bluuebunny/crossref_metadata_2025_split huggingface dataset:
World-Wide Applications of Microbial Technology for Improving Oil Recovery
Authors: Bryant Rebecca S. , Lindsey Rhonda P. 
Published: December 2007

Abstract
Microbial enhanced oil recovery (MEOR) technology has advanced, since 1980, from a laboratory-based evaluation of microbial processes, to field applications internationally. In order to adequately support the decline in oil production in certain areas, research on cost-effective technologies such as microbial enhanced oil recovery processes must be focused on both near-term and long-term applications. Many marginal wells are desperately in need of an inexpensive improved oil recovery technology today that can assist producers in order to prevent their abandonment. Microbial enhanced waterflooding technology has also been shown to be an economically feasible technology in the United States. The 5th International Microbial Enhanced Oil Recovery Conference and Related Technology for Solving Environmental Problems was held in September 1995. Various papers were presented from companies and researchers all over the world on field applications using microorganisms. This paper will compile pertinent information and results from those papers to provide an overview of the state of the art of microbial technology with specific emphasis on current field applications.
Evolution of Conformance Improvement Efforts in a Major CO2 WAG Injection Project
Authors: Fullbright G. D. , Hild G. P. , Korf T. A. , Myers J. P. , O’Toole F. S. , Wackowski R. K. , Smith M. E. 
Published: December 2007

Abstract
The Rangely Weber Sand Unit is giant oil field located in northwestern Colorado currently under miscible CO2 and water flooding operations. Field development has evolved through many stages, including infill drilling, waterflood expansions, and CO2 injection. Conformance improvement has become a major strategy as the CO2 project matures and production and oil cuts decline.
The success of a conformance improvement effort requires development of links to the business objectives of the field's operating teams. The effort to improve conformance, although not new, has taken on significant strategic importance to insure continued strong economic performance and maximum oil reserves.
A multi-disciplinary team was developed to focus on this issue. As with any effort attempting to change the focus of an operation, conformance improvement required a detailed study to scope the potential benefits, and to communicate those benefits to decision-makers. This paper summarizes the Rangely Conformance Improvement Team's efforts, including: Organizational approach to the effortStrategic alignment of conformance improvement with operating team prioritiesAssessment of the state of conformance and the tools developed for problem identification and opportunity rankingConformance improvement method selectionResults to dateFuture conformance improvement efforts and challenges.
New Insight into Aluminium Citrate/Polyacrylamide Gels for Fluid Control
Authors: Stavland Arne , Jonsbråten Hilde Carlsen 
Published: December 2007

Abstract
Aluminium citrate/polyacrylamide gels are found to be more sensitive and less robust than similar chromium systems. The main motivation for investigating aluminium based systems is the environmental constraints. This paper summarize the status on research of aluminium citrate gels. Several field experiments have been carried out, some of them claimed to be a success but yet the gelation mechanisms has not been fully understood. This paper demonstrates one possible gelation mechanism, where oligomerisation of the aluminium citrate complex is essential. The variation in gelation kinetic observed and to some extend gelation mechanisms for the different sources of aluminium is mainly because of the difference in oligomerisation.
The ratio between aluminium and citrate is critical. In seawater, precipitation of aluminium is observed at low amount of citrate (2:1) and precipitation of calcium citrate at ratios above 1:2. Within this window robust gels may be formed as long as pH is below 6 and hydrolysed polyacrylamide are used. In core flopds gel is formed if the sources to polymer degradation is removed. At aluminium to citrate ratios of 1:1 no precipitation and face plugging, that is a severe problem at lower citrate concentrations, have been observed.
Economics of Light Oil Air Injection Projects
Authors: Fassihi M. R. , Yannimaras D. V. , Westfall E. E. , Gillham T. H. 
Published: December 2007

Abstract
Several papers have been recently published1,2,3,4,5 discussing the process of air injection for light oil recovery and describing the criteria for a successful project. The performance of some light oil air injection field projects has also been discussed in these papers.2,5 However, the economics of this process have never been fully addressed before. This paper discusses the economics of a successful on-going project, the Medicine Pole Hills Unit (MPHU, ND), and a new project underway at West Hackberry, LA. The economics of air injection in low pressure fault blocks for repositioning and producing the oil rim are discussed as well.
Putting Technology to Work for Independents
Authors: Rowell D. , Benton J. H. 
Published: December 2007

