bluuebunny/crossref_metadata_2025 huggingface dataset:
Waterflood Operations in the North Meadow Creek Sussex Sand Unit
Authors: Myers L.B.
Published: December 2007

Basic reservoir data, geological data, and production history are given and a progress report presented on the North Meadow Creek Sussex Sand Unit water flood operation.

Water flood equipment, water supply, water treatment for bacterial control, and operating problems peculiar to Wyoming and the Rocky Mountain area are described. The five operating companies unitized interests for the purpose of water flooding early in the primary life of the reservoir. In Dec., 1953, after four years of primary life, water was initially injected. Four producing wells were converted to input, forming a 40-acre pilot five-spot. Injection well performance in the pilot area has shown the Sussex sand to have adequate receptivity to fresh water at moderate pressure. Injected volumes required for fill-up confirm estimates on water flood efficiency and indicate waterflood recovery will exceed primary.

The pilot was expanded in 1955 to encompass 80 percent of the reservoir productive acreage. Producing wells were converted to input on pattern except where faulting dictated otherwise.

Introduction

This paper is a report on a waterflood operation in the North Meadow Creek field, Johnson County, Wyo. The field, discovered in Dec., 1949, is located in the Powder River Basin near Linch, Wyo., 8 miles northeast of the famous Salt Creek field. Water is being injected into the Sussex sand reservoir at a depth of 4,000 ft. Before commencing the pilot injection test, the five working interest owners in the field unitized the Sussex sand reservoir with unit participation being divided among Delhi-Taylor Oil Corp., Continental Oil Co., American Liberty Oil Co., Mimi Corp., and Murchison Trust.

Although the operation is normal in most respects, it is the only full scale pattern water flood in the Rocky Mountain area. It is also of special interest to note that the operators recognized the adaptability of the Sussex sand to water flooding and unitized for this purpose early in the primary life.

It shall be the purpose of this paper to present basic reservoir and geological characteristics of the Sussex reservoir as well as to discuss operating practices, water supply, flood equipment, and pilot waterflood performance.
Permeability Reduction by Treatment With KUSP1 Biopolymer
Authors: McCool C. S. , Shaw A. K. , Singh Amitabh , Bhattacharya Saibal , Green D. W. , P. Willhite G.
Published: December 2007

The application of KUSP1 biopolymer for use in permeability reduction treatments of oil reservoirs was investigated. KUSP1 is a nontoxic polysaccharide that is produced by a bacterium. Alkaline solutions of KUSP1 have low viscosities and can be gelled by different methods. Three methods were examined to gel KUSP1 in porous media. Two of the methods are based on the reduction of pH of alkaline KUSP1 solutions. KUSP1 is soluble in alkali but forms a gel when the pH is lowered to values below 10.8.

The first method employed the hydrolysis of an ester to reduce pH and trigger gelation. Gel times on the order of days were observed for KUSP1 solutions that contained the monoethylphthalate (MEP) ester. The performance of the KUSP1-MEP system in treatments of sandpacks, Berea cores, and carbonate field plugs was studied at 25°C. Brine permeabilities were reduced by factors that ranged from 75 to 4,500. Permeability reduction by treatments with the KUSP1-MEP system was stable to brine flow for periods of up to six months.

The second method to gel alkaline KUSP1 solutions was based on the chemical interactions with rock material. It was found that interactions with Berea sandstone, Baker dolomite, silica sand-packs, and field core plugs were insufficient to reduce the pH of alkaline KUSP1 solutions to values required for gelation.

Alkaline KUSP1 solutions were gelled by the addition of boric acid in the third method. Bulk gelation studies conducted at 25, 45, and 65°C showed that gel times could be regulated up to several days by selection of pH and boric acid concentrations. The gels were more rigid than those produced by pH-reduction methods, indicating a different gelation mechanism. Syneresis was observed and was more pronounced at lower pH values and higher temperatures. The KUSP1-boric acid system reduced brine permeabilities in sandpacks and Berea cores (25, 45°C) by factors that ranged from 50 to 3,300.
Method for Accurately Measuring Produced Oil Volumes During Laboratory Waterflood Tests at Reservoir Conditions
Authors: Hvolboll V.T.
Published: December 2007

Introduction

Much usable information can be obtained from laboratory waterflood tests conducted at reservoir temperatures and pressures using reservoir fluids. Consequently, reservoir-conditions waterflood tests have been conducted by several laboratories even though such tests are much more difficult and expensive than routine waterflood tests. One of the most difficult problems with these reservoir-conditions tests is measuring incremental and total displaced oil volumes accurately. This study describes a method that produces a continuous record of oil production during a high-pressure, high-temperature waterflood test. With this method, oil is accumulated in a high-pressure separator, where its volume is monitored with a very sensitive differential pressure transducer. If the dimensions of the separator are selected properly, very small volumes (less than 1% of the pore volumes of typical test cores) can be measured reliably using commercially available pressure transducers. The basic method also can be used for tests involving gas displacing oil or water and water displacing gas. With minor modifications of equipment and operating procedures, produced volumes of gas, oil, and water can be measured during three-phase flow tests.

