bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multidisciplinary Reservoir Characterization and Simulation Study of the Weyburn Unit
Authors: Elsayed S.A. , Baker Richard , Churcher P.L. , Edmunds A.C. 
Published: December 2007

Summary
Reservoir characterization is important to EOR and numerical simulation studies, especially for complex naturally fractured reservoirs with low-permeability matrix rock. Solvent movement and volumetric sweep are controlled by fracture distribution and connectivity and by matrix permeability variation. All these factors were considered in our reservoir characterization and simulation study.
The reservoir characterization was so effective that, in a 63-well simulation study, 70% of the wells were history matched on the first simulation runs without modification to the original geologic/petrophysical data. This can be attributed to the team approach of using geological, reservoir engineering, and petrophysical input.

Introduction
The Weyburn Unit, in the southeastern corner of Saskatchewan, has produced medium-gravity crude oil from the fractured, low-permeability Midale beds of the Mississippian Charles formation since its discovery in 1954. Even though the Weyburn Unit has been on waterflood for more than 26 years, a significant target for EOR, horizontal wells, and waterflood optimization remains.
The Weyburn field is located ~130 km southeast of Regina, Sask. (Fig. 1). The productive portion of the field covers ~180 km2. The field currently has 627 producing wells and 162 water injection wells on ~24-ha spacing.
The Midale beds of the Weyburn field were produced by primary depletion from discovery until 1964, when an inverted nine spot waterflood scheme was implemented. Since 1985, both horizontal and vertical infill drilling programs have been undertaken to optimize waterflood performance.
The Midale beds of the Mississippian Charles formation were deposited on a shallow carbonate shelf in the Williston basin. The reservoir is informally subdivided into the upper Marly and the lower Vuggy zones (Fig. 2).
The Marly is a chalky intertidal dolostone with occasional limy or limestone interbeds. Porosity in the dolostones ranges from 16% to 38%, with an average of about 26%. Matrix permeability within this reservoir horizon ranges from 1 to &gt;100 md, with an average of &lt;10 md.
Comparison Study of Hydraulic Fracturing Models—Test Case: GRI Staged Field Experiment No. 3
Authors: Warpinski N. R. , Moschovidis Z. A. , Parker C. D. , Abou-Sayed I. S. 
Published: December 2007

SummaryThis study is a comparison of hydraulic fracture models run using test data from the GRI Staged Field Experiment No. 3. Models compared include 2D, pseudo-3D, and 3D codes, run on up to eight different cases. Documented in this comparison are the differences in length, height, width, pressure, and efficiency. The purpose of this study is to provide the completions engineer with a practical comparison of the available models so that rational decisions can be made as to which model is optimal for a given application.
An Integrated Approach to Evaluation of Horizontal Well Prospects in the Niobrara Shale
Authors: Stright D. H. , Robertson R. D. 
Published: December 2007

Summary
Integrated use of surface and subsurface geologic data, structural deformation analysis from second-derivative maps, and dimensionless type curves in identifying potential horizontal well locations in the fractured Niobrara Shale of northwest Colorado is described. The analysis included construction of detailed structure maps from surface geology with tie-ins to seismic surveys and well control and of second-derivative maps that were overlaid on production data to determine the minimum radius of curvature required for commercial production. Reservoir properties were calculated for known fields from type-curve matching with type curves for dual-porosity, anisotropic reservoirs with stress-sensitive permeability. The curves were constructed for vertical and horizontal wells by use of reservoir-simulation models. Spacing and economics of drilling horizontal Niobrara wells in northwest Colorado were evaluated. The analysis suggests that recoverable oil from the fractured Niobrara in northwest Colorado averages 1,392 bbl oil/acre on the basis of a productive fracture area identified by second derivatives of the structural surface with values &gt; 1 × 10−4.5ft−1. It is also indicated that horizontal wellspacing in the fractured Niobrara should be &gt; 640 acres. In some instances, it may be more economical to develop the fractured Niobrara with vertical rather than horizontal wells.
High-Temperature Reprocessing of Petroleum Oily Sludges
Authors: Hahn W. J. 
Published: December 2007

