bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibrating Fracture Models with Direct Diagnostics: A Necessary but Humbling Experience
Authors: Lehman Lyle V. , Weijers Leen , Mayerhofer Michael , Wright Chris , Fisher Kevin , Davis Eric , Fulton Dwight 
Published: December 2007

Abstract
Although fracture models are predictive, and physical measurements are accurate, both require a certain level of scientific knowledge and training to interpret and execute correctly. Based on this understanding, if we can create fracture models that are highly accurate, we can make predictions more effective and valuable.
One technique makes modeling a more useful tool for designing, fine-tuning, and implementing fracturing treatments. Physical measurements of mini-fracture dimensions are input into a fracture model, allowing the model to more accurately reflect reality. After the model matches both the observed net pressure response and the directly measured hydraulic fracture geometry (the model is calibrated), the model can more closely predict the outcome of a main fracturing treatment. A survey of stimulation experts indicates that many think this step can more than double the value of using a model compared to simply using fluid-efficiency data. This paper discusses how physical measurements from a mini-frac treatment can be input into a fracturing model. Case histories will illustrate how decisions were made to alter fracturing designs and mitigate the risks associated with proppant placement.
Buffalo Redevelopment "The Wee Field That Grew"
Authors: Begg Paul D. , Krasey Russell S. , Lehto Doug A 
Published: December 2007

Abstract
During 2001 an intensive geophysical, geological and reservoir engineering, analysis was carried out on Nexen's 100% WI Buffalo Project located in the Bonaparte Basin. The work resulted in the successful drilling of two infill wells, during March / June 2002. The value, reserves and economic life of the Buffalo Project has been extended by 2 years with additional recovery of approximately 8 MMbbl.
This paper will review the original geologic / geophysical model and the non-unique nature of the Reservoir Engineering history match. The pre-stack depth migration [PSDM] work and results will then be described in detail, along with an explanation of the revised geologic model for Buffalo and how it changed our concept of the upside in the field. The reservoir simulation, decision tree, production forecasts and reserve summary will then be described.
The PSDM work indicated that the field is a tilted fault block, analogous to other fields in the Bonaparte Basin, instead of a rollover anticline. In the rollover anticline model, both original producers, Buffalo 3 and Buffalo 5, were located along the central crest of the anticline. The new tilted fault block model indicated both a "Northern Attic" and a "Western Attic". The infill drilling program was designed to drain the yet unswept attic oil at Buffalo.
Since Buffalo has a very strong water drive, typical reservoir simulation would not "see" the presence of the attics in the field, and the simulation results are not unique. Nexen had developed a comprehensive decision matrix, which reduced risk and created maximum flexibility. The Buffalo 7 well was critical to proving the new geologic model of the field. The well was drilled and completed in March-April 2002 and was followed Buffalo 8, Completed as Buffalo 9, in May-June 2002.
Nexen used a multi disciplinary team to review Buffalo, which has resulted in a successful project. Nexen has applied its expertise gained in Western Canada, the Gulf of Mexico and Yemen to its operations in Australia.
The successful redevelopment of Buffalo has increased reserves, extended productive life and increased the value of Buffalo to Nexen. The work has enhanced the companie's reputation in Australia as an operator with experience in both exploration and exploitation.
Improving Field Recovery, Sweep Efficiency through Optimizing Gas Injection / Gas Production in a Complex Mature Field
Authors: Naguib Mohamed , Hamdy Ahmed , Hussein Ahmed 
Published: December 2007

