bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Risk Analysis Methods to Subsurface Well Collisions
Authors: Thorogood J. L. , Hogg T. W. , Williamson H. S. 
Published: December 2007

SummarySubsurface separation criteria have evolved empirically over the years. They still are based largely on untested assumptions about safety factors, comfort values, and survey tool accuracy. A mathematical analysis of the probability of collision combined with a decision tree describing the consequences provides a method of risk evaluation. The mathematics can be simplified under certain special assumptions, allowing key features of the problem to be illustrated. A flow chart of the directional-drilling tolerance setting procedure shows how the methods described can be used in daily well-planning operations.
Fatigue Testing of Drillpipe
Authors: Grondin G. Y. , Kulak G. L. 
Published: December 2007

Summary
Twenty-nine tests in air and 27 tests in a 3.5% NaCl solution were conducted to test the fatigue strength of Grade E 4.5-in.-OD, 16.6-lbm/ft [114-mm-OD, 24.7-kg/m] drillpipe. The effects of stress range, mean stress, corrosion, and upset geometry were tested on the drillpipe body alone and on specimens that included the tool joint, upset, and drillpipe body. Stress range and mean stress effects were significant in noncorrosive and corrosive environments. The effect of upset geometry was minimal on an external upset compared with that on an internal/external upset. Among the specimens that failed, grinding marks on the drillpipe surface, which occurred during inspection at the mill, caused failure of about 60% of the specimens. Grinding created a notch effect and induced a detrimental residual-stress pattern on the pipe surface, which decreased drillpipe fatigue life. API guidelines for cumulative fatigue of Range 2 drillpipe were evaluated in light of these experimental test results and were found to be unsafe for drilling in noncorrosive conditions and possibly too conservative for corrosive conditions.
Azimuthal Resistivity Imaging: A New-Generation Laterolog
Authors: Davies D. H. , Faivre Ollivier , Gounot M- T. , Seeman Bruno , Trouiller J- C. , Benimeli Dominique , Ferreira Antonio , Pittman D. J. , Randrianavony Mahaly , Smits J. W. , Anderson B. I. , Lovell John 
Published: December 2007

Summary
We describe a new-generation laterolog tool, the azimuthal resistivity imager (ARI). The tool makes deep azimuthal resistivity measurements around the borehole with higher vertical resolution than the Dual Laterolog (DLL). Twelve azimuthal electrodes are incorporated into the DLL electrode array to provide 12 deep, oriented resistivity measurements while retaining the standard deep and shallow laterolog measurements. To allow full correction of the azimuthal resistivities for borehole effect, a shallow auxiliary measurement is incorporated on the azimuthal array. Although the full-coverage azimuthal resistivity image has much lower spatial resolution than borehole microelectrical images, it complements these because of its lower sensitivity to shallow features. Evaluation of heterogeneous and fractured formations, and computation of fracture dip are applications of the tool's imaging capabilities and are discussed and illustrated with log examples. Other log examples cover thin-bed response and corrections for Groningen and borehole effects, including that for eccentering of the tool in the borehole.
Pressure Behavior of Laterally Composite Reservoirs
Authors: Kuchuk F. J. , Habashy Tarek 
Published: December 2007

