bluuebunny/crossref_metadata_2025 huggingface dataset:
The Range of Application of Reservoir Monitoring
Authors: Breitenbach E. A. , King G. A. , Dunlop K. N. B.
Published: December 2007

Reservoir monitoring is a new and emerging technology. It is the application of multiple surveys of reflection seismic integrated with reservoir description and reservoir simulation to track the movement of fluid Saturations in a reservoir.

Reservoir monitoring includes both the measurement of the past and current location of fluids and the prediction of how the fluids will move in the future. This breakthrough in technology is possible through the integration of several disciplines and the focus of each of these disciplines on the reservoir being monitored. Accurate monitoring of the interwell position and movement of fluids in a producing hydrocarbon reservoir can yield major economic benefits through, for example: avoidance of premature breakthrough, optimal placement of infill wells by accurately defining areas of high hydrocarbon saturation, measurement of cone development before coning into a producing well occurs, and other similar improvements in field development.

Seismic response to original fluid contacts has been observed in many fields and reported previously. Recent field experiments, based upon past research, has further shown that a differential technique using repeated seismic surveys, reservoir description, and reservoir simulation is capable of discerning moving oil-water fronts in a reservoir.1 Due to their experimental nature, these field studies have necessarily been conducted under almost ideal conditions for shallow, well defined reservoirs.

In this paper we address the concept of reservoir monitoring and how it is performed. In addition, we address several of the technical issues controlling the success of this technology when applied to the complex reservoirs found in practice and explore the economic justification for applying the technology.

It is concluded that many more reservoirs are potential candidates for reservoir monitoring than previously predicted.

It is further concluded that reservoir monitoring provides a substantial economic return. Guidelines are presented for the range of reservoirs which might benefit from reservoir monitoring.
Petroleum Engineering Manpower Supply Remains Low
Authors: Bourgoyne A. T. , Ghalambor A.
Published: December 2007

The purpose of this paper is to report the results of the Supply Survey conducted annually by the SPE Manpower Committee. The 1988-89 academic year survey was sent to educators from the 30 U.S. schools listed in the Petroleum Engineering and Technology Schools book published by SPE. Twenty-five of these schools offer degree programs in petroleum engineering and five offer options in petroleum engineering within another engineering degree program. Nineteen of the 30 schools, which accounts for about 86% of the U.S. enrollment responded to the survey.

The survey asks each school to report the number of graduates during the 1988-89 academic year at the B.S., M.S., and Ph.D. levels. The number of non-citizens included in these graduates and the number seeking employment in the U.S. job market are also reported. For those graduates who have reported to their school that they have found employment, the type of employer is requested. The following six employer categories are used:
Engineering Salary Trends in the Petroleum Industry
Authors: Lancaster D. E. , Brown D. C.
Published: December 2007

Results of the October 1988 SPE Member Salary Survey indicate an increase of about 4 to 5% in salaries received by SPE Member over salaries reported in October 1987. Results of the 1989 SPE Starting Salary Survey reflect an increase in starting salaries accepted by B.S. graduates in petroleum engineering to $2,900/month. This figure is up 5.5% from a year ago and is the largest increase in starting salaries since 1982.
Emergency Preparedness Training on Offshore Installations
Authors: Brooks K. C.
Published: December 2007

In light of recent accidents offshore, training in Emergency Procedures onboard Offshore Installations continues to receive major focus.

Just recently, the United States Coast Guard issued regulations regarding Emergency Evacuation Plans for Manned OCS Facilities. The current regulations regarding licensing of key personnel on Mobile Offshore Drilling Units (MODUS) is also focusing on the level of training supervisory personnel have in the way of Survival Craft, Stability, Firefighting and Well Control.

This paper will detail the elements of a course called "Emergency Preparedness Training" and the process of how it is conducted onboard Offshore Installations. The initial concept was developed jointly by Reading & Bates and a major oil company in an effort to heighten the awareness that an emergency can occur at any time and that response time is critical. Since the initial conception of this course, some changes have been made but the goals of the course have remained the same. These goals are as follows: Define the Rig Specific Emergency Organization of the Installation.Emphasize the need for realistic drills and show the importance of working through scenarios prior to an Emergency.Conduct major compartment surveys to assist personnel onboard learn how to fight compartment emergencies with available systems and equipment which are rig specific.Understand the capabilities and limitations of emergency equipment onboard and understand what type of back-up equipment is available should problems occur to first line defenses.

