bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Dynamic Mud Cake Formation: The Concept of Minimum Overbalance Pressure
Authors: Jiao Di , Sharma M. M. 
Published: December 2007

Abstract
Dynamic filtration experiments were conducted on cores with water based muds at different mud flow rates. It was observed that the thickness of the mud cake was a sensitive function of the mud rheology, the mud shear rate and the permeability of the rock. A model was developed to relate the process of cake buildup under dynamic conditions to the mud and rock properties. Excellent agreement between the model and the experiments was obtained. As predicted by the model (and observed experimentally) no cake was formed on rocks with low permeabilities when the overbalance pressure was reduced below some critical value.
It has been generally accepted that no filter cakes form on rocks with very high permeability (lost circulation). It is shown in this paper that there is also a lower bound on the permeability below which no cake will form and that a minimum overbalance pressure must be maintained in the mud column to ensure mud cake formation. We also present equations that allow laboratory dynamic filtration results to be used directly to predict the critical permeability and the minimum overbalance pressure required for cake formation in the field.
Risk Analysis and Monte Carlo Simulation Applied to the Generation of Drilling AFE Estimates
Authors: Peterson S. K. , Murtha I. A. , Schneider F. F. 
Published: December 2007

ABSTRACT
The purpose of this paper is to present a methodology for developing an AFE-generating model, using a specific offshore field development case study to illustrate the technique. The model utilizes risk analysis and incorporates Monte Carlo simulation in conjunction with statistical analysis of historical drilling data to generate more accurate, risked, AFE estimates. In addition to the general methodology, we present an example of an AFE estimate using the presented techniques with an interpretation and statistical analysis of three years of drilling data for the North Sea.
Drilling of Horizontal Wells in Western Siberia
Authors: Jelsma H. H. , Comeaux B. C. , Meyerov B. 
Published: December 2007

ABSTRACT
The pursuit of oil and gas in the former Soviet Union poses both technical and political challenges to Western companies. This paper discusses how some of the difficulties were overcome while drilling horizontal wells in Western Siberia. It describes various combinations of Russian and Western technology which have been used to provide the most cost effective methods. It also provides a general understanding of political and environmental issues involved in drilling in Siberia which are largely unknown to the West.
The Geological Influence in Offshore Directional Drilling
Authors: Pfau D.J. 
Published: December 2007

Abstract
Offshore Louisiana's early development was in shallow water, with virtually all wells drilled as straight holes. As drilling edged into deeper water, multiple-well jackets with one or more directional wells became an economic necessity to reduce structure and line costs. When larger platforms with more wells evolved, longer platforms with more wells evolved, longer directional kicks resulted which demanded more engineering effort. Today's offshore directional drilling programs are designed on a delicate balance of economics, engineering, and geology, with the latter factor exerting an ever-increasing influence.
Directional drilling has become an indispensable tool to the geologist or engineer planning offshore exploration and development. The problems inherent to this operation are often outweighed to the extent that some wells are directionally drilled when complete freedom of choice in surface locations is available. Testing an entire series of objectives at the optimum structural positions in an exploratory well, or penetrating several pays instead of one in penetrating several pays instead of one in a development well, can often justify the added cost or risk of unusually complex directional programs. Specialized directional drilling can make some development programs profitable that would otherwise be programs profitable that would otherwise be uneconomical, even with straight-hole development.
When drilling from fixed, multi-well platforms, the problems of attempting to platforms, the problems of attempting to adapt the directional programs to the geometry of domal or highly faulted geologic structures become extremely complex. A thorough study of the forces acting between the drill pipe and casing plus the walls of the open hole is necessary to determine what can be accomplished with the equipment available and what improvements are needed. By reducing these adverse forces and/or compensating for them, additional directional drilling capabilities are possible. Continued progress in providing this flexibility is essential if we are to economically discover and develop the smaller reserves in our offshore fields.
Introduction
Shell's effort in the development of Offshore Louisiana oil and gas began 20 years ago at Main Pass Block 69 Field, just east of the Mississippi River Delta.
Design Applications of Genetic Algorithms
Authors: Jefferys E. R. 
Published: December 2007

