bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of Engine Exhaust Emissions to Meet Present and Future Clean Air Regulations
Authors: Taber Walter R.
Published: December 2007

Increasingly stringent regulations by the EPA and state air quality agencies are making the reduction of exhaust emissions from industrial engines, such as are used in the oil and gas industry, ever more important for their operators. Not only are these regulations getting increasingly strict with time, but there will be both substantial fines and possible criminal penalties for non-compliance in the future.

This presentation describes how harmful exhaust emissions are formed during the combustion process, what the current regulations are in various areas of the country and where they are probably headed in the foreseeable future. It then discusses possible emission reduction strategies in two broad categories, combustion modification and exhaust after treatment, using catalytic converters.

Each of the three types of catalyst substrates are discussed, with the advantages and disadvantages of each, as well as the relative advantages and disadvantages of the two basic catalyst shapes and the four possible catalyst locations.
Performance of (UNS 8028) Production Tubing Material in Sour Service Environment of Khuff Gas Formation
Authors: Al-Maslamani Moh'd
Published: December 2007

Khuff gas formation is one of the largest reservoirs of non-associated gas in the world. Recent developments in exploration and production from Khuff gas formation at the Qatar North Field required materials of construction with long periods of production without work over and chemical inhibition.

Gas produced contains corrosive constituents such as 1% H2S, 4% co2 and brine at pressures exceeding 300 barg (CITHP).

For operational reasons, two of the 16 wells drilled were needed to work over after 2 years of service and showed evidence of crevice pitting corrosion and thread galling on the Corrosion Resistance Alloy (CRA) tubing material. Full inspection and analysis of the problem are addressed in this paper.
Reeled Pipelay Cost Reduction Using Workboat-Based Installation
Authors: Hoffman J. G. , El Laithy W. F. , Rothberg R. H.
Published: December 2007

Coiled "tubing" is a rapidly growing pipeline technology. Because this technology is relatively new, cost can vary significantly depending on deployment strategies and installation techniques.

Up until recently coiled pipe was used primarily by service companies for coiled tubing workovers. As the technology expanded the industry began using coiled tubing for other applications such as drilling, coring, logging, well cleanout operations and artificial lift. With the recent advent of larger sizes, three and one half inches, it was now possible to consider using coiled tubing as pipelines. The coiled pipe was proving to be a low cost, time saving, economic alternative to conventional welded pipe for flowlines. Coiled pipe applications have been used in 4 to 100 feet of water in the Gulf of Mexico area and the installation techniques have varied significantly. Considerable engineering work has been done in preparation for GUPCO’s first dynamic lay installation for a subsea well tie-in on Ramadan 22. Subsequently GUPCO installed the worlds longest known coiled pipeline on SB 367. This paper will cover the significant findings of that engineering work and present actual field case histories on Egypt’s first two coiled pipeline projects.
Asphaltenes: The Cholesterol of Petroleum
Authors: Kokal Sunil L. , Sayegh Selim G.
Published: December 2007

Asphaltene precipitation and deposition has been recognized to be a significant problem in oil production, transmission, and processing facilities. The precipitation of asphaltenes is caused by a number of factors including changes in pressure, temperature, chemical composition of the crude oil, mixing the oil with diluents or other oils, and during acid stimulation. The precipitated asphaltenes reduces the permeability of the reservoir near the well-bore region causing formation damage and can plug-up the well-bores and well tubings. Deposition of asphaltenic organic scales leads to operational problems, safety hazards and an overall decrease in production efficiency, thereby increasing the cost of oil production.

This paper presents a review of the important factors which affect asphaltene precipitation in petroleum reservoirs and in processing facilities. The nature and characteristics of asphaltenes in the crude oil and their molecular and colloidal properties are discussed. A description of the asphaltene deposition problem manifestations in the reservoir, well bores and well tubings, processing and transportation equipment is presented. Current research work in this area is also discussed.
Laboratory Study of Microbial Cleaning of Oil Spills Under Saudi Environmental Conditions
Authors: El-Sayed A-A. H. , Shebl A. M. , Ramadan M. A.
Published: December 2007

