bluuebunny/crossref_metadata_2025 huggingface dataset:
Well Test Analysis of a Multilayered Reservoir With Formation Crossflow
Authors: Park H. , Home R. N.
Published: December 2007

The purpose of well test analysis is to identify the type of a reservoir and to determine the parameters of the reservoir quantitatively. This work is about the well test analysis of a multilayered reservoir with formation crossflow. The results are described in two parts.

In the first part, the effects of the reservoir parameters such as permeability, vertical permeability, skin, storage coefficient, and the outer boundary conditions on the wellbore response (pressure and layer production rate) were investigated. Some important discoveries are: The wellbore response is observed in three different stages. It is identical to that of the commingled system at early time and and to that of the homogeneous system at late time. Transition occurs at intermediate time.The vertical permeability is the only parameter governing the initiation and termination of the transition from the early time commingled system response to the late time homogeneous system response.The direction of the formation crossflow is determined first by the layer permeabilities and later by the skin factors.The influence of the wellbore storage effect can be minimized by using sandface flow rate from each layer.The outer boundary conditions have only small effect on the wellbore response as long as the transition terminates before the system feels the boundary.

In addition, the early time and the late time limiting forms of the wellbore response were derived and some approximation for the late time layer production rate was suggested.

In the second part, the non-linear parameter estimation method was applied as a means to determine the layer parameters. Here, two new methods for the initial estimation of the parameter values were suggested and tested, where the early time and the late time limiting values of the layer production rate were used with the conventional pressure analysis for the average permeability and skin of the total system.
A Case Study of Improved Recovery Options in a Volatile Oil Reservoir
Authors: Schenewerk P. A. , Heath B.
Published: December 2007

The South Buck Draw (Dakota) Field lies on the eastern flank of the Powder River Basin along the border of Converse and Campbell Counties, Wyoming (Figure 1). The reservoirs in the field produce a volatile oil from stratigraphic traps made up of fluvial channel and marine longshore bar deposits. This paper presents the results from a field study which was made to determine the feasibility of partial pressure maintenance operations for improved recovery. While it was found that partial pressure maintenance operations could recover incremental oil, it was determined that the field would not be amenable to flooding operations because of reservoir discontinuities, a developed fracture system and highly unstable oil and gas prices.

The study showed that primary recovery in volatile oil reservoirs can be very good, generally in excess of 20% of the original oil-in-place. It also showed that estimation of original oil-in-place for volatile oils is difficult even when pressures remain above the bubble point. Additional work, done after the original study, is also presented which shows the effects of both full and partial pressure maintenance operations begun above and below the bubble point pressure. Incremental oil can be produced, however, the economics of these projects must be carefully scrutinized.

The Powder River Basin is located in northeastern Wyoming and southeastern Montana. The basin was formed as a result of deformation which occurred due to the late Cretaceous-early Tertiary Laramide Orogeny 1. The field produces from deposits of the Lower Cretaceous Fall River Sandstone which is known locally as the "Dakota Sandstone". Structure across the field is uniform with a southwest dip of approximately 100 feet per mile. Structure does not play a significant role in the production process in the field.
A Flexible Approach to Predictive Well Management Via User-Defined Strategies
Authors: Miertschin J. W. , Weiser A.
Published: December 2007

An integral part of any reservoir simulator is the well management program. In prediction mode, this program employs some of the simulator's most complex logic in an attempt to emulate the decision-making process in the field. During predictive well management, constraints are applied at various levels (well, platform, reservoir, trunkline, etc.) and corrective actions (remedies) are taken when a constraint is violated.

The types of constraints applied and the remedial actions taken when a constraint is violated can differ greatly from field to field. The traditional practice has been to customize the predictive well management code for the particular reservoir study at hand. This ultimately results in duplication of code and effort, since no customized well management program is general enough to be applicable to all new reservoir studies undertaken. In addition, later changes in well management strategies for a given field can require coding modifications which are often cumbersome and time-consuming, since they were not part of the original program design.

Our goal was to develop an engineering tool that would give users, for the first time, essentially unlimited flexibility in performing predictive simulation. The code we have developed accomplishes this goal by allowing users essentially to write their own well management strategies by way of input data. The input data can be viewed as a high level programming language with its own special syntax and structure.

An added benefit from our approach is that it allows users to have a better understanding of exactly what the well management program is doing during the simulation, leading to fewer wasted runs and improved interpretation of results.
Thermal Zone Monitoring in an Athabasca Oil Sands Pilot
Authors: Lowe K. W. , Donovan T. E.
Published: December 2007

The Gregoire Lake In-Situ Steam Pilot in northern Alberta, Canada investigated the use of steam for recovering heavy oil from the Athabasca Tar Sands deposit. To evaluate pilot performance, an extensive program was initiated to monitor the thermal zone development in the reservoir.

