bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Chemical Approach to Mitigate Sulfide Production in Oilfield Water Injection Systems
Authors: Johnson M. D. , Harless M. L. , Dickinson A. L. , Burger E. D.
Published: December 2007

Uncontrolled growth and activity of sulfate-reducing bacteria (SRB) in oilfield systems can create safety, environmental and operational problems such as microbiologically influenced corrosion (MIC), solids production and biogenic hydrogen sulfide (H2S) generation. A previously reported study showed that a group of structurally-related derivatives of 9,10-anthraquinone at micromolar concentrations effectively inhibits the process of sulfate respiration in SRB without having a bactericidal effect on the bacteria. This new technology was field tested in a California oilfield produced water injection system. Acrolein was being used daily as a biocide in this system to control the generation of iron sulfide solids resulting from SRB activity. The new treatment protocol field tested combined reduced frequency slug treatments of acrolein with treatments of a soluble form of anthraquinone. Laboratory studies were performed in conjunction with the field trial to confirm that laboratory evaluations of the anthraquinone treatments could relate to actual field usage. This paper describes the water injection system, the treatment program and presents the results of monitored parameters, including H2S concentrations, total suspended solids, SRB levels and anthraquinone residuals from three treatment periods and a control period. The synergistic effect of the two chemicals allowed for an extension of the time between acrolein treatments from one day to greater than one week while maintaining acceptable water injection quality.
High-Density Monomer System for Formation Consolidation/Water Shutoff Applications
Authors: Eoff Larry , Funkhouser Gary P. , Cowan Mike
Published: December 2007

This paper describes a monomer system for formation consolidation in deepwater applications. In deepwater wells, shallow zones may have pore pressures close to fracturing pressures. In these situations, lost circulation or flowing zones can be difficult to control and can lead to a complete loss of the well.

Hydroperoxide and azo initiators were used for polymerizing solutions of 2-hydroxyethyl acrylate in aqueous solutions of sea salt, sodium chloride (NaCl), calcium chloride (CaCl2), calcium bromide (CaBr2), and zinc bromide (ZnBr2) with densities from 8.6 to 17.5 lbm/gal. These monomer solutions undergo controlled polymerizations in the formation to yield stiff plugs that can withstand high differential pressures. A similar monomer system has been used for water shutoff applications, but had never been formulated in heavy brines or used in the cool temperatures (50° to 60°F) typical of the shallow water-flow zones. Using a high-density consolidation fluid would be advantageous in shallow water-flow zones. This fluid could be spotted over the problem zone and allowed to flow into the zone because of the hydrostatic pressure. This fluid would allow the treatments to be used in wells where high-pressure injection into the formation is not an option. Before this work, no high-density fluids were available for these applications.

Various data are shown describing the system's development, including gel-time curves and compressive strengths of consolidated sandpacks. Factors affecting the performance and application of the system are discussed.
Treatment of Salt Affected Soil in the Oil Field
Authors: Mishra Surendra K. , Evans William J. , Lacik John I.
Published: December 2007

Soils, drill cuttings and other solid wastes which are exposed to high levels of salt through spillage from drilling and producing operations, pipe line breaks or leaks, become saturated with sodium. Although the EPA and the industry have demonstrated that the vast majority of such wastes are non-hazardous, in actuality, they have an adverse impact on the fertility of the soil.

The degree of salt saturation is influenced by the soil mineralogy. Many native soils containing high montmorillonitic clays have the capacity of adsorbing sodium species in their crystal structure. Sodium adsorbed montmorillonitic clays being dispersed affect the physical structure of soil and, in turn, adversely influences its permeability. High salt content of soil also has a profound influence on its osmotic pressure. Consequently, it has a detrimental influence on the health of the commercial crops or native vegetation.

The physical structure of the soil can be chemically modified, allowing improved drainage of undesirable salt species. To store its physical structure and to make it permeable, the industry has practiced cationic amendment of sodium contaminated soil. Traditionally used gypsum, being sparsely soluble in water is unable to provide a readily available source of cationic species for amendment. A carefully designed product containing readily available cationic source along with other nutrients for the growth of vegetation has been highly successful. Field results from various geographical locations with different soil composition and degree of contamination showing rapid reductions in the sodium contents and, in turn, also having a dramatic effect on the restoration of vegetation are discussed in this paper.
Study on Design of Extended Reach Well Trajectory
Authors: Ma Shanzhou , Huang Genlu , Zhang Jianguo , Han Zhiyong
Published: December 2007

This paper presents three main principles on the design of extended reach drilling well trajectory. The profile of build up section is optimized within nine types of shapes. The results show that sideway curves, curvature decreasing curve and circular arc are better than others. The influences of kick off point, maximum build up rate or hold angle on torque and drag and well length of three kinds of optimum curves are discussed. The results obtained are important guidelines for design of extended reach well trajectory.