The course consists of approximately eight hours (two hours each day). Appropriate videos, class exercises, lecture, a workbook supplied by Exxon Production Research Company and "hands on" training is emphasized in the course.
A New Rock Bit Bearing Provides Superior Cone Retention
Authors: Pearce D. E.
Published: December 2007

A new bearing design was developed using a large threaded ring member to improve cone retention on rolling cutter rock bits. The new design has alleviated the risk of lost cones in over 1200 field applications by providing superior retention compared to bits with other cone retention systems.
Rigsite Well Control Training Pays Off
Authors: Stone M. D.
Published: December 2007

The need for effective training of rig personnel in kick detection and well control is widely accepted. However, while many supervisors and toolpushers receive MMS-Certified training of this type, a need exists for training drillers and roughnecks that are involved primarily in turnkey drilling operations on small and medium size land rigs.

These crews are the first line of defense against blowouts. They are constantly in the best position to observe the signs of impending trouble. Therefore, if possible, training programs should meet their needs at their rig site.

A customized, semi-annual, rig site training program was developed in conjuction with the University of Houston at Victoria to provide this training. A preliminary discussion of this program was presented in 1986 in the Drilling Contractor magazine.

The program has been successful and has been premanently retained. This paper will expand on details of the program, describe the introduction of computers for training purposes, and present results of how several kicks have since been routinely handled.
Case History Analyses of Shallow Gas Blowouts
Authors: Adams N. J. , Kuhlman L. G.
Published: December 2007

Blowouts have different characteristics for each situation that require a case-by-case analysis to develop the most appropriate control techniques. Shallow gas blowouts, which are the most common type of blowout, follow the same rule requiring a diagnosis for each case.

However, experiences gained from working on shallow gas blowouts during recent years and a study of other shallow events have shown important similarities in causes and probable results. If applied properly, these similarities can be used to avoid shallow gas blowouts or develop appropriate response plans.

Specifically, our work has shown that many shallow gas blowouts have some relationship to the cementing operations. Also, the paper discusses the details of several case histories (without specific references to the operator or the locale). Since most shallow gas kicks result in a blowout, an additional objective of the paper is to present emergency response procedures for personnel and rig safety. Information is provided which includes drilling procedures, equipment selection guidelines, response of various types of rigs in shallow gas blowouts and a discussion on nser/riserless drilling.
Early Automatic Detection of Drillstring Washouts Reduces the Number of Fishing Jobs
Authors: McCann D. P. , Arnold M. , Burgess T. M. , Curwen S. C.
Published: December 2007

Rapid detection of unexpected drilling events requires monitoring of drilling parameters. The introduction of a computerised monitoring system has led to the development of displays and intelligent alarms designed to help drilling personnel detect and observe events before they would normally be apparent. This paper describes an automated system which detects the early stages of drillstring washouts. Field results demonstrate the effectiveness of this intelligent alarm. Early detection allows the driller to react before failure of the drillstring results in expensive fishing operations.
Successful Deep Liner Cementing in South Texas
Authors: Rae P. , Roemer R. , Kirksey J.
Published: December 2007

In parts of South Texas, the cementing of long drilling and production liners has long been one of the most challenging aspects of well completion. High formation pressures require mud and cement weights that approach the equivalent fracture gradient of the exposed open hole interval. Very low pump rates and excessively long job times have been common due to the constraints imposed by tight annular clearances and the use of heavy, viscous cement slurries.

Another problem associated with these wells is the temperature gradient in this area. Geothermal gradients of 2 deg.F / 100 ft. create large temperature differentials from liner top to bottom, even with liners of only moderate length. Consequently, developing TOL compressive strength and adequate seal at the liner lap has been difficult with the cement retarder concentrations necessary for bottom hole conditions.

Positive and/or negative differential pressure tests are normally used to evaluate these jobs and, in many cases, results have been poor. Since these wells are subjected to hydraulic fracturing upon completion, the integrity of the cement sheath is essential and squeeze work must often be performed to achieve good zonal isolation.

A new design approach has significantly reduced the problems associated with cementing these wells. This approach centres on the careful selection of spacers and the use of highperformance cement slurries. Desirable properties of the latter include very low fluid-loss and exceptional fluidity (low rheology) without development of free water or sedimentation.

Early compressive strengths of these systems are also superior to those of the systems used historically in this area. Case histories from several wells are used to demonstrate the success of this approach.
A Mechanical Stability Log
Authors: Bruce S.
Published: December 2007

The mud weight at which lost circulation occurs depends critically on hole deviation. Similarly, collapse of a high angle well may occur with a mud weight which would provide adequate support in a vertical hole. For this reason, a Mechanical Stability Log (MSL)1 has been developed which, for a given well plan, calculates the range of mud weights which could be used for drilling that well without causing lost circulation or hole instability problems (eg sloughing or caving). It must be noted that chemical effects are not considered: that is, lost circulation or hole instability problems are assumed to have purely mechanical origins.

