures are compared with the correlations. It is found that the aggregation between water and tbutanol is responsible for the abnormal amounts of water in the upper phase, while the aggregation between water and oil is responsible for the large amounts of oil in the middle phase. The aggregations are modelled by chemical equilibria. The type II-/III/II+ phase transition for the above system upon successive addition of salts are correctly predicted. The critical salinities and phase compositions are also well correlated. Studies also show that the vertices of the three phase region are very sensitive to the alcohol concentration and suggest empirical correlations, such as Hand plots, may have to consider the surfactant effect as well as the salinity effect on the vertices of the three phase region.

Our studies show that the model is capable of modelling micellization and the complex phase transion of oil-water mixture containing an amphilphile, and that it can be incorporated in a simulator to study the mechanisms of recovery processes involving electrolyte solutions or to design such processes.
A Laboratory and Computer Model Evaluation of Immiscible CO2 Flooding in a Low-Temperature Reservoir
Authors: Sigmund P. M. , Kerr William , MacPherson R. E.
Published: December 2007

This paper describes the procedures used in evaluating CO2 for immiscible displacement of a 22-24 API oil saturated at its bubble point of 1650 psi (11373 kPa). The oil is contained in the low temperature 95.9°F (35.5°C) Glauconitic sand of the Retlaw Mannville V Pool located in South Eastern Alberta. A combination of laboratory experimental data and computer model studies used in the evaluation are discussed.

Phase behaviour and multiphase flow characteristics are examined for the CO2 – reservoir oil system at conditions where liquid/liquid and liquid/liquid/vapour phases exist. Measured experimental equilibrium phase, compositions, densities and viscosities are reported for single contact and multiply-contacted mixtures of recombined oil and CO2. Measurement of composition profiles obtained during slim tube displacement of recombined oil by CO2 at L/L and L/L/V conditions of temperature and pressure are also reported. The high displacement efficiencies that occur are attributed to the solvency of the CO2 rich phase that forms in the flood front after methane and nitrogen have been stripped from the oil. The effects of swelling and viscosity reduction on displacement efficiency are also discussed.

A 1-D model, calibrated with the experimental data was used to predict the effect of using a 25% PV CO2 slug before waterflood on recovery in swept portions of the pool. The results suggest that the use of CO2 followed by waterflood will result in high microscopic displacement efficiencies in swept portions of the reservoir even though miscibility between oil and CO2 does not develop.
Pressure Transients Caused by Fracturing
Authors: Oliver D. S.
Published: December 2007

Porous-elastic theory is used to explain how hydraulic fracturing operations can cause nearly instantaneous pressure responses in nearby wells. The theory is applied to a field example where it is used to estimate fracture azimuth for a vertical hydraulic fracture. Knowledge of fracture azimuth can be used to increase productivity from a reservoir.