bluuebunny/crossref_metadata_2025 huggingface dataset:
ZADCO Pipeline System: Operational Experience
Authors: Heraiba F. A.
Published: December 2007

ZADCO operates three offshore fields and an onshore oil stabilization, storage and loading center. The facilities in these locations are linked by submarine pipeline network of a total length exceeding 90 0 Km; and sizes which vary from 4 to 48 inch (101-6 mm to 1219 mm).

The analysis of water and sludge samples collected in front of the cleaning pigs indicated possible corrosion in the network. On-line Inspection Survey by "Intelligent" Pig was carried out in the Main Oil Line to evaluate its condition. The survey indicated appreciable amount of metal loss in several locations in the line. As a consequence of these findings; it was decided to run similar surveys in other lines in the network.

The corrosion in the network can be attributed to both microbial effects and the separation of formation water in the low points of the pipeline.
Reservoir Engineering Experience in Horizontal Wells
Authors: Mitwalli Magdi , Singab Ali
Published: December 2007

Horizontal Drilling as a new technique is being used in the tight reservoirs of Upper Zakum Field as means of Productivity enhancement. This work is concerned with the reservoir engineering involvement in the selection of the Horizontal Well Location, calculation of expected productivity increase and the analysis of transient test data. The state of art is reviewed, different methods are evaluated and compared with field results. Problems encountered during the interpretation of three tests and areas of concern which need-still-further development are highlighted.
Compositional Simulation Study of Miscible Gas Injection Pilot Project
Authors: Alves F. B. , Mostafa I.
Published: December 2007

The tight F and D units of the Bu Hasa field, in onshore Abu Dhabi, have undergone limited production, and are considered good candidates for a miscible gas injection project.

A field pilot was implemented with the objective of evaluating the potential of miscible gas displacement as a secondary recovery mechanism in this tight carbonate formation. A compositional simulation model was built to describe the mechanism involved in the process, and to predict the pilot performance.

The Peng-Robinson equation of state was used with a 4 pseudo-components system, based on a 13 components formulation. It was tuned on PVT laboratory data, and produced a good match of experimental results of slim tube tests.

A 3D radial model was constructed to represent the pilot. Simulation results indicate the development and propagation of a miscible front.

After validation by field data, the model will be used to predict the performance of a miscible gas injection development scheme, extended to the whole reservoir.
Planning of a Horizontal Well Offshore Qatar
Authors: Nasrulla I. M. , Rana L. A.
Published: December 2007

The main objective of drilling this well was to test the potential of a horizontal well as a powered water injector on Arab D reservoir with the view of optimising on the number of water injectors in the main project of the Idd el Shargi field development.

The major objective of this paper was to examine the practical aspects of drilling this horizontal well. However, due to programme changes, the well was not yet drilled at the time of publication of this report. Nevertheless as the well is expected to be drilled by Dec. 1990, these aspects will be discussed at the SPE Middle East Oil Show (Bahrain 2-5 March, 1991).

This paper will therefore discuss the planning of this well utilising the large radius technique to drill approximately 1500 ft horizontally through the reservoir parallel to the reservoir strike, with emphasis placed on well Design/Casing Scheme, Bottom Hole Assemblies, Directional Surveying, Drilling Fluids, Electrical Logging, Liner Selection and Cementation.
Monitoring and Evaluation of an Immiscible Gas Injection Pilot in a Massive Carbonate Reservoir with a Strong Water Drive
Authors: Shahsavari D. , Dabbous M. K.
Published: December 2007

This paper describes the development, monitoring programs and evaluation methodology of a gas injection pilot project carried out in a fractured carbonate reservoir with a strong water drive. Immiscible gas injection was recognized as a potentially viable economic recovery process, and a gas injection pilot was initiated in the field. The reservoir contained an undersaturated, intermediate gravity oil with a recovery of less than 6 percent after 40 years of primary depletion. The major areas of performance that were monitored thoroughly during the gas injection pilot project were:

Production (oil, gas and water) Reservoir pressure H2S concentration of the produced gas Reservoir gas saturation and gas-cap advance

A numerical reservoir simulator was used to history match reservoir performance under gas injection, and to investigate operative reservoir mechanisms which had resulted in improved oil recovery. The results were also used to confirm the validity of assumptions made in the design and performance prediction of the pilot project. The importance of collecting accurate data during the monitoring phase of the pilot was recognized so that meaningful field expansion guidelines and economic evaluation parameters could be established with a reasonable level of confidence. Immiscible gas injection in this watered-out carbonate reservoir resulted insubstantial increases in oil production rates and is expected to double the recoverable reserves from the field.
Digital Processing of Satellite Images of Saudi Arabia
Authors: Sabins F. F.
Published: December 2007

At the request of Saudi Aramco, Chevron Oil Field Research Company digitally processed 40 images acquired by the Landsat thematic mapper system and several images acquired by the SPOT panchromatic system. The images were geologically interpreted to aid Saudi Aramco's exploration program in the region beyond the "Retained Areas" of existing production.

