bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis and Prediction of Gas Well Performance
Authors: Coats K.H. , Dempsey J.R. , Ancell K.L. , Gibbs D.E. 
Published: December 2007

Abstract
This paper describes a numerical model for analyzing gas-well tests and predicting long-term deliverability. Field applications presented include an interpretation of a gas well test in a tight sand leading to an accurate long-term deliverability projection. The model presented numerically simulates two-dimensional (r-z) gas flow and accounts for effects of turbulence, skin, afterflow, partial penetration, pressure-dependent permeability and pressure-dependent permeability and any degree of crossflow ranging from complete to none. Through a novel treatment of the equations describing reservoir flow, skin and afterflow, the model simulates shutin at the wellhead and then calculates afterflow and any subsequent circulation of gas through the wellbore from some layers to others.

Introduction
Many gas wells exhibit pressure test behavior which is difficult if not impossible to interpret using conventional methods of analysis. Difficulty of interpretation is frequently encountered in low permeability reservoirs and in layered reservoirs with limited or incomplete crossflow. In these cases, assumptions in conventional analysis methods, such as complete (or no) crossflow and negligible effects of afterflow or interlayer recirculation through the wellbore, are frequently invalid.
This paper describes a numerical model which accounts for many factors which are neglected in conventional methods of analysis. The model numerically simulates two-dimensional (r-z), transient gas flow in a cylinder representing the drainage volume of a single well.
How to Evaluate and Select Premium Casing Connectors
Authors: Jellison Michael J. , Davila Manuel Alfredo 
Published: December 2007

Abstract
Selecting the appropriate connector for each casing string in a well represents a difficult challenge for drilling engineers. The engineer must decide if an application requires a premium connector or can be satisfied with an API connector. If use of a premium connector is dictated by the well conditions the large number of premium connectors available further complicates the decision of which connector to use.
This paper provides guidelines on how to evaluate and select premium connectors for drilling and production casing, tieback and liner applications. In addition, guidelines to assist in determining when a premium connector is required over an API connector are presented.
The Principles and Procedures of Geosteering
Authors: Lesso W. G. , Kashikar S. V. 
Published: December 2007

Abstract
The management of directionally drilled wells has recently progressed to the stage where targets have been reduced in size to a point in the earth with no tolerances. These targets can and are changed during the drilling process. The management of these point moving targets, usually in high angle or horizontal wells, is a precise form of directional drilling now called geosteering. It is this precise placement of the wellbore that creates the value in drilling these wells.
Several technologies have made this advancement possible. These include reliable steerable systems, improved and new physical formation measurements, log data modeling, sensors near the bit and instrumented motors, and detailed reservoir mapping with the help of 3D seismic processing. Most papers on geosteering have concentrated on one of these advances. This paper addresses how these technologies are merged to execute the successful geosteering project.
New systems, sensors, and computations have created a mass of data and control parameters that require real-time decisions bv operator personnel based on technical recommendations from service companies. These decisions have a critical impact on the net worth of a project. The team involved must rely on each other's expertise and understand the overall objective of a geosteering project. To do this, it is paramount that data from these different technological areas be merged into a 3D visualization encompassing geological structures and drilling trajectories.
Patterns in procedures have developed from these projects over the past three years which demonstrate the difference between a successful project and a failure. The examples in this paper illustrate the techniques that will enable a change in the outlook towards precision directional drilling and completion projects.
Multi Operator Programme for Deep Water Drilling
Authors: Talbot J. R. A. S. 
Published: December 2007

Abstract
During the last ten years, the majority of offshore exploration drilling contracts have been of short term duration with Operators able to pick up Mobile Offshore Drilling Units (MODUs) relatively easily and lay off the term risk onto the Drilling Contractors. At present, demand for deep water dynamically positioned drillships (D.P.D.S.s) and semi-submersibles exceeds supply and this trend is widely predicted to continue over the medium term.
This paper is offered as a framework to help promote the sharing of drilling assets by the Operators to the advantage of both Operators and Drilling Contractors alike. Drilling Contractors require long-term work schedules at reasonable rates to justify their investments – Operators in today's offshore market need to be able to access MODUs to effect their licence obligations and appraise new discoveries sufficiently prior to approving investments.
Hole Cleaning Modelling: What's ‘n’ Got to Do With It?
Authors: Kenny Patrick , Sunde Egil , Hemphill Terry 
Published: December 2007

