bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Experience with a Simple Compact Multiphase Flow Meter
Authors: Brown D. , van der Spek A. M.
Published: December 2007

Multi-capacitor multiphase flow meters have been tested at five field locations covering a wide range of crude properties and process conditions. Results of these field tests show excellent repeatability and good agreement with reference measurements, when available. These meters are now being applied at two different locations in Oman as the only means of testing individual wells.
Evolution of the Snorre Field Downhole Completion Systems
Authors: Gunnarsson Bengt , Tønnesen S. H. , Stensland J. F. , Haut R. C.
Published: December 2007

This paper discusses the development and evolution of cost-effective downhole completion systems for the Snorre Field Tension Leg Platform (TLP) and Subsea Production System (SPS). Included is a discussion of operational experiences that influenced the evolution. Also included in the paper are specific examples of how the completion times were reduced.
Dual-Completion Design for HP/HT Corrosive Oil Well, Villafortuna-Trecate Italy
Authors: Cerruti S. E.
Published: December 2007

Villafortuna-Trecate ( Italy ) oil field is one of the deepest hydrocarbon deposit in production with a reservoir pressure over 15 Ksi, bottom hole temperature in the range of 380 °F and corrosive environment due the presence of carbon dioxide and hydrogen sulphide in the production fluids.

The design of Villafortuna-Trecate completions requested effort in the selection of appropriate equipment and materials that would enhance the safety, longevity and production capacity of the wells.

The paper will discuss the dual completion design outlining the supporting logic and concepts together with the equipment innovations utilized.

It includes discussion on tubing material and design, tubing connection, wellhead equipment, completion schemes and related equipment, annulus fluid and displacement technique. Quality control aspects are also discussed.

It should serve as a general example of conditions unique to deep, high pressure, high temperature corrosive wells and should be of interest to engineers facing a similar task.
"Simpler": A Cost-Effective Re-Engineering of Drilling Operations
Authors: Guicheney P. B. , Mehra Sachin
Published: December 2007

Across the industry ways are being sought to find and extract oil and gas more cost effectively, while improving safety and environmental performance.

Drilling operations are not immune to this scrutiny, yet for the past fifty years there has been little fundamental questioning of how the drilling process is organised. Today the ever-increasing need for more cost-effective operations is bringing such questions to the fore.

The Simpler project, after a review of a wide range of issues related to the well construction process aims at developing an innovative approach to drilling operations resulting in significant costs savings.

The basis of this novel approach is to "Re-Engineer" and integrate well construction activities.

To demonstate it and maximise results, a fit for purpose rig design is presented which also targets enhancements in safety and environmental results.
Solving Gas Lift Problems in the North Sea's Clyde Field
Authors: Pucknell J. K. , Goodbrand Shona , Green A. S.
Published: December 2007

Gas lift wells in the Clyde field have a history of problems, described in this paper.

Due to high temperatures (300 degrees F), the use of corrosion inhibitors and asphaltene dissolvers, it was necessary to use gas lift valves containing high temperature elastomers. These were not always effective at maintaining the nitrogen charge at the correct pressure which resulted in unloading valves opening intermittently causing unstable flow.

Valve failures were not the only for reason unstable flow, other causes included: the use of an orifice valve with a port size which was too large;opening of unloading valves because tubing pressures were higher than expected.

The latter effect occurred because the multiphase pressure drop correlation, while reliably predicting bottom hole pressure, was less accurate in predicting pressures at the depth of the unloading valve. When the tubing pressure profiles were measured with gauges a further problem became apparent. The pressure at a given depth did not remain constant but oscillated about a mean due to normal slug flow. If the opening pressure of an unloading valve is set too close to the tubing pressure, these oscillations can cause unloading valves to open unexpectedly.

These and other problems have been corrected. Firstly, spring loaded valves with factory sealed bellows have been installed. The elastomers’ integrity in these valves are less critical for reliable valve operation. In addition the lack of temperature sensitivity of their opening and closing mechanism makes unloading more reliable. Secondly, a more conservative gas lift design policy is now used, so that despite fluctuating or uncertain tubing pressures, or slight changes in the valve set pressures, unloading valves do not open.

Finally, to ensure that planned gas lift designs are stable, they were also checked using a transient multiphase flow simulator specially constructed to model gas lift wells. The simulator appears effective at predicting when stability problems can be expected.

The paper also comments on corrosion in the gas lift wells, a problem that was anticipated. Calliper surveys and other data suggest that it is unlikely to result in workovers in the near future.
Hydraulic Fracturing in Medium-High Permeability Reservoirs: Methodology and Economic Advantages of Properly-Executed Jobs
Authors: Cleary M. P.
Published: December 2007

Recent (companion) publications have isolated some major new conclusions which have effectively led to reversal of many conventional practices in hydraulic fracturing: these conclusions are based on analysis of field data vs. erroneous theories which had influenced previous efforts. A prime example of such reversal is our conclusion that overall proppant concentration (i.e. total proppant over total fluid volume pumped) should vary essentially inversely with reservoir permeability. Other issues have been demonstrated by recently-published case-studies of fracturing in low-permeability reservoirs. This paper will extend that discussion to medium-high permeability applications, i.e. to gas (oil) reservoirs of order 1-10 (10-100) mD or more.

