bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of Gelled Polymer Projects Conducted in Central Kansas
Authors: Jack L. M. , Schoeling L. G. , Green D. W.
Published: December 2007

Crosslinked polymer treatments are being implemented on both the injection and production - side in central Kansas to increase oil production and reduce water-oil ratios. In the past few years, Murfin Drilling Company has utilized these gel treatments and have had both successes and failures. This paper presents the results of two injection-side projects in the Lansing-Kansas City formation and four producing-side treatments in the Arbuckle formation from an independent oil operator's point of view.

The Lansing-Kansas City formation is a sequence of limestone reservoirs separated by shales. When these reservoirs are simultaneously waterflooded, usually the highest permeability zone takes the majority of the brine, causing poor sweep efficiency in the waterflood. Injection of gelled polymers can plug these high permeability zones thus increasing the waterflood sweep efficiency. Results from two projects in Decatur and Graham Counties will be discussed.

The Arbuckle formation is typically a dolimitic limestone reservoir underlain by bottom water. Water coning usually occurs due to gradients in flow potential established around the wellbore by oil production. If vertical permeability exists, this difference in flow potential causes mobile water to flow into the wellbore. Gelled polymer treatments can reduce the permeability to this mobile water, thus reducing the producing water-oil ratio. Typically, a sharp decrease in WOR is noted immediately following a treatment. This decrease is followed by an increasing WOR as the oil production gradually resumes its normal decline. Four treatments conducted in Ellis, Graham, and Rooks Counties will be discussed.
A Further Stability Analysis for the ADI Procedure as Applied to Singular Matrices
Authors: Taylor Howard L.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Solving =, by numerical techniques requires application of ADI procedures to singular matrices which leads to numerical instability for small values of the ADI parameter w.

A study of this problem demonstrates that restriction of IRml/w (where Rm is the largest residual) will control these instabilities. Applications to compressible and incompressible Darcy flow are discussed.

Introduction

The equations of reservoir flow commonly have the following form V (KVP) Q where in two dimensions,

..........................................(1)

The ADI (or Peaceman-Rachford) procedure is one of the methods frequently used to solve the associated difference equations. In our mathematical discussion we will write these difference equations approximating the above differential equation In matrix notation as Au = q where u is a vector representing pressure or potential at node points, q is a vector of production rates and points, q is a vector of production rates and A is the matrix of coefficients which depend on the permeabilities or mobilities.

In using this procedure numerical instabilities often occur for small values of the parameter w,, particularly for incompressible parameter w,, particularly for incompressible flow with no-flow boundaries. These instabilities have been observed often and techniques to avoid them have been suggested. In this paper we will consider the mathematical and computational origin of these instabilities. This study will allow us to suggest improved methods of handling such problems and will give us a better understanding of the roll of the parameter w in the iteration process. process.

MATRIX DESCRIPTION OF THE ADI PROCEDURE

Consider three symmetric semi-definite n × n matrices A, H, and V such that

..........................................(2)

Let D be a symmetric, positive definite normalizing matrix, q a given vector, Uo an arbitrary initial vector, and w-a number for any positive integer k. Then the ADI procedure can be defined by procedure can be defined by ..........................................(3)

and

..........................................(4)

Here the vectors will approximate a solution to the equation

..........................................(5)
Combination of Numerical and Analytical Techniques To Improve Waterflood Model Efficiency
Authors: Roper William A. , Merchant Jack E. , Duvall Carolyn A.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Description of flow near wells is difficult when modeling steady-state flow in an oil reservoir. A technique is presented which avoids this difficulty by describing pressure and velocity in part numerically and in part analytically.

Introduction

Numerous mathematical models have been developed to predict water-flood recovery. Often a steady-state or semisteady-state model will yield adequate predictions. The method described predictions. The method described herein is the basis of an improved steady-state reservoir model.

A frequent numerical approach is to represent the reservoir by a grid network and to determine the steady-state pressure distribution by relaxation. pressure distribution by relaxation. The principle weakness of this method is that a rectangular grid is poorly suited to represent the pressure distribution around wells. Flow near wells is radially symmetrical and rapidly changing. Flow in a grid network is assumed to occur only along grid lines. Figure 1 depicts the difficulty of representing flow near a source by a grid network. For this reason most numerical models require a large number of grid points to adequately describe flow.

The method presented here utilizes pressure distribution and flow pressure distribution and flow velocities which are in part analytical. In essence, the point sources and sink are subtracted from the original flow problem, leaving a modified flow problem, leaving a modified flow problem with distributed sources and sinks. problem with distributed sources and sinks. The modified flow problem can then be solved numerically with less difficulty than the original flow problem.