P. 233
An Optimum Method of Early-Time Well Test Analysis -- Genetic Algorithm
Authors: Yin Hongjun , Zhai Yunfang
Published: December 2007

Conventional type curve fitting analysis of early-time transient pressure data influenced by wellbore storage effects can yield non-unique results due to similarity in the shape of the curves. In order to alleviate this problem, this paper proposed an optimum method based on adaptive genetic algorithm (AGA). This is a robust approach to get early-time well test interpretation. It is superior to the non-linear regression algorithms and standard genetic algorithm. Initial estimates of the parameters and operator probability (crossover and mutation probability) need not be specified. The diversity of the population and the convergence capacity of the GA can be maintained by using the adaptively varying probabilities of crossover and mutation depending on the fitness values of the solutions. By this way the optimum reservoir parameters can be obtained. Applicability of the proposed methods is demonstrated by analyzing a field example.

P. 265
Successful Application of Multistage Acid Fracturing Technology in Changqing Gas Field
Authors: Liu Hailang , Zhao Zhenfeng
Published: December 2007

The Ordovician carbonate reservoirs are heterogeneous with low formation pressure, low permeability in Changqing gas field. Multistage Acid Fracturing is a key technology for further stimulation in this field. This paper presents the technique mechanism, suitability analysis, lab experiments evaluation, optimization of key parameters, application results, and so on of this technology.

P. 323
Pressure Transient Analysis for Relaxation Model of Non-Newtonian Visco-elastic Flow in Fractal Reservoir with Wellbore Storage and Skin Effect
Authors: Tong Dengke , Chen Qinlei , Ge Jiali
Published: December 2007

The majority of the conventional pressure-transient models assume that permeability and porosity of a formation is invariant in space. Moreover, fluid flow in reservoir is Newtonian fluids or non-Newtonian power-law fluids. Such an assumption gives good results in many situations; but the geological complexity of units and/or non-Newtonian relaxation characteristics of visco-elastic fluids may make these assumptions of dubious value. The purpose of this study is to explore flow analysis of non-Newtonian visco-elastic fluids with relaxation property in reservoir that are not amenable to the conventional approach.

In the study, we present a pressure-transient radial relaxation flow model of non-Newtonian visco-elastic fluids in fractal reservoir considering the effect of wellbore storage and skin factor. Analytical solution and asymptotic solution in real space are obtained by using Laplace transform for a constant- rate condition at a single well in an infinite reservoir. The flow behavior of non-Newtonian visco-elastic fluids is also analyzed by using numerical inversion scheme of Laplace transform. We discuss pressure response of changing spectral dimension and rheological parameters. Conventional model (hornogenous reservoir, Newtonian fluids) is a special case of above model. The results obtained in the study extend previous pressure transient analysis for single phase Newtonian flow in a 2-D cylindrical system to reservoir of arbitrary fractal dimension and visco-elastic fluids of rheological parameters.

P. 343
Effect of Porous Medium Adsorption on Percolation Law of Condensate-gas Mixture
Authors: Du Jianfen , Li Shilun , Sun Lei
Published: December 2007

The condensate-gas mixture flowing process takes place in the porous media of deep strata. Owing to their giant specific area, the porous media are of a relatively strong adsorption capacity and the fluid exists as two states, i.e. adsorption state and free state. According to the basic theories of multiphase flow and the acting mechanisms of porous medium adsorption, a research approach of percolation law which contains the effect of the mixed gas, which is adsorbed on the surface of porous media under formation conditions, is proposed. A corresponding mathematical model is set up too. Through an example calculation, the effect of porous medium adsorption on percolation law is analyzed. It is concluded that the effect of porous medium adsorption on the flowing process of condensate-gas mixture is of objective reality and can't be neglected.

P. 459
Research and Application of Metal Complex - Amphoteric Polymer Drilling Fluid
Authors: Yabin Niu , Daming Zhang , Hongzhang Xiao , Wumuxi Zheng , Jian Li
Published: December 2007