Abstract
The Zeit Bay field reservoir units consist of sandstone and carbonates, partially overlaying a tilted block of fracture basement reservoir with a complex drive mechanism. A secondary recovery scheme of gas re-injection into the original gas cap was initiated to maintain reservoir energy and minimize pressure decline. Over 70 development wells are actively depleting the reservoir.
The original oil leg was 850 ft-TVT. However currently the oil leg varies from 150 to 250. With this limited oil leg different problem arise. The most serious problem was the increase in gas production that resulted in a decrease in gas injection to gas production ratio (GI/GP). The decrease in (GI/GP) ratio results in a significant drop in production increase in wells water cut and reduction in the field sweep efficiency. In addition this decrease will hinder the gas cap expansion, this has lead to activate the aquifer water breakthrough.
The gas sweep being preferred because it's low residual oil. As the oil leg gets smaller, the production strategy is adjusted to maintain the dynamic equilibrium and increasing the (GI/GP) to enhance gas expansion which slow down water rise in the reservoir, control water cut in the wells and minimize residual oil.
The paper represents a case study of applying the gas injection to reduce the field decline from 30 to 14%, controlling water production and improve reservoir sweep efficiency.
A New Completion Method Triples the Productivity of Infill Wells on Mature Oilfield
Authors: Wang Yupu , Yan Yaru , Liu Bing , Wan Jun , Ning Shufeng 
Published: December 2007

Abstract
With the rapid progress of oilfield development technology, the new completion method is playing a more and more important role. A new completion technology not only opens formations, but it also improves permeability in formation as well. This paper discusses the optimized application of completion technology of adjustment wells at the later stage of high water-cut on mature oilfield. This method well controls the initial water-cut of infill adjustment wells, as well as improves the initial productivity of new wells.
The infill wells modification will encounter many problems in the mature oilfield, such as the horizontal variations between wells, the vertically difference of water content in fomations, the pressure difference distribution in space, and the scattering distribution of the to be modified. On the other hand, the formations are all that with permeability less than 0.01μm2. Completion technology is a key to make the productivity more efficient. This paper discusses about the fact that under the geological condition of continental sediment reservoirs with water-cut larger than 85%, after applying adequate completion technology, it triples the productivity of formations with permeability less than 0.01μm2, thus it makes a good economic result.
Pressure Transient Analysis in Fractured Produced Water Injection Wells
Authors: van den Hoek P. J. 
Published: December 2007

Abstract
It is well established within the Industry that injection of (produced) water almost always takes place under fracturing conditions. Particularly when large volumes of very contaminated water are injected -either for voidage replacement or disposal-large fractures may be induced over time. The current paper aims to provide a methodology for Injection Fall-Off (IFO) test analysis of fractured (produced) water injection wells. Some essential elements of IFO for fractured water injectors are: Closing fracture, (early) transient elliptical reservoir fluid flow, finite (changing) fracture conductivity, and fracture face skin.
An exact semi-analytical solution is presented to the fully transient elliptical fluid flow equation around a closing fracture with changing finite conductivity, fracture face skin, and multiple mobility zones in the reservoir surrounding the fracture. Based on this solution, type curves of the dimensionless bottom-hole pressure as a function of dimensionless time are provided covering both the period during fracture closure and the period after fracture closure. The shape of these type curves is studied as a function of the different relevant parameters, in particular the fracture closure time, fracture compliance, wellbore storage, fracture conductivity, fracture skin, mobility ratio, and injection period. The type curves are compared in detail with pressure transient (build-up/fall-off) behaviour known from the literature, particularly with the aim to identify the well-known "storage", "linear", "bilinear" and "radial" flow regimes.
Furthermore, based on the conceptual results presented in this paper, a number of different methods to determine fracture length from fall-off tests are discussed.
Finally, these concepts are applied to two field examples, where the dimensions of the induced fractures are derived from the analysis of the IFO data.
Development and Laboratory Verification of High Membrane Efficiency Water-Based Drilling Fluids with Oil-Based Drilling Fluid-Like Performance in Shale Stabilization
Authors: Tan C. P. , Wu Bailin , Mody Fersheed K. , Tare Uday A. 
Published: December 2007

