bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Recovery from Deep Millidarcy Layered Gas Formations with Nonlinear Elastic Deformation Characteristics
Authors: John P. W. 
Published: December 2007

Abstract
Starting from Rotliegend well evaluation in parts of the European Southern Permian Basin this paper is adressed to a main problem of stimulation design in deep layered gas bearing formations:
Advanced in situ analysis discloses a gap in the approach of conventional theory to in situ reality of complex multilayersystems. Uniaxial strain tests on cores prove the presence of layers with non linear elastic deformation characteristics.
The impact of a hydraulic treatment on a strata-system comprising layerproperties beyond LEFM behaviour is not covered by conventional assumptions. Consequently it is neccessary to review basic treatment design approaches.
As a result this paper tries an analysis of sandstone-shale multilayersystems.
A layerspecific deformation characteristic supported from experiments is applied to quantify the interaction between the impact of a treatment and the layerindividual response due to timedependent in situ status and rock properties. The resulting reaction is expressed by parametervariations as a variabel function of stress status.
The consequence of these investigations leads to a new approach of an extended fracture criterium to cover multilayersystems including non linear elastic rockdeformation. This permits advanced modelling of multilayersystems, is important for realistic fracture geometry calculations, improved treatment design, selective access to gas accumulations and effective packed fracture systems.
Developing a PC-Controlled Digitizing Program
Authors: Brown S. L. , Walsh J. W. , Gibson M. M. 
Published: December 2007

Abstract
The digitizing tablet offers PC users the ability to input data from a strip chart or from printed graphs directly into disk files. To connect the digitizing tablet to the computer and to interpret correctly the stream of numbers output from the tablet, a driver program must be designed and implemented. This paper discusses digitizers for PCs and the design of driver programs for different applications.
Well Log Analysis Spreadsheet
Authors: Heemink G. H. , Bryant W. T. , Langenbuch T. L. 
Published: December 2007

Abstract
Log analysis without the aid of taped or digitized data, and a mini-computer, is a tedious chore. A typical desk top interpretation may consist of manual data extraction from log prints, hand plotting the appropriate crossplots for parameter selection, and then processing the data level by level in a hand held programmable calculator13. Fine tuning the calculations and documenting the results is very time consuming if the evaluation involves multiple zones and many levels.
This paper presents a spreadsheet log analysis program for the purpose of organizing pertinent well information and log data, minimizing computation time, fine tuning results, and producing documentation.
The program is very flexible, easy to use, and includes sophisticated techniques and industry standard logic. The program is open ended and is a suitable model for other similar applications.
Well log data is processed over multiple runs and includes zoning of log parameters, water saturation, porosity, and shale models.
Custom menu options are provided for easy use.
The program requires a 640K personal computer and was developed in LOTUS 1-2-3* version 2.01.
Enhanced Reservoir Evaluation System Analyzes Data From a Wide Range of Sources
Authors: Shuman J. L. , Ulloa K. , Wilkinson B. C. , Petak K. R. 
Published: December 2007

ABSTRACT
Drill stem and well test data from surface readout instruments, mechanical gauges, memory gauges, or any combination of these can be acquired, analyzed, processed and displayed at the well site using a recently developed interactive system.
Data acquired from one or more of the sources is stored on disc, from which it can be used to produce any known conventional plot while the data is being analyzed. In the case of surface readout operations, analysis can be conducted during data collection, and an operator can interact directly with the computer to perform the analysis. Conventional, pressure derivative, and non-linear regression analysis techniques are provided. One microcomputer, printer, plotter, and appropriate data acquisition interface comprise the hardware of the system. Training requirements are minimal due to simplicity of software, hardware, and procedure.
Decisions regarding the well can be made on the rig floor, based on complete information available from the system. Time required to acquire data from memory gauges is reduced to a few minutes, so that analysis from these sources can also be made at the well site.
Subject paper presents conceptual and operational details of the system and explains its application in a variety of field conditions. Buildups, drawdowns and surge tests have been conducted on the Gulf Coast, the North Sea and other locations around the world using this data acquisition system. Several techniques of analysis are demonstrated, based on data collected on actual jobs. Plots available from the system are presented.
Cost Effectiveness of Oil-Based Drilling Muds in the UKCS
Authors: Bailey T J , Henderson J D , Schofield T R 
Published: December 2007