DEVELOPMENT

The mathematical analog to steady state flow in a reservoir is based on Darcy's Law and the conservation equation. If the three-dimensional physical system is reduced to a two-physical system is reduced to a two-dimensional model, and if other simplifying assumptions are made, flow in a reservoir can be related to the solution of the following equations.
A Study of the Effects of Bit Gauge Length and Stabilizer Placement on the Build and Drop Tendencies of PDC Bits
Authors: O’Bryan P. L. , Huston C. W.
Published: December 2007

This paper presents field data that indicates the gauge on Polycrystalline Diamond Compact (PDC) bits may act as a near bit stabilizer. When used with a pendulum bottomhole assembly (BHA) having stabilizers placed at 60 and 90 feet above the bit, the BHA can have the tendencies of a building assembly.

Field observations were verified by computer simulation using a two-dimensional static BHA model providing a predictive method for BHA analysis when using PDC bits. The results of a sensitivity analysis using the computer model are presented and will provide guidelines for stabilizer placement when using PDC bits in straight hole drilling applications. Included in the analysis will be the effects of PDC bit gauge length, wellbore inclination, drill collar stiffness, and hole diameter on the build and drop tendencies of pendulum BHA's when used with PDC bits as a function of weight on bit (WOB).
Experimental and Modeling Studies of Asphaltene Equilibria for a Reservoir Under CO2 Injection
Authors: Novosad Z. , Costain T. G.
Published: December 2007

An experimental and numerical modeling program was undertaken to evaluate stability of asphaltenes in a 29°API gravity reservoir undergoing tertiary CO2 injection. The study aimed to develop a better understanding of asphaltic solids formation and possible ways of controlling it.

Asphaltene phase behaviour and the extent of asphaltene precipitation in live oil were investigated for a range of pressures and temperatures, in presence of CO2 and normal alkanes as precipitants. The nature of the solids formed was also studied using a variety of techniques. A molecular thermodynamic model with asphaltene-asphaltene and asphaltene-resin association was used to correlate the asphaltene precipitation data. The model not only matched the trends in asphaltene behaviour, but did so to a degree quantitatively.

The thermodynamic model calculations provided valuable insight into the behaviour of this complex system Destabilization of asphaltenes by CO2, the degree of which varied with system pressure and temperature, can be shown to be related to specific changes in the properties of the liquid (oil) phase, brought about by changes in system composition, pressure, and temperature. In agreement with observations in a recently completed CO2 flood pilot project, the model indicated asphaltene destabilization along the entire wellbore under the conditions prevailing in the pilot producing wells. The tuned asphaltene model allowed examination of asphaltene stability under a variety of wellbore conditions and gave indication of operating scenarios that should be avoided in a field project to minimize the solids formation.

The predictive capabilities of the model are critically evaluated in view of scarcity of reliable data on asphaltene properties and in-situ structure.
Reservoir Characterization by Seismic Classification Maps
Authors: Sonneland L. , Barkved O. , Hagenes O.
Published: December 2007

In a recent paper we introduced the seismic classifier concept. We have demonstrated how classifiers can help us to identify particular facets of the subsurface "architecture" and how they combine the structural interpretation and the 3D seismic data in a very compact way. Through classifiers like reflection intensity, acoustic impedance contrast and reflection hetereogenity indicator the interpreter can in a quantitative sense discriminate between properties relevant for his particular problem.

We will extend our classifier-family further and point out how the "resolution" in our data-set effect the construction of these new classifier maps. Interpretations based on classifier-maps require new functionality in the application software. Based on examples from case studies we will identify these requirements and apply them. Of particular relevance is when the projections of the geological model onto the classifier map can be revealed. Then these maps can indicate the paleogeographical scene.

Finally we will present some results from our efforts in compressing even more information into the classifier display. Among these are some 3D graphics displays where the classifier variations are distributed along a topographical surface. The objective here is to improve the interpreter's ability to comprehend the vast information volume he is dealing with, through meaningful graphics.
Naturally Occurring Radioactive Material Logging
Authors: Carroll J. F. , Scott H. D. , Gunn R. A. , O'Brien M. S.
Published: December 2007

The phenomenon of scaling in both downhole and surface production equipment is well knownwhere water-drive reservoirs are in production. Sulfate scales, consisting mainly of barium,strontium, and calcium, occur on surface and downhole equipment. Traces of radium may be present in such scales, making them radioactive. Removal and cleaning of such scaled equipment for later use can present a potential health hazard. Alternatively, the equipment may have to be removed, stored, and disposed of according to established procedures for low-level radioactive waste.

Measurement of radiation levels at the wellsite requires the use of rugged gamma ray survey meters by specially trained personnel. Measurement of low levels of radiation on individual tubing sections can be difficult in the presence of natural background radiation. However,gamma ray well logging tools are very sensitive instruments and can make radiation measurements inside scaled tubing in the well with less sensitivity to background signal.