This paper presents a summary of monitoring techniques utilized to quantify reservoir response from the Athabasca McMurray pilot. The techniques examined in this paper include temperature observation wells, 3-D seismic mapping, micro-seismic mapping, surface level surveys, tracer analysis, and tiltmeters.

Cross-correlation of data from the monitoring program allowed the effectiveness of individual techniques to be evaluated. The merits and the negative aspects of each technique are discussed. Specifically, the value of new remote sensing technology is appraised.

Data analysis utilizing computer-based graphic techniques is also discussed.
Recommendations for MWD Tool Reliability Statistics
Authors: Ng F.
Published: December 2007

MWD reliability plays a major role in the overall economic success of that service. MWD customers need to consider reliability when evaluating bids from various service companies. The least expensive bid may not necessarily correlate with the most economic service. Comparing different MWD services is difficult due to the variety of services available and the lack of a standard method for determining reliability. This paper outlines an equitable method to evaluate the reliability of different MWD services.
Petroleum Engineering Manpower Demand
Authors: Crouse P. C.
Published: December 2007

Over the years, the Society of Petroleum Engineers through the society-wide Manpower Committee has attempted to obtain a better understanding of manpower for the upstream side of the petroleum industry. One of the critical areas of this understanding is engineering manpower demand. In former years data has sometimes been sparse, negating any meaningful understanding of manpower drilling and production engineering needs and trends for the U.S. petroleum industry.

The basic questionnaire sent to companies is in need of revision to expand its scope to international engineering manpower for the exploration and production industry at large. Questions and data should be focused to obtain more interpretable information which would be beneficial to the overall industry and which could be easily correlated year to year.

This year the responses to the manpower survey were up significantly from 11 responses in 1988 to 23 responses in 1989. Responses were received from majors, large service companies, and independents. 5 respondents had 15-50 engineers employed in the subject sector, 5 with 51-100 engineers, 4 with 100-500 engineers, and 6 with more than 500 engineers. The remaining responses were not usuable.
Ultrahard Laser Coatings on Rock Bit Cutters for Wear and Erosion Resistance
Authors: Kar N. J.
Published: December 2007

Ultrahard coatings are being deposited on the exterior surfaces of rock bit cutters and other downhole tools for increased wear and erosion resistance. Processing entails hypersonic spray deposition of carbide containing coatings and subsequent fusion using high powered lasers. These coatings are put on finished components within a matter of minutes without damage to the cutting elements. Field tests conducted on 7 7/8 F27 and F17 type bits have indicated above average performance of the coatings. These hard coatings dramatically decrease fluid erosion of cutter surfaces, leading to improved insert retention and the potential for increased bit performance. Implementation of this state of art technology on entire families of downhole tools will be discussed.
The Effect of Extended Nozzles and Crossflow Hydraulics with 17½-in. Tricone Bits in Northern Germany
Authors: Young T. L. , Durkee D. L.
Published: December 2007

Penetration rates achieved with 17-1/2" bits in Northern Germany have historically been slow. Over the last 5 years, many different practical solutions have been tried to increase the ROP including higher rotary speeds, weights, different mud types, PDC bits and various hydraulic configurations. Of all of the different techniques attempted, the usage of crossflow hydraulics and extended nozzles brought about the biggest and most consistent improvement in bit performance. This paper will summarize the different nozzle configurations used and the performance rate gains achieved in each formation through the 17-1/2" section.
A Unique Spinoff of Inflatable Packer Technology to Enhance the Ability to Circulate Casing Down on a Top or Side-Drive Rig
Authors: Stokley C. O. , Scott S. R. , Sanford L. B. , Jordan R. A. , Mounteer J. M.
Published: December 2007

Problems are often encountered in running casing into a wellbore which require the "rig-up" of a circulating head in order to lower casing farther into the hole. A method of quickly and safely achieving circulation through the casing will be discussed in this paper, including tool development, deployment and field applications.
Back to the Basics: Planning the Operations for Drilling a Well
Authors: Chaney M. L.
Published: December 2007

The reduction of drilling costs is more important than ever in the oil industry today. The use of basic planning techniques and communication with all drilling personnel cuts costs even further.

As in many operations which exist today, communications in the drilling industry are fine until getting down to the day-to-day portion of the operation-the very point where communication makes or breaks a business. Communicating and planning, what I refer to as back to the basics, saves money for both operators and contractors. The method I use in planning the operations of drilling wells has been refined and detailed over several years.
Options To Increase Drillstring Reliability and Decrease Tool Joint Break-in Cost
Authors: Smith J. E. , Carlin F. J.
Published: December 2007

The API NC type thread form has been available on tool joints and drill collars for about 20 years. It has an advantage over the previously used (and interchangable V.Q65) thread form because it has a full 0.038" (0.97 mm) radius at the thread root.

