bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Perforation Schemes To Control Production and Injection Profiles Along Horizontal Wells
Authors: Asheim Harald , Oudeman Piet 
Published: December 2007

SummaryThe flowing pressure drop along the wellbore gives rise to increasing drawdown in the direction of flow. Particularly for long horizontal wells, this may lead to strongly nonuniform inflow. Lithology variation has similar effects.For production wells, nonuniform inflow may aggravate cresting and cause premature breakthrough of gas or water. For water flooding, sweep efficiency often depends on uniform injection over long horizontal distances. Thus, control of the injection profile may be imperative to efficient recovery.The paper describes a scheme for control of production and injection profiles by means of perforation-density variation. The method developed enables determination of such perforation schemes on the basis of classical inflow efficiency concepts and models.
Designing and Qualifying Drill Strings for Extended Reach Drilling
Authors: Hill T.H. , Guild G.J. , Summers M.A. 
Published: December 2007

Summary
Extended reach (ER) drill string design involves selecting from a variety of available drill string components, those best suited to drill an ER well. In a typical ER well, torsion loads will be higher and tension loads will be lower than for a vertical well of the same measured depth. These differences in applied loads and the need to apply bit weight with normal weight drill pipe pose design and operating questions that are answered in this paper. ER drill strings are often very complex. Also, most available components are in used condition, and thus have been exposed to unknown histories of wear and fatigue. A system for qualifying the drill string is required to ensure that the components we use conform to our design requirements. This paper covers some of the issues the authors have faced in designing and qualifying drill strings for extended reach wells, and how these issues were successfully resolved.

ER Drill String Design Model
Figure 1 shows a general model for drill string design in an extended reach well. We first estimate the loads that the drill string will experience (step 1), then select components that can safely carry these loads (step 2). Since the two steps are interdependent, this is an iterative process, and the arrow is drawn both ways. In addition, the final selection of drill string configuration is also heavily influenced by many issues other than applied loads. These "side issues" shown on Figure 1 are also interdependent, often conflicting one with another, and rarely cut-and-dried. For example, hole cleaning needs and pump pressure limitations may favor 6-5/8 inch drill pipe over 5-inch, but ECD, rig setback space and availability issues may be forcing us toward the smaller pipe. The final design is invariably a compromise between all these issues, and thus will rarely be "optimum", if indeed such a thing exists. Rather, we aim for a "successful" design, one that gets us safely to TD within budget and without either experiencing a drill string failure or wearing out our casing.

Typical Drill String Loads and Load Limits
Imagine that we plan to drill a series of 20,000 ft MD wells with 5-inch drill pipe. We'll drill the first one vertically to TD. The others will be kicked off at 1000 feet and build angle at 2 degrees/100 feet until they reach some desired tangent angle between 0 and 90 degrees, then continue straight until they reach 20,000 ft MD. Figure 2 shows the expected surface hanging load and torsion to rotate the drill string off bottom in these hypothetical wells as tangent angle increases to 90 degrees. Although rotating off bottom is only one of many possible operations, it's readily apparent from Figure 2 that torsion will often be a major concern in ER drilling.
Effects of Well Deviation on Helical Buckling
Authors: Mitchell R. F. 
Published: December 2007

ABSTRACT
Current helical buckling models are valid for vertical wells, but the validity of these solutions for deviated wells was not known. This paper describes the numerical solution of the non- linear buckling equations for arbitrary well deviation. Stability criteria are developed for lateral and helical buckling, and simple correlations are developed for buckling length change, maximum bending stress, and contact force.
Understanding the Performance of a Low-Permeability Gas Reservoir: Hyde Field, Southern North Sea
Authors: Baron R. P. , Pearce A. J. 
Published: December 2007