To evaluate scale radioactivity before removing the tubing from the well, a reconnaissance logging technique has been developed that uses a gamma ray logging tool calibrated specifically for radium. This new technique allows better decisions to be made prior to removing the tubing.

In this paper, procedures used to calibrate the logging tool are described, together withmeasurements made to correct for the effect of tubing wall thickness. Field examples are presented where this technique has been successfully applied.
Reasons for Differences in Recovery Efficiency
Authors: Arps J.J.
Published: December 2007

Introduction

The recovery efficiency or the percentage of stock-tank oil in place in the reservoir recoverable by natural expulsion mechanisms is known to vary over a wide range. Under the most favorable conditions recovery efficiencies as high as 85 percent to 90 percent of the oil in place have been repower At the other end of the scale recoveries as low as 10 percent of the oil in place have been experienced. The principal reason for such differences is in the displacement mechanism itself specifically whether the oil is displaced by invading water (water drive), by the expanding gas coming out of solution (solution gas drive) or by an expanding gas cap, or by gravity segregation.

This paper is a continuation of the study, made by the API subcommittee on recovery efficiency, which culminated in Nov., 1967, with the publication of API Bulletin D14, "A Statistical Analysis of Recovery Efficiency". For this study the sub-committee used case histories on some 312 producing oil reservoirs from which certain empirical relationships were derived by regression analysis. For the water-drive cases the following regression., equation for the recovery efficiency was found:

..........................................(1)

The basic data used for this equation came almost exclusively from sand and sandstone reservoirs. A comparison of the observed and computed values of the recovery factor for 70 water drive reservoirs is reproduced here as Fig. 1.

For the reservoirs under a solution-gas-drive mechanism the subcommittee established for the recovery efficiency below the bubble point the following regression equation:

..........................................(2)

The basic data used for this equation came from a variety of rock types, including carbonate rocks. A comparison of observed and computed values of the recovery factors from the 80 solution-gas-drive reservoirs below bubble point used in this study is shown as Fig. 2. For the units and nomenclature, reference may be made to the list of symbols at the end of this paper.

The cumulative distribution of the recovery efficiencies for four drive mechanisms as determined by this same subcommittee study is shown here as on the log-normal graph of Fig. 3. It may be noted that the recovery efficiencies both for water drive and for solution-gas drive below the bubble point follow a typical log-normal distribution as indicated by their straight-line trends on these charts.

P. 77^
New Techniques and Quality Control Find Success in Enhancing Productivity and Minimizing Proppant Flowback
Authors: Ely J. W. , Arnold W. T. , Holditch S. A.
Published: December 2007

Hydraulic fracturing has yielded successful stimulation results in hydrocarbon producing reservoirs for over 40 years. In certain reservoirs, however, hydraulic fracturing does not always achieve the desired results. In some cases, due to excess production of proppant or excess water production, the fracture treatment can cause operating problems. A paper published by Robinson et al.1 discussed the merits of flowing back a well on a small choke to minimize the closure stress on the proppant. In that paper, a recommendation was made to monitor the tubing pressures after the fracture treatment, and if closure times appear to be excessive, then one should initiate a low rate flowback of the fracture fluid to assist fracture closure.

Approximately 4 years ago, the initial treatment designed to use the "forced closure" technique was conducted on a Canyon Sand well in west Texas. The fracture treatment was successful, but the most surprising aspect of the procedure was that significantly less proppant was produced after the treatment when compared to other wells in the area. In the last few years, the forced closure technique has been used on several hundred wells in many different geologic horizons.

The forced closure technique, alone, may not be the reason for success. However, the use of forced closure combined with the use of aggressive proppant scheduling and the application of "intense quality control" can lead to dramatic improvements in stimulation success. Intense quality control involves field testing of fracturing fluids at reservoir temperature prior to pumping operations.2 In this paper, field results have been included to illustrate how the forced closure technique, coupled with high proppant concentrations and intense quality control, can significantly increase the productivity of low permeability oil and gas wells.
Three-Dimensional Well Model Pre-Processors for Reservoir Simulation With Horizontal and Curved Inclined Wells
Authors: Morita N. , Singh S. P. , Chen H. S. , Whitfill D. L.
Published: December 2007

This paper presents 3-D pre-processors to calculate proper well inflow relations for modeling horizontal or curved inclined wells in a finite difference reservoir simulator.

The technique frequently used in the oil industry is Peaceman’s analytical well model although several assumptions are violated in the case of a horizontal well. An error analysis was conducted for the well model proposed by Peaceman. Based upon this analysis, new methods are proposed to improve the accuracy of modeling horizontal and curved inclined wells.
The Concept of Critical Rate in Gas Coning and Its Use in Production Forecasting
Authors: Konieczek J.
Published: December 2007

Published critical rate formulae for steady state oil production from beneath a gascap pose difficulties when used to forecast well performance in practical situations. In this paper the dynamic deformation of the gas/oil contact is described based on the Dupuit-Forchheimer potential. By semi-analytical methods the production performance is derived for a horizontal oil well in a 2 phase system, chosen because of its simple geometry and because such wells are of recent interest.