Amphoteric polymer and MMH drilling fluid systems have been widely applied in oil fields in recent years with good benefits. The applications have shown the advantages and disadvantages of the two drilling fluid systems. Based on the analysis and research of molecular structure and mechanism of the two kinds of additives in drilling fluid, the molecular structures of new polymers, metal complex - amphoteric polymers PMHA, JMHA, are designed and researched. The new products have properties of both amphoteric polymer and MMH, that is, high inhibition, high thixotropic, stable drilling fluid rheological, excellent filtrate control ability and the ability of protecting production formation from damage. Applications in Zhongyuan, Jiangsu and Liaohe oilfields showed that it increased drilling rate, decreased the trouble under well bore and the enlargement rate of well diameter. The metal complex-amphoteric polymer products have good compatibility with other additives. The drilling fluid system formulated by these products has stable rheological properties with low cost. Now the drilling fluid system has been successfully applied in vertical, directional, deep and slim hole wells in China's oil fields. Taking advantage of the metal complex - amphoteric polymers, we have formulated drilling mud systems, such as the fresh water mud, high-density mud with high salinity, slim hole drilling fluid and completion fluid.
Research on Utilization Shallow Structure to Construct Underground Natural Gas Storage
Authors: Li Jianzhong
Published: December 2007

The constructed underground natural gas storage in the world can be divided into four types according to the storage style. This paper presents successful experience of foreign countries and by which to specify standards and conditions for utilizing shallow structures to construct underground natural gas storage in China. Two shallow structures discovered in Northern Jizhong area have been optimized and evaluated as the initial storage target in combination with the fact of supplying natural gas from Shanbei gas field to Beijing. The storage capacity of two shallow structures can meet the requirement of emergency and adjust the peak value seasonably. It can provide reference value to the decision of constructing underground natural gas storage in Beijing and Tianjin area, and it can be also applied to the similar project in other areas in China in the future.

P. 551
NMR Logging Studies of Igneous Reservoir by the Aid of Core Analysis on Linpan Area Shengli Oilfield
Authors: Lu Fenggen , Zhao Wenjie , Wu Jingli , Wang Weimin , Liu Wei , Sun Dianging , Li Pei
Published: December 2007

Linpan area of Shengli oilfield is rich in igneous reservoirs. The formation is hard to be evaluated by conventional logging methods because of complex lithology characters of the rocks. Nuclear Magnetic Resonance Imaging Logging (NMRIL), which can provide formation porosity, permeability, moveable fluid, has many advantages over other logging methods. It gives us a completely new method to evaluate igneous formation. In this paper we demonstrate an NMRIL interpretation method that combines NMR logging data with core analysis. Big size igneous cores with different lithology were selected for laboratory analysis. Their relationships among porosity, permeability, moveable fluid index, T2 distributions, and NMR signal have been analyzed and discussed. Logging data were precisely interpreted using our own software that allowed many more T2 points to be calculated from NMR echo data.

P. 557
Deliverability Enhancement of High-Volume Oriskany Gas Storage Wells Using Foamed Acid as a Damage Removal Medium
Authors: Fontaine James S. , Rouze Scott G.
Published: December 2007

As gas storage wells age over time they are susceptible to processes having negative impact on deliverability. The GRI study of 1993 determined that on a national average, 5% of storage deliverability capacity is lost per year.

This paper will discuss the successful use of foamed acid as a stimulation fluid in Oriskany gas storage wells in the Wharton Gas Storage Field in north-central Pennsylvania. Case histories of three treatments performed and the impact upon deliverability will be presented. Two of these treatments were performed on wells damaged during re-work projects and one was performed on a well suffering from a large decline in deliverability.
Reservoir Simulation and Analysis of the Sciota Aquifer Gas Storage Pool
Authors: Sawyer Walter K. , Zuber Michael D. , Bues Allen D.
Published: December 2007

This paper presents the results of a reservoir simulation study of the Sciota aquifer gas storage field in McDonough County, Illinois. The field has been in operation since the early 1970's and is currently operating with 12 injection wells and five observation wells. The field is operated by the Central Illinois Public Service Company, now part of AmerenCIPS.

The objectives of this study were to (1) build a computer database of all historical pressure and injection/withdrawal data, (2) determine inventory volumes over time, (3) determine the cause of the low working-gas to base-gas ratio, and (4) determine if field deliverability could be improved.

In this study, weekly injection/withdrawal data and daily wellhead pressure data were first computerized and analyzed to evaluate past reservoir performance. Analysis of the injection/withdrawal data indicated a cumulative net gas injection of about 4.7 Bscf from November 1972 to July 1997. However, the average working gas was only about 0.3 Bscf for the last nine storage cycles, giving a working-gas to base-gas ratio of only about 6.4 %.