The MSL uses wireline logs obtained in wells drilled in the vicinity of the planned well as input data. Ideally, density, gamma ray, compressional sonic and shear sonic logs are used. If all of these are not available estimates of "safe" mud weight can still be obtained although with less reliability.
A Full-Scale Wellbore Friction Simulator
Authors: Quigley M. S. , Dzialowski A. K. , Zamora M.
Published: December 2007

An operational wellbore friction simulator (WBFS) utilizing full-scale components for measuring drillstring torque and drag in simulated high-angle holes is described. The 15-ft long test section accommodates 8.5-inch (216-mm) to 12.25-inch (311-mm) ID permeable and cased wellbore inserts. Drilling and tripping operations at angles of 45-90° from vertical are simulated by moving a full-scale tool joint along a 4.0- inch (102-mm) diameter drive shaft. Axialvelocity 0-110 ft/min (0-0.559 m/s) and rotational speed 0-165 rpm represent typical field conditions. The wellbore insert can be pressed against the tool joint with a contact force up to 1000 Ibf (4448 N).

The WBFS was used to study effects of six operating factors on friction coefficients of unweighted lignosulfonate mud with and without a lubricant. Simulated cuttings beds were added for half of the tests. Effects of cuttings beds on friction coefficient were unexpected. In WBFStests, cuttings beds composed of crushed coal slag reduced friction coefficient. Results from large-scale WBFS tests with bare wellbore generally agree with results from certain small-scale lubricity tests. The WBFS results clearly show benefits to using top drives which allow rotation while tripping.
Horizontal Drilling Enhances Production of Austin Chalk Well
Authors: Slayton R. J. , Peach S. R.
Published: December 2007

TheG. W. Hatch No. 1 Well in Pearsall Field, Dimmit County, Texas, was proposed to achieve horizontal penetration in the Austin Chalk formation. Pinnacle Royalty and Operating Company, Inc. (PROCO), the independent operator of the well, elected a conservative long-radius approach that allowed the use of steerable positive-displacement motors (PDMs). The use of steerable motors resulted in a smooth wellbore, relatively low torque and drag forces while drilling the horizontal reach section of the well, and the ability to steer the wellbore to total depth.

Casing was set after the. first build section was completed into the top of the Austin Chalk formation in order to minimize hole problems and permit handling of any anticipated well kicks.

The 1253-ft horizontal section, drilled in underbalanced conditions, positively identified producing fracture systems while minimizing the formation damage that typically results from ongoing drilling operations.

Drilling continued horizontally in an underbalanced state, although occasional flowing conditions did occur, using both rotary and slide modes of steerable drilling.

Special surface production systems were utilized to handle well flow during drilling operations. The design and field operations of this equipment were critical to the safety and success of the project. Detailed planning prevented problems during actual operations.

Initial tests indicate production rates of 1600 bopd, a significant increase in production from adjacent vertical wells, making the G. W. Hatch No. 1 an economically viable project.
Pore Pressure Analysis Indicates Abnormal Pressure as Reason for Shale Instability in Offshore California Field
Authors: Barron J. G. , Weakley R. R. , Haas M. A.
Published: December 2007

A pore pressure analysis was conducted for an offshore California field which indicated that abnormal pressure in a shale section was the reason for hole instability problems in this area. Previously, the common belief was that the chemical reactivity of the shale caused the instability.

The wells were encountering a thick shale section which caused considerable drilling problems due to sloughing shale and eventual stuck pipe. The shale section was sandwiched between two permeable intervals that were normally pressured. The question presented was: Can a thick shale section be abnormally pressured even though normally pressured formation lie just above and below?

This paper illustrates a technique of creating a pore pressure overlay for the general geographic area to determine if the shale section could be abnormally pressured. Since conclusive abnormal pressure data from the subject area did not exist, known abnormal pressure data from a nearby field was used for the pore pressure overlay development. The similarity in the overburden gradients and depositional environment between the two fields is what made this analysis feasible.

The pore pressure analysis clearly defined the thick shale section as being abnormally pressured. Based on the predicted pore pressure schedule, mud weights in the subsequent well were increased and the well was drilled to TD without problems. The shale instability problems, which had plagued this field In the past, were not evident.
Simulation of a Single-Well Injection/Production Steamflood (SWIPS) Process in an Athabasca Tar Sand
Authors: Duerksen J. H.
Published: December 2007