The solutions distinguish two transient periods, before and after gas breakthrough. These demonstrate that the oil potential is initially constrained only by the vertical lift capacity, but declines after gas breakthrough in proportion to the inverse of the cumulative production. Typical for a horizontal well, some 20-30% of movable oil is produced under transient conditions. The decline changes again during the semi-steady-state period when the drainage area limits begin to have an effect.

The results are presented by dimensionless decline type-curves for various well spacings and well elevations.
Market Potential Of Deep Delaware Basin Gas Reserves
Authors: Bulla C.J.
Published: December 2007

The natural gas industry has had a unique and exciting growth record since the inception of the high pressure long distance pipelines in the early 1930's.

From a very limited requirement for natural gas in 1930 the total United States market has grown steadily, until in 1966 we produced and consumed slightly less than eighteen trillion cubic feet of gas. But is this the end? Is it true, as some have speculated, that the majority of the future energy requirements in this country will be satisfied not by natural gas but by nuclear energy, electricity, solar energy or other presently unknown sources of potential energy?

The Future Requirements Committee, a group made up of transmission and distribution company executives, believes otherwise. They have predicted that by 1975 the energy market in the United States will require 25.5 trillion cubic feet of natural gas per year, and by 1990 this requirement will increase to 36.0 trillion cubic feet per year. In cumulative figures this means that from the end of 1967 through 1990 the natural gas industry must discover and produce over 625 trillion cubic feet of natural gas if it is to serve this total requirement.

With the very large marketing area of the inter and intra-state transmission pipelines presently taking gas from the Permian Basin and the interest of other major pipelines in Permian Basin gas reserves it might appear that the market potential of deep Delaware Basin reserves is rather academic. Perhaps the real question should be, can the Deep Delaware Basin supply all of the gas reserves which will be demanded of it?
Know-How of Superdeep Drilling in the GDR
Authors: Kraus W. , Geisler H. J. , Heyne B. , Mohrmann R.
Published: December 2007

The paper describes conditions, features experience and practical knowledge of deep-hole drilling in the German Democratic Republic taking as an example borehole Schwerin-1.

The characteristics of Zechstein formation have a determining influence on planning and executing drilling operations. They affect to a high degree the well location, the casing, mud and cementing program, as well as complications encountered during drilling.

Thanks to the drilling of superdeep and a lot of deep holes GDR experts have ready-to-use know-how in all fields of deep-hole drilling.
Relief Well Breakthrough at Problem Well 2/4-14 In the North Sea
Authors: Aadnoy B. S. , Bakoy P.
Published: December 2007

After being out of control for a year, an underground blowout in well 2/4-14 in the North sea was successfully killed through a relief well. This paper covers mainly the breakthrough phase. A theory for relief well breakthrough is also presented along with the field case.
Effective Well Test Interpretation and Early Reservoir Simulation Help To Optimize Rotliegend Gas Reservoir Development
Authors: Andreae H. H. , Schalow G.
Published: December 2007

The sandstones of the Rotliegend formation are found throughout northwestern Germany as thick Permian deposits underlying permian evaporites. They are a large potential for Germany's present and future gas production. The reservoirs are located at depths of 4,500 to 5,000 m. Average reservoir thickness is between 10 and 150 m. Average porosities range between 10 and 18% and permeabilities between a few microdarcies and 1000 millidarcies.

The paper deals with reservoir evaluation in the Westerholz field, where three wells have produced gas from the Wustrow sandstone of the Rotliegendes for three years. It discusses the combined use of pressure transient interpretation, RFT pressure profiles, and production/interference test analysis.
Comprehensive Experimental Investigation of Drilled Cuttings Transport In Inclined Wells Including the Effects of Rotation and Eccentricity
Authors: Peden J. M. , Ford J. T. , Oyeneyin M. B.
Published: December 2007

This paper presents the findings to date of a research project initiated to investigate drilled cuttings transport in deviated wellbores. The research programme utilises a simulated wellbore to study the mechanisms of cuttings transport in deviated wells. The cuttings transport column, has been designed to allow easy variation of well geometry in terms of annular size, deviation angle and pipe eccentricity. The column is also equipped with a variable speed motor/gear system for the simulation of drillpipe rotation.

This study has investigated the influence of a range of variables such as hole angle, fluid rheology, cuttings size, drillpipe eccentricity, circulation rate, annular size, and pipe rotation on cuttings transport efficiency using the concept of Minimum Transport Velocity (MTV). This concept presumes that a hole can be efficiently cleaned by either maintaining cuttings rolling or in suspension, if the annular velocity is equal to or greater than a minimum transport velocity for that operational condition. Thus, the lower the minimum transport velocity the easier it is to efficiently clean the hole.

