bluuebunny/crossref_metadata_2025_split huggingface dataset:
Instrumentation for Simplified Commingling and Well-Testing Operations
Authors: Kite George 
Published: December 2007

Abstract
This paper discusses the theory, operation and practical application of a low-cost, field-proven instrumentation system which saves money and greatly simplifies lease-commingling and well-testing operations by providing an accurate, direct digital readout of the volume of net clean oil in oil-water streams containing up to 100 per cent water.

Introduction
Lease-commingling and well-testing operations usually require a measurement of the amount of "net clean oil" in an emulsion stream produced by a well or group of wells. Conventional methods of net oil metering require physical separation or treating and subsequent metering of oil and water volumes. Various arrangements of three-phase separators, gas-fired emulsion treaters, fluid meters and samplers are in wide use but are often unnecessarily expensive and complicated; frequently they leave much to be desired insofar as accuracy, operator convenience and adaptability to automation are concerned. The instrumentation system discussed automatically and continuously meters and monitors an oil-water stream containing pure oil, pure water, emulsion, or any combination thereof, and, without requiring physical treating or separation, provides an accurate digital readout of net clean oil volume, directly in barrels. No calculations, conversion factors, or interpretations are required; data are presented instantly, continuously and cumulatively in the most usable form. In addition, electrical digital signals for remote counting and an electrical analog signal for remote percentage water indication or recording are available at the computer terminal block.

Description of Equipment
The system uses an ordinary positive-displacement fluid meter, a wide-range electronic capacitance-measuring instrument, and an electro-mechanical computer. The PD meter measures total fluid volume and supplies a rotational, mechanical input to the computer. The capacitance instrument electronically determines the instantaneous percentage of water in the fluid stream. The computer subtracts the water volume from the total fluid volume and provides an output of the integrated volume of net clean oil. Fig. 1-A shows a typical skid-mounted net oil measuring assembly, consisting of a fluid strainer, a PD meter, a capacitance probe, the computer assembly and a diaphragm-operated fluid dump valve. This skid assembly would be installed downstream of a conventional fluid-gas separator, which is required only to prevent gas from damaging the PD meter. In operation all separator liquids would be discharged from the separator outlet through the skid assembly. Liquid dumping would be controlled by the pneumatic, snap-acting level control on the separator and the diaphragm-operated dump valve on the skid assembly. Two counters in the computer panel would then provide a direct readout of barrels of total fluid and barrels of net clean oil.
JPT
P. 732ˆ
Relative Permeability Modification in Gas/Liquid Systems Through Wettability Alteration to Intermediate Gas Wetting
Authors: Tang Guo-Qing , Firoozabadi Abbas 
Published: December 2007

Summary
The wettability of Berea and chalk samples for gas/oil and gas/ water fluids were altered from strong liquid wetting to intermediate gas wetting. Two polymers, FC-722 and FC-759, were used to alter the wettability. FC-759 is soluble in water and 120 as expensive as FC-722. Gas and liquid relative permeabilities were measured before and after wettability alteration. The results demonstrated a significant increase in liquid-phase relative permeability. Gas-phase relative permeability for a fixed saturation may increase or decrease; however, because of the very high liquid mobility and reduced liquid saturation, the gas mobility also increased for a fixed pressure drop.
A number of liquid injectivity tests were also carried out. The results revealed that the liquid-phase mobility could increase significantly when the wettability of rocks was altered from strong liquid wetting to intermediate gas wetting. All the results show clearly that the application of wettability alteration to intermediate gas wetting may significantly increase deliverability in gas condensate reservoirs.
The Integration of Capillary Pressures and Pickett Plots for Determination of Flow Units and Reservoir Containers
Authors: Aguilera R. , Aguilera M. S. 
Published: December 2007

Summary
This paper shows how to construct lines of constant capillary pressure, process speed, pore-throat aperture, and height above the free water table on a Pickett plot. The integration of these properties allows the determination of flow units and reservoir containers and illustrates the important link between geology, petro-physics, and reservoir engineering.
The concept of flow (or hydraulic) units and reservoir containers has been used in the oil industry with a good deal of success during the past few years. The process or delivery speed k/ϕ can be used in many instances to define a flow unit. Correlation of flow units between wells helps to establish reservoir containers and forecast reservoir performance.
We show that a Pickett crossplot of effective porosity vs. true resistivity should result in parallel straight lines for intervals with constant process speed k/ϕ. The slope of the straight lines is related to the porosity exponent m, the water-saturation exponent n, and constants in the absolute permeability equation. From the straight lines, it is possible to determine capillary pressures and pore-throat apertures directly for each flow unit at any water saturation. Pore throats at 65% water saturation compare very well with Winland r35 values. The method has not been published previously in the literature.
Building lines of constant k/ϕ allows the display of complete capillary pressure curves on the Pickett plot, including regions that are and are not at irreducible water saturation. Previous empirical methods for determining the absolute permeability of a given interval assume that the water saturation is at irreducible conditions. This paper presents a technique that allows us to estimate absolute permeability even if the interval contains moveable water.
The use of this technique is illustrated with previously published data from the Morrow sandstone in the Sorrento field of southeastern Colorado and carbonates from the Mission Canyon formation in the Little Knife field of North Dakota. We conclude that flow units can be determined reliably from the integration within one single log-log graph of Pickett plots, capillary pressures, pore-throat apertures, and Winland r35 values.
Heat-Transfer Models for Mitigating Wellbore Solids Deposition
Authors: Kabir C.S. , Hasan A.R. , Lin D. , Wang X. 
Published: December 2007