Abstract
To exploit the remaining resources in the lower 48 states, independent operators need access to new technologies that reduce the costs of finding, drilling, and producing oil. The problem is that new and existing technologies are often beyond the reach of independents, who have not engaged in research and development (R&D). These exploration and production (E&P) companies must gain access to available technologies if they are going to survive in today’s changing industry conditions.
The Petroleum Technology Transfer Council (PTTC) has been formed by the E&P industry as a national non-profit organization to address the technology needs of US companies, mainly independents. Its mission is twofold: (1) to facilitate and accelerate the effective flow of technology information from R&D organizations to the US upstream industry, and (2) to provide a feedback mechanism through which operators can inform the R&D community about their priority research and technology needs. The PTTC receives funding from the Department of Energy (DOE), several state governments, industry, the Gas Research Institute (GRI) and other sources.
Although it has only been in existence since 1994, the PTTC has made great strides in identifying and prioritizing the industry’s technical problems, and assessing which technologies provide possible solutions. Technology workshops are being held around the country to transfer information to the actual users of the technology in the field. Regional resource centers have been opened in many areas to provide producers with access to computers, analytical software, databases, referral services and technical assistance. The PTTC has established various forms of outreach, including a national electronic information system on the Internet, that links its national Home Page with ten regional Home Pages. Through its function as a national clearinghouse, the PTTC is successfully transferring the latest advancements in exploration, reservoir characterization, drilling, production, offshore, and environmental technologies.
Reservoir Characterization and CO2 Pilot Design in the Naturally Fractured Spraberry Trend Area
Authors: Schechter David S. , McDonald Paul , Sheffield Tom , Baker Richard 
Published: December 2007

Abstract
The Spraberry Trend Area in West Texas encompasses a productive area greater than 2,500 mi2. Spraberry was once deemed, "The largest uneconomic field in the world." The marginal economics and low recoveries of producing in Spraberry are well documented and have effectively prevented comprehensive reservoir characterization yet the Spraberry Trend Area continues to produce nearly 60 Mbopd from more than 7,500 wells and has produced 700 MMbbls during the life of the reservoir. Many wells have been abandoned due to low productivity and many more face the same fate unless new technology becomes available which will improve recovery over the current low value. Spraberry Trend Area reservoirs originally contained some 10 Bbbls OOIP of which less than 10% has been recovered. Obviously, the oil remaining in place represents a tremendous EOR target.
Many of the large Spraberry Units which were once operated by major oil companies have been acquired by independent oil companies. Development of these units has resulted in extensive in-fill drilling from 1991 through 1995. The consolidation of large tracts of unitized Spraberry production under one operator combined with a plentiful, local and relatively inexpensive supply of CO2 has raised some interesting questions. This paper addresses the necessary background and future plans for a proposed CO2 pilot in the Upper Spraberry.
The work in this paper also demonstrates the value of consolidating old data from several operators aud integrating with more recent data as a necessary step towards comprehensive fracture characterization, a precursor for developing all possible process options before vast numbers of Spraberry wells are plugged and abandoned.
3-D Seismic Texture Classification
Authors: Vinther R. , Mosegaard K. , Abatzis I. , Andersen C. , Vejbaek O.V. , Nielsen P.H. 
Published: December 2007

Abstract
Statistical recognition of seismic reflection patterns is a useful aid to seismic data interpretation. The seismic texture classification classifies and recognizes seismic data into a limited number of categories each characterized by a distinct style of reflectivity. The basis in the recognition is a set of reference windows (2D) or blocks (3D) representing all major types of reflectivity from the sections of interest.
The seismic data is analysed as 2-D windows each modelled as a Markov random field, where the probability distribution of small patterns in the window is used to characterize the seismic texture. In 3-D the seismic block is represented as a collection of 2-D windows, where the average probability distribution of small patterns in the windows characterize the seismic texture of the block. The recognition of the seismic texture uses a linear projection where the seismic texture is projected onto categories of reflectivity. This makes the method computationally efficient.
The information obtained by the seismic texture classification is most easily seen in the vertical display as illustrated on small extractions from 2-D and 3-D offshore dataset.
Effective Flow Parameters for 3D Reservoir Simulation
Authors: Pickup Gillian E. , Carruthers Dan 
Published: December 2007