The full root radius has a much lower stress concentration factor than the flat root and is much easier to cold roll. Both of these attributes give the NC thread form increased fatigue resistance and produce lower stresses when the joint is made up. Development of the NC thread form was a big improvement in drill collar and tool joint threads.

A similar improvement over the NC thread form has recently been developed. This thread form has a 0.057" (1.45 mm) root radius for a further reduction in the stress concentration fac?tor and a change in the pin taper to provide nearly equal loading of the threads along the length of the pin. On NC connections, apporoximately 28% of the total thread load is taken by the last engaged thread and approximately 3% is taken by the first thread. The loads on the last engaged thread and the first thread are about the same on the new connection. The new thread form is interchangable with the NC thread form.

Prebreak-in of tool joints before welding them to pipe can be a big rig cost saving and can provide more trouble free performance when the joints are put into service for the first time.
Measurements While and After Drilling by Multiple Service Companies Through Upper Carboniferous Formations at a Borehole Test Facility, Kay County, Oklahoma
Authors: Hutchinson M. W.
Published: December 2007

Over the past two years five service companies have field tested both their commercial and prototype Measurement While Drilling (MWD) petrophysical sensors in oil base and fresh water base test wells. This paper compares these data to wireline measurements, and also investigates the effect of rate of penetra-tion (ROP) on some MWD devices.A few operational details and some other aspects of the Borehole Test Facility are also discussed.
Predicting Gas Kick Behavior in Oil-Based Drilling Fluids Using a PC-Based Dynamic Wellbore Model
Authors: Van Slyke D. C. , Huang E. T. S.
Published: December 2007

The high solubility of natural gas in oil-based drilling fluids can mask the true nature of a gas kick. The sudden evolution of gas near the surface can lead to severe well control problems. The problem is accentuated to varying degrees by the presence of CO2 or H2S. Previous authors measured gas solubility and swelling behavior of oil-based drilling fluids and natural gases to tune the equation of state (EOS). Multiphase flow and EOS models run on mainframe computers were used to predict the effects of gas kicks on surface indi-cators such as pit gain and annular flow rate while gas kicks were allowed to travel to the surface uncontrolled.

This paper presents a new approach to predicting gas kicks in oil-based drilling fluids utilizing an interactive PC well control model originally developed for water-based drilling fluids. Experi-mental swelling and solubility data were obtained for mixtures of C02-rich gas and "non-toxic" base oil at simulated downhole temperature and pressure conditions. Instead of the EOS, a modular subroutine was written to describe the expansion of these mixtures as a function of pressure, temperature and mixture composition.

The modified model was used to predict pit gain, annular flow rate, casing pressure and gas distribu-tion in the annulus during simulated gas kicks in a hypothetical well. A comparison to water-based drilling fluids under similar conditions was made.

It is concluded that small but potentially dangerous gas kicks in oil-based drilling fluids may not be detected by an early increase in annular flow or pit gain.The dampening of surface response is due to the high gas solubility in the oil phase of the drilling fluid.Stopping circulation to "check for flow" can be used to detect gas kicks in both oil-based and water-based fluids. The well will be flowing in an oil-based drilling fluid because not enough drilling fluid is present deep in the annulus to mask a flow increase. Lower increases in casing pressure, annular flow and pit gain result when circulating a gas kick to the surface under controlled conditions in an oil-based fluid than in a water-based fluid, because all or a portion the gas is forced into solution by the back-pressure that is maintained on the annulus.
Rig Modifications Meet New U.K. High-Pressure Requirements
Authors: Hoopingarner J. B. , Greif C. V. , Neme E. E. , Rodt G. M. , Bates T. R.
Published: December 2007

After an explosion and fire on board a semi-submersible drilling rig in 1988 the UK Department of Energy (D.En.) placed a prohibition on the drilling of high pressure wells until a review of new equipment requirements and procedures could take place. This paper discusses seme of the concerns raised as a result of these investigations and details equipment modifications made to the semi-submersible drilling rig, DRILL STAR, in order to obtain D.En. approval to drill high pressure well 22/29-F. Areas of concern regarding high pressure wells included flexible hoses, BOP elastomers, capacity of mud gas separators, vent lines, well control procedures and training. In conjunction with equipment manufacturers, oil companies, other contractors and the D.En. a coitprehensive review was concluded in each of these areas.
Application of ADAMS (Advanced Drillstring Analysis and Measurement System) and Improved Drilling Performance
Authors: Besaisow A. A. , Ng F. W. , Close D. A.
Published: December 2007

Drillstring vibrations caused by Bottomhole Assembly (BHA) resonances can lead to partial or catastrophic failure of BHA and other drillstring components. Also, maximum bit performance is often not achieved due to drilling parameters that are not optimized. This paper presents case histories where improvements in these areas result from onsite measurement and analysis of dynamic drillstring data using the Advanced Drillstring Analysis and Measurement System (ADAMS).