Image processing routines are grouped in the following major categories:

Image Restoration – correct for errors, noise, and distortions introduced while data are acquired, transmitted, and recorded. Image Enhancement – modify impact of the image on the interpreter in order to improve the expression of geologic features. Information Extraction – recognize and display specific geologic attributes of images.

Each processing category includes a number of programs that are employed in various combinations to produce images. The resulting images contributed significantly to Saudi Aramco's successful exploration program.
Geologic Interpretation of Satellite Images, Saudi Arabia
Authors: Wender L. E. , Sabins F. F.
Published: December 2007

Digitally processed Landsat thematic mapper images covering the Central Arabian Arch were interpreted to map both regional geology and local anomalies. Two typical local anomalies are described and illustrated. The Shaib Thamamah anomaly is a topographic depression that interrupts the regional dip slope on the upper member of the Aruma Formation (Cretaceous). The lower member of the Aruma Formation is exposed on the floor of the depression. Seismic data show that the Shaib Thamamah Anomaly is a structural terrace underlain by basement faults that grade upward into a gentle anticline. The Raghib Anomaly is a topographic re-entrant in the dip slope of the Sulaiy Formation (Cretaceous). Seismic data show a single fault at depth that grades upward into an anticline and a structural terrace. The Raghib 1 exploratory well was drilled on the local anomaly and the crest of the subsurface anticline; an oil field was discovered in the Unayzah Formation (Pennsylvanian and Permian age). These examples illustrate the importance of Landsat images for oil exploration.
Hydrogen Sulfide Cracking of Downhole Tubulars
Authors: Kermani B. , Martin J. W. , Waite D. F.
Published: December 2007

The appropriate choice of materials for well completions in sour fields is an important factor in the economic success of oil and gas activities. The choice is governed by mechanical properties, resistance to both corrosion damage and sulphide stress cracking (SSC), availability and cost. Resistance to SSC is often the principal factor affecting the choice of materials for H2S containing environments, since the occurrence of SSC can result in a catastrophic and potentially hazardous failure. This often necessitates the selection of highly alloyed, highly priced materials. Therefore, it is important to have a method of assessing candidate materials that leads to the most cost-effective choice being made.

An alternative approach has been developed in which the emphasis is put on failure prediction. This approach combines the results of constant extension rate tensile (CERT) testing with fracture mechanic assessments. On the basis of this approach a "fitness for purpose" evaluation of a range of materials has been undertaken, thus allowing the selection of the most suitable/cost-effective material for the intended duty. Furthermore, the present concept has led to a better definition of operational limits of tubular goods for sour service applications over a wide range of testing conditions.
Application Of The Number Concept To Determine Initial Oil-In-Place
Authors: Chatas A.T.
Published: December 2007

The Number concept is introduced to define the G-Number and attack the problem of determining initial oil-in-place. A particular solution, corresponding to a given order of particular solution, corresponding to a given order of differentiation, is developed to provide suitable formulas for application. The method is then applied to the Haft Kel Field of Iran to illustrate its effectiveness. In conclusion, the potential application of the G-Number to the problem of oil-in-place is discussed, and the generality of the Number concept with respect to other scientific problems is mentioned.
Case Study: Performance of a Complex Carbonate Reservoir Under Peripheral Water Injection
Authors: Rahman M. , Sunbul M. B. , McGuire M. D.
Published: December 2007

The paper presents a case study of a major carbonate reservoir under peripheral waterflood. It illustrates the importance of good surveillance data not only for monitoring performance but also for characterizing reservoirs. It shows that fluid flow in a lithologically complex and highly stratified reservoir can be much simpler than would be projected from geology alone. The paper also discusses a production strategy that has improved areal and vertical sweep.

In this study, the available surveillance data including well performance, geochemical analysis, cased and openhole logs were utilized to determine water encroachment patterns, areal and vertical sweep, and identify the reasons for lack of sweep in certain areas of the reservoir. The observed flood performance has been incorporated into an updated geological model of the reservoir that will form the basis for a forthcoming 3-D simulation model.
Three-Phase Relative Permeability of Limestones Having Bimodal Pore-Size Distribution
Authors: Marek B. F. , Hartman K. J. , McDonald A. E.
Published: December 2007

Reservoir engineering calculations frequently require consideration of coexisting oil, water, and gas phases. Such three-phase flow occurs when a reservoir is produced below the solution gas/oil pressure or when enhanced recovery processes such as water-alternating-gas flooding or simultaneous gas/water flow occurs. For this reason, reservoir simulators generally include three-phase relative permeability prediction methods. Two- and three-phase relative permeabilities were measured on a mixed wettability carbonate sample having a bimodal pore size distribution. The results of the three-phase measurements were compared with values obtained from prediction models based on two-phase data. A model has been proposed that includes a "trapped gas effect" which leads to a reduced waterflood residual oil saturation. The proposed model appears to be superior to the Stone Model II, especially in the low oil saturation range.
Fracture Patterns of Natih Formation Outcrops and Their Implications for the Reservoir Modelling of the Natih Field, North Oman
Authors: Mercadier C. G. , Mäkel G. H. , Turkse Shell N. V.
Published: December 2007