The waterflood technique discussed here now is being used routinely and has proved satisfactory for the past 15 years. Using this method experienced operators easily can record the production history from several core floods running concurrently.

EXPERIMENTAL METHOD

Fig. 1 schematically shows the main items of required equipment. All components are off-the-shelf items except the core holder and high pressure separator, which must be shop built. During a waterflood test, fluid leaving the core enters a high-pressure separator, where produced oil accumulates in a collecting tube. Both the core and separator are in a constant temperature oven. The separator is a blind cell, thus the inconvenience and hazards associated with viewing windows are avoided. The system is designed so only one phase (gas or water is displaced through a backpressure regulator. This design has two advantages over methods that require all production to flow through a regulator:conventional commercial backpressure regulators can be used without modification to reduce holdup volumes andpressure fluctuations at the upstream side of the regulator are reduced significantly so the pressures in the separator and at the outlet end of the core are kept much more uniform.

The difference between pressures at the top of the collecting cube and the top of the annulus is measured with a sensitive differential pressure transducer. The portion of the annulus containing oil and the lines from the separator to the transducer normally are filled with live crude oil. At the start of the test water in the separator should have the same density as the flood water and water initially in the core.

SPEJ

P. 239
Influence of Drillpipe Rotation and Eccentricity on Pressure Drop Over Borehole With Newtonian Liquid During Drilling
Authors: Ooms G. , Kampman-Reinhartz B. E.
Published: December 2007

Field measurements have revealed that the pressure drop over a borehole during drilling of a slim oil well or a well with a long reach can depend significantly on the rotation speed of the drillpipe. In this paper we discuss analytical, numerical and experimental studies to explain this effect for the case of a Newtonian liquid in the borehole. Special attention is paid to the inertial forces in the liquid (in the annulus), caused by the rotation and eccentricity of the drillpipe. It is concluded that for large values of these inertial forces the axial pressure drop depends significantly on the rotation speed of the drillpipe. A pressure drop simulator (also valid for the case of a non-Newtonian liquid in the borehole) has been developed, that includes this effect and is in good agreement with field test data.
Bacterial Profile Modification With Bulk Dextran Gels Produced by In-Situ Growth and Metabolism ofLeuconostoc Species
Authors: Jenneman G. E. , Lappan R. E. , Webb R. H.
Published: December 2007

Growth of Leuconostoc mesenteroides in a synthetic sucrose-based medium resulted in production of rigid, bulk dextran gels, whereas, growth on a beet-molasses medium produced loose, colloidal gels. Addition of inexpensive protein hydrolysates to the synthetic medium allowed for formation of the best bulk gels. Bulk gel formation was favored by increased bacteria concentrations and harvesting of cells during exponential growth. Bulk dextran gels resulted in greater in-depth permeability reductions (>90%) than those supporting formation of colloidal gels but in-depth gel formation, and plugging in field cores was limited by transport of bacterial cells.
Analysis of a Single-Well Chemical Tracer Test To Measure the Residual Oil Saturation to a Hydrocarbon Miscible Gas Flood at Prudhoe Bay
Authors: Cockin A. P. , Malcolm L. T. , McGuire P. L. , Giordano R. M. , Sitz C. D.
Published: December 2007

In 1990, a single-well chemical tracer (SWCT) test was performed in Prudhoe Bay to measure the effective waterflood and miscible gasflood residuals over a 12 ft reservoir interval. This is believed to be the first such use of this technology for a hydrocarbon miscible gas. This paper describes how the usual SWCT design was modified to accommodate the miscible gas, the results of the SWCT, which indicate significantly higher residual oil saturation for miscible gasflood than expected from coreflood experiments, and the subsequent simulation of the test which has provided good agreement with the observed results. The paper shows, with compositional simulation support, that the high apparent residual oil saturation was a consequence of incomplete volumetric sweep by the miscible gas and draws on the experiences of this test to make recommendations for the design of future SWCT tests measuring residuals to gasflooding.
Performance Prediction of Floating Drilling Vessels for Various Operating Areas
Authors: Evans W.M. , Futoma G.A. , Lombana C.A.
Published: December 2007

This paper describes a computer program, composed of weather and drilling models, that was developed to help select floating drilling vessels for specific operating areas and start-up times. With these models, expected performance of different vessels can be simulated and their costs performance of different vessels can be simulated and their costs compared.

Introduction

Weather conditions vary considerably from area to area and even during the course of a year in a single area. Consequently, drilling vessels that have been used successfully in one region or at one time might not be suitable for different circumstances.

Since the day rate for different vessels also may vary, selection of a proper vessel involves both engineering and economic factors. If expected adverse weather or sea ice place time restraints on operations, reaching a desired place time restraints on operations, reaching a desired well depth by a certain date becomes an important consideration in vessel selection.