Abstract
The paper outlines the basis of Genetic Algorithm (GA) optimisation and discusses the areas where these powerful computer based search procedures can best be used. Applications include many kinds of engineering design, financial optimisation, scheduling and finding rules to describe data.
An interface between a GA package and the design engineer’s problem specification has been developed. The system is simple yet powerful, permitting the engineer to use sophisticated software on a PC without becoming an optimisation expert. Real applications to TLP column design optimisation and scheduling are presented to illustrate the power and flexibility of the method and the simplicity of the interface.
Future additional application areas are suggested.
A Cyclic Surfactant-Based Imbibition/Solution Gas Drive Process for Low-Permeability, Fractured Reservoirs
Authors: Flumerfelt R. W. , Li Xiaoyu , Cox J. C. , Hsu Wen-Fu 
Published: December 2007

Abstract
A surfactant based imbibition/solution drive process is described which has significant promise for application as a single well treatment in low permeability, fractured environments. The process utilizes a carbonated surfactant slug in a multi-cycle injection-soak-production sequence to increase production by (1) enhancing imbibition rates and (2) promoting an induced solution gas drive (SGD) mechanism. Imbibition is enhanced through surfactant and CO2 stimulated alternations in wetting and CO2 stimulated decreases in oil viscosity. The solution gas drive arises from the evolution and expansion of dissolved gas during pressure decline with production. The presence of the surfactant promotes the formation of an in situ foam which decreases the mobility of the gas phase and significantly enhances the effectiveness and the solution gas drive mechanism.
Here, laboratory studies are presented to evaluate the process for different oils (kerosene and crude oil) in low permeability dolomite rock samples. To provide baseline comparisons, separate imbibition/production tests were conducted with (1) water only, (2) carbonated water (no surfactant), and (3) carbonated water with surfactant. During the tests, advanced NMR imaging methods were used to track the temporal and spatial variations of oils saturation within the core samples. This provided a basis for evaluating the relative contributions of the imbibition and solution gas drive mechanisms.
The tests with kerosene in water-wet media clearly showed the effectiveness of CO2 in promoting higher imbibition rates and in stimulating the solution gas drive. In these tests, the surfactant improved the solution gas drive production, but the effect was marginal. In the crude oil tests, the surfactant based carbonated water imbibition and production was clearly superior to that observed with the carbonated water alone. The surfactant systems were particularly effective in rock samples with mixed or oil-wet conditions. The surfactant appears to alter the wetting state of the rock and promote imbibition significantly beyond that possible with water alone or water with dissolved CO2. Also, during the production phase, the SGD mechanism is significantly enhanced with the presence of the surfactant. Oil recoveries in excess of 50% were possible with multi-cycle treatments with the carbonated surfactant systems, while only 20% recovery was possible with carbonated water alone.
Determining Total Petroleum Hydrocarbons in Soil
Authors: Holliday G. H. , Deuel L. E. 
Published: December 2007

Abstract
Many state agencies, using an infrared analysis [IR], establish total petroleum hydrocarbon (TPH) levels above which soils are considered contaminated. As a result, clean closure of contaminated areas are prohibited and, in some cases, Deed Recordation required. In many instances, a fraction of the hydrocarbon observed using the IR technique is co-extracted carbohydrates, fats and proteins associated with the indigenous soil humus. Test results from the field biodegradation studies reveal TPH analysis by gas chromatographic [GC] technique provide an accurate index to treatment efficiencies and treatment methods establishing petroleum residual levels. Significant decrease in TPH-GC with time corresponds to a significant decrease in the dry weight loss on ignition [LOI] quantified at 150°, 200° and 250° C. The authors conclude complete analyses [IR and GC] are required to avoid improperly characterizing the source and level of TPH contamination.
Simulation of Foam Transport in Porous Media
Authors: Kovscek A. R. , Patzek T. W. , Radke C. J. 
Published: December 2007