A quantification of fracture dimensions and spacings has been obtained from a survey of outcrops of Middle Cretaceous Natih Formation carbonates in simple fold structures in North Oman. From the distribution of cross-axial and longitudinal extensional fractures in thickly-bedded limestone, our geological model has average matrix block dimensions of:

– 50 m (length) × 5 m (width) × 10-20 m (height) in gently dipping areas, – 50 m (length) × 0.5 m (width) × 10-20 m (height) in steeply dipping areas.

These blocks contain and/or are intersected by cross-axial shear fractures with variable spacings.

These results have been applied to the fractured limestone reservoirs of the Natih Formation of the Natih Field, located some 50 km to the west of the jebels studied. This field is a NW-SE trending anticline which contains a STOIIP of 500 million m3. Open, cross-axial (NE-SW trending) fractures dominate as shown by electrical borehole imagery, core, and tracer testing studies.

From the outcrop and Natih Field subsurface data, the open, cross-axial fractures are inferred to be regularly distributed over the Natih structure with a spacing of 1 to several tens of m (extensional fractures), and 0.1 to 2 m (shear fractures). The spacing of the closed or only partly open longitudinal and shear fractures varies probably more over the structure because it is more sensitive to lithological and dip changes than that of other fracture types. These data provided realistic fracture parameters for the Natih Field integrated reservoir modelling that was carried out to study the production mechanism of the field.
Field Performance of a Horizontal Well
Authors: Arima E. , Hirokawa S.
Published: December 2007

This paper presents a field example of a short-radius horizontal drainhole which was completed by sidetracking an existing vertical well. The main reservoir characteristics are unconsolidated sand, high permeability and increasing production water cut due to strongly active bottom water. The horizontal drainhole was aimed at increasing the critical rate under which oil can be produced free of water. Since the reservoir has a high transmissibility (Kh/μ), a vertical well is enough for meeting the target rate as long as water cut is maintained at a low level.

Performance was compared between a vertical well and a horizontal drainhole using analytical methods before implementing the horizontal recompletion. As expected, the horizontal drainhole has successfully maintained a high oil production rate without any water cut for more than one year. The field data proved the effectiveness of the horizontal drainhole on water control. Although recompletion to a horizontal drainhole resulted in successful production performance, there still remains room for improvement in well completion techniques. The unconsolidated sand required the use of heavy weight mud and caused difficulties during drilling. Sand problems had to be tackled and required a detailed design for well completion. In this paper, the drilling procedures and problems are also briefly mentioned.
Horizontal Drilling vs. Acid Fracturing: A Review of Results in the Upper Zakum Field
Authors: Fada’Q A. S. , Al-Tamimi Y. K.
Published: December 2007

In recent years, horizontal drilling has captured much attention in the oil industry. Acid fracturing on the other hand, has been long before adopted by the industry, both techniques have proved to be effective in enhancing the productivity of oil wells, their theory and merits have been tackled by numerous technical papers. However, in the majority of these works, comparisons were invariably made by discussing the performance of a vertical well versus a horizontal one, or fractured versus unfractured. The following paper is intended to present actual case histories comparing the performance of a fully completed horizontal well with that of an acid fractured well in the same field and within the same reservoir (carbonate), thus making the comparison more representative, because important "flow parameters" related to reservoir characteristics are similar in both cases. The paper will describe the environment in which these two techniques were field tested and present conclusions on the production enhancement achieved in each case, brief description of the additional cost incurred will also be highlighted.
The Role of Reservoir Simulation in Identifying Secondary Development Prospects
Authors: Tosdevin M. A. , Abdulla I. A.
Published: December 2007

A major Integrated Petroleum Engineering Study of the Bul Hanine Arab D, the most prolific reservoir Offshore Qatar containing a STOIIP of 2.4 billion bbl (382 Mm), has been completed. This paper will present not the detailed construction, history match and prediction runs of the model but, rather, concentrate on the steps leading up to identification of target zones for future redevelopment (the remaining oil).