Criteria necessary to establish estimated performance of a floating drilling vessel are moron characteristics, operating limits with respect to sea conditions or vessel motion, well design and expected drillability of the formation with no vessel motion, and weather data for the geographical area. This information is incorporated in drilling and weather models that then are combined to calculate predicted performance of the vessel.

Vessel-Motion Characteristics

Heave, roll, and pitch data for a specific vessel are determined from model tests in wave basins or from theoretical calculations. These data usually occur as response-amplitude operators (RAO) for regular waves (Figs. 1 through 3). Since sea conditions are not regular, vessel-motion characteristics in irregular seas must be determined.

As described by Michel and Minkenberg and Gie, vessel motion in irregular seas (heave, pitch, and roll spectra) can be determined by multiplying wave spectral density by the square of the vessel response for a range of frequencies.

The wave spectral density, Sw(w), for a frequency w is given by the Bretschneider spectrum:

4,200 H 2 - 1,050s Ts 4 w 4 Sw(w) = -------------- e, ..............(1)T 4 w5s

where Sw(w) = wave spectral density, sq ft-sec forfrequency wHs = significant wave height, ftTs = significant wave period, secondsw = wave frequency, sec-1.

With this definition, the area under the spectral curve equals the square of the significant wave height. Fig. 4 illustrates this spectrum for a significant wave height of 17 ft and a significant wave period of 10 seconds.

The heave spectrum in Fig. 5 was obtained by multiplying the wave spectral density by the square of the RAO for the corresponding frequency.

Z(w) = Sw(w) . RAO 2 (w),...................(2)

where Z (w)= heave-spectral density, sq ft-sec forfrequency w.

Significant heave, Zs, is obtained by

Zs (Hs, Ts) = Z(w) dw,...................(3)

JPT

P. 1688
Modern Seismic Methods - An Aid for the Petroleum Engineer
Authors: Ausburn B.E. , Nath A.K. , Wittick T.R.
Published: December 2007

This paper describes the emerging detailed seismic techniques that often can provide considerable help for the petroleum engineer. Five areas of mutual interest for the geophysicist and petroleum engineer are identified. Primary emphasis is on the use of seismic data for reservoir identification.

Introduction

Today, petroleum engineers are faced with unprecedented challenges in every phase of their profession. Increasing costs, more difficult development targets, and exotic recovery techniques make it imperative that the engineer be aware of all available technology for meeting these challenges. Of particular interest are new seismic acquisition, processing, and interpretative techniques that have improved significantly in the last 5 years and now represent an important new exploitation tool. The engineer should be aware of these improved capabilities and should be prepared to use appropriate seismic entry data to help solve his problems.

Areas of mutual interest for the petroleum engineer and the geophysicist can be summarized as follows.

Exploration/Production Interface

Preparation and Evaluation of Analogs. Petroleum Preparation and Evaluation of Analogs. Petroleum engineers are involved in evaluating existing fields, producing trends, or provinces. The engineer directly producing trends, or provinces. The engineer directly influences exploration efforts by his assessment of the economics of established production, and indirectly influences exploration activities by his evaluation of rock and fluid properties, which are, in turn, used in seismic interpretation.

Development of Velocity and Density Depth Trends From Wellbore Data. Similar to the preparation of analogs, engineers often develop formation parameter trends from which various combinations of earth acoustic properties can be tested. Since the quality of these trends properties can be tested. Since the quality of these trends often depends on the way wells have been drilled, engineers should have some degree of control over data acquisition.

Forecasting. Engineers may influence exploration activities by their forecasts of required drilling/production capital, operating costs, and product prices. However, a forecast of exploration activities influences such engineering predictions as drilling rig and tubular requirements, and production schedules for a trend, province, division, or company.

Bid Preparation and Property Purchases. In most companies, engineers and exploration personnel work together in preparing acreage bids and evaluating property purchases. The engineer must understand the property purchases. The engineer must understand the applications and limitations of seismic data, a principal exploration tool.

Field Development

Extent of Hydrocarbon Accumulation From Lateral and Vertical Limits. Lateral limits include salt face, porosity pinchouts, and faults; vertical limits include porosity pinchouts, and faults; vertical limits include fluid contacts and porosity pinchouts.

JPT

P. 1519
Performance of a Solution Gas Drive Reservoir, Rosenwald Pool, Oklahoma
Authors: Smith M.R. , Henderson J.H.
Published: December 2007

The Rosenwald pool, Okfuskee County, Okla., was discovered in June, 1949. Production is from the Union Valley limestone and Cromwell sand, both of Pennsylvanian age, at an average depth of about 3,450 ft. The Union Valley lies conformably on the Cromwell with the two formations forming a common reservoir. The pool is a stratigraphic trap with the limits defined by a pinchout of the sand and a loss of permeability in the lime. The pool as fully developed consisted of 31 producers drilled on 10-acre spacing.

All wells flowed upon completion, with initial productions ranging from 40 BOPD for edge wells to as much as 1,600 BOPD where good Cromwell sand development was encountered. Initially only a few feet of sand penetration was taken, for fear of encountering bottom water.