ADAMS is a surface measurement system comprising an array of strain gauges and accelerometers, which are mounted in a sub above the kelly. Measurements are transmitted by microwave telemetry to a receiving unit on site where the data is demodulated and processed. The unit provides real time visual displays of energy peaks in the drillstring related to hole making and to resonant vibrations. Evaluation of these peaks and adjustment of drilling parameters results in drilling conditions that avoid BHA resonances, produces near optimum bit performance, and extends drillstring life.
Analysis of Transient Foam Flow in 1-D Porous Media with CT
Authors: Liu D. , Castanier L. M. , Brigham W. E.
Published: December 2007

Transient behavior is likely to dominate over most of the duration of a foam injection field project. Due to the lack of experimental data, little is presently known about foam flow transient behavior. Foam flow does not follow established models such as the Buckley-Leverett theory and no general predictive model has been derived. Therefore, experimental data are badly needed. This study investigates transient foam flow in a simple linear porous medium.

Foam is injected at a constant volume rate into a one-dimensional sandpack of 1-inch diameter and 24-inch length, initially saturated with distilled water. The system is placed in a CAT-Scanner. Data are accumulated at low temperature and pressure including the pressure field and saturations obtained by scanning. The liquid saturation can be obtained at each point of a cross section of the pack with less than 1% error over the range of interest. Calculations from the numbers obtained from the scanner show that the best spacial resolution available is a volume element (voxel) of 0.5×0.5×5 mm. Hence a relationship can be found between saturation and pore volume injected for each location in the sandpack. The pressure profiles show that the pressure drop along the sandpack is not evenly distributed and varies with time. The pressure gradient is much greater between the injection end and the foam front than it is ahead of that front. Moreover, the pressure gradient keeps changing as the foam advances in the sandpack. It is this behavior that differs from Buckley-Leverett theory. The cat-scan results demonstrate that the foam displacement is not piston-like. Gas channeling appears near the front, and eventually the foam blocks all these channels. The foam flows through the sandpack, continuously breaking and reforming. It takes two or more pore volumes of foam injection to reach residual liquid saturation.

The saturation versus pore volumes relationships for a given section of the sandpack have been matched with exponential formulas. In general the matches are satisfactory, however the exponents and constants in the formulas vary as a function of the position of the section considered. Graphing the data as saturation versus equivalent pore volumes injected reduces the range of these variations but does not eliminate them. We are unable to explain this behavior to date.

Techniques of measurement of saturations by X-ray CAT-scanning as well as interpretation of CT data will be presented.
The Maximum-Rate Horner Method: An Improved Method of Analysis for Afterflow-Dominated Buildup Tests
Authors: Jones L. G. , Seetharam R. V.
Published: December 2007

The Maximum Rate Horner (MRH) method is a new technique to analyze the data from pressure buildup tests with significant afterflow. It can also be used when the buildup period is preceded by sequentially declining variable rates. In this method the pressure is plotted against a modified Horner time, defined using effective flowing (tp) and buildup (Δt) times. Both these times are corrected with a simple function to properly account for the total volume of fluid produced from the formation.

It is shown here that afterflow has a permanent effect on the slope of the Horner straight line if it is neglected. The estimates of permeability (k) and skin (s) are then wrong even if they are based on afterflow-free pressure data. Expressions for these errors in the slope and parameter estimates are presented here. It is also proved that, with its use of corrected values for tp and Δt, the MRH method is not susceptible to such errors. The MRH method also reduces the buildup time required to define the Horner straight line, typically by a factor of two to three.

The empirical parameter a in the van Everdingen-Hurst model for afterflow is shown to have a physical significance in the context of the MRH method. These findings are illustrated using field and simulated buildup tests.
Productivity-Based Service Contracts
Authors: Chambers M. R. , McCready K. E. , Rankin M. D.
Published: December 2007

This paper concerns a cooperative effort between a major producing company and a major service company to establish a business relationship which emphasizes workmanship and productivity instead of traditional unit pricing. The general concepts of and reasons for productivity-based contracts are explored. The viability of these concepts for six common maintenance services are discussed as well as specific results from more than two years of operating experience relating to routine production maintenance (well servicing).
Automated CO2 Injection Control and Well Test Monitoring System
Authors: Claassen M. J.
Published: December 2007

A carbon dioxide flood has been implemented in the Conoco operated Maljamar Cooperative Unit (MCA) which features automated control and monitoring of the injection and well testing facilities. A programmable logic controller (PLC) was used to provide the functionality requirements. The injection system design required the PLC to perform continuous closed-loop control of the CO2 injection well rates and pressures. The well test system design required the PLC to monitor the gas and liquid volumes, control the liquid dump valves, and control the switching of the test header valves. The PLC also functions as a remote terminal unit, transmitting selected information via radio to the host computer for alarm notification, reporting, and database management functions.