This paper will also emphasize many major unrealized and/or poorly-rationalized aspects of such fracturing operations: these will include identification and execution of adequately-packed fractures ("pack-fracs" vs. common near-wellbore "frac-packs"); related work has quantified the dominant role of permeability variation in fracture growth/geometry. It will be indicated that many of the common/expensive problems associated with correspondingly mal-designed/executed field operations may be easily remedied: primary among these concerns are premature screen-outs/wash-outs and proppant production problems.

This paper will also demonstrate the tremendous (incremental) economic benefits of fracturing most wells, especially where variable petroleum demand/price have made capital investment decisions difficult (and often foolish, at least in retrospect). Appropriate use of the right technology also serves to reduce (correctly/actuarially - accounted) risk, certainly when properly executed to avoid the common problems which have plagued previous experiences; proper execution should alsa serve to remedy unfulfilled claims/promises, which have previously hindered widespread hydraulic fracturing technology application. Reliable fracturing capabilities now create major new (overall project) options for/and greatly improved investment strategies.
Description and Performance of a Lacustrine Fractured Reservoir
Authors: Deo M. D. , Neer L. A. , Whitney E. M. , Nielson D. L. , Lomax J. D. , Pennington B. I.
Published: December 2007

The main sand body in the Travis unit, located in east-central Utah, is Lower Douglas Creek (LDC), the lowest portion of the Green River Formation. Recent research has revealed that LDC is a lacustrine sloped and basin reservoir. In this paper, reservoir characteristics of the Travis unit are presented along with a history match of primary recovery. Dual-porosity, dual-permeability representation was chosen for the reservoir based on the information from borehole imaging logs. The primary production history match was satisfactory. Response to a water flood has been disappointing to date. The reservoir model which matched primary production was unable to predict the slow response to the water flood. This was attributed to an inadequate understanding of the fracture network in the reservoir.
Mitigation of Reservoir Souring—Decision Process
Authors: Kalpakci Bayram , Magri N. F. , Ravenscroft P. D. , McTeir M. D. K. , Arf G. T.
Published: December 2007

In this paper a general H2S decision strategy, describing the types of information which should be gathered and decisions to be made addressing an existing H2S problem, or new field development is presented.

Taking H2S into consideration in initial facility design, types of monitoring of H2S that should be carried out during field development and exploitation will be discussed. The usefulness of computer phase modelling, including equation of state calculations, to determine H2S concentrations in all phases from reservoir through the production stream will also be described. From quantification of the souring problem it can then be decided if, and where in the production stream, the use of sulfide scavengers is required. A laboratory based testing procedure will be presented, along with experimental data.

In addition to consideration of the basic chemistry, results of an industry survey will be presented on the best applications for commmercial sulfide scavenging products.
Carbon Black: A Low Cost Colloidal Additive for Controlling Gas-Migration in Cement Slurries
Authors: Calloni Giuseppe , Moroni Nevio , Miano Fausto
Published: December 2007

ABSTRACT*

The effect of different additives on the permeability of cement slurries to formation gas has been studied with the aid of a gas flow apparatus. The performance of two commercial additives (polymer latex and silica fume) has been compared to that of a novel additive (carbon black) that has been developed in our laboratories with the aim of simplifying the cement slurry composition and reducing field operational costs. Data on the thickening time, fluid loss, rheology and compressive strength are also presented to provide a clear picture of the potential of carbon black as a substitute for silica fume and polymer latex in some field applications. Finally, the paper describes the results of a field application using carbon black as a gas-block additive in the cement slurry.
Development of a Complex Type of Pour Point-Viscosity Depressant and Infrared Spectrum Research
Authors: Fusheng Zhang , Biao Wang
Published: December 2007

EMS, a complex type of pour point-viscosity depressant for crudes, is composed of EVA, MVA and Surfactant. After adding EMS into the crudes, a very nice result in reducing pour point and viscosity for Daqing, Jianghan and Jidong crudes was got. From the research result of infrared spectrum of interaction between EMS or its components and wax or mixture of resin and asphaltene isolated from three crudes above-mentioned, it has been shown that the area ratio of the double absorption peaks of 719 cm−1 and 729 cm−1 or 1388 cm−1 and 1378 cm−1 changed remarkably after EMS or its components were added into wax. It can be infered that the cocrystallization probably happened between the EMS or its components and the wax. The position of 4000-3000 cm−1 infrared absorption peak of the mixture of resin and asphaltene moved to the lower wavenumber, and the ratio of the area of 1373 cm−1 absorption peak (methyl) to the combination area of 748,810 and 871 cm−1 absorption peak (aromatics) increased remarkably. It can be infered that the pour point-viscosity depressant molecules destroyed the original hydrogen bonds and overlapping of the aromatic ring planes among resin and asphaltene molecules to form new cubic molecular structure and new hydrogen bonds. With the results the viscosity of crude oil will be reduced.
A New Iterative Solution Method With Alternating Interblock Direction (AID) Preconditioner
Authors: Shin Dalsoo
Published: December 2007