Due to the large size and complex geology of this carbonate reservoir it was impossible, even if it would have been desirable, to design a simulation model to examine in detail all aspects of the historical and future development. This being the case a model was constructed which aimed to predict the likely future production of the existing wells and similarly completed new wells and to identify the location of the remaining oil which could be the target of an altogether different method of production. In the end two unswept zones have been identified for future development, one of which may involve the drilling of thirty horizontal wells. The necessity of studying the expected performance of the new type of wells with simulation models designed specifically for the purpose will be highlighted together with the need to perform field trials to confirm their results.
Effect of Stochastic Faults on Reservoir Permeabilities in Presence of Stochastic Shales
Authors: Abu-Elbashar O. B. , Daltaban S. T. , Wall C. G. , Archer J. S.
Published: December 2007

Due to the resolution limitation of seismic techniques, faults shorter than the distance between seismic lines, or faults with very small throws axe often not detected. The impact of such small (stochastic) faults on reservoir transmissibility can be extremely detrimental, especially in intensively faulted areas. Such faults are unlikely to be detected by well tests. In the presence of stochastic shales – which smear on the stochastic fault planes – the reservoir permeabilities can be considerably reduced as a result of the vertical barriers to horizontal flow created by the smeared fault planes. In this paper, a technique is presented for modelling such stochastic faults and for calculation of their effect on reservoir permeabilities (transmissibility). Continuity distribution functions (CDF) for stochastic fault dimensions are derived from published literature, and triangular distribution functions are used in modelling the faults.

The permeability computations are done in three stages: (i) calculation of the effect of stochastic shales on permeabilities (to obtain effective permeabilities for the reservoir blocks), (ii) generation of stochastic faults and specifying the faults encountering the block under consideration, (iii) and evaluation of the effect of the smeared areas of these faults on the reservoir permeabilities. These calculations are performed by a set of specially coded computer programs.

The calculations reveal the impact of stochastic faults on reservoir permeabilities (especially horizontal permeability) and suggest that the effect of stochastic faults should be assessed before simulating reservoir performance.
Performance Evaluation of Caustic Pilot Project of North Gujarat Oil Field, India
Authors: Goyal K. L. , Gupta R. K. , Nanda S. K. , Paul A. K. , Sharma P.
Published: December 2007

This paper describes the progress and experience gained in North Gujarat oi1 field, caustic flood pi lot project. Laboratory investigations on acid number and interfacial reduction studies, to firm up the optimum concentration of caustic solution, encouraged the investigators to undertake further flood studies on actual cores and long core packs, SEM Micrograph studies were also conducted to evaluate the effectivity, reactivity and absorptions characteristics. Based on these investigations an inverted 5 spot pattern on a 10 acre pilot area was choosen. A 0.1 PV preflush of Sodium carbonate solution was injected in Dec. 1987. This was followed in July 1988 by 0.2 PV of 0.25% caustic solution followed by chase water injection started in March 1989 and still continues.

At the time of writing this paper in March 1989, 23% additional oil has already been produced from the pilot area. The pilot is sti11 producing oil, with 40 to 45% water cut and some emulsion. The final recovery is expected to be around 38%. This incidently matches well with the laboratory results. The pi lot performance so far had been satisfactory. No scaling was observed in the production string. Slight increase in injection pressure of about 20 kg/cm2 was observed. This increase, however, was shortlived. This further confirmed the laboratory investigations that emulsification, as a result of decrease in interfacial tension, and subsequent demulsification to release the caustic once again, seems to be the predominently dominant mechanism responsible for enhanced recovery of oil.
Well Test Analysis of a Well With Multiple Horizontal Drainholes
Authors: Karakas M. , Yokoyama Y. M. , Arima E. M.
Published: December 2007

This paper presents interpretation of several transient tests conducted in a well with multiple horizontal drainholes. The subject well is located in the offshore divided zone of Saudi Arabia and Kuwait and was initially completed as a vertical producer. Recently, two medium-length horizontal drainholes, each in a separate layer, were drilled from the existing casing of this well. In order to evaluate the effectiveness of the horizontal completion, the well was subjected to four production tests before and immediately after the drilling of each drainhole. These flow tests were analyzed in detail to determine important reservoir and production characteristics. The observed pressure responses are compared with those obtained from analytical and numerical models. A discussion on the practical aspects of well test interpretation in horizontal drainholes is also provided.

Numerical simulations show that, for transient analysis purposes, most multiple drainhole systems can be approximated by an equivalent single-layer, single-drainhole systems. Additionally, the results demonstrate the importance of drainhole orientation when the vertical communication between the producing layers is not restricted by flow barriers.
Characterization of Bahrain Field Oil and Gas Using Semicontinuous Thermodynamics
Authors: Wolff M. , Al-Mahroos F. M.
Published: December 2007

This paper describes the use of semicontinuous thermodynamics1 to model Bahrain field oil and gas. This new method for heavy hydrocarbon fraction characterization is shown to be both simpler and more accurate in matching experimental data than conventional methods. Two separately tuned oil and gas models are then combined in a successful match of experimental data from an oil swelling study.
A Variable Cell Model for Simulating Gas Condensate Reservoir Performance
Authors: Al-Majed A. A. , Dougherty E. L.
Published: December 2007

A variable cell model for simulating gas condensate reservoir performance has been developed. The model closely approximates predictions of conventional compositional models but would only require a fraction of the computation time. The characteristic trend of oil saturation profiles, which is exhibited when gas condensate wells produce below dew point pressure, was utilized to divide the reservoir into three concentric regions. Each region is simulated by one cell, and the volume of each cell is varied as production continues. Dew point pressure and phase behavior of the reservoir fluid control expansion of the inner first and second cells and contraction of the exterior third cell.