This paper describes the instrumentation, PLC system hardware configuration, and programming that was used to perform CO2 injection control and well test monitoring at the MCA CO2 flood.
Effect of H2S on Coatings
Authors: Bouhroum A. , Marx C. , Schade W.
Published: December 2007

Coatings are developed to provide appropriate property response to severe environmental conditions; e. g. heat, stress at temperatures extremes and chemicals.

The influence of hydrogen sulfide on coatings and their protective functions for metal products was investigated in this work.

Six selected primer and one powder topcoat system were applied and exposed to five natural gas mixtures with hydrogen sulfide content of 5%, 10%, 15%, 20%, 25% and 30% to evaluate the chemical and thermal stability of these materials under the follow-operating parameters: –Temperature: 120 °C–Pressure: 15 MPa–Decompression velocity: 6 sec.–Duration of test: 48 h

As a result of exposure to hydrogen sulfide, embrittlement and discoloration of the coating was observed. A series of pigments like TiO2 and Fe2O3 formed sulfates as attacked by hydrogen Sulfide. With an increase in hydrogen sulfide content in gas mixtures, the embrittlement of the coating became more important.

Only one system (CEV-236, PR-8008) among the tested species was found to be chemically and thermally stable.

It is imperative to incorporate hydrogen sulfide scavenging components in coatings to increase chemical stability in sour gas field operations.
Waterflood Pattern Realignment at the McElroy Field: Section 205 Case History
Authors: Lemen M. A. , Burlas T. C. , Roe L. M.
Published: December 2007

A waterflood pattern realignment project in the Grayburg / San Andres McElroy Field is improving the waterflood performance. This paper presents a case history of a 640-acre [259 ha] section of the field that was realigned in 1988. Irregular and widely spaced patterns were developed into smaller and more uniform patterns. The results of the realignment are proving the economic viability of realignment work at McElroy and are improving reservoir characterization.
Reservoir Management: A Synergistic Approach
Authors: Thakur G. C.
Published: December 2007

Because of the complexities and varied areas of expertise involved in making a primary, secondary, or enhanced recovery project successful, it has become necessary to adopt a team approach for reservoir management. Until the early 1970s, reservoir engineering was considered the only item of technical importance in the management of a reservoir. However, after understanding the value of geology, this no longer holds true. The synergism provided by the interaction between geology and reservoir engineering has been quite successful, but the reservoir management has generally failed to recognize the value of other disciplines, e.g. production operations, drilling, and different engineering functions.

This paper provides information on the treatment of reservoir management as a SYSTEM. The System consists of: 1) reservoir characterization, 2) creation and operation of wells, 3) surface processing of the fluids, and 4) fluids and their behavior in the reservoir. These must be considered as interrelated parts of a unified system.

A reservoir management model involving interdisciplinary functions is discussed in this paper. Also, the success of this model in designing and implementing the North Ward Estes CO2 project, Ward/Winkler County, Texas, is discussed in detail. This reservoir management approach has yielded a better design and installation of this CO2 project. In addition, it has resulted in successful workovers, identification of waterflood improvements, and better plans for future CO2 projects.

A team building approach, involving "in-house" reservoir management forums/workshops, has also been employed. The main objective of the workshops has been to facilitate communication among engineering, geology, geophysics, and operations staff. Synergistic recommendations for project improvement have been a mutual outgrowth of these forums.
Horizontal Well Planning—Build Curve Design
Authors: Schuh Frank J.
Published: December 2007

The goal of most horizontal drilling projects is to place a long horizontal hole in a narrow vertical target. To accomplish this objective in the most economical manner, requires a build design that will hit the target without numerous bottom hole assembly changes and a rig that can handle the torque and drag loads produced by the drillstring in the horizontal hole. This paper describes several methods for designing the build curve that offer improved methods for hitting a small horizontal target while using a single bottom hole assembly for the angle building portions of the hole. The paper also presents a novel method for estimating the torque and drag forces for typical drillstrings in a horizontal hole.
Sensitivity to Gridding of Miscible Flood Predictions Made With Upstream Differenced Simulators
Authors: Stalkup F. I. , Lo L. L. , Dean R. H.
Published: December 2007

This paper examines the sensitivity to gridding of first-contact miscible and three-component multicontact miscible condensing-gas drive predictions made with an upstream differenced simulator. These cross-section simulations are made for various reservoir descriptions and for models of increasing numbers of grid blocks. The largest models range from 5000 to 24,000 grid blocks. The paper examines gridding sensitivity when the coefficients of convective terms are evaluated by the single-point upstream method, and it also examines the utility of two-point upstream weighting and selectively refined initial gridding for moderating gridding sensitivity.