This paper presents a new iteration method for the numerical solution of pressure equations arising in petroleum reservoir engineering. It utilizes a newly developed preconditioner and generalized conjugate gradient acceleration with a new residual constraint procedure. The Alternating Interblock Direction (AID) preconditioner exploits a natural way of alternating sweeps in xyz-directions and is free from the dependence on the choice of the first internal direction which is common with other methods. The generalized conjugate gradient algorithm is ORTHOMIN. It is further accelerated by an alternating direction residual constraints (ADC) which could make the summation of the residuals be zero simultaneously in all three axes. The new method can be easily vectorized and parallelized. It can also be adapted to equations other than the pressure equation. Its speed and robustness are proved to be favorable to previously published methods by numerical experiments.
Static and Dynamic Load-Balancing Strategies for Parallel Reservoir Simulation
Authors: Anguille Luc , Killough J. E. , Li T. M. C. , Toepfer J. L.
Published: December 2007

Accurate simulation of the complex phenomena that occur in flow in porous media can tax even the most powerful serial computers. Emergence of new parallel computer architectures as a future efficient tool in reservoir simulation may overcome this difficulty. Unfortunately, major problems remain to be solved before using parallel computers commercially: production serial programs must be rewritten to be efficient in parallel environments and load balancing methods must be explored to evenly distribute the workload on each processor during the simulation.

This study implements both a static load-balancing algorithm and a receiver-initiated dynamic load-sharing algorithm to achieve high parallel efficiencies on both the IBM SP2 and Intel IPSC/860 parallel computers. Significant speedup improvement was recorded for both methods. Further optimization of these algorithms yielded a technique with efficiencies as high as 90% and 70% on 8 and 32 nodes, respectively. The increased performance was the result of the minimization of message-passing overhead.
Compositional and Black Oil Reservoir Simulation
Authors: Coats K. H. , Coats K. H. , Thomas L. K. , Pierson R. G.
Published: December 2007

This paper describes a three-dimensional, three-phase reservoir simulation model for black oil and compositional applications. Both IMPES and fully implicit formulations are included. The model's use of a relaxed volume balance concept effectively conserves both mass and volume and reduces Newton iterations. A new implicit well rate calculation method improves IMPES stability. It approximates wellbore crossflow effects with high efficiency and relative simplicity in both IMPES and fully implicit formulations. Multiphase flow in the tubing and near-well turbulent gas flow effects are treated implicitly.

Initial saturations are calculated as a function of water-oil and gas-oil capillary pressures which are optionally dependent upon the Leverett J function or initial saturations may be entered as data arrays. A normalization of the relative permeability and capillary pressure curves is used to calculate these terms as a function of rock type and grid block residual saturations.

Example problems are presented, including several of the SPE Comparative Solution problems and field simulations.
Rabi Multi-Sector Reservoir Simulation Model
Authors: Bruijnzeels Chris
Published: December 2007

To ensure optimum ultimate recovery of the 46 meter thick oil rim of the Rabi Field in Gabon, a full field simulation model was required. Due to it's size and complexity, with local cusping, coning and geological circumstances dominating individual well behaviour, a single full field model would be too large for existing hardware. A method was developed to simulate the full field with 5 separate sector models, whilst allowing the development in one sector model to have an effect on the boundary conditions of another sector. In this manner, the 13 x 4.5 km field could be simulated with a horizontal well spacing down to 175 meter.

This paper focuses on the method used to attach single 3-phase tank cells to a sector simulation grid in order to represent non-simulated parts of the field. It also describes the history matching methodology and how to run a multi-sector model in forecasting mode.

This method can be used for any reservoir, where size and complexity require large reservoir simulation models that normally could not be modelled within the constraints of available computer facilities. Detailed studies can be conducted on specific parts of a field, whilst allowing for dynamic flow and pressure effects caused by the rest of the field.
Compositional Reservoir Simulation on CM-5 and KSR-1 Parallel Machines
Authors: Ghori S. G. , Wang C. H. , Lim M. T. , Pope G. A. , Sepehrnoori K. , Wheeler M. F.
Published: December 2007

Recently, use of parallel machines in reservoir simulation has received considerable attention from the petroleum industry. This paper presents parallelization of a 3D compositional, equation-of-state reservoir simulator on the CM-5 and KSR-1. To the best of our knowledge, this is the first time that the parallelization of a compositional reservoir simulator has been performed on both the CM-5 and KSR-1.