Summary
This paper presents a new general method for solving the pressure diffusion equation in laterally composite reservoirs, where rock and fluid properties may change laterally as a function of y in the x − y plane. Composite systems can be encountered as a result of many different types of depositional and tectonic processes. For example, meandering point bar reservoirs may be approximated as lateral composite systems. Reservoirs with edgewater encroachment are another example of such systems.
The new solution method presented is based on the reflection-transmission concept of electromagnetics to solve fluid-flow problems in 3D nonhomogeneous reservoirs, where heterogeneity is in only one (y) direction. A general Green's function for a point source in 3D laterally composite systems is developed by using the reflection-transmission method. The solutions in the Laplace transform domain are then developed from the Green's function for the pressure behavior of specific composite reservoirs. The solution method can also be applied to many different types of wells, such as vertical, fractured, and horizontal in composite reservoirs.
The pressure behavior of a few well-known laterally composite systems are investigated. It is shown that a network of partially communicating faults and fractures in porous medium can be modeled as composite systems. It is also shown that the existing solutions for a partially communicating fault are not valid when the fault permeability is substantially larger than the formation permeability. The derivative plots are presented for selected faulted, fractured, channel, and composite reservoirs as diagnostic tools for well-test interpretation.
It is also shown that if the composite system's permeability varies moderately in the x or y direction, it exhibits a homogeneous system behavior. However, it does not yield the system's average permeability. Furthermore, the composite systems with distributed low-permeability zones behave as if the system has many two no-flow boundaries.
Modeling Changing Storage During a Shut-In Test
Authors: Hasan A. R. , Kabir C. S. 
Published: December 2007

Summary
Phase redistribution has been observed to occur in oil, gas, and steam-injection wells during a shut-in test. Two empirical approaches—involving exponential and error functions—are currently available to analyze field data. However, these methods do not have any mechanistic basis and may lead to erroneous estimates of reservoir parameters, such as skin. More importantly, these methods cannot be used in a forward mode to predict the reservoir and/or well conditions that would cause changing wellbore storage situations. Such predictions are desirable for deciding on the need for expensive downhole shut-in or flow measurement. Phase redistribution is a consequence of the higher relative velocity of the gas phase in a well's production string after shut-in at the surface. The resulting segregation of phases caused by buoyancy of the gas phase may cause wellbore pressure buildup to be quite different from normally expected response before the onset of the middle-time period. Under one scenario, the bubbles may segregate rapidly to the top of the wellbore leading to an increasing storage situation. Conversely, the bubbles may travel slowly without reaching the top to precipitate a decreasing storage situation. In either event, the commonly used constant-storage model cannot be used for test interpretation. A mechanistic approach, based on the physics of migration of a swarm of bubbles, is developed that explains the changing storage phenomenon by incorporating continually decreasing afterflow from the reservoir after shut-in, the variation of void distribution within the wellbore with depth and time, and the combined effect of afterflow and bubble migration on the wellhead and bottomhole pressures (BHP's). The model is used to develop a simulator, and a few cases are examined to illustrate the simulator's capabilities.
Differentiation of Hydrocarbon Type in Gulf of Mexico Clastic Reservoirs by Inelastic Pulsed Neutron Capture Data
Authors: Scheibal J. R. , Weiland J. L. , Worrell J. M. , Bayer J. E. 
Published: December 2007

Summary
This paper outlines our results and experiences in hydrocarbon typing Pliocene/Pleistocene turbidite sand reservoirs in two Shell Offshore Inc. Gulf of Mexico fields. While differentiation of hydrocarbon type was important in identifying completion targets for Produce While Drilling (PWD) operations, hydrocarbon typing was extremely difficult. This hydrocarbon typing problem was a result of (1) compositional make-up of both oil and gas, (2) high reservoir pressures encountered (up to 10,000 psi), (3) geological complexity (structural and stratigraphic), (4) the use of oil based mud to drill many wells, and (5) complex mineralogical makeup of the sands.
Because openhole data and routine pulsed neutron capture (PNC) data were often inconclusive, secondary curves presented on PNC logs were extensively examined. The PNC ratio of inelastic short to long spaced data (RIN) was found to be an extremely diagnostic gas indicator, and has been used to further refine and calibrate petrophysical evaluations. These refined evaluations were then incorporated into redesigning a new completion strategy for each well examined.
EOS Modeling and Experimental Observations of Three-Hydrocarbon-Phase Equilibria
Authors: Godbole S. P. , Thele K. J. , Reinbold E. W. 
Published: December 2007