Summary
Hyde is a small, low-permeability gas field in the U.K. southern North Sea, which has been developed using horizontal wells. Shortly after production startup in Sept. 1993, the field performance began to give cause for concern. Both wells were producing formation water, and the gas deliverabilities were lower than predicted. This paper describes how field data were collected, analyzed, and used in a full-field simulation model to diagnose the cause of the poor performance and to plan the future development of the field.
A Review of Completions and Gravel-Pack Techniques of the Xijiang Development
Authors: Rodgers J. T. , Bennett J. S. , Grigsby Tommy , Zhang Y. K. , Yang Y. J. 
Published: December 2007

Summary
The first gravel-packed completions have been run in the Pearl River mouth basin of the South China Sea in the Xijiang fields. The reservoirs in these fields are characterized by unconsolidated, friable, high-permeability sandstones, and, as such, presented many challenges. This paper addresses the development of these fields and how reservoir characteristics and parameters and unexpected deviations were experienced by the operator, as well as the impact these deviations had on completion designs.
Important considerations included the need for sand control, zonal isolation, high-rate production, and reduced completion durations. Finally, the practical application and evaluation of pregravelpack stimulation techniques, gravel-pack carrier consideration, fluid-loss controls, and general completion procedures are presented, along with the innovative completion designs developed to manage these needs.
Zonal Isolation and Evaluation for Cemented Horizontal Liners
Authors: Gai Huawen , Summers T. D. , Cocking D. A. , Greaves Chris 
Published: December 2007

SummaryThis paper discusses the novel application of technology in the cementing and bond evaluation from the world-record breaking ERD (Extended Reach Drilling) wells in Wytch Farm, where horizontal liners of the order of 800m to 1300m at TvD of ca 1600m have been successfully cemented and perforated.Detailed analysis of the conditions by a multi-disciplinary team provided some practical procedures which enabled us to achieve our objectives of zonal isolation and cement bond evaluation successfully. Important aspects of zonal isolation, such as the use of spiral-blade centraisers, rotating the liner, and trials of the ECPs (External Casing Packer) are discussed in detail. Cement bond evaluation is also detailed, involving CT (Coiled Tubing) deployment and various bond logging tools, including ultrasonic tools. The CBL was found to be surprisingly reliable if used correctly.
An Experimental Evaluation of the Formation-Damage Potential of Cement Filtrates and Leachates
Authors: Hill P. I. , Hughes C. R. , Isaac K. P. 
Published: December 2007

Summary
Chemical reactions between reservoir minerals and cement filtrates and leachates have been investigated experimentally under simulated reservoir temperature and pressure. Results indicate that individual filtrate/mineral and leachate/mineral reactions are markedly different, with cement leachate appearing much more aggressive than cement filtrate. In all experiments, dissolution and precipitation reactions were rapid, on a scale of days, with the formation of a range of low-density, high-volume calcium/aluminium/silicate/hydrate minerals. A very large increase in solid volume was observed in a number of filtrate and leachate reactions with single mineral separates. Clearly, porosity occlusion associated with these reactions could lead to impaired permeability. In contrast, however, an observed decrease in cohesiveness in quartz sandstone used in coreflood experiments implies that permeability enhancement is possible through primary mineral dissolution. The significance of these results, with regard to cement/fluid reactivity under real reservoir conditions, needs to be investigated further.
Water Shutoff in the North Sea: Testing a New Polymer Gel System in the Heather Field, UKCS Block 2/5
Authors: Whitney D. D. , Montgomery D. W. , Hutchins R. D. 
Published: December 2007

Summary
A new polymer gel system developed for high-temperature applications was successfully employed on Well H-43 of the Heather Field to isolate a high-rate water production zone. The high-temperature, organic polymer gel system has demonstrated long-term stability when mixed with seawater at temperatures as high as 350°F. Gel times can be delayed, allowing a large volume of polymer gelant to be placed. For Well H-43, 1,095 bbl of gelant were pumped through 1½-in. coiled tubing into a 15-ft layer of the Brent Group. The treatment increased oil production by 300 B/D and decreased water production by 2,290 B/D. A production log run 8 months later confirmed effective isolation, allowing the lower Brent to produce.
A Quantitative Investigation of the Fracture Pump-In/Flowback Test
Authors: Plahn S. V. , Nolte K. G. , Thompson L. G. , Miska S. 
Published: December 2007