Early in the life of the reservoir, performance calculations were made using Muskat's differential form of the material balance equation for dissolved gas drive reservoirs, in an attempt to predict the future production history of the pool. A kg/ko curve for the performance calculations was constructed from data of other pools which have produced from Cromwell or sands similar in texture to the Cromwell. Subsequently the reservoir has been essentially depleted by primary means, enabling a comparison of the actual performance with that predicted. Actual recovery was 20 per cent of the original oil in place as compared to the prediction of 26½ per cent. Laboratory-determined relative permeability ratios and the assumed ratios used in the performance calculations are compared with those calculated from the field performance.

By the end of 1953 most of the wells had become marginal producers and the pool was unitized and is presently being waterflooded.

Introduction

The Rosenwald pool has afforded an excellent opportunity to analyze the performance of a solution gas drive reservoir. This relatively small pool was drilled on 10-acre spacing and had an over-all primary producing life of 41½ years. Care was taken throughout the life of the pool to obtain adequate production and engineering data to enable good comparisons of the actual performance with theoretical concepts.
An Approximate Method for Non -Darcy Radial Gas Flow
Authors: Rowan G. , Clegg M.W.
Published: December 2007

Approximate analytical solutions for non-Darcy radial gas flow are derived for bounded and infinite reservoirs producing at either constant rate or constant pressure. These analytical solutions are compared with published results for non-Darcy flow obtained on digital and analogue computers, and the agreement is shown to be very good. Some observations on the interpretation of gas well tests are made.

Introduction

The flow of gases in porous media is a problem that has been the subject of much study in recent years, and many methods have been proposed for solving the non-linear equations associated with it. The assumption that the flow satisfies Darcy's Law

(1)

leads to a non-linear equation of the form

(2)

in a homogeneous medium, assuming an equation of state(3)

It has been observed, however, that the linear relationship between the flow rate and pressure gradient is only approximately valid even at low flow rates, and that as the flow rate increases the deviations from linearity also increase. It has been suggested by a number of authors that Darcy's Law should be replaced by a quadratic flow law of the form

(4)

This form of equation was first suggested by Forchheimer and, later, Katz and Cornell, and Irmay, developed a similar equation. Houpeurt derived this form of equation using the concept of an idealized pore system in which each channel consists of sequences of truncated cones giving rise to successive restrictive orifices along the channel. This type of representation leads to a quadratic flow law of type, for all fluids, but it is found that the quadratic term is only significant in the case of gas flow. The methods of Houpeurt for solving gas flow problems will be discussed further in another section of this paper.

Solutions of the non-linear equation for Darcy gas flow may be classified as either computer (digital and analogue), or approximate analytical ones. The former include the well-known solutions of Bruce et al., and Aronofsky and Jenkins, but the latter solutions, apart from the simple linearization of equation [2] to yield a diffusion equation in p2, are not so well-known.

SPEJ

P. 96ˆ
Roughness of Hydraulic Fractures: Importance of In-Situ Stress and Tip Processes
Authors: van Dam D. B. , de Pater C. J.
Published: December 2007

The surface roughness of hydraulic fractures reflects the fracturing process at the tip. We conducted an experimental study of hydraulic fracture propagation and observed a characteristic roughness pattern. The roughness developed without shear or torsional loading in the plane of the penny-shaped fracture and is determined by material properties and the externally applied stresses on the sample, which represent the effective in-situ stresses. We quantified the roughness and showed that it correlated well with a measure of the plastic zone size around the fracture tip. New explanations for fracture surface roughness that develops under Mode I loading conditions are presented.
Composition Correlations of Natural Gas in Reservoir Engineering Problems
Authors: Eckles W.W.
Published: December 2007

This paper is presented as a summary report of the use of well gas composition correlations obtained from mass spectrometer recordings as a means of identification and determination of reservoir continuity.

Conventional methods for detecting composition differences are expensive, elaborate, and difficult to obtain. This excludes the use of extensive composition data for most applications.

During recent years the mass spectrometer has come into general use as an analytical tool in petroleum refineries. The use of mass spectrometer composition patterns in characterizing or "finger-printing" the produced gas from a reservoir, presents a novel method for correlating gas samples from well to well. The mass spectrometer provides a trace similar to an electric log, having peaks which represent the abundance of certain hydrocarbons in the well gas sample. Without going further into the detailed analysis, the idea has been advanced that these traces or patterns could be used as a means of identifying a particular natural gas. This theory has proven to be essentially correct. The mass spectrometer pattern method is simple and cheap as compared to other standard methods. It greatly facilitates the solution of reservoir and geological problems in which correlation of well gas compositions is a factor.

Specific field applications have been made. This paper concerns the results obtained in 465 individual gas analyses from 35 fields and 77 reservoirs. In a number of cases it has been found that such data have been extremely valuable in the determination of reservoir continuity. In at least one case, the method was a valuable contribution in tracing a reservoir from sand to sand in a complex faulted field involving numerous gas reservoirs.