Abstract
Foam is an excellent fluid for achieving mobility control of gas in porous media. Practical application of foams for EOR processes, however requires a predictive model of foam displacement. Further, quantitative information on foam-flow behavior at reservoir flow rates and pressures is required as input to any field-scale modeling.
An experimental and mechanistic-modeling study is reported for the transient flow of foam through 1.3 μm2 (1.3 D) Boise sandstone at backpressures in excess of 5 MPa (700 psi) over a quality range from 0.80 to 0.99. Total superficial velocities range from as little as 0.42 to 2.20 m/day (1.4 ftVday to 7 ft/day). Sequential pressure taps and gamma-ray densitometry measure flow resistance and in-situ liquid saturations, respectively. We garner experimental pressure and saturation profiles in both the transient and steady states.
Adoption of a mean-size foam-bubble conservation equation along with the traditional reservoir simulation equations allows mechanistic foam simulation. Since foam mobility depends heavily upon its texture, the bubble population balance is both useful and necessary as the role of foam texture must be incorporated into any model which seeks accurate prediction of flow properties. Our model employs capillary-pressure-dependent kinetic expressions for lamellae generation and coalescence and also a term for trapping of lamellae.
Additionally, the effects of surfactant chemical transport aie included.
We find quantitative agreement between experimental and theoretical saturation and pressure profiles in both the transient and steady states.
Team Strategies: Managing Technical Specialties
Authors: Woodyard Alan , Hall Jim , Kendrick Bob 
Published: December 2007

Abstract
Allocating technical and managerial staff based on the requirements of the activity may provide an effective application of skills, but the strategies of the 21st century demand that a more efficient use of staff be made. Conoco’s Production and Project Engineering Division response to this demand has been to "pilot" the organization of a corporate engineering support team around a selected core production area. This arrangement offers the greatest opportunity for profit with the least investment of people. The production increases resulting from this pilot effort have paid for the engineering support seven fold in one year.
A Robust Neural Network Model for Pattern Recognition of Pressure Transient Test Data
Authors: Ershaghi Iraj , Li Xuehai , Hassibi Mahnaz , Shikari Yusuf 
Published: December 2007

Abstract
A modified approach for pattern recognition from derivative plots by using neural network methodology is proposed. Instead of training only one single comprehensive neural net to recognize all possible patterns, multiple neural nets are employed in which each neural net is trained to recognize patterns for a specific conceptual reservoir model. This improves the full representation for each model. At the same time the proposed approach assists in recognition of various models with similar responses. A hybrid approach is suggested where the output from the proposed neural network can be cross correlated with models suggested from other data sources.
Logging of Water Mass Entry in Deviated Well Oil/Water Flows
Authors: Lenn C. P. , Kimminau S. , Young P. 
Published: December 2007

Abstract
A new interpretation has been applied to the WFL* Water Flow Log which determines the mass flow rate of water and gathers both velocity and holdup information from the activation signal. The interpretation enables the WFL log to function as an effective cased hole production logging tool. It has been tested with extensive laboratory experiments. Field trials at the Wytch Farm oilfield have demonstrated the practicality of the method in conditions typical of many offshore oil fields with medium to high production rates.
Downhole measurements of mass water flow rate that are consistent with other production logging and test separator data have been made in field conditions. The measurements have been used as part of an integrated program of waterflood management, and in the particularly complement the TDT* data.
The method is of value in highly deviated or even horizontal wells where conventional production logging (PL) sensors can be ambiguous in resolving oil-water flows. The pulsed neutron tool presents no external obstructions to flow.
Restrictive Diffusion From Uniform Gradient NMR Well Logging
Authors: Coates G. R. , Vinegar H. J. , Tutunjian P. N. , Gardner J. S. 
Published: December 2007