SummaryFracture-closure pressure is an important parameter for fracture treatment design and evaluation. The pump-in/flowback (PIFB) test is frequently used to estimate its magnitude. The test is attractive because bottomhole pressures (BHP's) during flowback develop a distinct and repeatable signature. This is in contrast to the pump-in/ shut-in test, where strong indications of fracture closure are rarely seen. Various techniques are used to extract closure pressure from the flowback-pressure response. Unfortunately, these techniques give different estimates for closure pressure, and their theoretical bases are not well established. We present results that place the PIFB test on a firmer foundation. A numerical model is used to simulate the PIFB test and glean physical mechanisms contributing to the response. On the basis of our simulation results, we propose interpretation techniques that give better estimates of closure pressure than existing techniques.
A New Approach to the Analysis of Drillstring Fatigue Behavior
Authors: Baryshnikov Anatoly , Calderoni Angelo , Ligrone Angelo , Ferrara Paola 
Published: December 2007

SummaryThis paper presents a method for determining the fatigue behavior of drillstring (DS) components under given environmental conditions. Over the past few years, field data for DS failures have been gathered from certain wells drilled in Italy and West and North Africa. Fatigue phenomena were identified as the main cause of most of such failures. Among the several factors that can affect DS-element fatigue resistance are tensile load, makeup torque, material properties, corrosive environment, abrasive wear, and so on. However, simply on the basis of the existing guidelines, it is difficult to define the real cause of a failure under given operating conditions. A comparative study of full-scale fatigue-test results and field data suggests a new approach for the analysis of some of the drilling technology factors that can affect the DS fatigue behavior.
Sonic While Drilling: Have You Thought About Cuttings?
Authors: Marsala A. F. , Zausa Fabrizio , Martera Mauro Della , Santarelli F. J. 
Published: December 2007

Summary
Sonic while drilling has long been considered a major goal by the industry because of its potential applications: real-time determination of pore pressure and overburden gradients, improved lithology change determination, seismic calibration, and detection of seismic reflectors ahead of the bit. Until now, only two methods were available to perform sonic measurements while drilling—the use of continuous coring or a specific measurement while drilling (MWD) tool. Unfortunately, both methods remain very expensive and suffer from technical limitations. A new technology [named pulsed ultrasound on cuttings (PUC)] has been developed to measure both compressional and shear-wave velocities directly on cuttings with dimensions as low as 1 mm. Laboratory and field implementations of the method are presented along with its validation against reference measurements.
NMR Imaging of Immiscible Displacements in Porous Media
Authors: Majors Paul , Li Ping , Peters Ekwere 
Published: December 2007

Summary
We introduce a rapid, quantitative nuclear magnetic resonance imaging (NMRI) technique to resolve and measure multiple fluid phases in porous media. Liquids are resolved on the basis of their NMR spin-spin (T2) relaxation times, and their intensities are corrected by attenuation analysis. The phase-resolved and corrected NMRI intensities are normalized to yield fluid saturations. We present the procedure and limitations of this technique.
We present in-situ saturation measurements for three immiscible (oil and water) displacements in the same Berea sandstone core. We compared NMRI and effluent recovery methods. T2 of the displacement fluids were sensitive to displacement conditions.
Improved Technique for Stochastic Interpolation of Reservoir Properties
Authors: Painter Scott , Paterson Lincoln , Boult Peter 
Published: December 2007

Abstract
Stochastic interpolation methods for generating input for reservoir simulations require accurate models for spatial variability. New models based on fractional Lévy motion, a generalization of fractional Brownian motion, have strong empirical support. Stochastic interpolations based on the Lévy model have a higher degree of spatial variability compared to Gaussian fractals. In two-dimensional waterflood simulations, the breakthrough curves for the Lévy interpolation method are better clustered around predicted production behavior based directly on outcrop data.
Pitfalls in Pressure-Gauge Performance
Authors: Kikani Jitendra , Fair P. S. , Hite R. H. 
Published: December 2007