Field applications are presented to illustrate the possibilities of the method at the present stage of development and to stimulate the employment of this new approach by geologists and petroleum engineers in the industry.
The Effect of Heat Transfer To A Nearby Layer on Heat Efficiency
Authors: Prats Michael
Published: December 2007

This paper provides an analytic solution in Laplace space for the heat distribution in two nearby layers undergoing heat injection at variable rates. The heat content in the layers undergoing thermal injection, divided by the cumulative net-injected heat, is known as the heat efficiency. In this treatment, the thermal properties of the layers, the thickness of the layers undergoing heat injection, and the intervening layer can have any values. The overburden and underburden are semi-infinite.

Examples are given for two sets of thermal properties and three values of the intervening layer's thickness. Only a constant rate of heat injection is considered in the examples.

Results indicate that significant thermal interaction occurs at an intervening layer thickness as great as 45 ft, with the effect being faster and more pronounced the thinner the intervening layer.
Interpretation of Water Saturation Above the Transitional Zone in Chalk Reservoirs
Authors: Larsen Jens K. , Fabricius Ida L.
Published: December 2007

The free water level (FWL) in chalk reservoirs in the North Sea may be hard to establish owing to strong influence from capillary forces and lack of pressure equilibrium across the reservoir. Even where wireline formation tester data on the FWL are available in one well, it is no straightforward task to predict the FWL in other parts of the field, where only conventional core analysis and logging data are available. It is thus difficult to predict the geometry of the hydrocarbon-bearing interval.

This paper offers a simple model which, in a given well, allows us to predict the location of the FWL from conventional core analysis and logging data if wireline formation tester data are available from another well.

Water saturation is averaged over the internal surface of the formation by applying Kozeny's equation, resulting in a pseudo water-film thickness (PWFT). The PWFT is larger than the equilibrium water-film thickness calculated from the augmented Young-Laplace equation because it includes water associated with grain contacts. The PWFT has a gradient with true vertical depth (TVD) that is related to the capillary pressure; this gradient is approximately the same for the wells investigated. Consequently, a unique relationship between the PWFT and the height above the FWL can be established, provided that the depth of the FWL is known from formation pressure data. The unique PWFT height above the FWL relationship can be used to establish the FWL in offset wells for which no reliable formation-pressure data exist. The estimation of the FWL in offset wells is inexpensive because it requires the use of log data and sufficient conventional core-analysis data only.

The model was tested on seven wells from the Gorm and Dan field in the North Sea and resulted in predictions of the FWL in the Dan field wells based on wireline formation tests in one Gorm field well.
Diaphragm Slush Pump
Authors: True Martin E. , O'Reilly W.M.
Published: December 2007

To provide means for improving the economics of slush pump operations, development work was initiated to perfect a pump in which the moving parts are in contact in a clean lubricating fluid. Alter years of research and laboratory and field testing, a full scale pump has been developed which incorporates means for isolating the abrasive drilling fluid from the rod, piston, liner, and rod packing. A diaphragm is employed as a membrane for separating the clean fluid reciprocated by the pistons from the drilling fluid. Automatic means are included for maintaining a constant volume of fluid in the intermediary system. The diaphragm slush pump, during an observation period of nine months in competition with a conventional rig pump in drilling service, operated satisfactorily. An appreciable cost reduction in the replacement of expendable parts, except valves, has been achieved through the use of diaphragm pump compared to a conventional pump.

Introduction

The method of circulating drilling fluid with reciprocating pumps today is basically the same as that employed in the early days of rotary drilling. A basic weakness of this equipment is that the working parts are exposed to an abrasive fluid which results in relative short life and a high operating cost. Improved design and materials of parts exposed to the abrasive fluid have contributed to prolonging the working life, but the cost per operating hour leaves much to be desired as reciprocating slush pump continue to increase in size and in horsepower to deliver fluid at the high volumes and pressures frequently employed to achieve increased rates of drilling.

Since the beginning of rotary drilling, much effort has been directed to various designs of pumps which would provide means of reducing the wear on expendable parts. Even as recently as the early 1940's, plunger-actuated diaphragm slush pumps were being manufactured and sold for rotary drilling service.
A Porous, Permeable Carbonate for Use in Oil Recovery Experiments
Authors: Meister John J.
Published: December 2007

Introduction

Previous research in the use of surfactants and polymers Previous researchin the use of surfactants and polymers in tertiary oil recovery concentrated onsandstone reservoirs, with most laboratory work for the design using Bereasandstone and with a final check on the system being made in reservoir corematerial. With increased understanding of how surfactants act to recover oilcarbonate reservoirs are being considered for surfactant flooding. However, aporous permeable, carbonate mineral is needed to permit numerous tests ofvarious compositions in carbonate rock during the design of an oil recoverysystem for carbonate reservoirs. An appropriate core material was found aftersearching for quarried, consolidated, fine-grained, carbonate minerals with 20%or more porosity and 100 md or more intergranular permeability. Only a rockmeeting these criteria will permit reproducible laboratory tests to beconducted under representative field conditions - a frontal advance rate of upto 0.6 ft/D and a pressure gradient of less than 1 psig/ft. A rock meetingthese criteria is described here.