For new users of the CM-5 machines, the software and hardware of CM-5 architecture is presented, as well as details of the parallelization techniques. For example, domain decomposition, I/O's, phase equilibrium computations, and well model are described. The parallelism techniques on the KSR-1 are presented with the emphasis on the porting of the phase equilibrium calculation.

The performance of each machine is evaluated by showing the speedup on different sets of processing nodes. Two test problems were used to explore the capability of the parallelized version of the code; one is a waterflood problem and the other is a CO2 multiple contact miscible flood, both in a West Texas oil field. These field problems were run on 1, 2, 4, 8, 16, and 32 processors to get insight into the locations of communication bottlenecks, generally occurring in the programming with distributed memory machines. The problems of latency and bandwidth which are associated with communication efficiency of the CM-5 are also addressed.
Commercial Valuation of Hydrocarbon Resources
Authors: Boardman John S
Published: December 2007

A practical business process is described which enables all categories of hydrocarbon resources to be valued in a commercially consistent manner. The benefits of the process are increased if there is a transparent corporate strategic plan which can be used to test the value of a resource against a desired portfolio, described quantitatively in terms of value and risk. Individual opportunities for both acquisition and disposal can then be measured against an assessed "Corporate preference profile" and pursued with increased confidence in the overall fit.
The Use of Coiled Tubing During Matrix Acidizing of Carbonate Reservoirs
Authors: Thomas R. L. , Milne A.
Published: December 2007

A laboratory and field study directed at improved well performance of horizontal wells is discussed. During the study, several wells were matrix acidized using bullhead and coiled tubing placement techniques. The study performed in carbonate reservoirs indicates acid placed with coiled tubing diverted with foam provides excellent zone coverage and damage removal. Conventional bullhead techniques do not result in effective damage removal. The study emphasizes the evaluation of the treatment results and the development of improved acidizing techniques.

Laboratory simulations of matrix acidizing indicate proper placement techniques are essential. This observation is supported by field data in oil wells completed in carbonate reservoirs. The key to successful damage removal is 1) the placement of acid via coiled tubing and 2) proper diversion. Production logging and well performance data support this claim.

The proposed treatment is applicable in both horizontal and vertical wells completed in carbonate reservoirs.
New Cement Additives that Eliminate Cement Body Permeability
Authors: Talabani Soran , Hareland Geir
Published: December 2007

An experimental investigation was carried out replacing some currently used cement additives with three new additives.

The experiments performed monitored the cement slurry pressure during the setting of the cement. During the setting period of the cement, two time cycles of cement expansion and contraction are observed. This is due to the individual contribution of each component in the cement mixture. To obtain the optimum tightness of the cement, final contraction in the cycle is crucial for blockage of gas migration. In these studies optimum concentrations of the additives were obtained experimentally, where the cyclic pressure behavior of the cement was optimized and the permeability reduced for the best final cement results. The parameters investigated in this study were; change in the applied pressure on the slurry with time, the compressive strength and permeability of the set cement. The major causes of the early microfractures are the in-complete cement – water reaction, low compressive strength of the set cement, and the sudden change in the hydrostatic pressure as the cement changes its phase from liquid to a solid state1. The fluid loss and free water content were measured and controlled for each sample.

One Of the new additives is used to eliminate the micro-annulus with the pipe and the other two are used to eliminate the micro-fractures within the cement body.

The correct Ironite Sponge concentration eliminated the micro-annulus with the pipe. The optimum amount of Synthetic Rubber powder needed during the optimum two cycle expansion-contraction process was also obtained under reservoir conditions.

The Anchorage clay concentration in the mixture that migrates for a limited time minimizes the cement body pores. This concentration can also be optimized.

The results of this study is that proper amounts of X-C polymer, Anchorage clay, Ironite Sponge, and Synthetic Rubber can be used to optimize the compressive strength and eliminate both micro-fracture and micro-annulus. There are certain limits to the amount and type of Synthetic Rubber powder which cement will set and the micro-fractures are eliminated. This experimental approach can be used to eliminate gas migration through a cement design that is environmentally safe, inexpensive, and uses recyclable materials.
Application Of Hydraulic Fracturing Technologies To The Shallow Telisa Formation
Authors: Poerwanto J.H. , Sugembong C.F. , Bagzis J.M. , Martinez A.D.
Published: December 2007

SPE Members

This paper describes the changes that have been made to the stimulation treatments in the Telisa formation over the past year. The Telisa formation in the South Balam Field is a shallow (+/-600 feet), high permeability (10-100 md), laminated sandstone reservoir. The South Balam Field is located near the large Duri Field in central Sumatra. Hydraulic fracturing was initiated in the Telisa formation at South Balam Field in 1990.