Summary
An equation-of-state (EOS) fluid characterization has been developed to model three-hydrocarbon-phase equilibria as part of the enriched-gas EOR research program for the Kuparuk hydrocarbon miscible flood on the Alaskan North Slope. Laboratory experiments with Kuparuk reservoir oils and miscible injectants have identified an apparent second equilibrium liquid that is heavier than the original oil and macroscopically reversible. A three-phase EOS fluid characterization was developed to match both two- and three-phase experimental data by use of a modified Peng-Robinson EOS. Experimental observations identified a relationship between the third phase and the oil's pentane-insoluble fraction. The characterization uses a total of 16 components, with the heaviest two approximating the pentane-soluble and pentane-insoluble portions of the C36+ fraction. The properties of these heavy pseudocomponents control the development and behavior of the heavy phase. The EOS fluid characterization was used to study three-phase, enriched-gas-drive displacement mechanisms. For the Kuparuk fluids, a condensing/vaporizing displacement mechanism is predicted in a three-phase environment. Reservoir-condition micromodel displacements were conducted to observe the phase-behavior and displacement mechanisms during Kuparuk enriched-gas displacements. Micromodel observations are consistent with a near-miscible condensing/vaporizing mechanism and qualitatively agree with EOS predictions.
Heterogeneity Modeling Used for Production Simulation of a Fluvial Reservoir
Authors: Tyler Kelly J. , Svanes Tarald , Henriquez Adolfo 
Published: December 2007

Summary
The application of a stochastic model used for the description of channel sand and overbank flood plain shales of the complicated and heterogeneous Statfjord formation of a field under evaluation for development in the North Sea is presented. The channel sands contain other internal sand facies that have permeabilities different from those of the channels. These internal facies are also modeled. Permeability variations are modeled for each facies type with a Gaussian random field. At the facies and permeability stages of modeling, the stochastic model honors well data, seismic interpretations, and sedimentological knowledge gained by geologists from neighboring fields, outcrop analog studies, and general sedimentological principles. Permeability data, modeled in a fine grid, is upscaled to a coarser corner-point geometry grid used in numerical reservoir simulation. Production profiles resulting from geologic realizations carried forward to the reservoir simulator are compared with profiles obtained from a base-case model with smoothed permeability. The uncertainty originating from the unknown facies architecture and permeability distribution between wells is evident from production-profile analysis.
Analysis of Transient-Pressure Response of Horizontal Wells in Bounded Reservoirs
Authors: Du Kui-Fu , Stewart George 
Published: December 2007

Summary
The main purpose of this paper is to present analysis methods for transient-pressure response of horizontal wells in bounded reservoirs. Several lateral-boundary models are examined, and detailed explanations of possible derivative responses are given. New, generalized diagnostic rules and well-test analysis procedures are provided. Practical issues are discussed at length.
Shallow Horizontal Drilling in Unconsolidated Sands Offshore California
Authors: Payne J. D. , Huston C. W. , Bunyak M. J. 
Published: December 2007

Summary
Four shallow horizontal wells were drilled from Platform C in Dos Cuadras field offshore California to recover reserves inaccessible with conventional drilling techniques. The wells had true vertical depths (TVD's) ranging from 746 to 989 ft with total horizontal displacements from 1, 613 to 3, 788 ft. The wells had horizontal displacement TVD ratios up to 3.95. The targets were unconsolidated, high-permeability sands. This paper details well planning, drilling, and completion.
Formation Damage and Filter Cake Buildup in Laboratory Core Tests: Modeling and Model-Assisted Analysis
Authors: Liu Xinghui , Civan Faruk 
Published: December 2007

SummaryA mathematical model for the analysis of formation damage in laboratory core tests is presented. The model considers filter cake buildup on sand face, invasion of external particles, release of formation fines, migration and retention of external particles and formation fines, interphase transfer of particles, and alteration of porosity and permeability. The effects of wettabilities of fine particles and pore surfaces, relative permeabilities and capillary pressure on formation damage in two-phase flow conditions are also included. Simulation results from the model are in good agreement with experimental results from core tests. This model can be used for the analysis of formation damage due to particulate processes in laboratory core tests.
Helical Buckling and Lock-Up Conditions for Coiled Tubing in Curved Wells
Authors: He Xiaojun , Kyllingstad Age 
Published: December 2007