SummaryTubular flow restrictions caused by solids deposition create serious oilfield problems. Solids normally originate from either asphaltic or paraffinic oil. Hydrates add another dimension to the problem when water production begins. Most solutions center on the use of aromatic solvents for asphaltenes and chemicals or heating for paraffins.In this study, we seek preventive measures to minimize solids deposition by altering characteristics of fluid flow in the wellbore. The knowledge of fluid thermodynamic behavior, and the application of fluid principles and heat flows, constitute the essence of our approach. Specifically, we present a steady-state model that allows computation of wellbore pressure and temperature profiles for a hot-circulating fluid in the case of parrafins. The same model is used to study the p-T behavior of asphaltic oil while circulating a cold fluid.A fluid-temperature model is also presented when intermittent or continuous injection of solvent is sought through a chemical-injection line. Both models are general in that flows in offshore wells can be handled rigorously.Computational results show that preserving energy of paraffinic oil is feasible by circulating hot fluid in the annulus and/or using insulation, thereby keeping solids in solution. The use of an unsteady-state flow model sheds light on the time available for well intervention before the onset of deposition. Similarly, cooling of fluids may help produce asphaltic oils under favorable conditions.
Engineering Planning and Supervision of Directional Drilling Operations
Authors: Edison J.E. 
Published: December 2007

Abstract
For many years the planning and supervision of directional drilling operations have been more-or-less limited to those organizations and individuals specializing in directional work. Without attempting to minimize the importance of and necessity for these directional specialists, operating companies have become increasingly aware of the contributions which competent engineering planning and supervision can make toward a successful directional drilling campaign.
The part which such planning and supervision can play in directional operations is illustrated by a recent drilling campaign undertaken by Sun Oil Co. To test a Marginulina sand structure underlying a portion of the lower Texas Gulf Coast, three relatively large-displacement directional wells were drilled from Padre Island out under the Gulf of Mexico. While the hazards and limitations involved in drilling high-angle wells were recognized, the cost advantage of a successful directional campaign, as compared with other methods of drilling in the 20- to 40-ft waters, made the calculated risk well worth accepting.
Careful and detailed planning preceded the operation. Among the factors considered were:selection of directional drilling specialists,study of rig requirements and selection of contractor,target tolerance,kickoff depth,casing and hole-size program, anddrilling mud program.
With the exception of one short fishing operation, the directional operations progressed in a satisfactory and troublefree manner. On each of the wells approximately 9,000 ft of hole were drilled to secure horizontal displacements ranging from 3,900 to 4,500 ft at true vertical depths of 7,900 ft. Maximum angles ranged from 31 ½ to 43 ½. All holes bottomed well within target limits, and the drilling times, raging from 32 to 42 days, are considered quite good for this specialized operation. No difficulty was experienced with any of the casing or casing operations.
Average cost of the directional wells was $125,000; it is estimated that vertical wells drilled by platform and tender or drill barge would have cost a minimum of $300,000 and probably $500,000.
Sun's successful directional program may be attributed largely to the following factors, all of which enhance the chance for success on any directional program:careful planning; close, informed supervision, andadequate drilling rig and equipment; cooperative and experienced rig personnel; a competent and responsible directional specialist.
Analytical Modeling of Oil Recovery by Steam Injection: Part I – Upper Bounds
Authors: Yortsos Y. C. , Gavalas G. R. 
Published: December 2007