Abstract
With the increasing use of detailed full-field 3D reservoir models, the issue of the correct determination of multiphase flow functions in three directions arises. Reservoir engineers are relatively familiar with the use of kv/kh ratios, but the correct kx/ky/kz functions for multiphase (or even single- phase) flow are less easily estimated. In this paper, we describe a model for a 3D sedimentary structure and we derive directional flow functions using a development of the geopseudo approach.
In order to incorporate the effects of 3D lamina structure, a new method of upscaling has been devised. In this method, the laminae are modelled as a series of plane surfaces. The effective permeability of these planes may be calculated analytically, and then a numerical simulation may be performed to obtain the effective permeability for the whole bed. This method can be used to calculate tensor permeabilities for either single-phase or two-phase flow. In this way we can generate 3D pseudo-functions which may be used as input for larger-scale simulations.
Using both the new method and the traditional Kyte and Berry pseudo-ising approach we have calculated the pseudo relative permeabilities for a model of a fluvial trough crossbed. We show that oil recovery may be significantly influenced by the 3D laminar structure. In particular, the nature of the bounding surfaces of the beds has an important effect on capillary trapping. In beds with high permeability contrast in the laminae, crossflow may be important indicating the need for full tensor upscaling methods.
Connected Volume Calibration For Well-Path Ranking
Authors: Gutteridge P.A. , Gawith D.E. 
Published: December 2007

Abstract
Presented here is a method by which we are using a shared earth model in the planning of development wells. The latest 3D modelling packages give us the ability to design non-conventional well trajectories interactively, inside a 3D geological model. This means that we can easily generate a number of possible well paths designed to penetrate particular features of the reservoir. Final well placement decisions are normally based on performance predictions from a reservoir simulator, but the time required to run the simulator for all possible wells would be prohibitive. There is clearly a need for a rapid screening or ranking technique to identify the well paths most likely to be suitable, and we describe here some recent work to meet this need.
Modelling Injection Strategies for a Reservoir with an Extreme Permeability Contrast: IOR Qualification
Authors: Surguchev Leonid M. , Hanssen Jan Erik , Johannessen Hege M. , Sisk Carl D. 
Published: December 2007

Abstract
Considerable hydrocarbon reserves are associated with heterogeneous stratified reservoirs. Many of these reservoirs demonstrate poor recovery efficiency, due to the low vertical and lateral sweep, if produced traditionally by depletion or waterflooding. Modern Improved Oil Recovery (IOR) methods have significant potential for such formations.
A Norwegian sandstone field was evaluated in this study. This field is characterized by extreme contrasts in reservoir properties. Horizontal permeability in the formation varies from 2 - 20 mD in the lower reservoir to more than 2000 mD in the upper reservoir. The sweep is accordingly very low in the lower reservoir, which contains 60-70% of oil in place.
A 3D model of the formation was constructed in order to investigate, in detail, potential IOR processes. The selection of the model area was conducted by a cross-discipline team. It was decided that a full field model was too resource intensive and a generic model would be too simplistic. A third alternative called, average pattern approach, was utilized. The cross-discipline team looked over the field and made a group decision to choose a specific area. A portion of the field that had average properties and well completion history was modelled. The area was large enough to capture different development schemes. The reservoir model reflects the main characteristics of the formation and, in particular, the high permeability contrast between the upper and lower reservoirs, interlayer communication and presence of faults. Actual operational and reservoir information was available for the selected pattern. This approach gives validity to predictions and evaluation of IOR processes and also minimizes the resources and time required for modelling.
Hydraulically Fractured Horizontal Well Simulation
Authors: Hegre T.M. 
Published: December 2007