Analysis of the wellhead pressure data indicated that the wells were loading up with water during each withdrawal period. Using all available reservoir and geology data, we constructed a two-phase gas-water model of the Sciota storage pool and history matched the injection/withdrawal on a monthly basis from 1972 to 1997. We determined that the working gas could possibly be increased threefold from 0.3 Bscf to 1 Bscf by maintaining lower bottomhole pressures during withdrawal.
Production Performance Analysis of Cavity-Completed Wells
Authors: Goktas B. , Ertekin T.
Published: December 2007

A parametric study investigating the performances of cavity-completed wells is presented. A three-dimensional, two-phase fluid flow model is used to conduct the study. Cavity-completed wells are described as a combination of fine rectangular grid blocks. The constructed fine grid lines are terminated at the coarse/fine grid block interfaces by implementing a local grid refinement technique. The model utilizes the residual equation rather than a wellbore equation to determine the flow into cavity-completed wells. The proposed approach is a significant departure from the current practice in which the performance of a cavity-completed well is predicted by assigning large wellbore radii and/or large negative skin values to a conventional well equation.

During the cavity completion process in coal seams, it is hypothesized that fracture networks are generated in certain directions around the cavity. These fracture networks are generally incorporated into a simulation study by modifying the permeability values around the wellbore. The model proposed in this study provides not only a more precise approximation to the shape of the cavity, but also an opportunity for altering the permeability values around the cavity more realistically to represent these fracture networks, utilizing the fine grid cells that are already in place around the cavity completions.

The effects of cavity dimensions and generated fracture networks on the flow performances of the cavity are investigated for various coal seam permeabilities. This study provides some quantitative and qualitative information for a well design engineer who is facing the challenge of making critical decisions for the cavity completion practice in coalbed field development studies.
Characterization of an Induced Hydraulic Fracture Completion in a Naturally Fractured Antrim Shale Reservoir
Authors: Hopkins C. W. , Rosen R. L. , Hill D. G.
Published: December 2007

In 1993, Shell began a cooperative evaluation with the Gas Research Institute to study factors controlling gas production from the naturally fractured Devonian shale Antrim formation in Montmorency Co., Michigan. The presence of multiple intersecting sets of natural fractures is the primary control on well deliverability and the Antrim must be fracture stimulated to be economical. However, due to the shallow depths (500-2000 ft) and naturally fractured nature of the Antrim, fracture geometry is complex, and the determination of the optimal fracture treatment or completion methodology is not straightforward.

To evaluate the effectiveness of fracture treatments in the Antrim, Shell conducted pressure transient modeling, microseismic tomography surveys for imaging created fracture dimensions (length, height, and dip), and the cutting of multiple coreholes to core the created hydraulic fractures. The integrated results suggest that fracture growth in the Antrim is very complex. A series of sub-vertical fractures were created that were parallel to the maximum principle stress and defined a zone of fracturing at least 50 feet wide. The fractures grew asymmetrically in height above the top perforation and appeared to follow a tortuous path along joint-set directions. Two coreholes drilled at 35-degree angles from vertical encountered 8 propped hydraulic fractures. Several of the cored propped fractures had varying azimuths suggesting that pre-existing natural fractures, which trend primarily NE/SW and NW/SE, were propped during the fracture treatment.
Case History: Cased Hole Horizontal Antrim Well Fractured in Multiple Intervals
Authors: Fink Kent T.
Published: December 2007

This paper discusses the design and execution and results of a Horizontal Antrim Shale well drilled to a depth of 3300' MD with a TVD of 852'. The well was cased with 5 ½" casing to TD, perforated and fractured in six isolated intervals. Drilling methods presented will be: drilling and running casing with a pull down top drive drilling rig. Pull down technology enabled the drilling and casing the hole with a KOP of 100'. Coil tubing completion methods presented are perforating and zone isolation methods allowing multiple stages in one day. Six separate intervals were successfully hydraulically fractured with foam fluid treatments. Design and observations of treatments will be given.
The Applicability of Waterflooding in the Appalachian Basin
Authors: Weber L. C. , Freeman D. C.
Published: December 2007

Oil production has been an important industry in the Appalachian basin for over a century. Most oil reservoirs in this region have been produced by primary recovery only, yielding some 5-25% of the stock tank oil originally-in-place. As a result, 75-95% of the STOOIP remains in the reservoirs. Waterflooding is one technique that could be used to recover these potential reserves. Waterflooding, the process of injecting water into an oil reservoir to displace the crude, is perhaps the most economical of any improved oil recovery process due to the general availability of water, ease of injection, and limited development costs. The waterflooding potential of the Berea, Big Injun, and Medina sandstone formations was evaluated to explore the applicability of waterflooding in the Appalachian basin. This paper documents those evaluations and gives guidelines for examing reservoirs of a similar nature. First, the geologic and engineering considerations for implementing a waterflood were assessed for each reservoir in detail. Then, predicted performance was modeled using the Dykstra-Parsons technique. The predictions of the model were verified by matching performance data from two Berea pilot waterfloods. Each of the reservoirs evaluated displayed good potential for waterflooding given sufficient oil to warrant an improved recovery process. A cursory economic analysis of a pilot waterflood in the Medina formation was also performed that showed a waterflood could be economical at $15/barrel. Since each reservoir evaluated displayed characteristics favorable for waterflooding, it was concluded that waterflooding is indeed applicable in the Appalachian Basin.
Drying of Porous Media To Create an In-situ Barrier
Authors: Aminian K. , Ameri S.
Published: December 2007