Summary
Often, pressure-gauge systems for surface read-out (SRO) wireline work or for permanent installations do not perform according to their specifications; i.e., the pressure resolution obtained is lower than the gauge-design values. This seems natural because the borehole environment is nastier than the quiescence of laboratory calibration set up. Nevertheless, it is difficult to attribute the loss of resolution to a single problem.
This paper introduces the functional components of the pressure-gauge system where loss of resolution may occur. Specifically, it addresses cable-related problems, crossover, signal transmission, signal processing, time stamping, and temperature compensation. We show determination of pressure resolution from a processed signal by means of example calculations. The role of transducer specifications on overall data quality is addressed; i.e., what causes a 0.01-psi-rated transducer to yield a signal of only 0.75 psi quality? Field data from Tahoe and Bullwinkle prospects are used to illustrate some of the gauge-related problems and the solutions being proposed by the industry to overcome some of them.
An Experimental and Numerical Study of In-Situ Steamdrive During Cyclic Steaming
Authors: Dehghani Kaveh , Kumar Mridul , deZabala E. F. , Meyer R. F. , Duran Henry 
Published: December 2007

Summary
A series of laboratory tests was conducted to investigate the in-situ steamdrive process and its effects on fluid displacement in porous media. The experiments show that in-situ hot-water flash may recover up to 60% of moveable oil and that the residual oil saturation after flash increases with lower initial water saturations. Conventional simulation with external-drive relative permeabilities led to under-prediction of oil recovery.
Auger Well Completions: Sand Control Installation and Mechanical Design
Authors: Norton S. J. , Smith C. D. 
Published: December 2007

Summary
Nine producing wells have been completed on the Auger tension leg platform (TLP). The results have been better than anticipated, with average production-rate capability exceeding 11,000 BOPD and 25 MMcf/D gas per well. Completing wells from a TLP in 2,860 ft of water posed several unique challenges from an equipment as well as an operational standpoint. This paper discusses the completion operations from gravel packing through tree stack-up, noting the original plans and changes that were made during the program. Special procedures for perforating, stimulating, and gravel packing, special equipment requirements, and material selection are discussed.
Two-Phase Gas-Condensate Flow in Pipeline Open-Network Systems
Authors: Martinez A. F. F. , Adewumi M. A. 
Published: December 2007

Summary
Even if gas transmission occurs after the necessary processing of the gas has been completed, condensation still occurs in the natural gas transmission and/or distribution systems. The quantity of the condensate formed will not only depend on composition, pressure, and temperature, but also on the unequal splitting phenomenon that takes place at T-junctions in a network system. This paper investigates the splitting phenomenon in horizontal-branching T-junctions. The compositional hydrodynamic model developed at Pennsylvania State U. is used to evaluate gas-condensate flow in a pipeline under steady-state conditions. Using a double-stream model for splitting analysis at T-junctions, the mass-liquid-intake fractions are determined. The junction is considered as a separator and the new compositions are calculated at the run and at the branch of the junction. Although quantitative validation of the model is limited by the incompleteness of the available data, a reasonable qualitative match of experimental data is achieved. The results demonstrate the predictive capability of liquid route preference in two-phase natural-gas/condensate flow at T-junctions. In addition to liquid split, compositional split is tested using polychlorinated biphenyl (PCB) as the focal point. It is found that the concentration of PCB is distributed in direct proportion to the liquid preference route, and the PCB concentration in the delivery points can be higher or lower than the inlet concentration at the supply point.
The Relation Among Porosity, Permeability, and Specific Surface of Chalk From the Gorm Field, Danish North Sea
Authors: Mortensen Jeanette , Engstrøm Finn , Lind Ida 
Published: December 2007