Abstract
Over the last five years the use of oil based mud in the North Sea has increased. This is principally for drilling the Tertiary and Cretaceous mudstones in the Central and Northern sectors and the massive salts in the Southern sector. The technical reasons behind this increase have been examined as has the cost effectiveness of using an oil based mud system.
To compare the performance between oil based and water based mud, operations in six distinct zones on the UKCS were evaluated; these included areas where several exploration or production wells had been drilled using both mud types. Only drilling operations which could be affected by the mud system were selected for comparison. This evaluation was done for the 17 1/2" and 12 1/4" hole sections of each well: the operations selected for consideration were drilling, tripping, reaming, conditioning mud and hole, and any instances of stuck pipe. Performance was compared using a time per metre drilled standard.
Analysis of the data shows that well sections drilled with oil based mud require fewer wiper trips, well costs are lower, average drilling rates are higher, there is a reduced need for reaming and mud conditioning, and mud related problems are fewer. Additionally the risk of stuck pipe in 12 1/4" hole is significantly reduced with the use of oil based mud. Overall, the cost effectiveness of using oil based mud is shown to be significant. In some instances significant savings are being realised; such savings could make marginal field developments economically viable from reduced drilling costs alone.
50/50 Oil/Water Ratio Invert Oil Emulsion Mud – A Useful Tool or a Sales Gimmick?
Authors: Daynes R , Pratt S , Coates J 
Published: December 2007

Abstract
It is proposed within this paper that the use of Less Toxic Oil Based mud (LTOBM) with an oil to water (o/w) ratio of 50/50 (as opposed to the more conventional 75/25 o/w ratio) significantly reduces mud costs and may also reduce the volume of oil retained on cuttings and hence reduce the volume of oil dumped into the sea along with the cuttings.
Mud properties from two Field Trials of the 50/50 LTOBM in the UK sector of the North Sea are presented and the oil on cuttings retention figures are discussed theoretically.
Techniques suitable for investigating water in oil emulsions (to see what physical changes are brought about by varying the oil/water ratio and other parameters) are reviewed, and Optical Microscopy, Laser Light Scattering and Electron Microscopy results are presented.
Down Hole Safety Valve for Concentric Completion
Authors: Geyelin J. L. 
Published: December 2007

Abstract
Gas lift is a widespread method of artificial lift. However, on wells where there is no provision for Side Pocket Mandrels one way to avoid a heavy work over, is to run a macaroni string inside the existing tubing; gas can be injected via the macaroni and the lifted fluid flowed through the tubing-macaroni annulus.
On offshore wells, regulations or Company policy may impose the use of Surface Controlled Subsurface Safety Valve. This paper describes a new type of SC-SSV, run as an integral part of the macaroni string, which will close the macaroni string and the tubing-macaroni annulus. Associated equipment to set the SC-SSV in place and to seal the macaroni string system in the Chrismas-tree is also covered in the paper. In addition, field experience on over 30 offshore wells equipped with such a system is related.
Control of Scale in Sea Water Applications by Magnetic Treatment of Fluids
Authors: Donaldson J. D. , Grimes S. M. 
Published: December 2007

ABSTRACT
The effects of magnetic fields on precipitates obtained from fluids that have been passed through the fields are studied for some potentially scale forming materials. The effect of the field is shown to vary with the material and with the method used to achieve precipitation. The changes that can be observed include changes in particle size, crystal morphology, crystal phase, solubility and rate of precipitation. Results from both laboratory and industrial case studies are presented. The data are interpreted in terms of the interaction between the applied magnetic field and the highly charged crystallisation nuclei being the major effect responsible for the changes.
Engineered Solutions to the Hazards of Oil Based Muds
Authors: Sweetsur A 
Published: December 2007

Abstract
In the drilling process, mud performs a number of functions requiring different physical and chemical properties and it is useful to consider how these are affected by the use of an oil based fluid.
The first function of the mud is to transport cuttings to the surface, which in general requires a velocity of around 100-200 ft/min and a viscosity of 30-50 secs/qt. The mud should have sufficient viscosity and gel strength to ensure that the cuttings are transported from the cutting surface and that they do not sink back to the bottom should circulation be interrupted. Secondly, the mud also works as a cutting fluid to lubricate and cool the bit and to ensure that it is working on a clean formation, and to assist cutting via the energy of the fluid jets from the bit nozzles.
The third essential function of the mud is as a primary means of pressure control. The hydrostatic head of the column of mud serves to counter-balance the formation pressure at any depth and must be amenable to adjustment to compensate for variations in pressure. Also, by measuring flow rates in and out of the hole, the volume of mud in the tanks and by monitoring whether the mud contains gas, fluids or hydrocarbons, a large amount of information about what is happening at the bit can be obtained.
End of Field Life Economics in the North Sea
Authors: Kellas G. K. , Kemp A. G. , Rose D. 
Published: December 2007