Containment is the primary technology for environmental protection when the contaminated subsurface sites cannot be economically remediated. In parallel to remediation efforts, confinement technologies are needed to retard or prevent the advancement of contamination plumes into the environment. This paper aims at investigating the feasibility of an innovative approach for preventing the movement of liquid contaminants toward groundwater. The concept involves using either vertical or horizontal wells to establish a pattern of air circulation to dry a soil layer. If the water saturation in the soil layer is lowered below the minimum required water saturation for liquid flow, the soil will tend to retain rather than transmit the liquids and as a result it will act as barrier to liquid contaminants. This technology can provide many advantages including non-physical confinement, commercially available oil and gas technology and equipment, active monitoring and leak detection, and high potential for integration with other remediation technologies. This type barrier is a crosscutting technology that would greatly benefit from proof of concept to gain regulatory acceptance.

A series of experiments have been designed and conducted to evaluate the feasibility of the concept. Several issues including the influence of the soil characteristics on drying profile, sweep efficiency and barrier performance have been investigated. Sand-packs, of different but uniform grain size have been utilized to investigate the drying process in porous media. The results have provided significant information regarding drying processes and the nature of fluid infiltration in porous media has been obtained. The experimental results indicated a great potential for applicability of the concept.
Application of Polymer Specific Enzymes To Clean Up Drill-In Fluids
Authors: Suhy Thomas E. , Harris Ramon P.
Published: December 2007

The industry recognizes that drilling muds can damage a well's producing zone, especially in highly deviated and open-hole completions. So-called "drill-in" fluids have been developed and used to reduce mud damage in vertical, horizontal, and multi-lateral completions. Although "cleaner" than conventional muds, drill-in fluids include polymers to build the required viscosity to transport cuttings and deposit a filter cake around the wellbore to reduce fluid loss. Most drill- in fluids are composed of starch, cellulose or xanthan polymers, plus bridging agents such as calcium carbonate or salt particles. Some of the polymer in drill-in fluids invades the near wellbore formation and creates skin damage. This is most noticeable in expensive horizontal and multi-lateral wells.

A break-through technology offers environmentally friendly enzymes that are tailored to remove most of these types of polymer damage. These polymer linkage-specific enzymes offer a safe, effective alternative to conventional clean-up methods that usually consist primarily of oxidizers like bleach and acid. This product has none of the "side effects" associated with non-specific reactants such as premature reaction, corrosive damage to down hole tools and tubular goods, and disposal problems.

This paper will detail the candidate selection process, applications methods, and the enzyme reaction mechanism. A number of selected application case histories in the South and Northeast U.S. production and gas storage fields will also be described.
Industry Attitudes Toward Slim-Hole Drilling
Authors: McLaughlin Philip L.
Published: December 2007

From a technical and economic standpoint slim-hole drilling promises to reduce drilling and completion costs. It may also result in reduced workover costs.

From the standpoint of industry acceptance, slim hole drilling does not fare so well. Producers, generally, have not accepted slim hole completion techniques for field development.

Contractors, generally, have been dissatisfied with profits. A mail survey indicates a need for additional information. Suggestions are given for improving the slim-hole picture.

Introduction

Since late 1952 there has been a considerable revival of interest in slim-hole drilling. Behind this revival are some hard economic considerations. There is no question that demand for new oil reserves will be greater in the future than in the past. The cost and difficulty of finding and exploiting these reserves will almost certainly be greater than ever before. Faced with this situation the oil industry is confronted with two alternatives.Industry can accept these higher costs without struggle and pass them on to the consumer.Industry can exert every effort to reduce the cost of finding and producing oil. This is the course industry will want to take if at all possible.

Of all the contributing items that make up the total cost of discovering oil reserves, drilling costs are by far the largest single item. (H. J. Struth, stated, In 1953, direct drilling cost comprised 61.9 per cent of total exploration expenditures.") It is quite evident that in order to cut the costs of finding oil, it would be a good idea to consider ways to reduce drilling costs.