Due to the shallow depth of Telisa formation surface treating pressure are typically 400 to 600 psi. These low pressure make pressure analysis very difficult. In many instances only 100 psi of net pressure is seen during the treatments. It is difficult to measure fluctuations in net pressure using only surface data. This has prompted the use of bottom hole pressure recorders with surface read-out which are more accurate and have higher resolution. The pressure recorders are hung inside tubing approximately 100 feet above the perforations, which eliminates pipe friction during the treatment analysis. The treatment are pumped down the annulus.

Minifracs were performed and analyzed using bottom hole pressure data to determine fluid efficiency, fracture closure pressure, and leakoff characteristics. Results of these tests have resulted in job modifications regarding pad and treatment sizes. History matching of treatment pressures, both post-frac and in real-time, have been performed using a hydraulic fracture simulator to determine created fracture geometries. Low level radioactive isotope tracer material was used to tag the treatments for determining the fluid and proppant distribution throughout the pay interval. The accumulation of this data indicates that hydraulic fractures in the Telisa formation are not horizontal, as expected for this shallow depth, but are vertical in orientation.

Additional treatment changes which were incorporated to increase fracture conductivity include pumping higher proppant concentrations, pumping increased proppant sizes and using higher quality proppant.

This paper indicates techniques and results which can be applied to other shallow high permeability sandstone reservoirs.

Introduction

The Telisa is the shallowest producing horizon in the South Balam Field, at an average depth of 600 feet, which is located approximately 50 km northwest of Duri Field in central Sumatra. Figure 1 is a structure map on top of the Telisa horizon.

P. 277
Near-Tip-Screenout Hydraulic Fracturing of Oil Wells in the Bach ho Field, Offshore Vietnam
Authors: Hung L. V. , San N. T. , Shelomentsev A. G. , Tronov J. A. , Lam D. D. , Thomas R. L. , Fox T. , Bisdikian C.
Published: December 2007

The first hydraulic fracturing of wells in Vietnam were successfully performed Offshore in the Bach Ho (White Tiger) Oil Field. Near-tip-screenouts rather than tip-screenout treatments were performed. The goal of the project was to improve production from existing wells rather than drill new wells and reduce the cost per barrel produced. This case study involves wells with multiple perforated zones completed in the Oligocene sandstone. Zones were selectively fractured in order to optimize production. A detailed description candidate selection, design, execution and evaluation processes are presented.

The Bach Ho field has been producing for 8 years but not at its potential due to various reasons including drilling and completion fluid damage. Although acidizing was an option for damage removal, hydraulic fracturing was selected as a way to bypass near-wellbore damage and generate a negative skin. Production simulators were used to quantify post-frac production. Due to suspected high closure stress, high strength proppant was selected and ramped in a high temperature fracturing fluid. Calibration treatments were conducted on several wells to quantify fluid leakoff, fracture height and Young's modulus. Based on the results of the calibration treatment, fracture designs were modified. As predicted by computer simulation, near-tip-screenouts occurred as planned.

The treatments were performed using a work boat with skid pumping/blending equipment, a computer monitoring/operation center and a laboratory. Strict QC procedures were followed to ensure the quality of all products.

Post-frac well tests results and production data are presented. Overall, the fracturing campaign was very successful with wells showing negative skins and up to a five fold increase of production in agreement with systems analysis predictions.
Experiences and Results of Acid Prepacking and Gravelpacking Wells in the West Lutong Field in Sarawak, Malaysia
Authors: Rajah Benny , Linder Ron , Todd Brad
Published: December 2007

Gravel packed wells in North Borneo have had a long history of impairment. The historical average skin factor for the wells in the Baram Delta area has been around 25.

As a result of the success reported in other locations, acid prepacking was chosen for field evaluation in the Baram Delta. Acid prepacking trials were carried out in the Bokor field with encouraging results. It was decided that the acid prepacking procedure would be used on all internally gravel packed zones during the 1992 – 1993 West Lutong field revisit campaign.

Flowing build-up surveys were ran on those zones that are currently producing. Because the wells are completed as dual selective, not all zones are available for testing. Good data is available for 13 of the 29 zones completed with the acid prepacking technique. The total skin values for the zones included in the analysis ranged from 1.3 to 20, with an average of 9.8 and an average removable skin of 6.6.
Combination Production of Vertical and Horizontal Wells
Authors: Jiali Ge , Demin Wang , Debin Qu
Published: December 2007

In the last few years horizontal wells are becoming increasly important. This paper presents a hydrodynamic method for solving the flow problem of areal water–flooding systems of combinations of vertical and hprizontal wells( 5–spot well pattern and 7–spot well pattern). The potential function, production rate, breakthrough time, areal sweep efficiency and stream functions are derived respectively. Also, the flow resistance method is used for getting the equations of horizontal well production for all the areal floods. Finally, the equations of oil productions derived by the two methods are compared.
A Review Of Offshore Oil Fields Development in Malaysia
Authors: Seong Chen Kah , Hong Teh Yat
Published: December 2007