Abstract
A major collaborative project was undertaken to develop novel environmentally acceptable water-based drilling fluids with high membrane efficiency to meet the future requirements of the petroleum industry. This paper describes various geomechanical considerations in the development and performance verification of the drilling fluids. Specialised test equipment, including a membrane efficiency screening equipment, an autonomous triaxial cell and a high pressure triaxial test equipment and associated test procedures, were either developed or modified for simulation of key drilling fluid-shale interaction mechanisms. More than 300 pressure transmission-chemical potential tests were performed on Pierre II shale samples to screen a wide range of novel chemical compounds for their membrane generation capacity in shales. Three of the compounds, which are capable of generating high membrane efficiency in the shale, were subsequently used to develop new generation water-based drilling fluids. Typical examples of the membrane efficiency screening tests conducted with novel compounds that generated highly and moderately efficient membranes are presented. The reasons for the difference in the membrane generation capacity of the compounds are discussed. The results demonstrate that the new generation water-based drilling fluids are capable of generating membrane efficiencies of between 55% and 85%. The shale stabilising capacity of the new generation drilling fluids developed was demonstrated and verified through a series of borehole collapse tests. Results of the borehole collapse tests are presented and discussed. The results clearly demonstrate the shale stabilising capacity of the new drilling fluids in comparison with the reference test which was not subjected to the mud pressure penetration and chemical potential stages with the drilling fluids.
A New Technique for Rapid Estimation of Fracture Closure Stress When Using Propellants
Authors: Cuthill D. A. , Schatz J. F. , Gilbert J. V. 
Published: December 2007

Abstract
Minifracs are used to assist with main hydraulic fracture design by generating estimates of the fluid efficiency, closure stress, fracture geometry, and leakoff coefficient prior to the main treatment. Closure stress is frequently determined by analyzing the pressure falloff response after pump shut-down using a Nolte G-Function analysis plot. Comparison of the measured data with the dimensionless Nolte G time indicates closure when used in combination with the derivative and pressure superposition derivative.
During perforating/propellant treatments of wells, the use of a high-speed downhole digital pressure data recorder enables a new rapid technique for determining closure stress using the G-Function and associated methods. The propellant event breaks down the perforations and extends fractures into the formation in the time span of tens of milliseconds, and can thus be treated as a high-speed minifrac. The analysis method and feasibility of this new technique are demonstrated.
The falloff pressure curve after a propellant event, typically lasting no more than a few hundred milliseconds, is shown in several case histories to provide sufficient closure information. Where these data are available, results are consistent with other methods. Although certain favorable conditions must exist for the method to be applicable, this new technique can be used where a quick estimate of closure stress is needed prior to hydraulic fracturing and while equipment is in place in the field. Work continues to fully define the range of applicability and accuracy of the new technique.
Increasing Leakoff Pressure With New Class of Drilling Fluid
Authors: Santos Helio 
Published: December 2007

Abstract
A new class of drilling fluid has been developed and proved to be extremely effective in increasing the leakoff pressure in permeable formations. A simple laboratory test is described to assess the limits of potential increase of leakoff pressure in the field. This paper describes some fundamental issues regarding fracture and leakoff pressures for well construction purposes and then shows how the increase in leakoff pressure can be achieved with the use of this new drilling fluid. Some case histories are presented in which the fluid has proven to increase the leakoff pressure effectively, and a comparison is made with drilling fluids traditionally used, highlighting the limitations of the current fluids to effectively deliver what the industry really needs. Several applications are presented in which an increase in leakoff pressure can hugely reduce the costs and risks of the wells.
Evaluating the Appropriateness of Intelligent Completion Technology - A Case Study in a Shallow Clastics Gas Reservoir
Authors: Bhat Suniti K. , Thomson Andrew W. , Sarkar Radheshyam , Mohd-Nor Norlizah , Huang Edmund 
Published: December 2007