With regard to field extension or field development, figures similar to those reported above are not immediately available. It is known, however, that drilling and completion costs are very large elements in the total costs of production, and well servicing costs are another important element. These two items will become even more important relatively, as the trend toward automatic leases continues.
Making Multi-lateral Wells Cost Effective
Authors: Chambers M.R.
Published: December 2007

This paper was prepared for presentation at the 1998 22nd Annual International Conference and Exhibition held in Lagos, Nigeria, 5-7 August 1998.
Practical Tools to Assist History Matching
Authors: MacMillan D. J. , Pletcher J. L. , Bourgeois S. A.
Published: December 2007

We developed a set of tools to assist the history matching process where we emphasize how the engineer's knowledge and expertise can be best utilized. A method is presented for obtaining meaningful residuals that correspond with what the engineer is trying to achieve. We then show how sensitivity information can be extracted for every variable and residual using every run, even if more than one parameter is adjusted. This allows continuous sensitivity updates throughout the history matching process. These sensitivities can be used to predict the parameter adjustments needed to obtain a better match. Our method accounts for all the complicated interactions involved when simultaneously changing multiple parameters, even those that are not intuitive to the engineer. It is very robust, easy to implement and is independent of the simulator used. It can even be used after the model has been drastically changed, e.g., reworking the geology, without completely starting over. The ability to detect redundant parameters is also discussed, even those that are not apparent by simply examining the sensitivities. Our method can determine if an improvement in the match can be made, and if so how much improvement is expected. Finally, we describe how to tell when the best match has been obtained and how to avoid bypassing the optimal match only to be stuck with a less than optimal match.
Geologic Modeling, Upscaling and Simulation of Faulted Reservoirs Using Faulted Stratigraphic Grids
Authors: Chambers K. T. , DeBaun D. R. , Durlofsky L. J. , Taggart I. J. , Bernath A. , Shen A. Y. , Legarre H. A. , Goggin D. J.
Published: December 2007

A key difficulty associated with modeling faulted reservoirs is honoring both the structure and stratigraphy while simultaneously generating models that are acceptable in terms of practical simulation run times. In this paper, we describe our approach for designing finely gridded, faulted simulation models which we then scale up using a flow based nonuniform coarsening technique that takes into account the impact of the faults. Two field examples of faulted reservoirs are presented to demonstrate the new grid design and upscaling tools and, also, to investigate the impact of faults on flow behavior.

An important characteristic of our work process to generate faulted simulation models is that all of the tasks, from horizon and fault mapping to geostatistical reservoir characterization to scale up, are performed within an integrated earth modeling environment. Our grid design and scale up calculations accommodate complex fault networks and non-vertical faults (including reverse faults), although in the current implementation we allow only "logically-vertical" faults; i.e., faults with slip along the w or nominally vertical coordinate in a u, v, w stratigraphic grid. The rationale for specifying logically vertical faults is that they represent a compromise between accurately modeling fault geometry while maintaining computational efficiency when simulating flow in faulted reservoirs.

Although fault geometry, which we capture with our grid design and upscaling tools, is an important component of fault transmissibility, it is not the only one. Consequently, we present a technique for modifying fault transmissibility by introducing transmissibility multipliers at fault locations in the grid. We use this technique to generate sealing faults. We then compare reservoir performance predictions based on sealing, partially communicating, and no-fault formulations. Plots of individual well performance from the field examples reveal significant differences between the three formulations.
An Algebraic Approach to the Adaptive Implicit Method
Authors: Watts J. W. , Ramé M.
Published: December 2007

We approach the adaptive implicit method (AIM) in a new way that is based on the implicit matrix equation. The first step is to recover from the implicit equations the underlying capacitance and flow coefficients. Then, from these, we compute switching criteria that determine whether a given gridblock is to be treated implicitly or in IMPES fashion. These criteria are closely related to the CFL condition and offer insight in certain instances in which a computation is stable despite having a CFL greater than one. We also use the capacitance and flow coefficients to construct the IMPES pressure equation at all gridblocks.

We solve the resulting mixed-implicit matrix equation using an iterative method based on a two-stage preconditioner. The first preconditioning stage is to solve the IMPES matrix equation for pressure at all gridblocks. The second stage is solution of the full set of equations on the implicit gridblocks only.

Limited computational results indicate that, though the adaptive implicit procedure works, it is not efficient. It obtains only an approximation of the implicit matrix equation solution, leading to an increase in the number of Newton iterations required. The two-stage preconditioner for solving the resulting mixed-implicit matrix equation appears to work well, but further evaluation of it is needed.
Low Frequency Vibration Recovery Enhancement Process Simulation
Authors: Zhang Lie Hui , Ho Peter , Li Yun , He Shengning
Published: December 2007

In China, reservoirs with low permeability and heterogeneity play an important role in recoverable reserves and production rates. These types of reservoirs have complex geological features, poor reserve employment, production rate decline, and unbalanced water-intake capacity between layers, low water sweep efficiency and low recovery. These phenomena are more pronounced especially when the reservoir reaches high water cut. Different types of well stimulation such as fracturing, acidizing and recompletion etc. are used in these reservoirs recently, but these remedies just temporarily slow down production decline, while they cannot change the fact of low recovery in essence. Therefore, how to improve EOR has a remarkably practical meaning for these types of reservoirs. Artificial seismic recovery process is a very effective physical process that can improve oil recovery.