This paper is a review of offshore oil fields development in Malaysia. Development of an oil field is typically divided into a number of major phases namely exploration and field appraisal, development planning, project implementation and field production. For an offshore oil field development, it requires careful planning and considerations during all of the phases. The requirements for field appraisal, subsurface development planning and facilities options are reviewed. During field production, special considerations are required to manage the field.
Reservoir Simulation of a high Viscous Crude and Strong Water Drive Reservoir in Sarawak, Malaysia
Authors: Ramli Adnan
Published: December 2007

The Bokor field is located offshore Sarawak, Malaysia and is one of the largest fields in the Baram Delta Province (Figure 1). The A3/6 group of reservoirs is the largest amongst the Bokor reservoir groups. The reservoir comprises a series of multiple, stacked, well-developed, fluviomarine sandstones connected to a large aquifer. Production from this reservoir started in 1983 and since then some 15 MMstb of oil have been produced.

To better understand the production performance, displacement mechanism and further development opportunities in this high viscous crude (10 cP) and strong water drive reservoir, a 3D sector reservoir simulation has been carried out. The model comprises 8640 active grid blocks, with 14 strings completed on four reservoir units with separate fluid contacts. The layering system and grid dimensions were found to be critical in the history matching process, which was supported by a X-sectional study carried out prior to embarking on the 3D model.

Based on the history match, remaining oil was identified on the eastern flank, at the top of each sand unit (due to water under-running) and in the downdip area due to the existing ‘crestal oriented’ development. The history matched model was subsequently used to aid further development planning and to formulate a cost-effective reservoir management strategy. Various development scenarios were tested in this 3D model, which include infill drilling, horizontal wells and pressure maintenance by water injection.

This paper describes the various steps taken to obtain a good history match over the 10 years of production history and discusses the findings of the prediction runs.
Conservation Versus Realistic Economics
Authors: Deegan Charles J.
Published: December 2007

The purpose of this paper is to sum up for you the economic point to which our technological progress in reservoir engineering has brought us; to analyze some of the current obstacles to more rapid progress; and to point out the broader responsibilities in the area of executive work that are more and more being opened to engineers.

With this group there is no need to trace the beginnings of reservoir engineering, nor to emphasize the accelerating rate of growth of our knowledge and understanding of its principles. Today reservoir engineering and it concepts are an accepted branch of oil producing technology; accepted by producers, by regulatory bodies, and by the courts. Its principles are inextricably woven into the general concept of oil and gas conservation. In fact the legal basis for acceptance of its findings by regulatory bodies and courts of law rests largely on the concept that application of reservoir engineering principles will result in conservation of oil and gas resources for the welfare of all the people.

Only a few of the new crop of engineers each year are unaware of the importance of economics in the practical application of reservoir engineering principles. The rest of you learned because management executives were always scrutinizing projects and laying down the law about the economic practicality of various proposals.

But that situation is changing rapidly these days. Many engineers are themselves part of management; others are in the process of being trained to become part of management. Therefore the detailed screening of the economic phases of reservoir engineering projects is being done more and more by engineers themselves. Top executives are apt to check only the overall figures and conclusions.

This is a highly desirable trend. But if it is to continue and accelerate, then engineers must become more executive minded in their thinking about the practical economics of reservoir engineering projects. They must display a willingness to accept responsibility for checking broader aspects and longer term phases of economic problems.

Let me cite an example of executive minded thinking about conservation projects. For many years now the elimination of flaring of casinghead gas has been recognized as a highly desirable conservation objective. Literally hundreds of people have talked and written about the subject.

Less than 10 years ago, two distinguished authorities in this field were testifying before a Federal Power Commission hearing on gas in Houston. Here is the gist of what they told the Commissioners at that meeting.

A price of 10 cents per thousand for gas at the well head will do more to stop waste and achieve true conservation than all of the actions of all the regulatory bodies in the country, plus all the public agitation on the question. Subsequent developments in gas prices and conservation results have served to emphasize the sagacity of these two men.
Field Trial of Simultaneous Injection of CO2 and Water, Rangely Weber Sand Unit, Colorado
Authors: Robie D.R. , Roedell J.W. , Wackowski R.K.
Published: December 2007

Field Trial of Simultaneous Injection of CO2 and Water, Rangely Weber Sand Unit, Colorado.

D.R. Robie, Jr, J.W. Roedell, R.K Wackowski*

The Water Alternating Gas (WAG) process is commonly applied in CO2 floods to reduce the mobility, to improve the stability of the flood front, and subsequently to improve recovery. There have been many modifications in the process over time to improve retention and operating conditions. Examples include tapering of the WAG ratio (an increase in the WAG ratio) and reduction of the half cycle slug sizes (the pattern hydrocarbon pore volumes of CO2 or water injected before switching to the alternate fluid.). At the Rangely Weber Sand Unit, WAG's at injection wells must be performed manually.