Abstract
Efficient hole cleaning is vitally important in the drilling of directional and extended-reach (ERD) wells. In previous works, the importance of fluid velocity/pump output has been emphasised, while in others, the importance of individual fluid rheological parameters has been stressed. Drillpipe eccentricity and rotation directly affect hole cleaning as well. Recent work on particle settling velocity has accelerated the understanding of the behaviour of drilled cuttings in wellbores.
This paper presents a new model to the industry, which combines recent developments in the fields of particle settling and rheology. This model provides a useful tool for the planning of hole cleaning for highly deviated wells through the use of Lift Factors under the eccentric drillpipe. Information from deviated wells in the field is used to illustrate the usefulness of this hole cleaning model. Importantly, analysis of the data indicates that fluid ‘n’ factors calculated using the yield-power law [Herschel-Bulkley] rheological model play a greater role in promoting good hole cleaning in ERD wells than has previously been recognised.
Mechanisms of Differential Sticking and a Simple Well Site Test for Monitoring and Optimizing Drilling Mud Properties
Authors: Reid P. I. , Meeten G. H. , Way P. W. , Clark P. , Chambers B. D. , Gilmour A. 
Published: December 2007

Abstract
Differential sticking has a major impact on drilling efficiency and well costs. Although some problems can be related to the characteristics of rock formations, or to drilling parameters not related to drilling mud properties, it is widely accepted that the mud formulation and condition strongly influences the risk and severity of differential sticking incidents.
In this paper we use our own laboratory data and information from industry publications to formulate the mechanisms of differential sticking and the key drilling mud parameters that can influence the process. Using this knowledge, we have built a simple and robust device for measuring the sticking properties of muds in the laboratory or at the well-site. This device comprises a half area HTHP fluid loss cell which is modified to allow a metal sphere to be placed in contact with a growing mud filtercake. The torque required to rotate the sphere free from the mud cake is determined using an electronic torque gauge. We find that a plot of torque against the 3/4 power of time (this power term derives from the build-up of cake around a spherical object) gives a linear fit to the data, and that the slope of this line is indicative of the sticking potential of the mud. An extensive analysis of laboratory-mixed and field muds indicates that the test gives a good indication of mud condition and allows the user to investigate various options for reducing the sticking potential of the fluid. This information is useful both in the initial selection of mud type and in making technical and economic analyses of various mud treatment options.
In addition to the laboratory evaluation described above, the sticking device has been used in several wellsite tests with encouraging results. Some of these are described.
How to Improve Rate of Penetration in Field Operations
Authors: Fear M. J. 
Published: December 2007

Abstract
A method has been developed that identifies which factors are controlling rate of penetration (ROP) in a particular group of bit runs. The method uses foot-based mud logging data, geological information, and drill bit characteristics, to produce numerical correlations between ROP and applied drilling parameters or other attributes of drilling conditions. These correlations are then used to generate recommendations for maximising ROP in drilling operations.
Safety By Design as Applied to the Design and Fabrication of Rig 200
Authors: Hubler Warren G. , Roberts H. D. 
Published: December 2007

Abstract
The foundation for safety of any operation is determined long before people, procedures and equipment come together to provide a service or produce a product. It is determined during design and construction. This paper begins by outlining the systems safety approach to minimizing hazards and integrating safety into the design and engineering of an operation (Part I). It describes methods for identifying, analyzing and eliminating workplace hazards. Part II of the paper describes the application of systems safety tools to the design and fabrication of a new construction, highly mechanized, platform drilling rig. Implementation of the systems safety approach impacts directly on safe, productive and cost effective operations.
Field Examples of Gas Migration Rates
Authors: Grace R. D. , Shursen J. L. 
Published: December 2007

Abstract
In recent years gas migration rates have become the center of considerable controversy. Historically, field personnel have used a "rule of thumb" that gas migrated at the rate of 1000 feet per hour. Early basic research1 illustrated that the factors affecting the rate of bubble rise were quite complex. For example, the rate of rise was affected by the properties of the influx, mud properties, the eccentricity of the hole, and the size of the annulus, to name a few.
The rate of rise was also affected by the manner in which the influx entered the wellbore. If the influx was dispersed in the mud as small bubbles, the rise characteristics were different than if the influx entered the wellbore as a continuous bubble. A dispersed influx generally migrated much slower than a continuous bubble.
It was generally expected and observed that as an influx began to migrate toward the surface, the surface pressure would begin to increase. The incremental changes in surface pressure were utilized to determine the rate of rise and predict the travel of the influx. In addition, these techniques were used to model the well control problem, expand the influx, protect the casing shoe, and otherwise analyze the problem. However, in many instances, the variables were too complex to permit accurate calculations and analyses in field operations and the old rules of thumb were utilized.
A Direct Approach for History Matching
Authors: Veatch R.W. , Thomas G.W. 
Published: December 2007