These simulations show the following behavior. For some problems with single-point upstream weighting, ultimate recovery changes monotonically with an increasing number of grid blocks. The change in recovery with increasing grid blocks can either be a decrease or an increase depending on the particular reservoir description, although decreasing recovery was the most common behavior for the reservoir descriptions examined here. Two-point upstream weighting and selectively refined initial gridding reduced, but didn't eliminate, this sensitivity. Some predictions appear to converge almost linearly with grid size to approximately the same answer in the limit of zero grid block size (i.e., infinite grid blocks) when the problem is worked in different ways, e.g., single-point weighting, two-point weighting, selectively refined initial gridding. Other problems, however, do not appear to be converging for the largest models that were feasible.

Addition of physical diffusion/dispersion of a magnitude that might occur in reservoirs didn't affect the gridding sensitivity for two of the three reservoir descriptions examined, at least not for grid sizes that were feasible. However, for one reservoir description, recoveries computed with and without physical diffusion/dispersion appear to be diverging with grid refinement.
Effects of Endpoint Saturations and Relative Permeability Models on Predicted Steamflood Performance
Authors: Kumar M. , Do T. N.
Published: December 2007

A comprehensive numerical study was conducted to quantify the effects of endpoint saturations and relative permeabilities on steamflood performance for a heavy oil reservoir. Results show that the region most important for performance prediction is the high-temperature, gas (vapor)-oil relative permeability near the residual oil saturation (Sorg). Furthermore, gas-oil relative permeabilities should be measured at steam temperatures because gas displacement occurs at steam conditions. For the water-oil system, irreducible water saturation (Swir) has a greater effect on performance than residual oil saturation to water (Sorw) and the effect of temperature-dependent endpoint saturations is small.

The linear interpolation model (SPE 17369) for three-phase oil relative permeability is preferable over the Stone's II model because it more accurately predicts residual oil saturation to steam. "Practical" endpoint oil saturations are adequate for performance prediction because very low values of oil relative permeability do not significantly affect recovery calculations. A 15% change in Sorg, Swir, and Sorw resulted in a 26, 13, and 7% change in cumulative oil recovery, respectively.
Reservoir Surveillance Impacts Management of the Judy Creek Hydrocarbon Miscible Flood
Authors: Pritchard D. W. L. , Georgi D. T. , Hemingson P. , Okazawa T.
Published: December 2007

Gravity segregation between water and a hydrocarbon based solvent during miscible flooding has been observed at the Judy Creek Beaverhill Lake (BHD ‘A’ Pool tertiary flood. The solvent override results in bypassing of potential miscible reserves and decreases ultimate oil recovery. An effort to improve overall pool economics through maximizing oil recovery and more efficient solvent utility was sought. A vertical sweep pilot was undertaken to identify optimum pattern sizes by defining the shape and size of the solvent-water comingled region in the reservoir. It was found that the gravity segregation model defined by Stone(1) was representative of the solvent-water comingled zone. A reduction in pattern size was seen to improve tertiary oil recovery levels. This has bolstered a pattern reconfiguration scheme to maximize ultimate oil recovery from the field.
Thermal Stability of Scleroglucan at Realistic Reservoir Conditions
Authors: Kalpakci B. , Jeans Y. T. , Magri N. F. , Padolewski J. P.
Published: December 2007

Thermal stabilities of scleroglucan and two xanthans were determined at 93, 100, and 105°C with and without additives. Aging times varied from 280 to 720 days. The polymers were dissolved in 30,000 ppm TDS seawater with an adjusted pH from 4.5 to 7.5.

Scleroglucan exhibited excellent thermal stability. Under certain test conditions, it lost little or no viscosity at 100°C over 720 days, and only 10 to 20 percent of the original viscosity at 105°C for over 460 days. In contrast to scleroglucan the xanthans were less stable. Depending on the source of the xanthan and the test conditions, viscosity losses varied from 10 to over 90 percent. The triple helix structure of scleroglucan may be responsible for its superior thermal stability.
Foams as Mobility Control Agents for Oil Recovery by Gas Displacement
Authors: Llave F. M. , Chung F. T-H. , Louvier R. W. , Hudgins D. A.
Published: December 2007

Experimental studies were conducted to facilitate understanding of the behavior of foam flow and its application in gas flooding processes. This paper presents the results of studies that involved: (1) foam flow behavior in smooth capillary tubes and packed glass tubes; (2) effects of changes in injection rates on foam performance; (3) effects of foams on unsteady state gas-liquid relative permeabilities; and (4) effects of foams on improving gas sweep efficiency.