ABSTRACT*
Nuclear magnetic resonance (NMR.) has long been recognized for its potential as a well logging method for measuring pore size and permeability. NMR spin–lattice and spin–spin relaxation times, T1 and T2, respectively, are typically used in these applications because they are related to the surface-to-volume ratio of the pore system via the surface relaxivity.
Another NMR measurement, restrictive diffusion at short interecho spacings, is also proportional to surface-to-volume ratio buthas no dependence on surface relaxivity. Anew pulsed NMR logging tool, the MRIL, is capable of making continuous restrictive diffusion measurements because its permanent magnet generates a uniform magnetic field gradient of 25 gauss/cm.
Restrictive diffusion logs run in Shell’s Johnson City test well clearly show the effect of nearly unrestricted diffusion in the permeable zones. The MRIL logs are confirmed by laboratory NMR measurements of restrictive diffusion on core plugs from the test well. Several NMR relations are then compared for permeability estimation using bound water, T1, T2, and restricted diffusion data.
The Pressure-Transient Behavior of Vertical Wells With Multiple Flow Entries
Authors: Larsen Leif 
Published: December 2007

ABSTRACT
Solutions and examples are presented for the pressure-transient behavior of vertical wells with multiple flow entries in homogeneous formations. Any number and pattern of intervals can be chosen, with skin values allowed to vary along the well. Total effective skin is also obtained as a byproduct of the solutions.
Using standard mathematical techniques, solutions are obtained with both a finite wellbore radius, as opposed to the more common use of a line-source well, and outer boundaries included for circular and unbounded systems. With boundaries that can be induced by image wefls one can also include these directly. However, except for cases with small distances involved, one can just as well add boundary effects from fully penetrating wells.
The pressure-transient solutions are first computed as Laplace transforms and then inverted numerically by standard techniques. With more than one interval, only the total well rate is assumed. The rate distribution along the well must therefore be determined numerically as part of the total solution.
Early Quantification of Uncertainty in the Estimation of Oil-in-Place in a Turbidite Reservoir
Authors: Norris R. J. , Massonnat G. J. , Alabert F. G. 
Published: December 2007

Abstract
A description of an integrated approach to the quantification of uncertainty in the estimation of oil-in-place (OIP) is presented. The approach is unusual in two respects: firstly, the uncertainty is quantified by using traditional stochastic methods combined with an analysis of the representative of wells, secondly, the oil-in-place is calculated within a sedimentological framework, that is, by genetic sedimentary units. The former step is performed by a method known as the "Bootstrap" technique. The geostatistical modelling is constrained by detailed seismic, well and pressure data.
The statistical and geostatistical methods are presented, along with a discussion of the broader implications for the quantification of uncertainty. The second part of the paper details the application of the technique to an appraisal stage field.
Reservoir Facies and Their Distribution in a Heterogeneous Carbonate Reservoir: An Integrated Approach
Authors: Vashist N. , Dennis R. N. , Rajvanshi A. K. , Taneja H. R. , Walia R. K. , Sharma P. K. 
Published: December 2007

Abstract
A new technique for defining reservoir facies has been established which incorporates the geological features of deposition and diagenesis with the dynamic flow capacity (kh) of the reservoir. This technique was designed to overcome the difficulties that a conventional porosity-permeability relationship has in a heterogeneous diagenetic carbonate reservoir. The vertical distribution of these reservoir facies has been established in the studied wells and their lateral variations mapped across the field using the ternary diagram approach. The reservoir description obtained in the study is being directly applied to numerical simulation and ultimately to the field development.
Geographical Distribution and Forecast Models of Infill Drilling Oil Recovery for Permian Basin Carbonate Reservoirs
Authors: Lu G. F. , Brimhall R. M. , Wu C. H. 
Published: December 2007