Summary
Crude oil tank bottoms and other petroleum oily sludges and emulsions containing paraffins and volatile hydrocarbons can be economically reprocessed with heavy-oil dehydration facilities to recover residual hydrocarbons and to achieve volume reductions. The main factors affecting the use of this alternative are (1) the characteristics of the sludges requiring treatment, (2) the availability of waste heat or existing high temperature (&gt;350°F) dehydration facilities, (3) air emissions from the process, and (4) effluent criteria for treated residues. This paper discusses operational variables that affect high-temperature reprocessing (HTR) and illustrates an application of the process. The example pilot project evaluated the feasibility of high-temperature reprocessing for tank-bottom sludges and skim oils from Kern County, CA, light- (&gt;30°API) oil-producing leases. The process performance was quantified in terms of general operating parameters (flash point and paraffin, oil, water, and solids content); specific constituent analyses for benzene, toluene, ethylbenzene, and xylene (BTEX); and analyses for total petroleum hydrocarbons (TPH) content. Information on the percent removal of these parameters, characteristics of the treated residues, and the hydrocarbon recovery efficiency of the process are presented.
Numerical Simulation of Coning Using Implicit Production Terms
Authors: Spivak A. , Coats K.H. 
Published: December 2007

Abstract
This paper describes the use of a multiphase, multidimensional mathematical model to predict two- and three-phase coning behavior. Severe computational instability in the form of saturation oscillations in grid blocks near the wellbore is commonly encountered in the mathematical simulation of coning. This instability is due to the explicit (dated at the beginning of a time step and held constant for that time step) handling of saturation - dependent transmissibilities and production terms in the finite-difference solution of production terms in the finite-difference solution of the flow equations. An analysis of stability with respect to explicit handling of saturation-dependent transmissibilities is presented in this paper. This analysis shows why explicit transmissibilities can result in a severe time-step restriction for coning simulation. The use of implicit production terms in the difference equations to reduce instabilities is discussed and examples are given. These examples show that the implicit handling of production terms alone can result in a fivefold increase and permissible time step for a coning simulation with virtually no increase in computing time per time step. A laboratory water-coning experiment was simulated and excellent agreement was obtained between computed and observed results. A three-phase coning example for a gravity-segregation reservoir is also presented.

Introduction
Simulation of coning behavior is normally done by numerically solving the flow equations expressed in cylindrical (r, z, theta) coordinates with symmetry in the theta direction. The finite-difference technique of numerical solution of differential equations requires that the portion of the reservoir being simulated be divided into grid blocks as shown in Fig. 1. Since coning is a well phenomenon and not a gross reservoir phenomenon, the grid blocks must necessarily be relatively small in the vicinity of the wellbore because both pressures and saturations vary rapidly in this region. Severe computational instability is commonly encountered in the simulation of coning due to the relatively small grid-block sizes and high flow velocities in the vicinity of the wellbore. During a time step that would be considered normal for most reservoir simulation problems, a block near the wellbore is required to pass a volume of fluid many times its pore volume.
SPEJ
P. 257
Aromatic Recovery Unit: A Process Enhancement for Glycol Dehydrators
Authors: Choi M. S. , Spisak C. D. 
Published: December 2007

Summary
A process enhancement to the standard glycol dehydration unit (GDU) was developed to recover hydrocarbons (including the aromatic compounds) normally vented with vapor during glycol regeneration. The gaseous hydrocarbons are recovered as a condensate product (stock-tank oil) and regenerator fuel. This paper describes the technology and proposes a proactive compliance strategy with the U.S. Clean Air Act Amendments (CAAA).
Permeability of Stylolite-Bearing Chalk
Authors: Lind Ida , Nykjaer Olav , Priisholm Soren , Springer Niels 
Published: December 2007