The apparent viscosities and mobilities of foams flowing through smooth capillaries and packed glass tubes were measured. The experiments were designed to observe and quantify the behavior of foam under various conditions including foam quality, shear rate, surfactant concentration, and temperature. The bubble size distribution of pregenerated foam was measured to determine the contribution of foam texture to its flow behavior. Experimental results were evaluated using available mathematical models developed for predicting apparent viscosities of foam in smooth capillary tubes and packed glass tubes.

Coreflooding experiments were conducted to evaluate effects of variations in injection rates on foam performance as a mobility control agent. Results of the experiments showed that higher injection rates of nitrogen displacing a surfactant solution resulted in foam generation that contributed to a significant increase in sustained pressure gradient across the core. The unsteady state method was used to study the effects of foam injection on gas-liquid relative permeabilities and improving sweep efficiency in Berea sandstone cores. The presence of foam resulted in a significant reduction of the permeability of the core to gas. The ability of a foam of known texture to sustain differential pressures across a core in the absence of flow was also determined. Using a parallel coreflood setup, fluid flow was preferentially diverted from a high-permeability core to a low-permeability core.
History Matching of a Heavy-Oil Combustion Pilot in Romania
Authors: Petit H. J-M. , Le Thiez P. , Lemonnier P.
Published: December 2007

Many papers have been published in recent years on the numerical modeling of in-situ combustion. They have mainly dealt with numerical formulations, but very few have been devoted to field history-match, especially concerning heavy-oil.

Among the fields exploited by in-situ combustion, Suplacu de Barcau in Romania, with its very high-viscosity oil (2000 mPa.s at reservoir conditions), offers an interesting case for bringing out the main difficulties encountered during history-matching with a 3D in-situ combustion simulator.

This paper describes the different phases of the numerical study made on the initial 5-spot pattern using a compositional thermal model. An effort was made to simulate the reaction aspects in radial geometry (ignition phase and propagation of the combustion front) and then to perform 3D match of production data.

The different choices concerning the description of the reservoir, the definition of the kinematic parameters related to the laboratory tests performed and the numerical parameters are described. In spite of various uncertainties as to the pilot test data and the reservoir description, it was possible to: (1) obtain very good agreement for the propagation of the combustion front and the temperature distribution; and (2) reproduce the oil and gas production curves and the injection pressure.
An Evaluation of Cubic Equations of State for Phase Behavior Calculations Near Miscibility Conditions
Authors: Danesh A. , Xu Dong-Hai , Todd A. C.
Published: December 2007

The paper presents results from vapour-liquid equilibrium experiments simulating gas injection processes, using 25-component fluids as black and volatile oils. Gases were added to the oil to approach the system to the critical point (miscibility) and the volume, density and compositions of equilibrated phases were measured at various levels of pressure and added gases. The measured near miscibility data as well as pertinent literature data have been used to evaluate the reliability of EOS modelling. It is shown that whilst certain EOS are capable of predicting the phase behaviour at these conditions, others, including some widely used equations, can give unreliable results. The predicted volumes of equilibrated phases are shown to be particularly inaccurate with deviations over 100%. A volume translation method, based on equilibrium ratios, has been proposed to improve the predicted phase density for mixtures near critical point. The significance of input compositional and volumetric data for accurate phase behaviour prediction near miscibility is demonstrated.
An Expert System for Casing String Design
Authors: Jellison M. J. , Klementich E. F.
Published: December 2007

This paper describes the design and implementation of a rules-based expert system for casing string design. The expert system functions as a front end to a sophisticated, technically-robust tubular design and analysis model which is capable of generating a minimum cost-safe casing string design considering both API load capacity and von Mises equivalent stress-intensity criteria. Consequently, the extensive input parameters required for such a computer model are greatly reduced.

Based on a limited number of input parameters, the expert system generates service conditions which depend on the function of the casing string – conductor, surface, protective, production, etc., design criteria including material grades and connectors, and hole diameters for buckling considerations.

General well information provided by the designer to the expert system consists of the well type – Exploratory or Development, to set the gas kick tolerance, the geology type – hard rock or recent sediments, to set the fracture gradient parameters, and the drilling environment – onshore or offshore, to adjust the fracture gradients and set the design criteria.

After execution of the expert system, the designer can either transparently let the casing model design the string or review the data created by the expert system. Of course if desired, the user can modify, delete, and/or add additional parameters to the casing model created with the expert system.

The benefit to the user of the expert input system for casing string design is a rapid and consistent generation of the standard input parameters for the sophisticated structural design and analysis program, allowing the well designer more time for actual well planning and review functions.
A 3D Integrated Structure for Computer-Aided Reservoir Characterization
Authors: Touffait Y. , Beucher H. , Guerillot D.
Published: December 2007

An accurate understanding of the internal architecture of a reservoir is required to improve oil recovery forecasts.

This article describes a software which gives 3D images of this architecture using conditional geostatistical simulations and provides tools to study the influence of these lithological descriptions on fluid flow behavior.