The simulation of a single-well injection/production steamflood (SWIPS) process in an 80 ft (24 m) thick Athabasca tar sand shows a favorable production response from a 152 ft (46 m) drainage radius (1.67 acre or 6,757 m2 well spacing) at a depth of 450 ft (137 m). After 10 years of steam injection, cumulative bitumen production and steam/oil ratio were: (1) 192,800 bbls or 30,650 m3 (62.8% of OOIP) and 3.8 for a homogeneous reservoir; (2) 134,300 bbl or 21,350 m3 (46.6% of OOIP) and 4.4 for a heterogeneous reservoir; (3) 130,680 bbl or 20,780 m3 (45.4% of OOIP) and 4.1 for a heterogeneous reservoir with vertical permeability constraints; and (4) 125,900 bbl or 20,020 m3 (46.8% of OOIP) and 4.7 for a heterogeneous reservoir with a 5-ft (1.5 m) bottom water layer. The application of the process at shallower depths (150 ft or 45.7 m) just beyond the maximum depth for surface mining is limited by the constraints on steam injection pressure and temperature. The best predicted performance with the producer pumped off was 46,660 bbl or 7,420 m3 of bitumen (15.2% of original oil in place (OOIP)) and a steam/oil ratio of 3.6 after 10 years of steam injection.
Evaluation and Treatment of Organic and Inorganic Deposition in the Midway Sunset Field, Kern County, California
Authors: Bilden D. M. , Efthin F. P. , Garner J. J. , Pence T. C. , Kovacevich S. T.
Published: December 2007

The Midway Sunset Field is the 2nd largest oil producing-field in the state of California. Current production is approximately 155,000 barrels of oil per day -from 9,200 wells. Due to variable productivity exhibited by wells in this field, an extensive study was conducted to determine potential production impairment mechanisms. This study was accomplished by analyzing cores, produced fluids and the organic deposition found in and around the slots of liners pulled from two wells.

The reduced productivity exhibited by these wells was determined to be due primarily to the deposition of organic and inorganic components in the liner slots. This deposition can be associated with the asphaltic properties of the crude, the unconsolidated nature of the formations and the use of Thermal Enhanced Oil Recovery techniques. Quantitative and qualitative studies were performed to evaluate the damage and generate an operationally feasible and cost effective treatment. This investigation resulted in the design of a unique treatment and placement technique.

Production response is presented from 35 wells included in this ongoing stimulation program. Candidate selection criteria and related stimulation performance are also discussed.
Quality Control Assures Successful In-Situ Internal Pipeline Coating Operation: A Case History
Authors: Hagood D. S. , Choate L. C.
Published: December 2007

In situ applied internal pipeline coatings are used to control internal corrosion, rehabilitate existing pipelines and improve flow efficiency. Internal coatings are applied to product pipelines, flowlines, water injection lines and any other lines that are subject to internal corrosion. Internal coating operations originated in the 1940's and have been performed until the present with varying degrees of success. present with varying degrees of success. Although improvements have been made in the coatings as well as in cleaning and application procedures, quality control is recognized as the primary factor determining the success or failure of an in situ internal coating operation. This paper describes the quality control procedures and equipment which were recently employed to insure the successful coating of a 4-inch, 14,000 foot sour service flowline in Tunisia, North Africa.

Quality control procedures were applied from initial pipeline design through the construction and coating phases of the project. The measures implemented are listed project. The measures implemented are listed and described below as they were applied either pre-construction or post-construction.

PRE-CONSTRUCTION PRE-CONSTRUCTION 1. The pipeline was designed for ease of pigging.

In situ internal coating operations rely on the use of multiple pig trains to clean, dry and coat the pipe wall; therefore, it was necessary to design the flowline for ease of pigging. The flowline diameter was held constant while sharp bends and changes in elevation were avoided. A bend radius of five pipe diameters was utilized.

2. Mill applied coatings were avoided.

No mill varnish or oil was applied to the internal or external pipe wall after manufacture. Any coating intentionally or inadvertently applied to the inner pipe wall would require removal prior to coating.

3. The proposed coating was tested for suitability to the expected service.

The coating to be used was tested under the anticipated operating conditions to verify its suitability. Adhesion and resistance to abrasion were the primary concerns.

POST-CONSTRUCTION POST-CONSTRUCTION An internal coating operation consists of cleaning, drying and coating the pipe wall. A portable laboratory was mobilized to the work location in order to adequately monitor the critical parameters as discussed below. An inventory of the equipment in the portable laboratory is included as Attachment 1.

1. The chloride levels of the cleaning and rinsing water were monitored.

Chloride levels in excess of 400 ppm will have a tendency to cause coating disbondment; therefore, it was imperative to monitor the chloride levels in the water used for cleaning and rinsing the flowline prior to coating. The chloride content was determined by mercuric nitrite titration using a Hach Digital Titrator Model CD-DT.

2. The pipe was inspected for cleanliness prior to coating.

P. 596
Saturation Evaluation of Secondary Recovered Reservoirs
Authors: Hashem M. N.
Published: December 2007

Consider the case of a sand stone reservoir that has been under a water or steam flooding program, that was not efficient. A lot of effort is currently being done to evaluate and recover the oil that was left in the ground. As the flood fluid has now been introduced to the Reservoir element, it becomes very difficult to find the value of the water saturation as the salinity of the flood water is different from the original formation water, and involves a lot of coring and other expensive operations to come up with the value of Sw; water saturation.