Porous Permeable Carbonate Porous Permeable Carbonate The most appropriatecombination of rock properties for core tests was found in a dolomite quarriedby J. E. Baker Co.* Baker dolomite quarried in Millersville, Sandusky County, OH, is a primary, sedimentary dolomite formed in a warm. shallow marineenvironment. This rock is from the Niagara group, Guelph formation, UpperSilurian epoch, Paleozic era and is considered 400 to 425 million years old.The dolomite is highly crystalline, generally massive and varies from nearlywhite to light

TABLE 1-DATA FOR BAKER DOLOMITE

Porosity, Permeability, and Grain Density Porosity, Permeability, and GrainDensity Porosity Permeability Grain Density Plug (vol%) (md) (g/cm3) Plug(vol%) (md) (g/cm3) 1 22.5 65.7 2.86 2 26.8 126.0 2.86 3 28.2 187.2 2.86 4 23.376.2 2.86

Chemical Composition

Weight Percent Element Composition Ca* Mg** Fe Mn Si Cr Upper limit 0.1 0.030.01 0.01 22.6 12.7 Lower limit 0.01 0.003 0.001 0.001

Relative Displacement Index Relative Plug Displacement Index 1 +0.414 2+0.689

JPT

P. 1632
Pore-Scale Modeling of Multiphase Flow in Fractures and Matrix/Fracture Transfer
Authors: Hughes Richard G. , Blunt Martin J.
Published: December 2007

We use pore-scale network modeling to simulate imbibition in fractures and the matrix/fracture interaction accounting for viscous forces and flow in wetting layers. We represent the fracture as a 2D lattice of conceptual pores and throats connected to a 3D network that models the rock matrix. We find that the matrix adjacent to the fracture plays an important role in controlling matrix/ fracture transfer.
Conditioning of Lévy-Stable Fractal Reservoir Models to Seismic Data
Authors: Gunning J. , Paterson L.
Published: December 2007

We have developed methods of conditioning nonstationary Lévy-stable geostatistical models1,2 to 3D seismic data. The technique involves adapting the sequential Lévy simulation method so that the convolutional response of the realizations acceptably matches the seismic amplitude map. A rejection scheme is used, which requires fast, repetitive simulation of gridblock columns and generation of convolutional responses. The nonstationarity of the model means that this cannot be achieved using the conventional large kriging system. We use a different, but comparably rapid method, based on storing the relevant parts of a sequential simulation calculation for the column. Working directly with the amplitude traces also has the advantage of avoiding the ambiguities and nonuniqueness involved in inverting the traces to acoustic impedance.

The most difficult part of the problem is estimation of the seismic wavelet, and this is often done nonoptimally. We describe a sophisticated method of estimating the wavelet and show that this can yield better-than-expected results. Suitable rejection criteria are proposed, based on reasonable probabilistic models. The application of the technique is demonstrated with a field example.
Life Evaluation of a 35-kV Submarine Power Cable in a Continuously Flexing Environment
Authors: Pieroni Charles A. , Fellows Bruce W.
Published: December 2007

JPT Forum articles are limited to 1,500 words (including 250 per table or figure) or a maximum of two pages. Forum articles may present preliminary results or conclusions from continuing investigations or may impart general technical information that does not require publication as a full-length paper. Forum articles are subject to approval by an editorial committee. paper. Forum articles are subject to approval by an editorial committee. Letters to the editor are published as Dialogue and may cover technical or nontechnical topics. SPE-AIME reserves the right to edit letters for style and content.

Introduction

This paper evaluates the life of a 35-kV power cable for connecting a single-anchor leg mooring (SALM) buoy with a deepwater, offshore platform. This system is unique in that the cable flexes constantly during compression as the mooring buoy moves in the water. To predict the effects of this constant flexure while energized, a flex simulator and electrical circuit were devised to duplicate the service environment as closely as possible.

System Description

A deepwater platform is connected by power cable to a SALM buoy a few asks away. The buoy design (Fig. 1) includes an articulated leg with universal joints to which the cable is clamped. Flexing of the loop in the cable where it crosses a universal joint was our major concern. The cable must operate continuously at 34.5 kV for an expected life of 30 years.

Test Cable and Apparatus Description

A three-conductor cable nearly identical to the production cable was manufactured for the evaluation. It production cable was manufactured for the evaluation. It consisted of three No. 1/0 AWG stranded copper conductors with an extruded ethylene-propylene rubber (EPR) insulation, These conductors were cabled together and armored with 30 No. 4 BWG galvanized steel wires, each jacketed with high-density polyethylene.

The test apparatus consisted of a fixed cable support at one end and a pivoting swing-ann 18 ft (5.49 m) away powered by a hydraulic piston (Fig. 2). The swing-arm pivoted at the fixed base and was raised and lowered at the free end in a sinusoidal motion by a hydraulic piston. The test cable was clamped to the fixed support and the swing-arm, with a loop of the desired size in between.