Abstract
In recent years, the deployment of intelligent completion technology has increased as has the range and functionality of the systems available. The focus has been on developing intelligent completions that will allow a greater degree of controlling reservoir inflow. Improvements in the methods that could be used to model the values of these complex completions have in general lagged behind. In this paper, a phased process for evaluating the productivity benefit offered by an intelligent completion system for a multi-layered, shallow gas reservoir system is described in detail.
To start the process, an intelligent completion system was selected that was compatible with the well architecture and would provide maximum flow control capability (infinitely variable choke). Analytical methods where then used to conduct a screening exercise in order to evaluate the production benefit this high-end intelligent completion could offer. This screening exercise provided a fuller understanding of the hydraulic interactions occurring within the wellbore. As such, it was possible to tailor the level of intelligent completion functionality to the production benefits derived. A detailed study was then carried out using dynamic 3D-simulation modelling, which incorporated the selected intelligent completion components as a part of the reservoir simulation.
This phased approach helped in determining the optimum intelligent completion configuration taking into account the time related reservoir performance changes.
Locating 3D Wells in Deep Offshore Channel Reservoirs Using High Resolution Seismic Data and Reservoir Model: An Example from the Rosa Lirio Project
Authors: Verdière S. , Guyotte E. , Verpeaux J. -F. , Gazaniol D. , Clavel J. 
Published: December 2007

Abstract
The development of Oligocene deep offshore turbidite channels has begun in Angola Block 17 with the Girassol field. Jasmin, RosaD, Rosa E, Cravo and Lirio are additional reservoirs in the same setting, for which subsea development is also planned.
Conventional 3D seismic, although fit for exploration purposes, has not adequate resolution to take into account the heterogeneities suspected in turbidite channels and shown by the well tests. To overcome this shortcoming, High Resolution seismic has been acquired. The images presented, coming from the interpretation process, show spectacular results. The identified heterogeneities result in a good match between the model and the well tests.
Detailed interpretation has been input in a deterministic way in the reservoir model. For instance, sand juxtaposition along the faults, seismic facies units, lateral and vertical connectivity and potential barriers have been analysed and represented. The resulting connectivity within the channelled reservoirs appears complex and its interpretation required combining deterministic picking and more automatic approaches. Highly integrated work between geologist and reservoir engineer results in a refined geological description that enabled initial well targets to be defined.
Heterogeneities that may result in by-passed oil are accounted for at this stage in the completion and selectivity philosophy. The well pattern must also be consistent with the drilling constraints and the location, type and number of subsea manifolds. Optimisation of the well pattern needs to consider these aspects in conjunction with the geology. This is achieved through multidisciplinary teamwork with a fully integrated software.
In such a channelled deep offshore context, the challenge of development well definition can be overcome thanks to early identification and consideration of the most influential parameters. Understanding and compromises within the integrated team are the underlying keys to obtain coherency between the sub-surface and surface constraints.
Tertiary Miscible Gas Injection in the Alwyn North Brent Reservoirs
Authors: Burns L. J. , Richardson G. J. , Kimber R. N. 
Published: December 2007

Abstract
The Alwyn North complex is located in Block 3/9a of the Northern North Sea, UK sector. Production commenced in 1987 from the Middle Jurassic Brent Group, and was supported by water injection from early 1988. In 1997 a Tertiary Miscible Gas Injection project was sanctioned with incremental reserves for the four main reservoir panels, estimated at 33Mboe. This figure includes a waterflood phase post MGI and field depressurisation, and was evaluated against a continued waterflood scenario.
Gas injection commenced in late 1999 into the Brent East-South panel followed in September 2000 by injection into the Brent North West panel. The early part of the project was interrupted by facilities difficulties, however by mid 2002 1.68Gsm3 of gas had been injected.
In the 2 1/2 years since first injection, incremental oil has been observed in four wells showing between a 2 to 10 fold increase in oil potential. Associated gas breakthroughs have been experienced in 2 of these wells and can be related to zones of high permeability. A positive correlation can be seen between the gas injection rate and the oil production potential and by 2 1/2 years into the project around 1 1/2 million bbl of incremental oil had been recovered. Ensuring voidage replacement is maintained is key to the success of this project with average reservoir pressures only marginally higher than Minimum Miscibility Pressure.
Intensive reservoir monitoring (permanent downhole gauges, wellhead pressure & temperature data, tracers, production logging, fluid sampling and regular well tests) has been fundamental to improving the understanding of field performance. This information has been regularly integrated into full field geological and compositional simulation models to optimise the near term performance of the panels and to plan the future strategy.
Liberal Art College Graduates - A Promising Source Of Drilling Personnel
Authors: Wilson L. 
Published: December 2007