Summary
Permeabilities were measured on core plugs from stylolite-bearing chalk of the Gorm field in the Danish North Sea. Air and liquid permeabilities were measured in directions parallel to and perpendicular to the stylolite surface. Permeability was measured with sleeve pressure equal to in-situ reservoir stress. Permeabilities of plugs with stylolites but without stylolite-associated fractures were equal in the two directions. The permeability is equal to the matrix permeability of non-stylolite-bearing chalk. In contrast, when fractures were associated with the stylolites, permeability was enhanced. The enhancement was most significant in the horizontal direction parallel to the stylolites.

Introduction
Stylolites are common in North Sea Chalk reservoirs (Albuskjell, Tyra, Ekofisk, West Ekofisk, Dan, and Gorm, Fig. 1). Typical stylolites of the Chalk have amplitudes of &lt;1-cm size and clay-bearing drapes of &lt;1-mm thickness. Stylolite-associated leaching, which can be prominent in limestones, has not been reported in the Chalk. In some reservoir intervals, stylolites are associated with fractures. These stylolite fractures commonly terminate against stylolite seams, perpendicular to or at least at high angles to the stylolite surface (Fig. 2). These fractures are 0.5 to 5 cm long and 0.01 to 0.1 mm wide.
In the Gorm field, stylolites are common with a vertical density of two to four stylolites per foot. Densities up to 20 stylolites per foot have been noted. A decreasing stylolite density is observed as porosity increases (Fig. 3). A similar trend was noted in the Upper Cretaceous chalk of England.
The influence of stylolites on effective permeability has been discussed by several authors. The consensus, based on petrography, is that stylolites in North Sea chalks act as barriers to flow in the vertical direction owing to their planar horizontal fabric and concentration of clay minerals. Flow in the horizontal direction may be enhanced if open fractures are associated with the stylolites. The present study does not support the assumption that stylolites form vertical barriers.
Actual measurements of stylolite permeability are few. One reason is that plugs tend to break along stylolite surfaces during drilling and routine core analysis, rendering them unsuitable for permeability measurement.
The objectives of this work were (1) to determine whether reliable measurements of permeability across and along stylolites are possible and, if so, under what test conditions; (2) to determine the influence of stylolites on the permeability of the chalk; and (3) to examine the relationship among stylolite-affected permeability, petrography, and mineralogy.
Reservoir Anisotropy Determination Using Multiple Probe Pressures
Authors: Head E.L. , Bettis F.E. 
Published: December 2007

Summary
Wireline formation testers are commonly used to produce a profile of pressure vs. depth through a reservoir by performing a series of point pressure tests during one descent in the well. A new test tool which can conduct a number of controlled pressure interference tests between multiple probes produces a profile of permeability anisotropy vs. depth. Anisotropy, the ratio of vertical to horizontal permeability, is one of the parameters required to predict production performance. The 70 cm vertical separation between probes provides this information on a more macroscopic scale than core plugs. This paper defines the practical operating domain for multiprobe tests, and gives field examples to illustrate environments ranging from high to low permeability, with both large and small anisotropy. Repeatability and interpretation sensitivity are demonstrated.

Introduction
Reservoir anisotropy, here defined as the ratio of vertical to horizontal permeability kv / kh, is one of the parameters needed to predict production performance. A multiprobe wireline formation tester allows determination of both vertical and horizontal mobilities at specified test depths. The transient pressure responses at monitor probes displaced radially and vertically are measured while a controlled 1000 cc fluid sample is acquired through a sink probe. One objective of multiprobe testing is to provide a profile vs. depth of permeability anisotropy. The 70 cm separation between sink and vertical probes provides this anisotropy index on a more macroscopic scale than core plugs, which typically represent only a 2.5 cm sample.
This paper defines the conditions which can limit multiprobe operation and interpretation, and presents field examples which cover a wide range of environments. The examples illustrate high horizontal permeability with good vertical permeability, high horizontal permeability with low vertical permeability, and low horizontal permeability with a wide range of permeability anisotropy. Repeatability and interpretation sensitivity are demonstrated.
An Integrated Approach to Drilling in the Gulf of Mexico
Authors: Peery Michael D. , Bullock R.D. 
Published: December 2007