The technique suggested in this paper finds the value of the saturation using logs, both old and new, that are available for that field, the old being the original resistivity logs and the new being the logs of the new well drilled and recorded after the flood.

This technique agrees very well with the saturation obtained by other methods including other logs such as the EPT log, and the core analysis results, within a tolerance of ± 7%.
Successful Installation of a Gas-Gathering System in a Waterflood Environment: North Riley Unit
Authors: Pietsch C. E.
Published: December 2007

Casinghead gas gathering systems are generally limited to low pressure reservoirs; however, they may also be used successfully in reservoirs under pressure maintenance. This paper discusses the theory, design, and results of an 82 well gas gathering system at the North Riley Unit, a Clear Fork reservoir under waterflood operations. The design of the system includes: 1) sizing the gathering lines, 2) isolating portions of the system, 3) modifying existing production wellheads, and 4) locating possible areas of liquid accumulations. Gas gathering has resulted in lower operating pressures of surface facilities, increased oil production, and increased downhole pump efficiency.
Using Short-Term Pressure Buildup Tests To Calculate Gas Reservoirs
Authors: Vu T. , Chen H. Y. , Poston S. W.
Published: December 2007

Static reservoir pressures are required for all gas material balance calculations. There are no techniques currently available for using isochronal, transient pressure buildup tests to estimate original gas in place.

A method to extrapolate the slope of a line generated from two or more isochronal or short-term pressure buildup tests to initial conditions to estimate gas reserves has been developed. Simulation as well as theoretical studies prove the technique may be applied to gas reservoirs with a permeability of one md or greater. However, the extrapolations become skewed for gas reservoirs displaying a permeability of less than one md. The isochronal test method may not be used with a high degree of accuracy for these low permeability reservoirs. The divergence of the extrapolations was found to be caused by the μc product term evaluated at a subsequent pressure differing significantly from the pc product term evaluated at static conditions. This pressure drawdown effect was found to only be significant in reservoirs displaying a permeability of less than 1 md.

Analysis of the fundamental concepts has formulated a relationship between the diffusivity equation and the material balance equation to account for changing fluid properties during pressure buildup. A method has been developed from these relationships to adjust the real time isochronal interval for the changing gas fluid properties. The adjustment technique permits the transient pressure, isochronal method to be applied to very low permeability reservoirs as long as the pressure is 1,000 psia or greater.
The Determination of the Static and Dynamic Properties of Nitrified Cements
Authors: Mueller D. T. , Franklin V. L. , Daulton D. J.
Published: December 2007

The process of foaming oil well cements entails the injection of a known quantity of nitrogen gas into a given volume of cement slurry and foaming agent. The amount of nitrogen injected at surface, to produce a foamed cement of a desired density in situ, is a function of the temperature and pressure conditions in the annulus where the slurry will reside when pumping ceases.

Pressure and temperature variations between the point of injection of nitrogen into the slurry and its final annular location create a system that will fluctuate in density, viscosity, volume, and rate depending on the downhole conditions at the moment of observation. This inherent variability in the gas fraction (quality) of a nitrified cement is an important engineering consideration since formations will be exposed to fluids whose dynamic properties are different than those anticipated when in place. These variances can profoundly impact the success of the cementing operation.

Mathematical solutions originally developed for foam fracturing treatments have been applied to nitrified cements. This paper provides a method of quantifying the dynamic and static properties of a nitrified cement at any point in its pumping history.
Breaker Concentrations Required To Improve the Permeability of Proppant Packs Damaged by Concentrated Linear and Borate-Crosslinked Fracturing Fluids
Authors: Brannon H. D. , Pulsinelli R. J.
Published: December 2007

The permeability of proppant-packs may be significantly damaged by the gelling agents used in hydraulic fracturing fluids. Several recent fracture conductivity studies have sought to quantify the damage caused by common fracturing fluids over a wide range of downhole conditions. However, viable approaches to reducing the proppant-pack permeability damage caused by these fluids have rarely been discussed.

Oxidative breakers have been well documented as being useful for degrading the viscosity of hydraulic fracturing fluids. Degrading the fluid to a non-viscous state was long thought to provide sufficient polymer degradation to minimize the proppant-pack permeability damage. Recent studies have illustrated that the permeability is significantly impaired by the concentrated polymer residue even though sufficient breaker concentrations have been added to effectively reduce the fluid viscosity.

This study is concerned with the determination of the concentrations of an oxidative breaker which are required to significantly reduce the proppant-pack permeability damage caused by concentrated aqueous hydraulic fracturing fluids. Long-term proppant-pack permeability testing was performed using a modified API-type fracture conductivity cell which permitted fluid loss through two low-permeability cores. The fluids which were evaluated were linear and crosslinked gels of natural guar and hydroxypropyl guar (HPG). The effective polymer concentrations were varied from 100 to 440 Ib/Mgal to account for concentration due to fluid-loss.