Introduction
Mathematical reservoir simulation models are widely used to predict field behavior. Their use requires that permeability and porosity be specified at numerous points throughout the reservoir. The usual procedure is to first estimate these parameters, compute the past field history and then compare the computed results with the observed performance. If the comparison is not satisfactory, the estimates are repeatedly modified until an acceptable match is obtained. It is then assumed that the rock properties are adequately specified for future predictions.
This trial and error procedure can consume considerable computer time and money. In view of this, some people have investigated iterative adjustment and regression techniques linear and nonlinear programming methods and energy dissipation analysis in an effort to automate the procedure. These methods are essentially similar insofar as they are ex post facto techniques; i.e., after one or more computer runs have been executed, then the known performance history is used in some fashion to performance history is used in some fashion to deduce an acceptable set of rock parameters. This approach is tantamount to using a differential equation solver for treating an inverse problem, and is not the most efficient.
In this work, we present a direct method for treating the inverse reservoir simulation problem. The technique enables one to compute problem. The technique enables one to compute reservoir permeabilities and porosities in a single computer run utilizing appropriate data from several periods of the performance history. It is applicable to multiphase, compressible flow in heterogeneous reservoirs. A procedure is described that recognizes, during the course of the computation, whether or not a unique solution can be obtained. The method is capable of handling inconsistent data and constructing the best set of non-unique properties within realistic limits when unique solutions do not exist.
Results of studies on several hypothetical reservoir problems are presented. Finally, examples which show the effect of non-unique history matches on future predictions are also cited.
Mathematical Modeling of Gravity Drainage After Gas Injection into Fractured Reservoirs
Authors: Schechter D. S. , Guo B. 
Published: December 2007

Abstract
This paper addresses mathematical modeling of free-fall gravity drainage which is believed to occur in naturally fractured reservoirs after depletion of oil in the fractures or gas injection into the fractured system. Comparison of wetting phase recoveries calculated using existing math-ematical models with experimental data indicates the in-accuracy of these models. The causes of error are identified to be the unrealistic assumptions made in formulation of the models. Based on Darcy's law and film flow theory, we have developed a new mathematical model to describe the free-fall gravity drainage process, A simple non-linear governing equation for phase demarcator in dimensionless form was formulated and solved numerically as a function of dimensionless time. Based on the dimensionless demarcator, fluid recovery during free-fall gravity drainage is calculated. Comparisons of wetting phase recoveries given by the new model with 20 sets of experimental data obtained under thermodynamic equilibrium conditions for a variety of fluids and cores show much better accuracy of the model over the existing models. Using the dimensionless time, tD — ke∆𝜌gt/𝜇L, fluid recovery obtained from laboratory studies can be scaled to field applications for estimation of projected oil recoveries in oil fields. We have also applied the new model to simulation of free-fall gravity drainage under non-equilibrium conditions where molecular diffusion between phases is considered. Experimental oil recovery data obtained from CO2 injection into a Berea core and a reservoir sandstone core, which were saturated with separator oil, have been matched by the model using empirical correlations for fluid properties. The objective of this paper is to provide reservoir engineers with a useful tool for estimating the oil recovery from fractured reservoirs after gas injection.
The Application of Hydraulic Fracturing Models to Characterize Fracture Treatments in the Brushy Canyon Formation, Delaware Group, Eddy County, New Mexico
Authors: Johnson Raymond L. 
Published: December 2007

Abstract
In this study of the Brushy Canyon, sonic-derived, rock-mechanical properties and bottomhole treating pressure (BHTP) data from mini and main fracture treatments will be history-matched with three-dimensional (3D), lumped 3D, and pseudo 3D fracture models. Height dimensions obtained from these history-matches are compared with temperature and radioactive tracer surveys to better characterize fracturing mechanics in this Delaware Mountain Group formation.
A New Approach to Large-Scale Infill Evaluations Applied to the OZONA (Canyon) Gas Sands
Authors: Voneiff G.W. , Cipolla Craig 
Published: December 2007

Abstract
Historic "sweet spots", areas of well-to-well interference, and infill potential were determined for an 1800 well area of the OZONA (Canyon) field using a new approach that focuses on the age of the wells, their location, and production profiles. At the core of this new approach, termed "moving domain", is a mosaic of automated studies that draw statistical conclusions about well performance, depletion, and undrained acreage. Preliminary infill estimates in one to two weeks are possible and the technique is typically linked to conventional reservoir engineering to improve estimates. When applied to OZONA (Canyon), 1246 infill locations were identified with 636 Bcf of gas reserves.