Abstract
An improved formula for critical buckling loads has been derived. This formula, which takes the well curvature into account, has been verified in small scale laboratory tests. The theory has been applied to survey data from a real horizontal well and it predicts that the well curvature substantially affects the critical force for helical buckling, and thereby also the maximum run-in length of coiled tubing. Criteria for operational limits, such as lock-up and tubing failure, are also discussed in the paper.
Effects of pH and Shear on the Gelation of a Xanthan-Cr(III) System
Authors: Dolan D. M. , Thiele J. L. , Willhite G. P. 
Published: December 2007

SummaryA study was undertaken to determine the effects of pH and shear rate on the gelation of a xanthan-Cr(III) solution of the type that has been used successfully for permeability modification of oil fields. The rate of gelation and gel strength were determined using small-amplitude oscillatory methods under zero shear and superimposed steady-shear rates approximating those anticipated during placement in the porous matrix. At zero-net shear, the rate of gelation was first order in the inverse of the hydrogen-ion concentration up to pH 6.5. At pH 6.5 and above, precipitation of chromium slowed the gelation. The effect of shear was quite pronounced. No permanent gel structure was observed while the gel was under shear, regardless of pH or shear rate. Gelation was observed after shear was removed. However, the rate of gelation was 1.5 to 2 orders of magnitude slower than observed for zero-net shear runs. The rate of gelation decreased with increasing duration of shear. This effect was more pronounced at higher pH, indicating the ratio of applied-shear duration to solution-gel time may be the factor controlling gelation. Gels were not observed when the gel system was subjected to continuous shear for times longer than the zero-shear gelation time.
Relationship of Core-Scale Heterogeneity With Non-Darcy Flow Coefficients
Authors: Al-Rumhy M. H. , Kalam M. Z. 
Published: December 2007

Summary
An experimental research program to investigate the effects of liquid saturations upon non-Darcy flow coefficients is presented. The presence of a wetting phase fluid plays an important role in high velocity flow of a gas well, producing condensate or water, and in propped fractures containing liquid saturations.
This study initially examines the errors commonly encountered but ignored in evaluating the permeabilities and the coefficient of inertial resistance during the flow of gases through porous media. Experimental techniques, such as constant overburden pressure, changing overburden pressure, forward flow, and backpressure flow, are applied to optimize and obtain accurate evaluations of Klinkenberg parameters and inertial resistance coefficients for a selection of Omani reservoir cores. Gas-slippage factor significantly influences the derived viscous and inertial coefficients from highvelocity gas flow data. An increasing wetting phase saturation increases the non-Darcy coefficient up to thirty-fold.
Analysis of the experimental data revealed that unique relationships exist between the non-Darcy flow coefficients and the equivalent liquid permeability, porosity, and liquid saturation. Heterogeneity of the core as mapped by pore-scale measurements provide an insight into the mechanism for such a large increase in the non-Darcy coefficients.
Drilling Extended-Reach/High-Angle Wells Through Overpressured Shale Formation
Authors: Guild G. J. , Jeffrey J. T. , Carter J. A. 
Published: December 2007

Summary
This paper discusses Amoco U.K. Exploration Co.'s unsuccessful attempt to drill an extended-reach well in Arbroath field (U.K. Block 22/17) and how problems encountered were resolved on subsequent high-angle and extended-reach drilling operations in the field. The resolution of these problems over the course of drilling four high-angle wells and one extended-reach well involved (1) de-termining mud weight by use of rock mechanics principles, (2) evaluating hole conditions with a wellsite torque-and-drag program, (3) optimizing BHA performance, and (4) developing techniques for effective high-angle hole cleaning. By use of the methods outlined in this paper, improved drilling performance and significant cost savings are demonstrated.
A New Methodology for Minimizing Investment in the Development of Offshore Fields
Authors: Garcia-Diaz Juan C. , Startzman Richard , Hogg Gary L. 
Published: December 2007