Abstract
A large international drilling contractor was faced with a severe shortage of promising new employees to fulfill its needs and help provide for further growth. A whole new source of entry level personnel were hired from among liberal arts college graduates. After indoctrination they were sent to overseas assignments, and the results of the 4 1/2 year old program are summarized in the paper.

BACKGROUND OF PROBLEM
It has been documented in many places that there was a huge increase in drilling activity both in the U. S. and overseas during the early 1970's. The resulting shortage of skilled drilling personnel became acute at that time and has personnel became acute at that time and has remained somewhat critical since that time. As a result, there has been a proliferation of recruiting activities as well as intensive training programs of one sort or another. programs of one sort or another. In the case of SEDCO, Inc., the shortage of U.S. personnel was compounded because:We had no U.S. based operations to serve as a training facility.The equipment with newer rigs demanded more technological knowledge.Most nations demand that training be done with their own citizens rather than U.S. citizensLanguage aptitude became much more important than ever before.Any U. S. citizens had to be raised to a skill level acceptable to the various governments overseas.
With this background we recognized that the shortage was not only in quantity but in quality, so we determined to search for a whole new source of people who could help sustain our growth both from a standpoint of rig count and quality.

SELECTION OF LIBERAL ARTS GRADUATES
In the beginning we considered the high school graduates who formed most of the skilled drilling personnel pools of today and had to reject them as a source for new people. One of the principal reasons was that the high school graduates of today tend to have a multitude of opportunities that will keep them near home, and, of course, for an overseas assignment they tend to be somewhat immature and certainly not prepared to deal with foreign nationals. Even if prepared to deal with foreign nationals. Even if they met the criteria of supplying the quantity needed the quality was sadly lacking since they had no demonstrated ability to learn at a rapid rate.
We next considered junior college graduates who mostly have taken vocational courses, such as diesel mechanics, etc. The graduates of such institutions seemed ideally suited for careers in the drilling business and satisfied essentially all of the requirements we had.
A New Approach for Reservoir Characterization
Authors: Aminian K. , Thomas B. , Ameri S. , Bilgesu H. I. 
Published: December 2007

Abstract
To reliably predict the reservoir performance, an accurate model of the reservoir is necessary. For reservoir simulation purposes, the flow unit model is most practical approach. The flow units are defined according to geological and petrophysical properties that influence the flow of fluids in the reservoir. Identification and prediction of flow units are strongly dependent on the availability of permeability distribution. This need for permeability distribution significantly limits the identification of flow units in reservoirs where permeability measurements are not abundant such as most reservoirs in the Appalachian Basin.
In this study, statistical and artificial intelligence techniques were employed to identify flow units based on limited data obtained from core analysis supplemented by mini-permeameter measurements, geological interpretations, and well log data in a heterogeneous oil reservoir in the Appalachian Basin. An innovative methodology was then developed to predict flow units using only well log data. The distribution of flow units in the reservoir was then predicted based on abundant well log data. Finally, permeability and porosity distributions were predicted based on the distribution of the flow units in the reservoir. This approach led to development of a reliable reservoir model. The accuracy of model was verified by successful simulation of the production performance. The methodology presented in this paper can serve as a new guideline for the characterization of heterogeneous reservoirs.