Introduction
History - The OZONA field, located in Crockett County in Southwest Texas (Figure 1) contains two major producing sands, the Canyon and the Penn. These sands are complex turbidite deposits that are characterized by numerous gas productive members with permeabilities from less than 0.001 mD to over 0.10 mD and are found at depths of 6,000 to 8,000 ft.1 A recent change in field rules will allow drilling to 40 acres spacing in most parts of the field. Initial development began in the early 1960s on 320 acre spacing, with subsequent infill drilling on 160- and 80 acre spacing. Typical completions require fracture treatments using water based fluids containing 50 to 250 klbs of 20/40 sand to achieve economic production rates. Ultimate gas recoveries range from 200 MMCF to over 2000 MMCF and can vary significantly from well to well. Historically, many wells with multiple pay zones were fracture treated simultaneously, while other wells were fracture treated in isolated stages.
Problem - Quantifying the infill potential in the OZONA (Canyon) field is difficult for several reasons: the layered and low permeability nature of the reservoir, the hydraulic fracturing of wells, the variation in well spacing, and the local and regional variations in rock quality. These complicating factors often cloud the extent of depletion, benefits of improved completion and operation techniques, and make the quantification of infill potential rather difficult. Because of these complexities and the fact that our study area contained over 1000 wells, the time and cost requirements of a conventional reservoir engineering study were unacceptable. Instead we applied a new technique that was found to be useful in a large tight gas field in East Texas.2
Improved Water Flood Operation in the Permian Basin Through Microbial Culture Treatment
Authors: Ratliff T. , Hoskins B. C. , Schneider D. R. 
Published: December 2007

Abstract
Microbial cultures can be used to reduce or eliminate scale formation in water flood injection systems. Several water floods have been treated for over a year with microbial culture products and the effects of the treatment on operating performance has been studied. The injection systems initially showed significant scale problems from calcium sulfate and calcium carbonate. Tracking water flood performance parameters such as injection pressures and volumes over the treatment period showed that, as compared with prior treatment historical data, a variety of positive results of treatment were evident. For example, the flood injection volumes were stabilized or increased, injection pressures were stabilized and oil and gas production was increased. Laboratory studies of injection water showed that filtration times could be significantly reduced by microbial treatment, indicating that near well-bore occlusion could be reduced by such treatments. The microbial treatments were considered more effective than prior alternative treatment technologies. This new technology offers a cost-effective superior alternative to conventional technologies.
Review of Downhole Dynamometer Testing
Authors: Soza Roberto L. 
Published: December 2007

Abstract
Electronic Downhole Load Cells (DHLC) have been used to quantify rod loadings calculated by predictive and diagnostic wave equation programs. Test results to date show that software calculations agree closely with DHLC measurements. However, there is a difference in how software programs account for buoyant forces which results in discrepancies in reported loads and placement of the zero load line. The overall impact of this difference in the tests run to date, has not been large and may only be critical in the most demanding rod pumping conditions.
CO2 Huff-n-Puff: Initial Results from a Waterflood SSC Reservoir
Authors: Wehner S. C. , Prieditis J. 
Published: December 2007

Abstract
The application of cyclic CO2, often referred to as the CO2 Huff-n-Puff (H-n-P) process, may find its niche in the maturing waterfloods of the Permian Basin. Coupling the CO2 H-n-P process to miscible flooding applications could provide the needed revenue to sufficiently mitigate near-term negative cash flow concerns in these capital intensive projects. Initial results from a field demonstration of the process are provided. The paper briefly reviews the reservoir characterization associated with the project and the compositional simulation of the CO2 H-n-P process. Simulation results suggest that reservoir characterization of flow units is not as critical for a CO2 H-n-P process as for a miscible flood. Entrapment of CO2 by gas hysteresis is considered the dominant recover» factor for a given volume of CO2. The repetitive application of the process was found to be unwarranted in a waterflooded environment. Future history matching of the performance will allow better forecasts and evaluation of the economic impact available with this underutilized process.
Reduced Costs Propel Shallow Gas Program in Southeast New Mexico
Authors: Bounds C. M. , Brown E. K. 
Published: December 2007

Abstract
A significant reduction of drilling and completion costs in the Eumont and Jalmat Fields of Lea County, New Mexico has resulted in the continuation of Conoco's development program in a soft gas price environment. Average 1995 costs for drilling, completion and facilities have been reduced to $180,000 for single zone completion wells and $240,000 for two completion wells. This paper focuses on the process and equipment changes that resulted in the cost improvements as well as the method used to identify the improvements.