AbstractThis paper deals with the derivation of upper bounds for the growth of the steam zone in steam injection processes for one- or multidimensional reservoirs at constant or variable injection rates. The bounds are derived from the integral balances describing a reservoir of arbitrary geometry by introducing lower bounds for the heat losses to the surrounding area and the hot liquid zone. In this way, the effect of preheating in the hot liquid zone is estimated to determine the recovery efficiency of a steam drive.The growth rate of a one-dimensional steam zone at variable injection rates is subject to two upper bounds resulting from the total thermal energy and the latent heat balances, respectively. Each of the bounds controls the rate of growth of the steam zone in a certain time interval, depending on the dominant mode of heat transfer in the hot liquid zone. At constant injection rates, the steam zone growth at large times is controlled by the bound based on the latent heat balance. This balance depends on a dimensionless parameter, F, defined as the ratio of the latent heat to the total heat injected. Based on the relative magnitude of F with respect to the critical value F = 2/π, the region of validity of the Marx-Langenheim solution is delineated on a Ts vs. fs diagram. The Marx-Langenheim solution is satisfactory at large times when F&gt;2/π and becomes less satisfactory as F assumes smaller values.Similar upper bounds are obtained for a two-dimensional steam drive (thin reservoirs). In three-dimensional reservoirs, on the other hand, bounds are derived only for a special form of displacement (separable front). These bounds depend on the geometric parameter κ that measures the extent of gravity override. By means of simple analytical models for the steam front shape, κ can be determined in terms of the physical variables of the process.
An Application of Cemented Resistivity Arrays To Monitor Waterflooding of the Mansfield Sandstone, Indiana, U.S.A.
Authors: Bryant I. D. , Chen M.-Y. , Raghuraman B. , Raw I. , Delhomme J.-P. , Chouzenoux C. , Pohl D. , Manin Y. , Rioufol E. , Oddie G. , Swager D. , Smith J. 
Published: December 2007

SummaryIn 1999, an oilfield experiment was initiated to test the application of electrical measurement technologies to permanent reservoir monitoring. The principal objective of the experiment was to demonstrate the feasibility of monitoring water movement between an injection and an observation well. This paper describes the interpretation of the data provided by the resistivity arrays and discusses the data quality and reliability of the measurements.Two wells were drilled into the Mansfield sandstone reservoir in Indiana, U.S.A. The D-8 injector well was located in the center of four development wells. The OB-1 monitoring well was offset 233 ft to the southwest in a location midway between the D-8 injector and the No. 3 production well. The injector was instrumented with a 16-electrode resistivity array that was run on the outside of insulated casing and cemented into the annulus of the well. A similar array was cemented into the annulus of the monitoring well.In March 1999, the D-8 well was perforated and acidized. A surface gauge was used to monitor injection rates and pressures. Initially, injection proceeded at a rate of approximately 20 B/D, increasing to 90 B/D after fracture stimulation. The D-8 array records responses to wellbore operations and injection. It clearly distinguishes the movement of the waterfront in different zones. The OB-1 electrical array clearly indicates early water breakthrough by means of an induced fracture. The data show good signal-to-noise ratio and high reciprocity.The experiment has demonstrated the viability of using permanently installed resistivity arrays to monitor the movement of oil/ water contacts and salinity fronts that are some tens of feet away from the wellbore. Results demonstrate the feasibility of using such arrays to monitor oil/water contact movements remote from injection, monitoring, and production wells.
Modeling of the Acidizing Process in Naturally Fractured Carbonates
Authors: Dong C. , Zhu D. , Hill A. D. 
Published: December 2007

Summary
When a naturally fractured carbonate formation is treated with acid at pressures below the fracturing pressure, the acidizing process will likely be different from either a matrix treatment or an acid fracturing treatment. Our previous experimental study shows three kinds of acid etching patterns after acidizing naturally fractured carbonates, and it also illustrates their relationships with the fracture properties and acidizing conditions. Based on the experimental observations, a mathematical model of acidizing naturally fractured carbonates has been developed. The model includes bulk solution transport, acid transport and reaction, and the change of fracture width by acid dissolution. A new approach was used to treat leakoff acid and acid-rock reactions at the fracture walls. The new acidizing model for numerically generated rough-surfaced fractures predicts the same kinds of acid etching patterns and the same relationships between acid etching patterns and the fracture width, surface roughness, and leakoff rate as observed in experiments.
Lateral Buckling of Pipe With Connectors in Curved Wellbores
Authors: Mitchell Robert F. 
Published: December 2007

Summary
Connectors should clearly have an effect on pipe loading. For nonbuckled pipe, Lubinski analyzed the effect of connectors on pipe in tension in a curved borehole and Paslay and Cernocky extended this analysis to pipe in compression. Recently, helically buckled and laterally buckled pipes with connectors have been analyzed. In these papers, analytic solutions of the beam-column equations were developed in 3D, and critical loads were determined for buckling initiation. Conditions for positive contact forces were determined and compared to previous buckling criteria, such as Dawson-Paslay.
In this paper, the wellbore curvature effects studied by Lubin-ski, Paslay, and Cernocky are included in the buckling effects. The modifications necessary to analyze lateral buckling are made for a curved wellbore. The resulting model gives a buckling criterion similar to He and Kyllingstad's results for pipe without connectors. The buckling model is integrated with the Paslay-Cernocky analysis to resolve some of the odd bending-stress results developed by their model. Pipe deflections, contact loads, and bending stresses are determined with explicit formulas. Sag between connectors is calculated so that pipe contact with the wellbore between connectors can be determined. Conditions for positive contact forces are determined and compared to previous buckling criteria, such as Paslay-Dawson and He-Kyllingstad.
Applications include the analysis of bottomhole assemblies (BHAs), drillpipe, casing, and tubing. The solutions are simple formulas that are suitable for hand calculations.
A Simple Model To Predict Natural Gas Separation Efficiency in Pumped Wells
Authors: Harun A. F. , Prado M. G. , Serrano J. C. , Doty D. R. 
Published: December 2007