This software establishes the link between wells data and fluid flow reservoir simulators. Each step of this interactive and graphic system is explained here: –geological and geostatistical analysis to characterize a suitable model for the following steps,–conditional geostatistical simulations giving a lithological description of the internal heterogeneities on high resolution grids,–quantification of the reservoir assigning petrophysical values to each lithofacies grid cell (porosity and absolute permeability tensor),–scaling up methods computing in a cost effective way the averaged petrophysical values associated to reservoir simulator grid cells.

This new software concept which integrates multidisciplinary methods helps production geologists, geostatisticians, applied mathematicians and reservoir engineers to work in the same environment.
Bluepack 3-D and Its Use in the Petroleum Industry
Authors: Renard R. D.
Published: December 2007

It is now 15 years since the first research version of BLUE-PACK 3-D was developed at the Centre de Geostatistique of the Paris School of Mines in Fontainebleau (France). It has taken 15 years time to test and adapt the results of Prof Matheron's works to the industrial world. Today BLUE-PACK 3-D is considered as the leading product for applied geostatistics by the major petroleum companies as well as major institutions in other fields of Earth Resource Management such as oceanography, hydrogeology, forestry, dredging, mining… The purpose of this paper is to review the features included in the latest version of the package (Release VI) and to illustrate how it is used for kriging (i.e. estimation) and for simulating spatially distributed variables.
Petroleum Computing in the 1990's: The Case for Industry Standards
Authors: Schwager R. E.
Published: December 2007

The petroleum industry has reached a point where significant breakthroughs in future computer-related productivity gains are constrained by currently implemented computer systems and applications software. This paper discusses in detail the problems associated with these existing petroleum software systems, leading to specifications for enhancements and the relevant industry standards required to solve those problems. In addition, the pros and cons of a "multi-company consortium" will be weighed as the most cost-effective means of developing a true petroleum industry standard for technical computing.
Fully Implicit Black-Oil Simulation on Personal Computers
Authors: Qi Y.
Published: December 2007

For many difficult reservoir simulation problems, the fully implicit black-oil models are the only efficient and viable means to the solution. Because of their stringent demands on computer's power, the fully implicit simulators are generally run on mini, main or super computers. However, the current trend of 32-bit microprocessors being used in the main-stream Personal Computers(PC) opens a new horizon for reservoir simulation applications. This paper examines the feasibility of a fully implicit black-oil simulator run on these PCs. The simulator uses a general black-oil formulation and can solve 3-dimensioual. 3-phase problems with multi-layered wells.

Two aspects which affect the applicability of personal computer environment in reservoir simulation are addressed. First, various considerations for model's efficiency in program design and coding are discussed. Second, the model's performance and requirements on different PC systems are compared. The calculation examples show that the fully implicit black-oil model presented can be run efficiently on the current i386 type of PCs for problems up to several thousands grid blocks. For putting the advances of personal computer environment in perspective, some runs made on the new IBM RISC/6000 320 desktop are also presented.
Two-Phase Linear Fluid Flow Modeling for In Situ Combustion
Authors: Thurnau D.H.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Background

Considerable experimental and theoretical effort has been devoted to understanding the heat flow and stoichoimetric problems associated with the underground combustion process of oil recovery. Results of these efforts have been vital to success in the engineering of field applications of underground combustion.

Continued success in applying this process to diverse petroleum reservoirs would be aided by a quantitative understanding of the associated fluid flow phenomena. Semiquantitative notions about the oil displacement mechanisms and the nature of the "oil bank" are presently employed in the evaluation of underground presently employed in the evaluation of underground combustion prospects. A quantitative delineation of the fluid flow aspects would facilitate better engineering predictions of:

Injectivity history (compressor requirements), Sweep pattern, Fuel content dependence on air flux.

A reasonably complete theoretical treatment of the in situ combustion process would require simultaneous solution of the heat flow, distillation, and three-phase fluid flow problems. Further, this should be done for a multidimensional medium which is not necessarily homogeneous or isotropic. While it is perfectly feasible to develop the necessary equations for such a model, their general solution was much too ambitious an undertaking for the computing capacity available when this work was begun.

We therefore confined this effort to exploring the numerical methods required and to becoming familiar with the displacement mechanisms that would be evidenced in the solution of a greatly simplified mathematical model. Specifically, the following restrictions were adopted:

Two-phase fluid flow (oil and air only). No distillation effects. Temperature profiles obtained from an independent study of the associated heat-flow problem.

To provide a basis for evaluating the results of the model study, a special laboratory tube run experiment was conducted. Here the sandpack was initially saturated with oil only, omitting the usual "connate" water. During burning, the only water present was the water of combustion. The experiments were conducted under psuedo-adiabatic conditions for which temperature distributions are known.