An active strain of Pseudomonas sp. isolated from oil-contaminated soil at the Arabian Gulf was able to utilize the crude oil at a concentration of 5 mg/ml added to sterile Gulf water. Microbial growth and gas chromatographic analysis of the remaining oil were used as a criteria for oil degradation by this strain. The bacteria at a cell density of 105 CFU/ml was able to degrade the crude oil at concentrations ranged from 2.5 to 15 mg/ml in Gulf water samples. At low concentration (2.5 mg/ml), about 70% of crude oil had disappeared within 7 days. At high concentration (15 mg/ml), the extent of oil degradation decreased, where only 50% of the added oil had disappeared. The rate of degradation by the inoculated bacteria was slightly increased by the addition of inorganic nutrients, mainly P or N to the Gulf water. The degradativ capacity of Pseudomonas sp. was optimum when the bacteria was incubated at 25°C, where 47% of the added oil has disappeared within 5 days of incubation. Low cell density (103 CFU/ml) of the degrading bacteria required a long lag period before initiation of oil degradation, whereas high cell density (106 CFU/ml) rapidly degraded oil with a short lag period under the same conditions. This strain could be useful in decontamination of spilled oil in Gulf water if it acts well under field trial test and survived for a reasonable period sufficient for oil biodegradation.
An Improved Reservoir Conduction Heating Model
Authors: Connaughton Charles R. , Crawford Paul B.
Published: December 2007

Steam injection into petroleum reservoirs has become a common method of increasing producing rates and ultimate recovery. In producing rates and ultimate recovery. In addition, hot fluids are being studied for producing shale oil utilizing conduction producing shale oil utilizing conduction heating. This is a study of the temperature distributions resulting from heat conduction.

When steam enters an oil reservoir or shale-oil bed through a single high-permeability channel or fracture, conduction may be a principal heating mechanism. Under certain principal heating mechanism. Under certain assumptions this can be likened to the conduction heating of an infinite body from a disk source. This problem of reservoir or rock heating has been treated by Boberg, Satter, Thomas, Marx-Langenheim and others. Satter and Thomas proposed conduction models for reservoir problems. In reviewing these two models it was problems. In reviewing these two models it was found that both assumed vertical linear heating above and below substantially disk sources. It was suspected that the above models would lead to very optimistic heating as each lacked terms providing for radial or horizontal conduction. providing for radial or horizontal conduction. The radial-horizontal heat conduction terms have now been added, and it was found that the Thomas model forecast an optimistic heated zone. A Thomas isotherm may be 50 percent farther out than the same isotherm in percent farther out than the same isotherm in the new model incorporating radial heat conduction terms. Briefly, the radial term withdraws heat from the region above and below the source, thereby lowering the magnitude of the isotherms. Satter's model is similar to Thomas' model, and it, too, gave optimistic answers by about 25 percent or more.

In the new model, superposition of heating rates was used to evaluate temperature distributions for varying heat rates. Assuming that production can be simulated using negative conduction heating rates, temperature distributions through multiple injection-soak-production cycles were studied.

Using this model, it was found that, after steam injection, the temperature distribution is characterized by nearly horizontal isotherms. For injection periods and rates normally used in petroleum reservoirs, the vertical penetration of the isotherms is much less than penetration of the isotherms is much less than their radial spread for the initial injection period. During soaking, little radial spread period. During soaking, little radial spread of the isotherms occurs, but more vertical penetration occurs. Production of fluids results penetration occurs. Production of fluids results in a removal of heat from above and below the initial heat source. During any production period, a maximum of approximately 36 percent period, a maximum of approximately 36 percent of the injected heat can be removed in practical times. As a result, heat buildup occurs during successive cycles and both radial and vertical spread of the heated zone occurs.
Management Information Systems Software Evaluation
Authors: Al-Tunisi Nabilah , Ghazzawi Amin , Gruyaert Frans , Clarke David
Published: December 2007

In November 1993, Saudi Aramco management endorsed a proposal to coordinate the development of the Management Information Systems (MISs) of four concurrent projects for its facilities Controls Modernization Program. The affected projects were the Ras Tanura Refinery Upgrade Project, The Abqaiq Plant Controls Modernization and the Shedgum and Uthmaniyah Gas plants Controls Upgrade Projects. All of these projects had a significant requirement for MISs in their scope.

Under the leadership of the Process & Control Systems Department, an MIS Coordination Team was formed with representatives of several departments.

An MIS Applications Evaluation procedure was developed based on the Kepner Tregoe Decision Analysis Process and general questionnaires were sent to over a hundred potential Vendors.

The applications were divided into several categories, such as: Data Capture and Historization, Human User

Interface, Trending, Reporting, Graphic Displays, Data Reconciliation, Statistical Analysis, Expert Systems, Maintenance Applications, Document Management and Operations Planning & Scheduling.

For each of the MIS Application areas, detailed follow-up questionnaires were used to short list the candidate products.

In May and June 1994, selected Vendors were invited to Saudi Arabia for an Exhibition which was open to all Saudi Aramco employees. In conjunction with this, the Vendors were subjected to a rigorous product testing exercise by independent teams of testers.