Simultaneous injection of CO2 and water (SI) is essentially the reduction of the half cycle slug size to the limit. Simulation suggested that improved recovery could be realized from the application of this technique. In addition, reduced half cycles were being applied at injectors in increasing numbers due to the reductions in the wide fluctuations in produced gas rates. This required additional time to manually switch the injection wells from one fluid to the other.

Based upon potential improvements in recovery and work force utilization, a field trial was implemented to verity that the process could be successfully performed. This paper reviews the testing of various processes to perform SI, as well as the implementation of a larger scale trial.

Introduction

The Rangely Weber Sand Unit is in Rio Blanco County in northwestern Colorado, U.S.A, about 5 miles east of the Utah-Colorado border (Figure 1). It is the largest field in the Rocky Mountains in daily and cumulative oil production. Currently, there are 372 active producers and 300 active injectors, 259 of which are injecting CO2.

Weber sandstone production was discovered at Rangely in 1933 by the California Company. Development of the field began in 1944 spurred by World War II oil demand, Initial 40-acre spacing development was completed in 1949. Infill drilling in the 1970's and 1980's reduced the spacing to 20-acre throughout nearly the entire field.

P. 719
An Oil Production Model for a Well Producing by Both Gravity Drainage and Viscous Flow From a Mature Steamflood
Authors: Owens B.K. , Ziegler V.M.
Published: December 2007

B.K. Owens* and V.M. Ziegler*

This paper presents a simple analytical model that determines the oil production rate for a well producing from a mature steamflood. Fluid flow in steamfloods exhibiting gravity override is frequently assumed to be dominated by gravity drainage, and viscous flow is considered insignificant. However, this paper presents a model that includes the effects of both gravity drainage and viscous flow. The model indicates that viscous flow or "steam drag" may be a significant force contributing to the oil production rate. Gravity drainage does dominate when thick liquid columns and low horizontal pressure gradients exist, but viscous flow may be dominant when the liquid column is thin. A reservoir may initially be dominated by gravity drainage, but as the reservoir depletes and the steam chest descends, the viscous flow force may become the dominant component.

Development of the model involves adapting a previous analytical prediction model that only considered gravity drainage. The new model can be set up to be handled in a spreadsheet.

Validity of the model is demonstrated by comparison of forecasts against Kern River field data. The first set of field data involves an entire steamflood project's performance after complete steam overlay has occurred. The second set of field data examines a situation where reservoir drawdown on several wells was decreased by shutting in a casing vapor recovery system. The final set of data deals with a scenario where reservoir drawdown was increased by installation of a casing vapor recovery system to an injector that was converted to a producer.

Introduction

Closmann presented an oil production model for a mature steamdrive that included the effects of gravity drainage and neglected viscous flow. The model was based on a reservoir where steam overlay has occurred and the steam zone completely covers a reservoir. Both Clossman and Vogel discussed situations where the viscous flow component was insignificant and the gravity drainage component dominated. However, since Kern River field experience shows that increased wellhead casing pressures result in decreased oil production, the viscous flow component is known to be sometimes significant. Therefore, Clossman's model was modified to include viscous flow. The resulting model tested favorably with three sets of field data.

P. 409
A New Analytical Model for Assessing the Role of Steam Production in Mature Steam Floods
Authors: Kimber K.D. , Deemer A.R. , Luce T.H. , Sharpe H.N.
Published: December 2007

K. D. Kimber,* A. R. Deemer, T. H. Luce, and H. N. Sharpe*

One of the keys to optimal steam flood operation lies in understanding the complex relationship between energy utilization and fluid flow phenomena. In assessing heat management strategies, it is important to consider not only the thermal requirements of the process but the impact these strategies may have on the mechanisms of oil production. It is important to know whether steam injection rate cuts, intended to reduce cost by supplying only the energy required for heat loss and steam zone growth, impact oil production rates and whether casing vapor shut-in will result in reduced oil recovery.

During the past two years, a study aimed at improving the understanding of the mechanisms affecting these critical questions was conducted. The investigation focused on the after-steam breakthrough stage of steam flood oil production. It helped identify the relative influence of gravitational forces and the additional force provided by the increased pressure gradient due to varying amounts of steam flowing between the reservoir and the production well during this stage. Several 3-D partially scaled experiments studying these mechanisms under conditions similar to the Kern River Field in California were completed. Numerical simulation and field data from operations at Kern River Field contributed to the findings. Study of the relationships between oil recovery and various steam flood mechanisms has led to the development of a new analytical model tailored to the after-steam breakthrough stage of the steam flood process. The contribution of each mechanism studied and the implications on field operating strategies will be discussed.
Using Geostatistics To Evaluate Cleanup Goals
Authors: Marcon Michael F. , Hopkins Loren P.
Published: December 2007

Michael F. Marcon and Loren P. Hopkins

Geostatistical analysis is a powerful predictive tool typically used to define spatial variability in environmental data. The information from a geostatistical analysis using kriging, a geostatistical tool, can be taken a step further to optimize sampling location and frequency and help quantify sampling uncertainty in both the remedial investigation and remedial design at a hazardous waste site. Geostatistics were used to quantify sampling uncertainty in attainment of a risk-based cleanup goal and determine the optimal sampling frequency necessary to delineate the horizontal extent of impacted soils at a Gulf Coast waste site.