Test results indicate that elevated breaker concentrations can very effectively reduce proppant-pack permeability damage. The breaker concentrations required to show significant reduction in permeability damage were found to be strongly dependent upon the polymer concentration and the presence of crosslinker. An understanding of the relationships of these parameters and the resultant retained proppant-pack permeability can be very useful in the design of fracturing treatments or the prediction of well performance.
Pressure Transient Behavior of Vertically Fractured Wells in a Closed Square Multilayered Reservoir
Authors: Okoye C. U. , Oshinuga A. D. , Ghalambor A.
Published: December 2007

This study presents the application of a new analytical model for analyzing pressure transient data for wells intercepted by a finite-conductivity vertical fracture in a closed square multilayered reservoir using the concept of a dual-porosity system. The solution takes into account the effect of wellbore storage. Our specific objectives are twofolded: first, to estimate fracture half-length, fracture conductivity and to correlate multilayered (two-layered) solution with the single-layer solution; secondly, to verify the numerical solution with the analytical solution. A set of asymptotic analytical (early-, intermediate-and late-time) solutions is also presented.

In addition, we developed constant rate drawdown type curves applicable for analyzing transient pressure data. These type curves are used to match drawdown and buildup curves to determine fracture half-length, reservoir permeability and fracture conductivity. The results obtained from our type curves indicate that if the reservoir conductivity is known or can be calculated from given data, the estimated values of the aforementioned parameters compared favorably with the value? of the designed parameter.

Although this study presents the solution to a twolayered system, it can be extended to a n-layered reservoir system.
Evaluation of Steam Resistance of Gravel Packing Material
Authors: Weaver J. , Knox J.
Published: December 2007

Carefully sized sand has been used for gravel packing for many years. With the advent of steam flooding it was observed that the pack sand disappeared from the well, The realization that sand was soluble in hot water gave rise to several studies which evaluated this problem, Common proppants and other materials were evaluated but no viable packing material was found.

This study compared the available packing material by flowing low quality steam through a cell containing the gravel. Ionic composition and concentration of the effluent were monitored throughout the flow tests. These data gave an indication of the mechanism of certain types of deterioration. Weight loss of the gravel with respect to flow volume was determined for each material. Micrographs of the packing material before and after the tests indicated that weight loss data was not sufficient for the selection of the preferred material.

Most of the aluminum oxide based materials were found to selectively dissolve and reprecipitate, forming potential permeability damaging fines. While much of the gravel remained, the fines were responsible for reducing the permeability of the pack. In some cases the test cell was plugged. Some of these fines are identified.

Several materials which are not commonly available as proppants were evaluated. One was found to withstand the harsh conditions of the hot water flow test with minimal weight loss and no fines formation. This material is now being evaluated as a gravel packing material in field trials.

It is readily available and inexpensive compared to the aluminum oxide materials. Acid solubility and crush resistance are similar to Ottawa sand but is slightly more angular.

This paper presents detailed results of the laboratory testing of the packing materials including photomicrographys before and after testing. Field results available will also be included.
Strength, Volume and Weight Loss of Gravels and Proppants Due to HF-Based Acids
Authors: Roberts S. S. , Binder M. S. , Lane R. H.
Published: December 2007

Acidization by HF-containing acids can drastically reduce both the physical strength of synthetic ceramic proppants and the permeability of gravel packs and propped fractures that utilize these materials. The strength of most acidized ceramics will decrease at a rate faster than implied by weight loss. It is therefore misleading to use weight loss as a measure of stability of ceramic proppants to HF-containing acid. Even seemingly mild acid treatments (low temperature and closure stresses) can have a negative impact on proppant strength and performance. Laboratory measurements on proppant acidized with HCl/HF acid at 176°F (80°C) and 64°F (18°C) verify major strength losses of synthetic proppants even under mild temperature conditions. These results are supported by observed degradation of intermediate strength proppant (ISP) recovered from an acidized well in a shallow, low-temperature formation.
Immiscible Fluid Flow Simulator
Authors: Breitenbach E.A. , Thurnau D.H. , van Poolen H.K.
Published: December 2007

This paper is on the MUFFS (internal program library name) computer program. It program library name) computer program. It also outlines potential applications in reservoir engineering. Actual uses range from small-scale studies of the basic fluid flow mechanics in particular circumstances to full-scale simulation particular circumstances to full-scale simulation of reservoir/aquifer systems. Potential applications in exploration, ground water, hydrology, and gas storage are also discussed.

Emphasis is placed on the versatility of MUFFS in studying a wide range of problems involving immiscible flow of one, two, or three phases in one, two, or three dimensions. Gross phases in one, two, or three dimensions. Gross effects simulation of processes is also possible. The problem solution is conducted internally in terms of a system of finite difference equations based on fundamental fluid-flow concepts and on reservoir data and well data furnished by the user. However, mathematical solution results can be viewed in engineering-oriented formats in tables and figures.