Abstract
With many North Sea oil fields now well into the decline phase of their production profiles, interest is now being shown in the management of a field in its latter years of production. The realisation that reservoirs have a finite limit and that this limit is approaching prompts two questions:
What determines how much of the remaining oil reserves can be produced and how can this be maximised while retaining economic efficiency? What determines when a field should be abandoned and what constraints are there on the decision to abandon?
Prediction of Drilling Trajectory in Directional Wells Via a New Rock-Bit Interaction Model
Authors: Ho H.-S. 
Published: December 2007

ABSTRACT
This paper presents the basic concepts and methodologies of a new general rock-bit interaction model useful in predicting drilling trajectories in directional (and deep vertical) wells. This model is a generalization of existing similar models. It accounts for the anisotropic drilling characteristics of both the formation and the bit. The model is developed in a 3-D geometry. Therefore, it is capable of predicting the walk tendency and the build/drop tendency of a given BHA (bottomhole assembly) under any drilling condition. The model can be used as follows: in the forward mode to predict the drilling direction; in the inverse mode to generate the rock and bit anisot ropy indices; in the log-generation mode to generate drilling logs, such as a drilling dip log. Examples of the first two uses are shown.
The drilling directions predicted using various practices and theories are compared to those using this general theory in parametric form. Significant differences can be seen, not only in the predicted walk tendency, which is often missed, but also in the predicted build/drop tendency of the BHA.
This paper also shows why a 3-D analysis is essential to properly predict the drilling direction. A 2-D analysis not only completely ignores the walk tendency of the BHA, it also incorrectly predicts the build/drop tendency.
Drilling a 2,000-ft Horizontal Well in the Devonian Shale
Authors: Yost A. B. , Overbey W. K. , Carden R. S. 
Published: December 2007

ABSTRACT
This paper discusses drilling a 2,000-foot horizontal well in the Devonian Shale, Wayne County, West Virginia, to test the concept that multiple hydraulic fractures from a horizontal wellbore can increase gas recovery efficiency over vertical stimulated boreholes. Discussion focuses on the air/mist drilling, wireline probes, and bottomhole assemblies that were used to drill the well. The target was a 50-foot zone located at a depth of 3,400 feet. Total hole length was 6,020 feet. The angle-building section was achieved using a 4.25°/100-foot design to reduce the risks associated with casing installation in the horizontal section. Directional control methods proved to be unreliable in an air-drilling environment. Bottomhole assembly performance was heavily dependent on motor life and lithologic type. The completion program for the well consisted of installation of 4 1/2-inch casing with external casing packers and port collars. This completion string was installed in 2,000 feet of open hole section that was air drilled. Both geophysical well logs and a borehole television camera survey were used to design the casing string so that shale intervals could be isolated for testing and evaluation before and after stimulation.
Oil Displacement Experiments in Heterogeneous Cores: Analysis of Recovery Mechanisms
Authors: Sorbie K. S. , Wat R. M. S. , Rowe T. C. 
Published: December 2007

ABSTRACT
In a previous paper, we reported on an extensive series of single phase stable displacement experiments in a heterogeneous core system consisting of a cylinder of sandstone with a central core removed and filled with high permeability unconsolidated material; this is referred to as a cored core [1]. These experiments were designed to show some of the main viscous cross flow mechanisms which occur in processes such as polymer flooding in stratified systems. In this work, we extend these results in the cored core system by reporting on a series of oil displacement experiments. The objective of this work is to establish how the recovery mechanisms observed in the single phase experiments in the dual permeability core are modified when there is two phase flow with changing mobility in the aqueous phase. Qualitatively, the viscous cross flow recovery mechanisms seen in the single phase experiments, are also observed here although they are modified to some extent by two phase (relative permeability) effects. As in our previous work, numerical simulation is used in order to interpret and model the main experimental observations. Good agreement is obtained between experiment and theory in that observed cumulative oil curves, watercuts, layer flow rates and tracer profiles are well reproduced by the calculations. The simulation results lead to a clear interpretation of the two phase displacement experiments in terms of effects associated with relative permeabilities and the presence of the glycerol viscosifier.
East Vacuum Grayburg-San Andres Unit CO2 Injection Project: Development and Results to Date
Authors: Brownlee M. H. , Sugg L. A. 
Published: December 2007