The model was used to study the effect of liquid flow on well-stream fluid composition. Also, the influence of reservoir fluid phase equilibria data on the extent of two phase flow dominated region was investigated.
Factor Affecting Mercury Capillary Pressure Behavior of Saudi Arabian Carbonate Reservoir Rocks
Authors: Al-Fossail K. A. , Saner S. , Asar H. K. , Hossain M.
Published: December 2007

Capillary pressure can be viewed as the pressure required to drive a fluid through a pore throat, with greater pressure being required as the pore throat becomes smaller. The size and distribution of pore throats within a host rock control its capillary pressure characteristics, which in turn control fluid behavior in the pore system. The pore geometry of carbonate rocks has as great influence on the ability of the rock to contain and produce oil and gas as do porosity and permeability. This has been demonstrated by examining a large number of samples from a Saudi Arabian carbonate reservoir. By studying the lithology and genesis of the rocks, and comparing families of capillary pressure curves, it was possible to establish very clear mutual relationships.

The mercury injection technique followed by ejection and reinjection was used to determine capillary pressure behavior for each sample. Experiments were also performed to test the plug size and surface effects on capillary pressure characteristics. A detailed interpretation of the data was carried out in order to extract various correlation parameters. These data were combined with basic rock properties and incorporated in generating families of capillary pressure curves for several carbonate rock types, and in the computation of pore throat size distributions.

Experimental data are presented using J-Functions for the correlation of capillary pressure and saturation relations for all samples. It is shown that the correlation improves significandy when the samples are grouped together based on the rock lithology.
Magnetic Logging: Borehole Magnetostratigraphy and Absolute Datation in Sedimentary Rocks
Authors: Lalanne B. , Bouisset P. , Pages G. , Pocachard J.
Published: December 2007

A new magnetic logging tool has been designed and developed for precise and reliable in-situ magnetic measurements in the sedimentary formations encountered when drilling for oil.

The tool consists of two probes, measuring respectively the in-hole effect of the Earth's magnetic field and the magnetic susceptibility of the rocks, and is operated as a standard logging tool.

A proper combination of these magnetic measurements provides the determination of Natural Remanent Magnetization polarity, from which the polarity of the Earth's magnetic field at the time of sedimentation is deduced.

A magnetostratigraphic sequence is obtained for each well, and appears to be similar to the Magnetostratigraphic Reference Scale.

Application of this method to wells in the Paris basin (France), gives good results for correlations and absolute age determination.

Further comparison of results obtained from magnetic measurements and from sequence stratigraphy applied to conventional logs, shows that sequence boundaries can be diachronous in wells 80 km apart. Although the potential of magnetic measurements is still under investigation, the first encouraging results clearly show that the new dating method presented in this paper can be very helpful in petroleum geology.
Petrophysical Approach to Description of a Producing Fractured Basement Reservoir
Authors: Khalil M. M. , Pigaht J.
Published: December 2007

A study was initiated with the objective to provide a better estimate of petrophysical parameters in a producing fractured basement reservoir. Emphasis was put on fracture and matrix porosity determination and its vertical and areal distribution. This uas essential in order to accurately define STOIIP as well as to improve the reservoir description and provide a data base for modelling studies. This paper gives an insight into the techniques applied to classify different rock types and the approach taken to compute the mineralogical model as basis for the porosity evaluation with minimum available core data to calibrate the results.

With the help of a program to identify electro-facies a minaralogical model was assigned to each facies and the petrophysical constants were then computed. Whenever possible test and production logging data and Formation Micro Scanner data were utilized to confirm the study results.

Based on the analysis it was possible to subdivide the fractured basement body into segments. Problems in determining porosity as well as water saturation in this type of reservoir are highlighted and the need to initiate a world-wide data base for granitic rocks is stressed.
Geological Controls on Reservoir Quality of Arab Formation in Satah Field
Authors: Kawaguchi K-l.
Published: December 2007

The Upper Jurrasic Arab Formation in the Satah Field is composed of two major rock units, i.e. shallow marine carbonates and cyclic carbonates-anhydrite sequence. The former is defined as the Arab D zone, while the latter is divided into three zones, i.e. Arab A, B and C in descending order. The Arab C and D zones comprise hydrocarbon bearing formations in the field.

The Arab D reservoir is characterized by upward shallowing sequence. Its lower and middle portions are dominated by mud supported facies deposited on a shallow shelf, while its upper part is composed of various lithology types resulting from upward shallowing system. Total eight lithology types were identified within the Arab D reservoir. The petrophysical characteristics of the Arab D sequence is determined by the original sedimentary fabrics and by various diagenetic processes. Leaching and dolomitization can enhance both porosity and permeability, whereas bitumen fills associated with paleo O.W.C. and matrix cementation related to paleo acquifer reduce the reservoir quality. In general, below "Bitumen Mat" both porosity and permeability deteriorate rapidly. In other word, the Arab D reservoir is considered to be bottom sealed reservoir. According to the lithological and petrophysical variations, the Arab D reservoir was subdivided into fifteen reservoir layers.