JPT

P. 914
Multibranch Injector/Producer Wells in Thick Heavy-Crude Reservoirs
Authors: Ehlig-Economides Christine A. , Fernandez Belkis , Economides Michael J.
Published: December 2007

With modern drilling techniques, it is now possible to drill wells with multiple branches emanating from the same vertical or even horizontal trunk. Several heavy-crude reservoirs are very thick, and low vertical permeability would make them unattractive for single horizontal wells. Further, the much higher viscosity of the reservoir fluid results in highly unfavorable mobility. Thus, drilling stacked horizontal branches would create effectively thinner drainage areas in which the vertical mobility is far more forgiving. However, the clear benefit derived from thermal recovery favors steam injection and invites investigation of ways to improve on the Steam Assisted Gravity Drive (SAGD) application.

As an extension of the SAGD concept, this paper uses thermal reservoir simulation to investigate the effects of increasing the spacing between the injector and producer, or adding producers above or below the SAGD configuration, to mine more of the heat transferred to the reservoir by the injected steam. Simulations are performed with the Eclipse 500 thermal simulator using reservoir and fluid properties typical of the Bachaquero field in Venezuela. Economics confirm the merits of the approach.
The Effect of Heat Transfer Between Nearby Layers on the Volume of the Steam Zones
Authors: Prats Michael
Published: December 2007

The work of Mandl and Volek1 is extended analytically to include the effect on the volume of the steam zone in one layer owing to heat transfer from a second layer undergoing steam injection. The contribution of the heat transfer delays the onset of heat convection across the advancing condensation front (the critical time) and significantly increases the volume of the steam zone even where 30 or more feet separate the layers. The increase in the heat content of the steam zone (or volume) increases with increasing ratio of the sensible to latent heat of the injected steam, and is larger than the increase in the total heat content. The interpretation for this behavior is that heat transfer delays the rate of condensation of the steam vapor, this being more important at poor steam qualities. Results of the simple approach presented here have been confirmed qualitatively through numerical simulation.
Dynamically Overbalanced Coiled-Tubing Drilling on the North Slope of Alaska
Authors: Kara D. T. , Hearn D. D. , Gantt L. L. , Blount C. G.
Published: December 2007

Coiled-tubing drilling (CTD) continues to play a dominant role in through-tubing sidetracking of wells on the North Slope of Alaska. Recently several CTD candidates were targeted in an overpressured reservoir. Three wells were successfully CT sidetracked as a pilot project in this overpressured reservoir. The ultraslimhole directional-drilling system with a 2.75-in. nominal openhole diameter developed at Prudhoe Bay1 was used in combination with an unconventional approach to maintain overbalanced conditions when sidetracking these wells.

Hydraulic modeling showed that with a kill-weight drilling fluid, the calculated equivalent circulating density (ECD) at the sand face could approach the regional fracture gradient. In addition, kill-weight mud in the formulation required for CTD operations would be a significant expense. To address these concerns, the wells were CT sidetracked using a less expensive underbalanced drillingfluid system. Although the drilling-fluid hydrostatic pressure was less than reservoir pressure, overbalanced drilling conditions were maintained dynamically by the high ECD while circulating, and controlled by increasing the surface pressure using a choke when circulating at less than drilling rates.
The Effect of Uncertainty in Wave Force Coefficients for Offshore Structures
Authors: Nolte Kenneth G.
Published: December 2007

A probability distribution, which incorporates the random occurrence of wave heights and the uncertainty in the force coefficients of the Morison equation, was derived for the forces on offshore structures.

The random occurrence of wave heights was assumed to be described by a Weibull distribution, and the uncertainty in the force coefficients was assumed to be represented by a normal distribution. Wave force was assumed to be proportional to wave height raised to a power.

The assumed distributions and force relationship may not describe exactly the actual problem within a general framework, but the assumptions are believed to be applicable to the range of wave heights and conditions occurring for the selection of static design criteria for the forces on offshore structures. The applicability of the assumptions is enhanced because the primary results are expressed as ratios, which require only relative accuracy and not quantitative accuracy.
Hawser System Design for Single-Point Moorings
Authors: Woehleke S.P. , Flory J.F. , Sherrard J.R.
Published: December 2007

This paper presents design data for mooring hawsers for single-point moorings (SPM)-Properties of materials and constructions commonly used are discussed and compared. Factors that affect new and used hawser strength are discussed. Recommendations are made for SPM hawser material, construction, and safety factors for U.S. deepwater ports.