Summary
The origin of the difference in the relationship between permeability and porosity for Danian and Maastrichtian chalk from the Gorm field offshore Denmark has been investigated. The investigation was based on 300 sets of core data (He-expansion porosity and air permeability) from Well Gorm N-22X. On 24 of the core plugs, the specific surface was determined by BET and, on 14 of these samples, image analysis was made.
The data were rationalized by the use of the Kozeny equation and it was found that each geologic unit had a characteristic relationship among porosity, permeability, and specific surface. Furthermore, it was found that the nature of porosity (intrafossil, intergranular, etc.) had no significant influence on the air permeability, so that the permeability of the chalk can be calculated from total porosity and specific surface.
Kozeny's empirical constant, c, was determined analytically from a simple porosity model and Poiseuille's law.
Downhole Measurements of Synthetic-Based Drilling Fluid in an Offshore Well Quantify Dynamic Pressure and Temperature Distributions
Authors: White W. W. , Zamora Mario , Svoboda C. F. 
Published: December 2007

Summary
Accurate downhole and surface measurements of a synthetic-based drilling fluid were taken in a Gulf of Mexico well to resolve variances between actual and calculated pump pressures and to quantify equivalent circulating densities. Current American Petroleum Inst. (API) equations seriously underestimated drillstring losses, which accounted for the pump-pressure differences. Conversely, annular losses were much lower than predicted.
Waterflooding of Gas-Condensate Reservoirs
Authors: Fishlock T. P. , Probert C. J. 
Published: December 2007

Summary
Gas-condensate reservoirs are usually produced by primary depletion. This technique is normally an efficient means of producing the gaseous hydrocarbon components but can be very inefficient in producing the more valuable liquid components that are left in the reservoir in a condensed liquid phase (oil). The recovery efficiency of the liquid components decreases with increasing richness of the gas condensate, making for a large improved oil recovery (IOR) target in some reservoirs. The usual approach to improving liquid recovery is to recycle produced gas through the reservoir. However, this technique may not be economically attractive when there is the possibility of immediate gas sales because of the discounting applied to the gas value when sales are delayed. An alternative means of improving liquid recovery is to keep the reservoir pressure above the dewpoint for a period by injecting water. Depending on reservoir characteristics, water injection may be continued throughout field life or the reservoir may be pressure depleted after a period of injection. Special relative permeability data, describing the mobilization of waterflood trapped gas by expansion, are necessary for the latter case.
This paper reports a simulation study that quantifies the potential benefits of the waterflood technique by use of simple reservoir models. For a fluid with a condensate to gas ratio (CGR) of 180 STB/ MMscf, total hydrocarbon recovery was optimized by injecting 0.25 hydrocarbon PV of water before pressure depletion. This increased the recovery efficiency of both the liquid and gaseous components, raising the total hydrocarbon recovery by 10% of the hydrocarbon mass initially present in the reservoir. For a richer, near-critical fluid with a CGR of 300 STB/MMscf, continued water injection gave the optimum total recovery, which was 21% of initial mass higher than for primary depletion. This improvement was achieved by greatly increasing the liquids recovery at the expense of a smaller reduction in the gas recovery. The results of this paper suggest that waterflooding of gas-condensate reservoirs might be a valuable IOR technique.
A Statistical Approach to Infill-Drilling Studies: Case History of the Ozona Canyon Sands
Authors: Cipolla C. L. , Wood M. C. 
Published: December 2007

Summary
This paper details the application of limited single-well reservoir modeling to predict infill-drilling potential in tight gas fields. Distributions of ultimate recovery and drainage area were developed from a small sample set to estimate incremental reserves. A case history from the Ozona gas field, Crockett County, TX, illustrates this technique. Fifty-one wells were randomly selected from more than 1,500 producing wells to estimate the potential of 40-acre infill drilling. The distributions of production characteristics from the modeled wells reproduced those of the "full field." Calculated drainage areas ranged from less than 10 acres to more than 320 acres, with a median drainage area of 36 acres. Approximately 75% of Ozona Canyon wells drain less than 80 acres (current spacing), with 52% draining less than 40 acres. The statistical drainage area and estimated ultimate recovery (EUR) data were combined to estimate the potential reserve growth with 40-acre development. Approximately 1,125 locations, adding 400 Bcf of incremental reserves were identified. The average EUR for 40-acre infill wells is 353 MMcf of gas.