Some of the flexible input/output options of MUFFS are gained from auxiliary programs. Important among these is an economics program that may be used to analyze reservoir behavior predictions. The net result is an ability to make predictions. The net result is an ability to make combined engineering/economic forecasts of future reservoir performance.

Introduction

Petroleum reservoir engineering is a branch of applied science concerned with the quantity of fluid within rocks and the flow of such fluids through rocks. Reservoir engineering may be defined as the study of the microscopic and macroscopic behavior of multiphase fluid flow through porous systems (geometrically difficult to describe) and the application of the knowledge attained from such a study to the efficient operation of petroleum reservoirs.

With modern developments in computing numerical analysis, the practical solution of a large class of multidimensional problems has been possible, and hence the introduction of the reservoir model, mathematical model, and the petroleum or natural gas reservoir simulator. petroleum or natural gas reservoir simulator. A simulation model may be either physical or mathematical, and may represent the behavior of laboratory experiments, individual wells, or complex reservoir-aquifer systems. The simulator enables the engineer to examine and evaluate the physical and economic consequences of various alternative production policies.

Historically, the prediction of the performance of a new reservoir was based on the performance of a new reservoir was based on the knowledge of the performance of a depleted or nearly depleted reservoir with similar properties.
Optimization of Waterflood Performance and CO2-flood Design Using a Modeling Approach, Mallet Unit, Slaughter Field
Authors: Kuo M. C. T. , Dulaney J. P. , Deer M. W. , Evans B. S. , Granquist M. R.
Published: December 2007

The Mallet Unit, located in Cochran and Hockley Counties of west Texas, produces oil from the Permian San Andres dolomite as part of the larger Slaughter field. The Mallet Unit was evaluated for waterflood improvement and CO2 enhanced oil recovery. This paper discusses the modeling approach for optimizing the existing waterflood and designing a CO2-flood. Four components were found instrumental in achieving a reliable CO2-flood design. These four components are: (1) an Equation-of-State accurately matched with representative PVT data, (2) a reliable geological description validated by 23 years of waterflood history, (3) a compositional model which adequately describes the phase behavior and CO2 displacement mechanism, and (4) a valid scale-up technique for forecasting field-scale CO2-flood performance from pattern CO2-flood performance. With these four components, oil and CO2 production response forecasted from the compositional model and scale-up study were found to be in reasonable agreement with the field observation of a near by CO2-flood. This nearby CO2-flood has similar geology and fluids. Recommendations for waterflood improvement and CO2-flood design were made based on both black-oil and compositional simulation results.
Experimental Investigation of Drilled Cuttings Transport in Inclined Boreholes
Authors: Ford J. T. , Peden J. M. , Oyeneyin M. B. , Gao Erhu , Zarrough R.
Published: December 2007

This paper describes an experimental investigation into drilled cuttings transport in inclined boreholes carried out in the Department of Petroleum Engineering at Heriot-Watt University.

The paper describes how a 21 ft. borehole simulator and peripheral equipment built within the department has been used to determine the effects of various drilling parameters on the circulation rate required to ensure that the drilled cuttings in a deviated borehole are efficiently transported to surface.

The procedures used to conduct the experiments are fully explained and experimental results and observations are discussed.

Two distinctly different cuttings transport mechanisms were identified. The first occurs where the cuttings are transported to surface by a rolling/sliding motion along the low-side wall of the annulus and the second is where the cuttings are transported in suspension in the circulating fluid. The latter mechanism requires a higher fluid velocity than the first. Although these two mechanisms produce the same effect (to clean the hole) their response to variations in the drilling parameters investigated was significantly different.

The main conclusions from the experiments carried out to date are that the annular fluid velocity required to initiate cuttings transport with either of the two different transport mechanisms is sensitive to variations in hole angle but that the relationship between the required fluid velocity and hole angle is different for each of these transport mechanisms. The effectiveness of a circulating fluid in removing drilled cuttings is not only dependant on the rheology of the fluid but also on whether the fluid is in laminar or turbulent flow. Water in turbulent flow, can be a very effective cuttings transport medium. Pipe rotation had little or no effect on the fluid velocity required to transport the cuttings when circulating water but significantly reduced the fluid velocity required to transport the cuttings when circulating medium or highly viscous fluids. It should be noted however that these experiments were conducted on a relatively small annulus. The fluid velocity required to transport the cuttings is a function of the size of the cuttings.
Investigation of Barite "Sag" in Weighted Drilling Fluids in Highly Deviated Wells
Authors: Hanson P. M. , Trigg T. K. , Rachal G. , Zamora M.
Published: December 2007

Significant mud weight variations greater than 4 Ibm/gal have been measured in flowline returns when circulating bottoms up after trips. This phenomenon, called "sag", has preceded pack off, lost circulation, failure to get logging tools to bottom, stuck pipe, and other drilling problems on some directional wells.