Abstract
This paper presents the results of a study on the geographical distribution of oil recovery efficiencies of carbonate reservoirs in the Permian Basin of West Texas. The primary oil recovery efficiency of San Andres units was grouped into five geographical regions and that of Clearfork units into six geographical regions. Results indicate that the initial waterflood recovery efficiency appears to be dependent on the primary recovery efficiency; and the infill drilling waterflood recovery efficiency on the initial waterflood recovery efficiency. The geographical location of a unit with reference to a paleo-depositional setting appears to have an important bearing on the waterflood infill drilling oil recovery efficiency.
The forecast models for primary recovery and waterflood infill drilling recovery efficiency were developed for each region. Infill drilling recovery index (IDRI) was introduced to develop the infill drilling oil recovery forecast models. It represents the effectiveness of infill drilling and is correlated with the reservoir, process and operational parameters. Three carbonate reservoirs were used to demonstrate the application of these models for forecasting waterflood infill drilling recovery.
Stress-Induced Permeability Reduction in Fissured Reservoirs
Authors: Buchsteiner Hubert , Warpinski N. R. , Economides M. J. 
Published: December 2007

Abstract
Stresses near any wellbore are different and likely to be higher than the far-field stresses. In addition, fluid production and the corresponding pressure drawdown lead to an increase of the effective stress. This increase results in a substantial reduction in the corresponding permeability, especially if the latter is primarily due to natural fractures. The phenomenon may result in unequal reduction in the components of the permeability tensor, thus inducing permeability anisotropy and, in certain naturally anisotropic cases, may alter the direction of the maximum and minimum permeabilities. A model, relating effective stress and permeability / permeability anisotropy has been employed to study the expected well performance and implications on hydraulic fracturing. The effect of the permeability alteration ranges from moderate to severe and appropriate reservoir exploitation must consider these phenomena.
High-Pressure Packing with Water: An Alternative Approach to Conventional Gravel Packing
Authors: Ledlow L. B. , Johnson M. H. , Richard B. M. , Huval T. J. 
Published: December 2007

ABSTRACT
Many methods of gravel packing have been applied to control sand problems in injection or producing wells.1 Successful application of a sand control technique to obtain a productive well completion requires an understanding of the process limitations of the selected method. Some of the limitations imposed on a gravel packing process are operational. These constraints are more often dictated by operating company philosophy than by technical limitations. In some cases operational goals are in conflict with well productivity goals. A lack of understanding the relationship between the various components and disciplines in gravel packing can magnify productivity problems encountered in gravel packed well completions.
This paper presents an alternative approach that challenges the conventional wisdom of gravel packing below fracture pressure. High rate/pressure water packing breaks down damaged perforations with small amounts of gravel at low pump rates and with a limited volume of fluid. This meets the completion objectives of lower cost, higher productivity and simpler field operations. In a previous paper2 examples of HEC "gel" gravel pack completions were presented that demonstrated the beneficial effects of exceeding fracture pressure to enhance the slurry dehydration and increase the packing efficiency.
Laboratory research as well as field experience has demonstrated that gravel packing with water is an effective method of placing sand in the perforation tunnels and the annulus.3-4
Influence of Light Ends on the Onset Crystallization Temperature of Waxy Crudes within the Frame of Multiphase Transport
Authors: Meray Véronique Ruffier , Volle Jean-Luc , Schranz C. J. P. , Le Marechal Pierre , Behar Emmanuel 
Published: December 2007

Abstract
For some offshore fields, multiphase production and transport can be an economic solution. In the case of waxy crude reservoirs, keeping the light ends in contact with the stock tank oil can reduce the onset crystallization temperature.
The influence of light components and ends on the wax appearance temperature (WAT) of two oils has been studied by differential scanning calorimetry.
In order to determine the role of the pressure, an equipment based on the use of an ultrasonic pulse has been designed. The main features of this device are presented.
It has been found that light components induce a decrease of the onset crystallization temperature of waxy crudes. This decrease is proportional to the amount of light ends, inversely proportional to their carbon atoms number, and dependent on the chemical nature of the components added.
Furthermore, it has been possible to correlate these experimental data, in order to calculate the variation of the wax appearance temperature of two stock tank oils, due to the addition of a light end.