The results so far have shown that depending on the level of eccentricity and annular size, fluid rheology as well as flow regime appear to have highest impact on the MTV. With low viscosity circulating fluid, turbulent flow regime seems to predominate for concentric pipes with suspension and rolling attained at low MTV. The use of high viscosity fluids appeared to improve the cuttings transport further especially at highly deviated angles. The transport efficiency is further enhanced by pipe rotation at various levels of eccentricity. Smaller cuttings appeared to be easier to remove than larger ones. There is however a small exception to this when larger cuttings were found to be much easier to remove at low angles with the use of high viscosity fluids.

The experimental results have been compared with the predicted MTV from the computer model concurrently being developed and good agreement has been observed.
Development Planning for the 1990's
Authors: Cuckson J. , Colclough J. G.
Published: December 2007

The response of the offshore industry to the 1986 price collapse showed how flexible the industry can be when faced with unexpected challenges. In this case the challenge was met by following a "lean and mean", essentially short term view. This, coupled with a depressed market led to a marked increase in activity in the Dutch offshore sector reflected in an increased rate of development of hitherto marginal fields which are now coming on stream. The Paper takes a somewhat unusual view in questioning whether extrapolation of this approach is wise in the circumstances likely to prevail in the 1990's. Growing concern about the environment, redoubled efforts to improve safety offshore and, probably, a hardening in the prices for goods and services lead us to question whether extrapolation of the minimum facilities approach remains the most appropriate way to develop the smaller fields typical of the Dutch continental shelf.

The paper describes the present development concepts of minimum facilities platforms, mini-satellites and highly deviated wells as well as novel techniques and the advantages and disadvantages they bring with them. The role of the "soft" long term issues of manning philosophy, logistics and waste management, which play an increasingly significant role in selection of development plane, is also explored. It is shown that the planning of future developments requires an integrated exploration and development strategy and a willingness to formulate a long term view. The implications this has for the continued momentum of development are discussed.
Poseidon: The Multiphase Boosting and Transportation Technology Now Reaching the Pre-Industrial Stage
Authors: Lafaille A.
Published: December 2007

The POSEIDON Project, the first R&D Project entirely devoted to Subsea Multiphase Production, was launched in 1984, by TOTAL CFP, IFP and STATOIL. After nearly 7 years of joint endeavour, this international team work has resulted in the development of some completely new techniques and tools that are among the most promising today. This paper presents the overall strategy deployed by the POSEIDON partners from the beginning of the Project, and its evolution in the light of the demands of a changing subsea market.
Polymer Treatment for Water Control in High-Temperature Production Wells
Authors: Kohler N. , Zaitoun A.
Published: December 2007

A polymer treatment based on the use of a nonionic high-molecular-weight polysaccharide has been proposed for water control in high-temperature production wells. This polymer has excellent viscosifying power in all types of reservoir brines, high shear resistance and good thermal stability. Its ability to decrease the relative permeability to brine without affecting the relative permeability to hydrocarbons is demonstrated for both matricial sandstone and limestone reservoirs.

The superiority of this polysaccharide based water control treatment over other competitive processes seems obvious as soon as the reservoir temperature exceeds 70-75°C. With specially designed additives, treatments at temperature up to 120-130°C may be proposed. Moreover, because of its high shear resistance and its strong shear-thinning behavior this polysaccharide can be pumped at high injection rates with a slight wellhead pressure increase. Shut-in times of the wells treated may thus be considerably reduced.
The Effect of Temperature on the Gelation Time of Xanthan/Cr(III) Systems
Authors: Kolnes J. , Stavland A. , Thorsen S.
Published: December 2007

The potential for applying polymer gels for reducing the watercut in the North Sea reservoirs is increasing, as more reservoirs experience water breakthrough. In the high temperature environment near a North Sea producing well the effect of high and varying temperature can have large impact on the placement of the gel, which again is crucial for the performance of the process.

This paper reports a laboratory study concerning the effect of temperature on the rate of gelation of xanthan / chromium (III) systems. Measurements both in bulk and during flow have been performed. In the bulk experiments the gelation rate was determined using a low shear viscosimeter. The flow experiments were designed in such a way that the in-situ pressure gradient could be measured during the flow of gel in a Ballotini pack.