SummaryThe development of an offshore field is often a long, complex, and extremely expensive undertaking. The enormous amount of capital required for making investments of this type motivates one to try to "optimize" the development of a field. This paper provides an efficient computational method to minimize the initial investment in the development of a field. The problem of minimizing the investment in an offshore field is defined here as the problem of locating a number of offshore facilities and wells and allocating these wells to the facilities at minimum cost. Side constraints include restrictions on the total number of facilities of every type and design and various technology constraints. This problem is modeled as a 0/1 integer program. The solution method is based on an implicit enumeration scheme using efficient mathematical tools, such as Lagrangean relaxation and heuristics, to calculate "good" bounds and, consequently, to reduce the computation time. The solution method was implemented and tested on some typical field-development cases. Execution times were remarkably small for the size and complexity of the examples. Computational results indicate that the new methodology outperforms existing methods both in execution time and in memory required.
Drilling Fluid Conversion: Selection and Use of Portland or Blast-Furnace-Slag Cement
Authors: Schlemmer R. P. , Branam N. E. , Edwards T. M. , Valenziano R. C. 
Published: December 2007

Summary
Conversion of drilling mud to oilwell cement has advanced from an unpredictable laboratory curiosity to a practical reality. Recent field introduction of polymer dispersants, organic accelerators, and an alternative cementitious material have provided two refined and prac-tical conversion methods. Each method claims universal applicability plus performance superior to that of conventionally mixed and pumped Portland cement. Both blast-furnace-slag (BFS) and Portland cement are used for drilling-mud conversion. Portland and BFS mud conversions can use the same recently developed polymer dispersants, filtration-control materials, defoamers, and other additives that are typically used to treat high-temperature, highly-salt-contaminated drilling muds. Experience in the field and laboratory has demonstrated that conversion with BFS or Portland cement is essentially one technology from a pilot-test and application standpoint. While use of these two materials reflects essentially one technology, distinct performance and cost differences exist. These differences define the specific economic application advantages and must be considered when a decision to use BFS or Portland cement is made. Rational selection of mud-to-cement conversion depends on a detailed economic comparison of basic materials, logistics, and equipment availability.
Effects of High-Speed Pipe Rotation on Pressures in Narrow Annuli
Authors: McCann R. C. , Quigley M. S. , Zamora M. , Slater K. S. 
Published: December 2007

Abstract
Variations in annular geometry, eccentricity, and pipe rotational speed strongly affect pressure loss of a fluid flowing in the narrow annulus of a slimhole well. Due to these factors, accurately calculating and controlling pressures in slimhole wellbores are difficult. Accurate pressure calculations are crucial for safely controlling formation pressures and protecting wellbore integrity. Attempts to model non-Newtonian fluid flow in narrow annuli with high-speed pipe rotation have been hampered by the lack of quality data. The results of numerous annular flow experiments presented herein partially correct this deficit. These results supplement annular pressure data from a 2500-ft slimhole test well and standpipe pressure data from a slimhole exploration well.
Sensitive pressure measurements were used to characterize fluid flow in concentric narrow annuli created by a 1.25-in. diameter (Dp) steel shaft inside clear acrylic tubes with 1.375-in. to 1.75-in. inside diameter (Dh). Similar tests were conducted in a fully eccentric annulus formed by the steel shaft inside an acrylic tube with Dh = 1.50 in. Maximum shaft rotational speed was 900 rpm and maximum fluid flow rate was 12 gpm. Test fluids included water, glycerin solutions, viscosified clear brines, and several slimhole drilling muds.
Models selected from the public domain were used with varying success to calculate results from the hydraulics tests. Simple models typically used by the drilling industry calculated annular pressure loss for non-rotating cases with reasonable accuracy. However, the simple models seldom calculated absolute effects of pipe rotation even though calculated trends correctly match those in measured data. For turbulent flow, annular pressure loss increased with increasing pipe rotation. For laminar flow, annular pressure loss decreased with increasing pipe rotation. In all cases, annular pressure loss increased with increasing mud rheology and decreased with increasing eccentricity.