On the other hand, the Arab C zone is made up of alternated carbonates and anhydrite and was accumulated under the various depositional environments ranging from supratidal-sabkha to subtidal conditions. The carbonates are dominated by grain-supported facies and divided into six lithology types. The original fabrics of the sediments play an important role on the reservoir quality, as well as several diagenetic events. Good reservoir characteristics are distributed where the secondary pores by leaching and dolomitization are connected with the primary pore networks. Major porosity reduction as observed in the Arab D reservoir is not recognized.

Such geological analysis is considered to be not only essential but helpful for the reservoir layering scheme and simulation study.
Impact of Oil Spill on Intertidal Organisms in Bahrain
Authors: Mohamed S. A.
Published: December 2007

This study was carried out after a major oil spill hit the coasts of Bahrain in 1988. A total of fifteen stations around the Island of Bahrain were monitored for a period of six months in order to measure the impact of the spill on marine organisms and in particular those living in the intertidal zone. Large quantities of heavy hydrocarbons accumulated on the shores and caused death or serious damage to many organisms, including birds and fishes. The spill first hit the northwest shores. The oil spill was also reported to be the main factor in damaging the traditional fishing traps in the coastal waters, which caused serious effects on the fish catch for seven months.
The Application of Model Testing to Offshore Mobile Platform Design
Authors: Barkley W.B.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Model testing of offshore mobile platforms and related marine equipment, as a means for improving designs and increasing operating profits, is currently receiving considerable attention. Model testing presents the best method for investigating the dynamic characteristics of mobile platforms, thereby predicting the force and motion platforms, thereby predicting the force and motion response in waves and wind.

The validity of scaling model results to fullscale proportions is predicated upon the application of appropriate engineering factors which have been derived from experiments in fluid mechanics. For most platform parameters, scaling accuracies to within 5 per cent - 6 per cent are obtainable.

Improved scaling accuracies may be anticipated in the future as a result of improved modeling techniques and additional correlation between model data and prototype performance. Development of computer-implemented mathematical simulations promises additional assistance.

Although design of offshore platforms and related equipment is influenced by a number of factors in addition to hydrodynamic considerations, new and improved model test data, correlated with prototype results, may be expected to accelerate technical advancement. These factors, combined with the potential for new concept development, will influence future industry planning.

Introduction

Model testing of offshore mobile platforms and related marine equipment is currently receiving greater attention than ever before. The reason for this increase in model testing activity stems primarily from the progressive movement to deeper water and the attendant requirements for floating structures.
Partial-Exclusion Sand Control Technique for Improving the Efficiency of Thermal Operations From Unconsolidated Heavy Oil Formations
Authors: Toma P. , King R. W. , Harris P. , Jha K. N. , Korpany G.
Published: December 2007

A sand control device using prepacked metallic wool designed for total exclusion of sand in thermal operations was tested in Lloydminster and Athabasca unconsolidated sand formations. The results obtained from 20 different applications, which are summarized in this paper, indicate that sand production previously plaguing some locations disappeared after the new filter was introduced. However, high pressure drops and reduction in production rate were sometimes associated with partial plugging of the filter in fine grained formations.

As a result of the field observations, a laboratory investigation was undertaken to design new criteria for the prepacked metallic wool filter and to achieve better control of solids by using a partial filtration strategy. The experimental program presented in the paper includes a laboratory testing method which replicates open-hole completions. Alteration of filter permeability, including the formation of a filter cake in open-hole conditions, indicates that a different sand control strategy should be designed for set-through and open-hole completions. A filtration model based on laboratory experiments using a prepacked metallic wool filter for sand control in an open hole is suggested. The model assesses the risk of plugging as a function of formation median grain size, filter compression, and the grade of metallic fibers. The model provides practical criteria for designing a prepacked metallic wool filter for partial exclusion of sand and to avoid a rapid loss of filter permeability in fine-grained, unconsolidated formations.
Steam-Solvent Injection, Well LSJ-4057, Tia Juana Field, Western Venezuela
Authors: Bracho L. G. , Oquendo O. A.
Published: December 2007

The purpose of this paper is to present the results obtained in the well LSJ-4057, Tia Juana field, Western Venezuela, by injecting steam and solvent simultaneously.

According to laboratory tests, industrial diesel, which is considered a medium weight solvent, showed to be the most compatible with the crude produced in the area, and because of its availability and lower cost, it was selected for the pilot test.

During this pilot test, which corresponded to the second cycle of steam injection of the well, a total of 31.5 MSTB [5 015 stocktank m3] of steam (cold water equivalent) was injected with 1876 STB [298 stock-tank m3] of solvent, in a 3-stage injection procedure.