Bulk measurements showed that a linear relationship existed between the logarithm of gelation time and the reciprocal of absolute temperature. The slope of lines corresponding to different concentrations of xanthan and Chromium (III) were the same. Using the theory of Hurd and Letteron, the activation energy for the xanthan / chromium (III) reaction were calculated to 96 kJ/mol. Flow experiments were consistent with the results from the bulk-experiments, since the formation of flow resistance were seen to occur closer to the inlet as temperature increased.
A New Inhibitor for Scale Squeeze Applications
Authors: Pardue J. E.
Published: December 2007

Tests in Berea sandstone cores have been carried out which simulate scale inhibitor treatments by the precipitation squeeze method. The studies have shown that squeezes with common phosphonate inhibitors last twice as long as squeezes using common polymer inhibitors in cores containing brines with low calcium content (1,000 ppm). However, an inhibitor new to the oilfield has been shown to have a squeeze life double that seen with phosphonate inhibitors.

This new inhibitor is a phosphorous containing oligomeric product. As such, its residual can be determined easily in the field. This product is as effective as phosphonate inhibitors in controlling calcium carbonate and sulfate scales. It is superior to most products in controlling barium sulfate scales. This product should have special utility in reservoirs containing low concentrations of calcium.
How Ferrous Carbonate Kinetics Impacts Oilfield Corrosion
Authors: Tomson M. B. , Johnson M. L.
Published: December 2007

Operators have long observed that the severity of downhole CO2 corrosion is often largely dependent on location in the tubing string. At greater depths (corresponding to temperatures greater than 150 C), ferrous carbonate (FeCO3 or siderite) forms a tight adherent scale, effectively inhibiting corrosion. At intermediate depths, a patchy scale forms which results in accelerated pitting attack. A laboratory apparatus developed to test the temperature dependence of the kinetics and solubility of FeCO3 is described. Field and laboratory observations concerning ferrous carbonate scale adherence are compared to laboratory kinetics data. The solubilities and rates of formation of ferrous carbonate and calcium carbonate scales are contrasted.
Factors Influencing the Reaction Rate of Hydrochloric Acid and Carbonate Rock
Authors: Mumallah N. A.
Published: December 2007

A systematic investigation of some factors which affect the reactivity of HCI towards carbonate rock was undertaken to provide technical criteria for the design and implementation of acid fracturing operations. This paper reports on the influences of pressure, temperature, acid concentration, flow rate, and gravity on the reaction rate of hydrochloric acid with carbonate rock. The experiments were conducted using an annular flow reactor which proved to be superior to previously reported reaction rate measuring equipment as it can be operated easily over a wide range of experimental conditions. The present study revealed that the reaction rate is an increasing function of temperature up to 200°F, then becomes independent of temperature above that. It is also an increasing function of acid concentration up to 15% but it becomes a decreasing function if the acid concentration is larger than 15%. The reaction rate is a decreasing function of pressure even if the pressure is larger than 1000 psi. The reaction rate is fastest when the acid flows in the direction of the gravitational force. To provide realistic data, laboratory determinations of reaction rates at high temperatures should be conducted under system pressures of 3000 psi or more.
Applications of the Electromagnetic Propagation Tool During Exploration of Block 16, Oriente Basin, Ecuador
Authors: Jones Russel N. S. , Belforte Alberto S.
Published: December 2007

In reservoirs with low or varying salinity formation waters traditional methods of identifying and quantifying hydrocarbon saturation with resistivity measurements can be very difficult and inaccurate. The Electromagnetic Propagation Tool (EPT*) responds to the dielectric constant of the formation which leads to an alternative method for differentiating between water and hydrocarbon zones which does not depend upon salinity. For the recent eight well exploration program in Block 16 of the Oriente basin in Ecuador, the conditions were expected and found to be those where the EPT would help greatly with formation evaluation for wellsite decisions and also for analysis of residual hydrocarbons. In this paper a brief description is given first of the principle of measurement, tool design, interpretation methods and general applications of the EPT. A discussion of the geological background to the exploration program then follows, and finally the results obtained in two representative wells are presented and explained in detail.
High Pressure Swivel for Floating Production Systems
Authors: Pollack Jack , Carneiro Paulo R. B.
Published: December 2007

The application of Floating Production Systems (FPS) has been limited to pressures of less than 3000 psi, because of the lack of sealing technology making large diameter high pressure toroidal swivels possible.

A joint industry project involving British Petroleum (BP), Mobil North Sea Limited, Petrobras, Petro-Canada, Statoil, and Sun Oil, was set up in 1987 to extend these pressure ratings to as much as 6000 psi.

A full scale prototype swivel, having an 8-inch nominal pipe diameter and a 48-inch toroid diameter, was fabricated and tested. The swivel sealing system was designed to seal 620 Bar static and 114 Bar dynamic applications. The testing of the swivel was carried out at the BP research facility using methane gas at 380 Bars and 93°C. The swivel sealing system included a pressure balanced isolation system, which protects the pressure seals from product ingress which can lead to seal deterioration. The swivel cycling simulated a 5 year operation of an articulated yoke type mooring system moored in North Sea conditions. At the conclusion of testing a rapid decompression of the swivel was performed.