Artificial seismic recovery method is a low frequency vibration recovery enhancement process. It is to apply low frequent wave produced by the surface high power extra - low frequency controllable seismic source on the formation, so as to improve the physical characteristics of groundfluid and the percolation condition of the formation, and achieve the purpose of enhancing the ultimate oil recovery. Field tests such as Xinjiang, Jiling oilfield in China are very successful and encouraging.

In order to get a further understanding of vibration recovery, this paper uses a coupled geomechanic black oil simulator to simulate flow behavior of a reservoir with vibration recovery -Block 1764 of Xinjiang under surface vibration and have successfully matched the production history of this technology of the reservoir.

This paper provides field test, simulation results and some in-sights to the mechanisms of the process.
The Effect of Discontinuous Shales on Reservoir Performance During Immiscible Flow
Authors: Jackson M. D. , Muggeridge A. H. , Huxley T. H.
Published: December 2007

We investigate quantitatively the effect of inclined and intersecting discontinuous shales on horizontal waterfloods, using generic, dimensionless 2- and 3-D models. We find that dis-continuous shales have a significant effect on reservoir performance only if they are >95% continuous, and are steeply dipping or intersecting, or if the displacement is unfavourable. 2-D simulations can significantly overestimate the effect of discontinuous shales, because they assume that the shales are entirely continuous in the third dimension.
Exploratory Reservoir Evaluation for Sour Gas or Crude
Authors: Montgomery J.M. , Gaskins J.F. , Coleman J.E.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

The early evaluation of a reservoir's contents has become extremely important. As it has become necessary to investigate deeper production zones, completion costs have increased by geometric progression.

In the drilling phase it should be determined as early as possible whether zones that are penetrated present a hostile environment. The energy of each zone must be fully determined to insure safe drilling practices.

After the well has been drilled to total depth, the reservoir's extent and capabilities should be thoroughly evaluated. The presence of H2S and CO2 should be determined, both from a qualitative and quantitative standpoint. This, along with producing temperatures, will determine the most efficient and economical completion.

Conventional means of open hole sampling are not consistent with safety requirements necessary for evaluating the deeper, hotter, and higher pressured reservoirs. When these samples are brought to the surface under a charged condition, containing sour gas or crude, they are potentially dangerous to anyone trying to potentially dangerous to anyone trying to evaluate its contents.

A joint cooperative effort in the industry has set practical and basic guidelines for a method that will meet these requirements. This paper will discuss methods that will give considerable additional reservoir information that wig help in a safer drilling and completion program. program

Introduction

The energy situation has been constantly changing over a short period of time. The rising costs, increase in the price of crude and gas, the scarcity of pipe and tubular goods, the near impossibility to get surface equipment made from forgings; these and many other factors have caused industry to set new and different priorities. About two years ago it was determined that to meet the energy goals for the present and future, it would be necessary to drill deeper wells in search of production. In doing this the geophysicists projected that we could meet new problems and hostile environments.

Energy seeking companies and independents have several deep wells in the planning stage.
Optimizing the Development of a Giant Deepwater Multireservoir Oil Field through Reservoir Simulation
Authors: Corbishley D. W. , Guedes S. S. , Pinto A. C. C. , Corá C. A.
Published: December 2007

Reservoir simulation can be a cost-effective tool for helping to optimize the development scheme and minimize economic risk for practically any hydrocarbon reservoir. Simulation of giant deepwater fields can require an increased level of model sophistication, as in many cases there are multiple reservoirs, and planning for a large number of production and injection wells connected to various platforms over large distances. Risk analysis is important, as much of the development planning is based on a limited acquired database. This extended abstract presents a summary of the modeling techniques employed for such a field: Marlim Sul, offshore Rio de Janeiro, Brazil.
Comparison of the Performance of a Discrete Fracture Multiphase Model With Those Using Conventional Methods
Authors: Kim Jong Gyun , Deo Milind D.
Published: December 2007

Results from a new multiphase discrete fracture model are compared to simulation results using a variety of homogenization methods. A 2-D random fracture network is used as an example. The discrete-fracture model has been developed as an alternative to the dual porosity models. It will be difficult to capture the features of the fracture network using dual porosity models. At low permeability contrast (between the matrix and the fracture), as expected, the new model showed symmetric water advance in a water flood simulation. At high permeability contrast, features of the fracture network became critically important with great deal of oil bypassing at higher flow rates. The results also showed that even though specific, mathematically rigorous homogenization captures the fracture network features, especially at fine resolution, the results are vastly different from the discrete-fracture model.
Numerical Simulation of the Impact of Flow-Induced Geomechanical Response on the Productivity of Stress-Sensitive Reservoirs
Authors: Osorio Jose G. , Chen Her-Yuan , Teufel Lawrence W.
Published: December 2007