The average initial production was 301 B/D [47.8 m3/D], resulting 63.6% higher than the average initial production rate for second cycle wells in the same area. Also, the cumulative production for a 30-month period was 85.9% higher than that of neighboring wells.

These results suggest the potentiality of this technique to increase the final recovery of oil by cyclic steam injection in heavy oil reservoirs.
Hot-Water and Steamflood Studies Using Kern River Oil
Authors: Bousaid I. S.
Published: December 2007

This paper presents the results of hot-water and steamfloods conducted in a five-foot linear cell. The effect of injection rate of 240°F water and steam was studied for the Kern River viscous oil (13°API) using a fine graded silica sand.

Temperature profiles along the sandpack were used to relate changes in oil saturation with temperature effects. An increase in the water rate resulted in higher temperature profile and minimum Sorw values obtained near the sandface. The results were used for determining the optimum temperature for mobilizing and effectively banking Kern River oil by hot-water floods. A correlation was obtained relating final Sorw values to the oil/water viscosity ratio, thus removing the temperature dependency for the viscous oil (6800 cp @ 80°F).

The steam rate was varied between tests to observe its effect on the steamflood recovery process. The oil and temperature response at the production end was related to the steam fronted advance along the sandpack. The oil response and recovery at steam breakthrough increased with increase in the steam rate. The opposite effect was obtained after breakthrough. The frontal velocity to steam and gas saturation in the steam zone varied with the steam rate. The study evaluates the effect of steam rate on frontal advance, oil banking process, oil recovery, and production to injection ratio as a function of a dimensionless time factor based on steam breakthrough.
Mount Poso Upper Vedder Simulation Study
Authors: Iyican L. M.
Published: December 2007

The Upper Vedder sand is the main productive horizon in Mount Poso, a heavy oil field in San Joaquin Valley, California. It is a homogeneous sand with very high porosity, permeability, and N/G ratio. Following 45 years of primary production, a very successful steam drive has been in operation since 1971. This line drive thermal development with updip steam injection is now at its final stages. The purpose of the simulation study is to determine the changes in operating policy to optimize financial performance. The study consists of developing a numerical reservoir simulation model, calibrating the model, testing various operating scenarios, and making recommendations. The recommendations include a series of steam cuts, steam injector moves, and increased aquifer withdrawals. These recommendations are currently being implemented. Results to date are also discussed.
Transient Pressure Analysis In Partially-Penetrating Wells
Authors: Yildiz Turhan , Bassiouni Zaki
Published: December 2007

A new mathematical model is developed to predict the transient pressure behavior of a partially-penetrating well (PPW). The model is derived by solving the two-dimensional (2-D) diffusivity equation. The Laplace transformation and the separation of variables technique are used. A convolution technique is used to incorporate the well bore storage and skin factor. The solution has the form of the infinite Fourier-Bessel series and can be easily implemented using a personal computer.

Using the new model, the pressure behavior of a PPW is analyzed, and the approach of current interpretation techniques is investigated. Currently, it is claimed that a plot of pressure vs log (time) displays an early- and a late-time straight line. It has also been assumed that there is a spherical flow period between the early-time and late-time radial flow regimes. This investigation shows that there is neither early-time straight line nor spherical flow period. What may appear to be a straight line on these plots is merely the result of an inflection point. Therefore, the interpretation techniques based on the existence of an early-time radial flow period and spherical flow in the transition period are questionable. Further study has also shown that the type-curve matching methods provide a non-unique solution.

Pressure-derivative and pressure-integral behavior of a PPW are also examined. Derivative and integral type curves were constructed, and their ability to interpret the test data is investigated.

A new interpretation technique is proposed to alleviate the short-comings of existing methods. The new method provides unique solutions to horizontal and vertical permeabilities and skin effect. The method is based on the deconvolution of measured pressure and flow rate data. The limitations of the proposed interpretation technique are also outlined.
Laboratory Study Provides Guidelines for Selecting Clay Stabilizers
Authors: Crowe Curtis W.
Published: December 2007

Various clay stabilizers are discussed, and methods are proposed for evaluating their effectiveness. Laboratory tests are used to rate the relative efficiency of potassium chloride vs other salts and organic compounds. Advantages and limitations of the various clay stabilizers are described. These studies show that increased temperature improves the efficiency of KCI and that pH is not a significant factor, except in low-salinity solutions. Alternate materials are sometimes superior to KCI, but care must be taken when using substitute products.
A Unified Treatment of Material-Balance Computations
Authors: Vo Dyong T. , Jones Jack R. , Camacho-V. Rodolfo G. , Raghavan Rajagopal
Published: December 2007