Details of the swivel development, analysis, design, fabrication and testing is presented.
Marlim Field Development: A Challenge in Deepwaters
Authors: Vieira de Macedo Roberto Alfradique , Asrilhant Boris
Published: December 2007

The Marlim Complex is a system of oil accumulations in the Campos Basin, offshore Brazil, which extends over an area of 381 sq km (94,100 acres), at water depths ranging from 400 m to 1,800 m (1,312 to 5,906 ft). With an estimated oil-in-place totaling 2.2 billion cubic meters (14 billion barrels), the Marlim Complex corresponds to 32 % of the Brazilian oil-in-place.

The overall development of the Marlim field itself will consist of several production systems, which will produce up to 109 subsea completed wells. The exploitation development plan will be divided into three step-by-step modules, in order to greatly reduce initial investments and allow development of technological capabilities in deepwaters.

Due to several delays in the beginning of the first module, called Pilot Production System, a one-year-test with start-up in the first quarter of 1991 will be used to gather performance data from a two-satellite-well production system. An additional eight-satellite-well production system will follow, complementing the original Pilot Production System, gathering reservoir and operational data during approximately a four-year period. All information will subsidize the overall field development.

The subsequent module, called Phase I, will consist of two semi-submersible units moored at 910 m and 980 m (2,986 and 3,215 ft) water depths and will start operating in 1994, with an estimated peak production of 31,600 cu.m/d (200,000 bpd) in 1996, from 32 wells. Phase II will correspond to the remaining part of the field development.

This paper describes many alternatives of drainage grids, production philosophy, subsea arrangements, and exporting of oil and gas shorewards for the Marlim field development plan. Additionally, an economical evaluation will demonstrate the profitability of the above mentioned Phase I cost-effective project.
Computer Control and Monitoring of Offshore Production
Authors: Pierce Dewey W. , Finch Clyde L.
Published: December 2007

This paper presents a new concept for supervisory control and monitoring of offshore gas-condensate production. The philosophy of the automation system's design, its attractive features, and operating experience gained to date are covered.

Introduction

The Lake Charles District of the CAGC Marine Region is predominantly a gas producing district operated by Continental Oil Co. for itself, producing district operated by Continental Oil Co. for itself, Atlantic-Richfield, Getty Oil Co., and Cities Service Oil Co. Gas discoveries and subsequent development in the East Cameron and West Cameron areas offshore from Cameron, Louisiana, now constitute a gas system consisting of 91 gas and gas-condensate wells located on 15 producing platforms. The gas system was put on production in 1958 after the platforms. The gas system was put on production in 1958 after the completion of a gas transmission line to the offshore platforms. Daily gas deliveries are averaging 350 MMcf along with 4,000 barrels of condensate per day. per day. The system has always been operated by personnel quartered in the field adjacent to one of the producing platforms. These operating personnel make daily trips by boat to their assigned platforms to check operations, change meter charts, pump inhibitor into the wells, and perform general maintenance duties. When personnel worked on a production platform, there was no communication with, or control of the producing variables.

Process Description Process Description The producing equipment on each of the platforms in the Cameron Gas System is basically the same, differing only in capacity and brand. The attached isometric drawing of a typical platform layout, Exhibit I, shows the components of the producing equipment, their relative positions on the platform and the flow plan of the connecting piping. platform and the flow plan of the connecting piping. In general the functions that are performed on the platform are separation of water and condensate from the gas, dehydration of the gas by glycol absorption, and disposal of the free water. In addition to the production separator through which the commingled production from all of the wells flows, there is a test separator for determination of each individual well's flow rate and liquid production at least once each month.

The well streams flow through individual flowlines into headers which are manifolded to facilitate flow either to the production separator or the test separator. The gas from the headers is expanded through adjustable chokes on the low temperature type separators, and separation of the free water and condensate is made. If it is necessary, the gas can be directed through a heating coil in the glycol reboiler to prevent freezing of the separator choke.
Maximizing Gas Recovery from Strong Water Drive Reservoirs
Authors: Randolph P. L. , Hayden C. G. , Anhaiser J. L.
Published: December 2007

Commercially viable production of 150 SCF/STB (27 m3/m3) of gas per barrel of brine has been achieved for reservoir pressure substantially below hydrostatic. Reservoir pressure at 9100 feet (2 990 m) has been drawn down to below 3460 psi (23 620 kPa) or 0.380 psi per foot (0.085 1 kPa/cm). Those wells having a gas/brine ratio in excess of 100 SCF/STB (18 m3/m3) flow because of lift by produced gas. Injection of lift gas is used 1) to start production after wells are shut-in, 2) to maintain production for lower gas/brine ratios, and 3) to increase rate or to increase wellhead pressure for operation of the surface facilities.