Abstract
Simulation of hydraulically fractured horizontal wells is discussed in detail. Horizontal wells intercepted by both transverse and longitudinal fractures are evaluated. It is shown that fractured horizontal well representation in simulation models is dependant on the study objectives. For single well studies of the early pressure transient behaviour it is in general necessary both to explicitly model the fracture with small highly conductive grid cells, and to specify relatively small grid cells in the near fracture area. The effect of both grid cell size and fracture conductivity on the transient pressure behaviour and computer time is demonstrated by several examples. Based on these examples it is possible to construct a grid system which satisfies the accuracy required. For reservoir management purposes, reasonable accurate results may be obtained utilising the equivalent effective wellbore radius concept or the transmissibility corrected method presented in this paper. The effective wellbore radius concept is a simple way to model fractured horizontal well behaviour in a full field model. The fractured horizontal well is modelled as a standard vertical well with an equivalent effective wellbore radius. The effective wellbore radius can be derived from analytical solutions. This method is applicable only if the effective wellbore radius is smaller than the pressure equivalent radius of the grid cells. Generally this restriction requires that the horizontal wellbore with its hydraulic fractures are completely located within a single areal grid cell. A more flexible method is to compute both corrected transmissibilities and well connection factors for a coarse grid which gives the same long term pressure behaviour as a fine grid model. This procedure to adjust coarse grid model transmissibilities and well connection factors based on fine grid simulation results is also simple. In general, it is however required to have a simulation model where it is easy to include local grid refinement and which automatically computes adjusted transmissibilities and well connection factors that can then be applied for coarse grid simulations. The main part of this paper is devoted to single phase problems. However, it is demonstrated that the equivalent wellbore radius concept can be applicable also for multiphase problems.
Direct Inversion for Porosity of Post Stack Seismic Data
Authors: Rasmussen K. B. , Maver K. G. 
Published: December 2007

Abstract
3D seismic data is inverted directly for porosity by implementing a non-linear, globally optimised seismic inversion scheme. The technique takes into account the lithology dependent relationship between porosity and acoustic impedance without requiring the user to make a detailed interpretation of the seismic data and specifying the correlation between acoustic impedance and porosity for each lithological unit. For comparison seismic inversion for acoustic impedance is also carried out.
Seismic inversion directly for porosity is implemented by utilising that the correlation between acoustic impedance and porosity has a negative slope which is often approximately constant and not lithology dependent.
A wavelet is derived that inverts directly for porosity reflectivity and the absolute level of porosity is defined by constraining to a low frequency porosity model which is specified from available well logs.
To invert the seismic data a non-linear globally optimised seismic inversion technique is used. This full 3D multi trace technique does not directly include well logs or seismic horizons and therefore unbiased results are generated from post-stack, migrated seismic data. The seismic inversion is performed by utilising an estimated wavelet, a low frequency model and by specifying 5 inversion parameters.
The seismic inversion for both acoustic impedance and porosity is illustrated by a 3D seismic survey. The seismic data was acquired in the Danish part of the Central Trough with the main target being the Chalk Group which includes Upper Cretaceous-Danien chalk reservoirs. 7 wells are used in the study in order to invert a time window from 1.5 to 2.5 sec TWT, that includes a total of 456,000 traces covering an area of 71 sq km.
The results show that the technique is a fast and reliable method for estimating porosity directly from seismic data. However, the match between the porosity log and the inversion result is not as good as the correlation between the acoustic impedance log and the corresponding inversion result. This is attributed to the non-unique correlation between acoustic impedance and porosity.
Optimisation of Production Strategies using Stochastic Search Methods
Authors: Harding T.J. , Radcliffe N.J. , King P.R. 
Published: December 2007

Abstract
This paper describes the application of stochastic search techniques to the production scheduling of a group of linked oil and gas fields. The goal was the maximisation of total net present value and a genetic algorithm using problem-specific crossover operators was particularly successful in this respect.
Introduction
Reservoir engineers must decide upon a "best" management strategy for the exploitation of each petroleum resource, typically the strategy which will maximise economic return. In particular, a production schedule, specifying rates of extraction over the lifetime of the reservoir(s), must be chosen. From this, decisions about the construction of processing facilities and pipelines will follow. A quantitative approach to the search for the "best" production schedule requires the construction of a mathematical model, which must capture enough characteristics of the reservoir(s) to predict the costs and benefits of any given schedule.
Even when a single independent field is under consideration, finding the "best" schedule can be a non-trivial problem, as all but the simplest models are likely to be non-linear and contain discontinuities. BP has a number of multi-field potential developments world-wide. In such cases, the problem is more difficult still. The total number of production rates is of course proportionately larger, but extra complexity arises from the inter-dependence of the fields. There are extra degrees of freedom, namely the respective timing of each field, and in addition the costs associated with each field depend on the sum of the production rates from some or all of the other fields.
If possible, the reservoir engineer will also wish to ensure robustness of the choice of extraction strategy in the presence of uncertainty in the economic model - the most obvious source of uncertainty in this case being the reservoir characterisations.
This paper describes how several techniques - genetic algorithms in particular - were used to search the space of possible production schedules based on an indicative data set from one multi- field development. The techniques show potential ways to achieve significant increases in net present value, which were consistent with traditional discrete analysis.