Summary
A new mechanistic model to predict natural separation efficiency in vertical pumped wells has been developed. The model is based on the combined phase momentum equations and a general slip-closure relationship. New drag-coefficient correlations have been developed that correspond to bubbly (i.e., undistorted particle) and churn-turbulent flow regimes. The model indicates that natural separation efficiency depends strongly on geometry, void fraction, and in-situ gas flow rate.
An Alternative View of Filter-Cake Formation in Fractures Inspired by Cr(III)-Acetate-HPAM Gel Extrusion
Authors: Seright R. S. 
Published: December 2007

SummaryA new model was developed to describe water leakoff from formed Cr(III)-acetate-HPAM gels during extrusion through fractures. This model is fundamentally different from the conventional filter-cake model used during hydraulic fracturing. Even so, it accurately predicted leakoff during extrusion of a guar-borate gel. Thus, the new model may be of interest in hydraulic fracturing. Contrary to the conventional one, the new model correctly predicted the occurrence of wormholes and stable pressure gradients during gel extrusion through fractures.
A Two-Scale Numerical Subgrid Technique for Waterflood Simulations
Authors: Arbogast Todd , Bryant Steven L. 
Published: December 2007

Summary
We present a two-scale numerical subgrid technique for simulating waterflooding. Local subgrid computations are combined with a coarse-grid computation to provide a fine-scale resolution of the solution. We use porosity, relative and absolute permeabilities, the location of wells, and capillary pressure curves defined on the fine scale. No explicit macroscopic coefficients nor pseudofunctions result. The method is several times faster than solving the fine-scale problem directly, generally more robust, and yet achieves good results as it requires no ad hoc assumptions at the coarse scale and retains all the physics of the original multiphase flow equations.
Concentric Workover Operations in Deep Sour Wells
Authors: Fincher Norton E. 
Published: December 2007

This paper describes an effort to reduce workover cost by applying concentric workover operations to deep sour wells. A medium-duty workover rig performed a variety of remedial procedures through the production tubing. Successful use of the concentric technique at great depths and in a hostile sour environment provides a valuable tool for recovery of additional oil and gas at lower cost.

Introduction
Exxon Co. U.S.A. operates more than 130 deep [15,500-ft (4724-m)] sour Smackover and Norphlet oil and gas wells in five fields in northwest Florida and south Alabama. Concentric workovers were performed in four of the fields (Jay/Little Escambia Creek, Big Escambia Creek, Blackjack Creek, and Flomaton); however, the program at Jay/Little Escambia Creek (LEC) field has been the largest and is the one discussed here. Conditions applying at Jay/LEC also apply in the other fields.Conventional workovers to recondition a well require a rig to remove the Christmas tree and pull the production tubing. At Jay/LEC this involves using drillpipe to mill out a permanent-type packer to perform the required remedial work. These conventional workovers cost between $700,000 and $1,000,000. In contrast, concentric workovers perform the required work by use of small work pipe run through the production tubing using a small rig or other hoisting unit. The cost of a concentric workover at Jay/LEC averages about $175,000 or approximately one-fourth the cost of a conventional workover.Concentric methods are not new. The techniques have been in use for about 25 years. Concentric workovers have been used at lesser depths to wash out obstructions, fish, acidize, squeeze cement, drill cement, consolidate sand, etc. The uniqueness of the work described in this paper is that the work was performed at greater-than-usual depths and in wells which produce with 10% hydrogen sulfide in the well fluids.

Objectives of Workover Program
Work is performed on producing wells and water-injection wells with the following objectives:to increase well producing capacity, capture additional reserves, and improve waterflood conformance by opening zones not perforated or stimulating zones perforated but not producing,to restore dead wells to production and capture additional reserves by sealing off zones of floodwater invasion and recompleteing in water-free zones,to prevent interzonal crossflow to water-free zones by plugging zones of water breakthrough,to improve waterflood conformance by opening selected new zones for water injection, andto restore to production wells off due to mechanical blockage in the tubing.
JPT
P. 1674＾