The paper will describe the methods used and the lessons learned in this extensive software evaluation phase, which was a first for Saudi Aramco.
Origin Of NORM in Ras Budran Oil Field
Authors: Abdeen F. , Khalil M.
Published: December 2007

The Ras Budran (R/B) field lies in the Gulf of Suez and consists of a massive Nubian Sandstone which is compartmentalised by partially sealing major faults.

The field is undersaturated and production is maintained by gas-lifted wells with the field under secondary water flooding and limited aquifer drive.

Down-hole scale formation was recognised following the breakthrough of water at the well-bore. Initially diagnosed as calcium carbonate scaling, later observations, following breakthrough of injected seawater, revealed deposits of calcium, barium and strontium sulphates. Plugging or partial plugging of the production strings has provided the most common evidence of scale deposition either in the tubing and/or perforations.

During PLT and TDT logging the plugged intervals exhibit high gamma ray response with the retrieved scales from the tubing showing low Specific Activity (LSA) radioactive material.

Modified scale dissolvers have been applied in the R/3 field to dissolve the scale and keep the Naturally Occurring Radioactive material (NORM) in a highly diluted solution.
An Investigation of the Feasibility of Air Injection into a Waterflooded Light Oil Reservoir
Authors: Sakthikumar S. , Madaoui K. , Chastang J.
Published: December 2007

Insitu combustion or fireflooding has been extensively investigated and field tested in particular for heavy oil reservoirs. Despite many successfull projects of air injection into heavy oil reservoirs and the higher energy efficiency of insitu combustion process, application of the process has not increased due to high capital costs and complicated nature of the process compared with steam injection.

In heavy oil operations air injection has been used primarily as a viscosity reducing agent. In this paper we address the problem of air injection into light oil reservoirs.

Air injection / insitu combustion has been shown to be technically feasible in light oil reservoirs following waterflooding, but wide economic viability under tertiary conditions has not been firmly established. Air is a low cost injectant and unlike in the case of heavy oils the primary factor responsible for improved oil recovery is not just the viscosity reduction. In fact depending on the circumstances air injection into a light reservoir can serve a multiplicity of functions. Air injection at high temperature and pressure (deep reservoirs) could lead to unique economic and technical opportunities for improved oil recovery in many candidate reservoirs under both secondary and tertiary conditions, well beyond the traditional combustion applications.

This paper describes the experimental and numerical work performed and the design of a suitable pilot to assess the feasability of air injection into a waterflooded light oil reservoir. Some of the advantages leading to improved oil recovery and the specific operational problems are discussed.
Water Coning in Fractured Basement Reservoirs
Authors: Saad Saad El-Din M. , Darwich Tarek D. , Asaad Yousri
Published: December 2007

The problem of water coning in fractured basement reservoirs has been addressed in this Work. The outcome of experimental and theoretical investigation to determine the critical production rate for single- and multi-fractured system, the capillary pressure effect, and the break-through time is presented.

The results of the experimental work verify the presented theoretical relationship for different fluid viscosities, fracture angles, oil-Water contacts (OWC), and rates for the case of a single fracture system. The results also indicate that the capillary pressure effect may be generally neglected if the distance between the OWC and the fluid entry is sufficiently large compared to the capillary, rise. The extension of the critical rate determination for a multi-fractured reservoir is also discussed. Finally, the main factors influencing the break-through time were investigated. The difference in viscosity between the oil and water phases has been found to be the main factor affecting the breakthrough time.
Successful Field Evaluation of the Efficiency of a Gas Gravity Drainage Process by Applying Recent Developments in Sponge Coring Technique in a Major Oil Field
Authors: Durandeau Marc , El-Emam Medhat , Anis Abdel-Hamid , Fanti Gianni
Published: December 2007

This paper describes the application and integration of new technologies and recent developments in Sponge coring and presents the methodology used to carry out successfully the various phases of well designed Sponge coring project, including the coring phase, the on-site measurements and the full evaluation of the Sponge core samples. A field case is presented where a Sponge coring project was accomplished to obtain accurate fluids distribution and evaluate the gas gravity drainage efficiency in one of the Arab D sub-reservoirs of a major oil field offshore Abu Dhabi.

A Sponge coring technology team was created to optimize the methodology used during Sponge coring and minimize the uncertainties which persisted on some of the previous operations. The effectiveness of the technique is discussed, with comparison to open hole logs and SCAL data.