Two key findings have emerged from an extensive project to investigate and minimize sag in highly deviated wells. First, the density variations are caused by the slumping of beds which form when weight material settles to the low side of the hole. Second, most of the bed formation occurs while the mud is circulating. Previous efforts to investigate sag have focused on static settling.

Case histories, results from laboratory flow-loop studies, and operational guidelines to minimize sag and its consequences are presented in this paper.
Specialized Shale Control Additives and Selective Drilling Fluid Design Prove Successful in Offshore Gumbo Environment
Authors: Bruton J. R. , Stamatakis E. , Pixley D. , Young D. B.
Published: December 2007

Drilling highly reactive gumbo shale sediments offshore in the Gulf of Mexico has been and currently still is problematic, particularly when drilling deviated wellbores. Borehole instability can result from erosion and dispersion of formation clays. Bit balling may induce high torque and drag, swabbing, and stuck pipe. The multitude of drilling fluid systems that have been used vary greatly, from simple 2 or 3-component to very complex systems containing a wide range of shale-control additives with differing chemistries. It is not uncommon that a particular fluid performs well in one area or on one well, but is not successful on the next well or in a different area.

A water-base drilling fluid system has been developed containing proprietary shale control additives coupled with a fluid selectively formulated to drill reactive formations. The additives analyzed and subsequently field tested possess dual functionality in both controlling shale swelling and limiting the tendency for the gumbo to stick or "ball up" bottom hole assemblies. A unique feature of these additives is that they do not alter the rheological properties of the fluid.

The design and application of the fluid has been an evolutionary process. Systematic laboratory testing of shale samples from the area to be drilled were analyzed and fluid formulations tested for inhibitive qualities. Once a formulation was selected, the system was field tested and further refinements were made to adjust the system chemistry for optimum performance. Over 25 wells have been drilled with the fluid showing exemplary performance. Borehole stability has been achieved and bit balling has been minimized or eliminated. Refinements to the original shale control additives utilized have created "second generation" materials to meet environmental concerns and provide more flexibility, particularly if used in other mud systems.

This paper describes the shale control additives, the fluid systems they can be used in, performance testing, and field results from several wells.
Conversion of Mud to Cement
Authors: Wilson W. N. , Carpenter R. B. , Bradshaw R. D.
Published: December 2007

A dependable method for converting drilling fluid into a cementitious slurry has been sought for many years. Recent advancements in copolymer technology have made it possible to introduce Portland cement directly into drilling fluid while maintaining control over the rheology of the resultant slurry. For purposes of brevity, converted drilling fluid as described herein will be referred to as mud-to-cement, or MTC.

Conversion of drilling mud into a cement slurry has several unique advantages. As examples, conversion of spent drilling mud reduces disposal costs. Secondly, the superior compatibility built into MTC significantly improves annular displacement efficiency by controlling the flocculation that normally results when drilling mud and cement contact. Thirdly, MTC makes the most benefit of manpower, equipment, time and materials by consolidating services at the rig site.

Consolidation of drilling mud and cementing technologies to cut costs while improving the quality of completions is the underlying topic of discourse in this paper. In addition to presentation of the slurry design process, laboratory data, mixing and handling concepts and case histories are discussed. Also, several important avenues of potential savings are suggested. Applications in a variety of locations using different types of completions have all been successful both operationally and from the standpoint of results.
Mathematical Modeling of Microbial Enhanced Oil Recovery
Authors: Islam M. R.
Published: December 2007

Microbial enhanced oil recovery (MEOR) is receiving renewed interest worldwide. Microbial enhanced oil recovery involves the injection and transportation of microorganisms into the reservoir followed by nutrients which act as in situ growth products. These bacteria act as either a mobilizing agent of residual oil or a plugging agent for selective plugging of an undesired reservoir zone. Even though the concept of MEOR activities is rather straight forward, field tests have often been dismal. One of the reasons for such failure has been reported to be the inability to set up proper field strategy. In order to develop a proper strategy, a reservoir simulator capable of predicting bacterial movement and reactions in an oil reservoir. Such a simulator has been nonexistent to-date. This paper presents formulation and results of reservoir simulation using microbial EOR.

The formulation developed in this paper describes microbial transport in multidimensional porous medium. This description is completed with a kinetic model of bacterial growth which leads to either bacterial plugging and mobility control or alteration of oil properties (reduction of oil viscosity, interfacial tension (IFT), etc.). Reservoir simulation results are given for different types of bacteria used. A Canadian heavy oil reservoir was used as the prototype for all numerical simulation results.