Introduction

During 1977, Exxon Research and Engineering Co. conducted a study for the U.S. Coast Guard to prepare guidelines for evaluating single-point moorings (SPM) for U.S. deepwater ports. As part of the study, SPM hawser systems were examined. This paper covers the major findings pertaining to hawsers.The hawser system serves to moor tankers to the SPM. An SPM hawser assembly consists of a large synthetic rope spliced to form eyes at both ends, or spliced end-to-end to form a loop, referred to as a strop. The eyes or ends of the strop are placed on thimbles, and chafing chains are attached to the thimbles. Flotation devices are provided to keep the chafing chains and hawsers afloat when a tanker is not moored. A typical SPM and hawser system with a moored tanker is shown in Fig. 1.Our examination of SPM hawser systems focused mainly on design. Information from many sources was gathered and analyzed in a comprehensive study of synthetic rope properties of interest in SPM hawser design. Data also was gathered for analyzing the associated hawser components, such as thimbles, flotation units, and chafing chains. Based on this study, guidelines were prepared for designing SPM hawser systems. Flory et al. presented a complete study of SPM hawser systems, along with studies on other aspects of SPM design. They included information on SPM hawser materials, constructions, breaking strengths, elasticities, safety factors, and assemblies. Supportive information presented here is not always complete. In some areas, we can give little more than conclusions and recommendations. Flory et al. give a more complete understanding of and more background to support our conclusions and recommendations.

SPM Hawser Materials

Nylon, polyester, and polypropylene synthetic fibers commonly are used for SPM hawsers. Other synthetic and natural rope fibers have properties detrimental for use in SPM'S. Fig. 2 gives comparative load-elongation curves for new nylon, polyester, and polypropylene ropes of the same construction. Table 1 shows comparative breaking strengths for large ropes made of each material.Fiber manufacturers often coat synthetic fibers to obtain desirable characteristics. Fibers of different coatings are differentiated by grade. Fibers used to manufacture rope are coated for maximum strength and to resist abrasion. Fiber manufacturers consider these fiber coatings proprietary, so it is difficult to compare the qualities of coatings used by different manufacturers. The characteristics imparted by the coating greatly influence the performance of an SPM hawser.

Nylon

Nylon is the most commonly used fiber for SPM hawsers.

JPT

P. 917
Lime Treatment of Oily Saline Drilling Wastes
Authors: Deuel Lloyd E. , Holliday George H.
Published: December 2007

Land treatment of oily saline drilling wastes is problematic in lowpH, high-iron, and aluminum-activity soils commonly found in China, Southeast Asia, and the Americas. Problems stem from the addition of salts promoting hydrolysis of iron and aluminum acidity, exacerbating an often extreme (pH < 4.0) acid reaction. Most drilling wastes are strongly alkaline and offer a beneficial neutralization reaction when mixed with native acid soils. However, land treating of oily saline drilling wastes generally is limited by either the petroleum hydrocarbon content or salinity before sufficient base is added to neutralize excess acid in the receiving native soil.

This paper offers a practical and economical means of managing potentially problematic reactions by the prophylactic treatment of oily saline drilling wastes with agricultural-grade hydrated lime (calcium hydroxide) prior to land application.

The results presented show that hydrated lime reacts with the oil-base drill cuttings/acid-soil mixture in a manner promoting the biological degradation of the oil. Lime also functions to sequester free-oil fractions, making it easier to land-apply oily wastes and to control application rates. Free lime neutralizes excess soil acidity. The high pH associated with hydrated lime is ameliorated in the lime/drilling waste/receiving soil blend by fixation of atmospheric carbon dioxide to a pH < 8.3 (carbon dioxide and water naturally attain a pH of about 8.3, as shown by the decrease of reserve pit fluid pH with time). The data suggest that the optimum lime application is equivalent to the total petroleum hydrocarbon (TPH) content as measured on a dry-weight basis.
The Effect of Drilling Fluid Base-Oil Properties on Occupational Hygiene and the Marine Environment
Authors: Saasen A. , Berntsen M. , Løklingholm G. , Igeltjørn H. , Åsnes K.
Published: December 2007

Drilling operations can require the use of oil-based drilling fluids (OBM). These fluids are formulated as an emulsion consisting of water emulsified into a continuous oil phase. During the past decade, the North Sea drilling industry has moved from using diesel oil to low-toxic base oils in OBM. Further development of low-toxic base oils has continued on the Norwegian sector of the North Sea and has resulted in the use of nonaromatic base oils.

This paper describes the results from a field test in which the introduction of nonaromatic base oils reduced the hydrocarbon content by more than 50% in head space level in the shale shaker area, compared to the use of low-toxic base oils. In this test, two wells were drilled in which the hydrocarbon vapor and mist were collected at the same locations in the shaker area. The first well was drilled with a more traditional low-toxic, mineral-oil-based drilling fluid. The second well was drilled in a comparable formation with a drilling fluid based on the nonaromatic base oil. The paper also describes how skin irritation is reduced when using the nonaromatic base oils, compared to the use of previous base oils and synthetic base oils.

The paper discusses biodegradability and toxicity of different base oils. Ecotoxicological test results indicate that use of the nonaromatic base oils may result in less environmental impact, compared to the use of other mineral oils or the synthetic oils used in Norway, if an accidental discharge occurs.

Finally, the paper discusses dermal irritation effects from the different drilling fluids. It is shown that use of the nonaromatic base oil reduces the skin irritation index compared to use of other oil or synthetic base oils.