A unified treatment of materials balance computations to estimate hydrocarbons in place is presented. This method generalizes the normal procedures for gas reservoirs to all fluids of interest to the petroleum industry. We show that a plot of average pressure divided by a two-phase deviation factor can be used to compute hydrocarbons in-place. A simple procedure to estimate the required two-phase deviation factors for black oils and volatile oils is discussed. This extends the method of Vo et al. for gas condensates to these other systems. We concluded, in particular, that data above the phase envelope (single phase information) can be extrapolated and combined with data inside the phase envelop (two-phase information) to obtain initial hydrocarbons in place. The need for accurate fluid property description is emphasized and potential information that is obtainable from accurate fluid descriptions is noted. It is shown that data above the phase envelope can be extrapolated to obtain initial hydrocarbons in place.
An Improved Model for the Development and Analysis of Partial-Water Drive Oil Reservoirs
Authors: Saleh Saad T.
Published: December 2007

In recent years, the use of numerical reservoir simulation to predict reservoir's future performance has shown a steady and strong increase. For meaningful result, however, reservoir simulation requires an extensive amount of data. In addition, many months of time is generally required to assemble and collect the data. Therefore, reservoir simulation is often impractical for small fields.

This paper presents the development and results of a comprehensive and rigorous material balance mathematical model which simulate an oil reservoir bounded by a gas-cap and a finite aquifer. The model incorporates the dynamics of oil/water and gas/oil contacts movements within a hypothetical cone-shaped, radial reservoir geometry. The basic components in the model are the material balance equation, water-influx model, a model for tracking the oil/water contact position, and a model for tracking the gas/oil contact.

The model was used to study the phenomenon of "late-water drive" which is an apparent increase in the activity of water influx in the late part of reservoir's life. The study concluded that the "late-water drive" phenomenon is caused primarily by the expansion of trapped gas behind the advancing oil/water contact. The study showed that even small aquifers (aquifer-to-reservoir radii ratio Ra/Ro < 3) demonstrated strong water influx activity in the late part of reservoir's life. This behavior is often misinterpreted as an influx from a large aquifer.

This paper presents the results of a sensitivity analysis of the effect of aquifer size, gas-cap size, reservoir's permeability, etc on the movements of all fluid contacts in particular and reservoir performance in general. In addition, it was demonstrated that average reservoir pressure must be corrected to the original oil/water contact (commonly not done in conventional reservoir analysis studies) in order to correctly calculate water influx. The procedure of pressure correction is given with many examples of reservoir's performance prediction with and without pressure correction.
Improving Oil Recovery in the Naturally Fractured, Tight, Dirty Sandstone of the Townsend Newcastle Sand Unit - Weston County, Wyoming
Authors: Hochanadel Steven M. , Townsend Charles L.
Published: December 2007

This paper summarizes the waterflood performance of the Townsend Newcastle Sand Unit (TNSU). Production is from the Muddy Newcastle sandstone located in the Powder River Basin of northeastern Wyoming. The field was discovered in June, 1960 and was depleted under solution gas drive to recover 13.0% of the original oil-in-place (OOIP) of 2.8 million STBO.

Waterflooding the TNSU faced three obstacles; first, the reservoir is naturally fractured; second, the reservoir contains clays which can swell and migrate to reduce injection rates; and third, the matrix rock is heterogeneous and low in permeability (40 md average).

A process approach was taken to overcome these adverse waterflooding conditions. First, the injection wells were pretreated with potassium hydroxide to permanently stabilize the clays. Then, cationic and anionic polyacrylamides and aluminum citrate crosslinker were injected to reduce flow through the factures as well as through any high permeability channels in the matrix rock. This was followed by a blend of phosphates and anionic polymer to maximize imbibition.

The flood began in May, 1986. Oil production went from 3 BOPD prior to injection to a peak flood rate of 343 BOPD in November. 1988. Ultimate recovery is now projected to be 29.8% OOIP. Without the use of this process technology it is doubtful the field could have been economically flooded.
Use of Conventional Reservoir Models for Coalbed Methane Simulation
Authors: Seidle John P. , Arri Luis E.
Published: December 2007

The recovery of gas from coalbeds is a two-step process. First, the gas diffuses through the matrix then, secondly, it flows through the cleats to the wellbore. If the release of gas from the matrix to the cleats is very rapid compared to the flow of gas and water in the cleats, the desorption kinetics are relatively unimportant in modeling coalbed methane production. If the coal is well cleated, it can be assumed for engineering purposes that the gas desorbs instantaneously from the matrix to the cleat when the pressure in the cleat decreases. This assumption allows the adsorption of gas on the surface of the coal to be modeled as gas dissolved in an immobile oil. Conventional reservoir simulators can then be used for coal bed methane modeling purposes. The solution gas-oil ratio of this immobile "pseudo" oil is calculated from the Langmuir adsorption isotherm constants and coalbed properties. Additional modest modifications are required in the data describing the porosity and gas-water relative permeability curves to account for the presence of the "pseudo" oil. No code modification is required. This concept has been used with several different simulators to successfully model both single well and 3-D, multiwell coalbed methane problems. A coal well simulation using this method and COMETPC, a simulator developed by ICF-Lewin, are compared.