Introduction

Statistical assessment of pre- and post remediation data is a critical step in evaluating contaminant characterization and attainment of cleanup standards. This paper discusses the incorporation of geostatistical methods in sampling strategies at hazardous waste sites. A Phase I Contaminant Assessment (conducted in two stages) completed at a chemical blending facility in the Gulf Coast indicated that eight compounds had significantly impacted superficial soils. A second phase sampling plan was developed using geostatistical tools and the Data Quality Objective (DQO) Process (1) to define the horizontal extent of contamination which exceeded preliminary remediation goals.

The purpose of the Phase II sampling plan was to identify all one half acre plots on the site which potentially posed an unacceptable risk to human health and the environment. The Phase II program was based on: preliminary remediation goals (PRGs) established during the risk assessment; the future land use for the property; uncertainty levels acceptable to both the Environmental Protection Agency (EPA) and the property owner; and the amount of expected concentration variability observed at the site. These inputs were used in a geostatistical analysis to develop a final sampling program to delineate the horizontal extent of contamination and eliminate the need for confirmatory sampling after remediation was completed.

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Multi-Temporal Environmental Analysis Of Oil Field Activities In South-Central Oklahoma Using Landsat Thematic Mapper, Aerial Photography And GIS
Authors: Janks J.S. , Edwards G.S. , Prelat A.E.
Published: December 2007

J.S. Janks, G.S. Edwards, and A.E. Prelat

Environmental assessments of oil field activities, historical and present, were made using a combination of Landsat Thematic Mapper, aerial photographic and GIS information. Landsat data was used to assess vegetation health in and around the oil fields, and aerial photography was used to document historic changes. We found no evidence of vegetation damage from the oil field activities, even though many fields are located along anticlines and drain into major waterways. GIS technology, mapping roads, wells, rivers, ponds and environmentally-sensitive areas, was used to minimize environmental effects on the placement of shotpoints and receivers. When either shotpoints or receivers were found to interfere with sensitive areas, the points were moved to nearby roads or other open locations. The application of this technology resulted in minimal environmental damage and significant cost savings.

Introduction

South-central Oklahoma has been the center of oil field activity since the early part of the 20th Century. The region is in part associated with the Ardmore basin, to the west of the Arbuckle Mountains (Figure 1). The many fields in the area, including Velma, Healdton, Sholem Alechem, Wheeler, Fox, Wildcat Jim and Velma are among the oldest in the country. Production comes from most of the permeable formations in the stratigraphic section.

Environmental practices have varied widely through the region's history, both within the oil field and without. Groundwater salinity gradients are sometimes reversed in this section of Oklahoma. Total Dissolved Solids (TDS) are 100,000 mg/L at the top and decrease to 1,500 mg/L at the base. All inverted water tables in the region have not been attributed solely to the effects of surface water pollution, as naturally-occurring inversions have also been documented.

P. 31
Impacts of Environmental Regulations on Future Resource Development in Louisiana Wetlands
Authors: Harder Brian , John Chacko , Dupont Allen
Published: December 2007

Louisiana wetlands require careful management to allow exploitation of non-renewable resources without destroying renewable resources. Current regulatory requirements have been moderately successful in meeting this goal by restricting development in wetland habitats. Continuing public emphasis on reducing environmental impacts of resource development is causing regulators to reassess their regulations and operators to rethink their compliance strategies. In addition regulators need forecasts of future E&P trends to estimate the impact of future regulations. To determine future activity we created two econometric models of North and South Louisiana relating drilling activity, success ratio, and price to future wetland drilling locations. Results of the models indicate that environmental regulations have a small but statistically significant effect on drilling operations in wetland areas.

Operators want cost effective means of access that will reduce environmental impacts, decrease permitting time, and limit future liability. We examined the regulatory system and found that reducing the number of applications required by going to a single application process and having a coherent map of the steps required for operations in wetland areas would reduce regulatory burdens. Incremental changes can be made to regulations to allow one agency to be the lead for wetland permitting at minimal cost to operators.

In the interim, careful planning to account for environmental impacts in all stages of the exploration process can reduce environmental costs for operators. Operator emphasis should be on avoidance rather than mitigation. Alternative methods of access to avoid impacts exist but at present they are not cost effective for all locations. Future technological innovations such as waste minimization strategies, 3-D seismic and coiled tubing will lead to reduced environmental impacts and costs for operators.