Key features of the well completions and surface facilities to maximize recovery are: Minimizing friction losses by 1) using annular production, 2) installing tubing only to the depth required for gas lift and chemical injection, 3) using large-diameter wellhead valves and downstream piping, and 4) injecting scale inhibitor through chemical treat strings.Utilizing freewater knockouts followed by separate oil-gas separators that facilitate cooling of condensate before placing it into the stock tanks. This minimizes evaporative loss.Keeping operating costs low by 1) maintaining brine pressure above atmospheric to keep oxygen out of the system and to reduce disposal pumping costs, 2) creating large sand surface areas in the disposal zones to reduce the injection pressure, and 3) using the same compressor for both gas lift and gas sales.
Use of Surface Seismic Data to Predict Formation Pore Pressure Worldwide
Authors: Weakley R. R.
Published: December 2007

An accurate prediction of formation pore pressures prior to drilling a well can significantly improve drilling performance, reduce the number of costly drilling problems encountered, and in many instances, can be the determining factor in successfully reaching objectives. This is particularly true when dealing with exploratory wells. The fact that we are going to penetrate the same stratigraphies as offset wells does not equate to being in the same pore pressure environment. In fact, when dealing with exploratory wells, there is a high percentage of the time when this is not the case.

This approach to predicting formation pore pressures utilizes offset log information, and velocity information from surface seismic data. All surface seismic data has velocity information built into it in the way of stacking velocities. From these stacking velocities, estimates of interval velocities can be made. We have developed a quantitative technique for determining formation pore pressures from the relative changes in these velocities.

From the stacking velocity data, we develop curves we refer to as ITT (Interval Transit Time) curves. ITT curves are generated at offset locations as well as the proposed drilling location. Actual offset well pore pressures are determined from the logs and the ITT curves at these offsets are calibrated to the known pressures. After this calibration process, the ITT at the proposed location can be interpreted to predict formation pore pressures to be encountered.

The combination of these tools yields a reliable pore pressure scenario from which to plan a drilling program and execute the operations. This procedure has been utilized on numerous wells throughout the Gulf of Mexico as well as a number of wells around the world. The technique will be illustrated with figures as a step by step analysis is done. Results of the use of this methodology will also be illustrated.
An Evaluation of Carbon Dioxide Flooding
Authors: Mungan Necmettin
Published: December 2007

Laboratory core displacement tests were made to better understand the effects of miscibility, swelling and viscosity reduction on oil recovery by CO2 flooding. Also, certain field applications were reviewed to assess performance of CO2 flooding under miscible and immiscible conditions. Achieving miscibility is shown not to be essential to recovering incremental oil since viscosity reduction and oil swelling can also be very important. Recommendations are offered as to how best to pilot test CO2 flooding in the field to obtain reliable performance data.
Minimizing Drilling Fluid Waste Discharges While Drilling an Arctic Exploratory Well
Authors: McKay M. , Seward M. W. , Smith G. , Brady S. J.
Published: December 2007

Ever more restrictive regulations have necessitated minimal impact drilling procedures that have led to the development of a variety of methods for the disposal of liquid drilling waste. Current Alaska regulations severely limit the use of reserve pits other than in an emergency situation for the disposal of liquid phase waste. Current efforts are being directed at minimizing liquid discharges while conserving water and maximizing solids control efficiency.

This paper presents a case history of a recent project on Alaska's North Slope where operator requirements and logistics necessitated on site dewatering of drilling fluids. A retrofitted chemically enhanced centrifuge was utilized for this process. The design, fabrication, operations, and economics are summarized. The conclusions should prove beneficial for future planning of restricted discharge drilling operations such as will be necessary should Alaska's Arctic National Wildlife Refuge be opened to drilling.
Control System Design and Simulation for Dynamically Positioned Vessels
Authors: Hammond C.H. , Horn Kurt
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the 43rd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Sept. 29-Oct. 2, 1968. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. 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.

Positioning a vessel dynamically over a fixed or moving point in the ocean requires the generation and control of a thrust vector to overcome the environmental forces which tend to disturb the vessel's position. This paper describes the development of thruster control logics and control systems for this purpose. The control logic provides a unique position for each of the four thrusters in azimuth and required thrust level. It features the ability to change without discontinuities any of the forces or moment involved in the three degree-of-freedom motion of the vessel. The control systems are conversional with rate, position and reset feedback and utilize a unique position and reset feedback and utilize a unique RPM feedback to overcome data lag in the velocity feedback loop. The control systems and their logics, the ships, and the thruster dynamics are programmed on an analog computer. The procedure of using this simulation to determine the design parameters (gains) of the control system as well as typical results of this simulation in terms of vessel response are discussed. After the control system is finalized, the dynamic simulation is also used to investigate overall system performance as a function of environmental condition.