Fluid production from oil/gas reservoirs perturbs the local stress state, both through variations in pore pressure and also changes in the local total stress. In stress sensitive reservoirs, these changes in the stress state cause deformation in the solid part of the rock which, in turn, affects the fluid-flow properties and, consequently, the reservoir productivity. Different reservoir conditions and production scenarios yield different degrees of reservoir productivity reduction. Therefore, a model that can be applied to study the effect of fluid flow/ deformation processes on the productivity of stress-sensitive reservoirs is essential for optimum reservoir management.

This paper presents a 3D finite difference, fully implicit model to simulate the physical phenomena occurring during the production from reservoirs with stress-sensitive mechanical and fluid-flow properties. The model considers two different physical domains: (i) an inner porous domain representing the reservoir, where fluid-flow and rock deformation occurs, and (ii) a surrounding domain representing the extended stress-disturbed region caused by the reservoir depletion. The inclusion of the surrounding domain leads to a more realistic modeling of the actual reservoir geomechanical boundary conditions. The reservoir is treated as a poro-elastic system consisting of a deforming solid skeleton and a moving compressible fluid. Nonlinear elastic deformation is assumed for both domains.

The model has been applied to illustrate the effect that rock deformation has on reservoir productivity. Results show that for stress-sensitive reservoirs, calculated flow rates obtained from conventional fluid-flow models can be significantly different from flow rates calculated from coupled fluid-flow/geomechanics models. Also, production rates calculated from fully coupled, single-domain models may differ from flow rates calculated from fully coupled, two-domain models.
Application of a New Two-Phase Upscaling Technique to Realistic Reservoir Cross Sections
Authors: Wallstrom T. C. , Hou S. , Christie M. A. , Durlofsky L. J. , Sharp D. H.
Published: December 2007

This paper describes further development and testing of the Renormalization and Nonuniform Coarsening (RNC) scale up algorithm, which was recently introduced in Ref. 13. RNC scale up combines nonuniform coarsening with upscaling of the absolute and relative permeabilities to provide coarsened descriptions of two-phase immiscible flow. We diagnose a known bias in the two-phase upscaling algorithm used in RNC. An unbiased alternative is introduced and incorporated into RNC scale up. The modified RNC scale up algorithm is tested on displacements through two dimensional cross sections with permeability and porosity data from conditioned reservoir simulations, and three dimensional linear and quarter-five-spot pattern displacements through computer generated permeability fields. Each reservoir description, measured or synthetic, contains highly heterogeneous and highly layered permeability fields. RNC scale up is used to coarsen these reservoir descriptions by a factor of 300 to 1000. The coarse grid oil cut curves show consistently close agreement with the fine grid curves in overall shape and in breakthrough time. The results are comparable to earlier results in Ref. 13 on displacements through synthetic two dimensional data.
The Development of Pseudo Functions for Gravity-Dominated Immiscible Gas Displacements
Authors: Darman N. H. , Sorbie K. S. , Pickup G. E.
Published: December 2007

In this paper, we investigate the use of pseudo functions in immiscible two phase displacements in oil-gas systems, where the effects of large mobility differences and gravitational forces are normally encountered. For this specific reason, a new pseudo-isation scheme known as the Transmissibility-Potential-Weighted (TPW) method has been developed and tested against several well-known pseudo methods such as the Kyte and Berry1, the Stone2 and the Vertical Equilibrium3 (VE) methods. Better performance relative to the other well-known pseudo methods was found especially in the gravity-dominated cases encountered in immiscible gas injection. This is shown for a wide range of cases. In addition, a detailed discussion on the limits and applicability of the VE method is also included.

Based on results from the TPW method, a new grid coarsening scheme for pseudo-isation has been developed and validated. This technique takes into account not only the static properties (i.e. permeability, porosity etc.) of the fine grid models, but also the dynamic properties of the fluid flow. The idea of this coarsening scheme is to identify regions (possibly layers) of the fine grid where there is low variability of gas saturation, and to take such regions as the corresponding coarse grid blocks. The measure of variability used is the coefficient of variation of the gas saturation. The resulting coarsening scheme may be non-uniform, but fulfils the purposes of using pseudo functions (i.e. to control numerical dispersion, to capture the effects of small scale heterogeneity, to reduce the number of grid blocks etc.) with less error and without any adjustment to the pseudo equations themselves.