Summary
This case history reviews the results of a single well and subsequent geological sidetrack drilled under an integrated partnering approach in East Cameron Block 306 of the Gulf of Mexico. The project demonstrates the benefits of partnering relationships. The integrated partnering approach proved to be an efficient and cost-effective means for the operator and service company to achieve objectives.

Introduction
The well, East Cameron Block 306 No. A-3, is located about 110 miles offshore Louisiana (Fig. 1). The operator had two wells on the structure drilled in 1990 and 1991, respectively, and wanted to evaluate the merits of using an integrated partnering approach to drill subsequent wells. Both offset wells were drilled recently using modern technology and equipment similar to that being proposed for a new well to be drilled under an integrated partnering approach. Because the operator had drilled two wells on the platform, a comparison of results could be made easily. The operator was able to get a quantitative cost comparison between wells drilled under a traditional format and wells drilled with an integrated partnering approach.
The operator believed that synergy could be achieved, resulting in advantages in both the planning and execution phases of the well. Specific advantages identified were the opportunities to access underutilized service company expertise and assistance, to establish common goals and objectives, and to reduce administration and prognosis development time and cost. In addition, through total project immersion, this "team approach" would make the service company an active participant, rather than a traditional vendor (Fig. 2). It was recognized that participant involvement and open communication at all levels - from the planning stage through project completion - creates synergy and esprit de corps.
Historical operator/vendor relationships are being re-evaluated throughout the industry, with partnerships, strategic alliances, and cooperative relationships now being seen as a more mutually beneficial means of conducting business.
Settling Velocity of Irregularly Shaped Particles
Authors: Chien Sze-Foo 
Published: December 2007

SummaryA new correlation has been developed to predict the settling velocity of irregularly shaped particles in Newtonian and non-Newtonian fluids for all types of slip regimes. The correlation was derived from extensive data on the drag coefficients and particle Reynolds num-bers of irregularly shaped particles. The effective fluid viscosity at the settling shear rate is used in the correlation. A trial-and-error or numerical iteration method is required to predict the settling velocity for non-Newtonian fluids. The correlation predicted and verified the effects of fluid properties, particle properties, and operation parameters on the settling velocity.
Pulsed Neutron Capture Log Interpretation In Laminated Formations: A Dual-Exponential-Decay Model
Authors: Haley R. A. 
Published: December 2007

Summary
Industry standard shaly sand equations for pulsed neutron capture (PNC) logs are premised upon homogeneous formations. Many interlaminated sands and shales, however, may not appear as homogeneous mixtures to PNC logs, despite the fact that the laminations may be very small (3 or 4 in.) and well below the vertical resolution of the PNC device. This can result in serious interpretation errors leading to bypassed pay. Log response equations and interpretation techniques for inhomogeneous formations are derived in this report and compared with a large sampling of observed data in river-dominated delta fringe sands of the Louisiana Gulf Coast. The excellent agreement warrants consideration of the new PNC log equation over the current industry standard equation as the primary method of evaluation in this type sandstone. The response of the natural gamma ray log to shaly sandstones is also reviewed. Possible misapplication of the industry standard PNC equation in deriving gamma ray/shale volume relations for inhomogeneous laminated formations is illustrated. The resulting impact on log interpretation is examined, and more appropriate relations are discussed.
Texas Offshore Bidding Patterns
Authors: Crawford Paul B. 
Published: December 2007

If bids on offshore leases are determined by competent people, each acting independently and all evaluating each tract on the basis of the same criteria, what would be the general characteristic of the bids? An analysis of the bids on several tracts reveals that a pattern can be anticipated if the many factors involved are individually scrutinized beforehand.