ABSTRACT
The East Vacuum Grayburg-San Andres Unit, operated by Phillips Petroleum Company, is the site of the first full scale miscible carbon dioxide injection project in the State of New Mexico. Since unitization in December, 1978, the unit has undergone infill drilling, repressurization by water injection, and is now in its second WAG (water-alternating-gas) cycle of CO2 injection. Early engineering efforts, based on the high fluid conductivity of the reservoir, prescribed the use of larger than normal downhole equipment in conjunction with the choice of an injection pattern with a high producer to injector ratio. This effort made possible the very short transition time between late primary production and early tertiary development. Due to over thirty years of primary production, reservoir pressure in the unit had fallen well below minimum misciblility pressure. Reservoir repressurization, accomplished with water injection, was conducted prior to the initiation of CO2 injection in September, 1985. During this time, the injection scheme was also determined, contracts for the purchase and delivery of the CO2 were negotiated, and design and construction of the CO2 injection system and produced gas gathering system were completed. Handling of the CO2 contaminated hydrocarbon gas production was also considered, resulting in the design and construction of a dehydration and reinjection facility. Treatment of the produced gas for the recovery of hydrocarbons is still under investigation.
Results have been encouraging with a large percentage of the wells exhibiting no CO2 breakthrough to date. However, isolated cases of CO2 breakthrough have been observed in a small number of wells in the more heterogeneous section of the tertiary project area. Future plans for the project include continued monitoring of reservoir performance, the evaluation of a proposed ten acre infill pilot project, and optimization of the CO2 reinjection facility.
Sensitivity of Steam Displacement Predictions to Three-Phase Relative Permeability Models
Authors: Sato K. , Aziz K. 
Published: December 2007

Abstract
Users of thermal simulators usually provide data in terms of two sets of two phase relative permeability functions: (1) krow and krw in a water-oil system, and (2) krog and krg in an oil-gas system. Within the thermal simulator two-phase relative permeabilities are used to predict effective permeability of each phase when all three phases are flowing simultaneously in a block. The most frequently used models for making these predictions are due to Stone (Model I and Model II) and their modifications. The literature does not provide clear guidance on the selection of a relative permeability model for a given problem. In this paper we present theoretical and numerical analyses of three-phase relative permeability models for steamflood problems.
Our analysis shows that relatively high krw and krg (from two-phase data) lead to higher kro from Model I than Model II, and the reverse is true when krw and krg are relatively low. The differences in predicted kro by the two models are greatest in the range of low oil saturations.
We have selected three sets of relative permeability data from the literature that have been previously used for the modelling of steamfloods. Data Sets 1, 2 and 3 are characterized by moderate, low and high values of krw and krg, respectively. The oil relative permeability (kro) predicted for Data Set 1 by the Stone's two models is about the same. As expected from our theoretical analysis, Stone's two models yield quite different kro's for Data Sets 2 and 3. However, oil production predictions with Model I and Model II for Data Set 3 are not too different, but these two models show significant differences in the simulation results for Data Set 2. Investigation of saturation profiles near production and injection wells show that low krw and krg values (Data Set 2) tend to drive saturations into the range where Stone's two models give different results, and high krw and krg values (Data Set 3) tend to keep saturations in the range where the two models give similar results.
The results of this study should be of value in selecting three-phase relative permeability models for steamflood simulations.
In-Situ Combustion With Oxygen-Enriched Air
Authors: Petit H. J. M. 
Published: December 2007

ABSTRACT
To evaluate the field of application of in—situ combustion with oxygen, research was performed on the specific characteristics of in—situ combustion with oxygen-enriched air as compared to conventional combustion with air using two oils having different specific gravities (0.90 and 0.96).
The equipment is made up of an outer cell and an inner tube, equipped with heating collars. Since extensive safety precautions must be taken when using high oxygen concentrations, special attention was devoted to the choice of materials and equipment when the device was being designed. The device is combined with a computerized control system (flowrates, pressures, heat losses control) as well as data acquisition and processing of the experimental results.
The effects of total pressure, oxygen partial pressure and injected oxygen flux were studied. When the total injected flux (N2+O2) is constant and oxygen partial pressure increases, there is a less than proportional increase of the combustion front velocity no matter what pressure and oil are considered. This result is due to insufficient residence time of the oxygen in the reaction zone when the oxygen flux becomes very high. The results obtained at low pressure (1 MPa, 145 psi) at a constant oxygen flux show that the fuel availability and the air requirement at front are slightly affected by the oxygen partial pressure. Indeed, a slight increase in these parameters is found with oxygen enrichment for the heavier oil, and the opposite effect for the lighter oil. When the oxygen concentration increases at higher total pressure (7 – 10 MPa, i.e. 1015–1450 psi) and at constant oxygen flux, the characteristics of combustion are hardly affected for the heavier oil, whereas a reduction of about 40% is observed for the oxygen requirement at front for the lighter oil. These results can be explained by heat–exchange and mass –transfer phenomena. Combustion tests performed in sand packs that had first been swept by carbon dioxide, so as to simulate its effect in the zones downstream from the oxygen combustion front, revealed the influence of this gas on the process.
This laboratory study allowed us to compare the performances of combustion with enriched air in relation to those of conventional combustion with air. The results showed, in some cases, the advantage that can be obtained by using a gas richer in oxygen than air.