Introduction
Half a billion dollars in bonuses was paid at only one offshore oil and gas lease sale last year. For each tract the cost of the bids ranged up to $43 million, and the number of bidders ranged from one or two to more than a dozen. The quality of the prospects varied widely and was reflected in both the bids and the number of bidders. In an effort to account for this variation, the bids on several tracts from a recent Texas sale have been analyzed. Many factors enter into the deliberations and formulation of a large sealed bid. All factors believed to affect the value of the property must be considered; these factors can be estimated with varying degrees of certainty. Among intelligent bidders the estimate of any single factor will vary and will always be uncertain; and the uncertainty will depend upon the individual. The "eternal optimist" in an organization may be inclined to estimate too highly, which could result in the acquisition of the property even though it might be of little financial merit. It will also result in the bids being too high from the bidding standpoint; that is, the next highest bid would be considerably lower. With this in mind, we intend to postulate how sealed bids on the offshore properties should be distributed.

Basic Premise
In arriving at the proposed distribution of bids it was postulated that competent earth scientists were to postulated that competent earth scientists were to make completely independent appraisals of an offshore prospect. Commencing with this premise, it is not difficult to arrive at the expected distribution of bids on a single tract. We are led to expect a straight-line correlation of bids when they are plotted in a certain manner. The present worth of a prospect may be arrived at by an independent decision based on the many factors affecting the bid on a property. This could be formulated in simple algebra as follows:
Sealed Bid (number of pays) × (average pay thickness) × (average length of reservoir) × (average width of reservoir) × (fraction of pore space occupied byby hydrocarbons) × (fraction recovery) × (average profit per Mcf of gas orbbl of oil produced) × (discount factor) × (expected occurrence of finding oilor gas,)..................... (1)
In simple language we shall say that the bid comes from the product of the many factors above, or
(1a)
The terms A, B, C, etc., represent a single bidder's estimate of the number of pays, pay thickness, etc., required to satisfy all terms in Eq. 1.
JPT
P. 283
Creation and Application of Multidisciplinary Teams in the Regulated Natural Gas Storage Business
Authors: Fay W.C. , Egden J.G. 
Published: December 2007

Summary
Union Gas Ltd. is Canada's largest operator of underground natural gas storage facilities, with more than 126 Bcf of working capacity in southwestern Ontario. Recent advancements in E&P technology (3D seismic, reservoir simulations) have been applied successfully to storage. This technology has revealed a high degree of complexity in storage reservoirs that previously were considered relatively simple systems. Critical to the success of this technology transfer was the creation and management of multidisciplinary teams. Teams were small initially but have grown to include service companies and consultants from the planning stages through final project evaluation. Evolution of the team approach has resulted in faster, more cost effective and detailed projects. This paper presents specific team projects and case studies illustrating the difficult transition to the team approach in an extremely traditional, conservative environment.

Introduction
The establishment of multidisciplinary team environments has been common and successful within the upstream oil and gas industry for many years. Over the past 10 years, utility companies in Canada and the U.S. have experienced significant changes in terms of deregulation. In this changing marketplace, gas utilities have become more aware of their environment, developing markets external to their franchise areas and more aggressively developing transportation and storage projects. These challenges make multidisciplinary teams a necessity in the new and expanded market. Multidisciplinary teams have evolved to become the vehicle of choice for achieving a time-efficient and cost-effective position in a competitive market.
Union's storage reservoirs are all Silurian Age pinnacle reefs of the Guelph formation in Lambton County (Figs. 1 and 2). The areal extent of the reservoirs ranges up to several hundred acres. Well spacing ranges from 1,500 to 300 ft. The high well density, unlike production reservoirs, is necessary to ensure complete seasonal inventory turnover and to meet high peak daily demands in the winter at relatively low inventory levels. These reefs are ideal for storage because of their high permeability and porosity and a "super caprock" top seal.