Realistic petrophysical parameters were obtained from non-invaded, native-state core samples. The effective oil saturation obtained from the Sponge core analysis results showed that the gravity segregation mechanism has been very active and efficient to recover the oil in the reservoir.
Modelling of Multiple Horizontal Wells in Full Field Models Using Local Grid Refinements
Authors: Mohammed Sabry Abdel-Alim , Al-Ansari Faisal
Published: December 2007

This paper investigates different techniques of modelling horizontal wells in full field simulation models. Two distinctive approaches were followed in this regard: (1) Approximating each horizontal well by a few vertical wells, and (2) Rigorous modelling of the horizontal well by implementing Local Grid Refinement (LGR). These techniques were applied on a full field model of one of Upper Zakum reservoirs to evaluate its new development plan Which optimized number and location of the infill wells with the application of horizontal wells.

Horizontal well completion profiles have been studied to investigate their effect on the sweep efficiency and oil recovery. Pressure drop ih the horizontal wellbore due to friction losses has also been studied. The results of this study were in agreement with actual field performance.
New Fullbore Production Logging Sensor Improves the Evaluation of Production in Deviated and Horizontal Wells
Authors: Kessler Calvin , Frisch Gary
Published: December 2007

A new-generation, production logging toolstring is being introduced with a sensor that can measure fullbore gas holdup. Unlike previous center-sampling holdup sensors (whether radioactive fluid-density or capacitance holdup), this new sensor responds to the entire cross-sectional area of the production tubulars (casing, tubing, or slotted liner) occupied by gas and liquid. From this response, the holdup fractions for liquid and gas (Yl and Yg) can be determined.

The fullbore measurement eliminates previous uncertainties in holdup fractions that can occur when flowing conditions are nonuniform or when water cut is high. This new capability is shown by flow loop comparisons between measurements taken with the fullbore gas-holdup tool and those taken with previous center-sampling holdup sensors in horizontal stratified flowing conditions.

The new production logging toolstring includes a high-speed, bidirectional, monocable digital telemetry system. This system permits simultaneous logging with additional tools such as pulsed neutron tools, oxygen-activation water-flow tools, or other radioactive fluid-velocity tools. The combination of production logging sensors with oxygen activation measurements are important for the evaluation in complex well completions where there are flow paths both inside and outside of the production tublars, such as with slotted liners.

An interactive wellsite production logging analysis package has been developed to utilize the improved data. Both flow-loop-based and conventional slip-velocity interpretation methods are available for determining the flow rates of the individual phases. A new method for determining the downhole flow regime is presented which utilizes both the center-sample holdup and the fullbore holdup measurements.
Water Shutoff Results in High Permeability Zones in Saudi Arabia
Authors: Al-Khawajah M. A. , MacDonald H. W.
Published: December 2007

Wells in one of Saudi Aramco’s oil fields produce under flowing conditions with pressure support provided by a peripheral waterflood. As the waterflood matures, water breakthrough occurs in the lower zones of the oil wells and production rates decline due to increased flowing pressure gradients. This paper details work done by Saudi Aramco to reduce water cycling and increase oil rates in one area of the field. The field results from 49 bottom water shutoff jobs during the last 6 years are presented. The techniques used include workover rig jobs and jobs using coiled tubing and through tubing bridge plug technology. Success in reducing water production and increasing oil rates by the different methods is compared.
Selective Stimulation of Varying Characteristic Carbonate Reservoir Using Acid Activated Gel Diverter
Authors: Mirza A. , Turton S.
Published: December 2007

An off-shore field in Abu-Dhabi has water injectors with dual completions injecting into 3 carbonate subzones A, B and C, separated by dense carbonate layers which act as impermeable barriers. Each completion has one of the two strings completed into two consecutive subzones. The irony is that subzone B is the most permeable and robs the other two of their injection quotas.

This was occurring as the low permeability zones could not be acidized properly due to inefficient diversion. Repeated acidization of the coπimingled zones with benzoic acid diversion had not yielded desired results. In the on going inquest to select a positive diverter, a polymer based system was investigated as a diverting agent.

This paper discusses the use of this polymer based acid activated diverting agent in staged stimulation’s performed in injector wells in an off-shore field, Abu-Dhabi.

The diversion mechanism is explained including how it compares with the other techniques. Polymer properties and characteristics are also explained.
Review of Horizontal Completion Practices Offshore Abu Dhabi
Authors: Hassan M. M. , Abu-Sharkh AF.
Published: December 2007

Horizontal drilling and completion technology has been advanced to the point that oil companies are obtaining a maximum return on their investment due to improvement in the oil recovery as well as maintaining better development plans for their fields.

This paper highlights the different types of well completion, the use of slotted liner completion utilizing 7" cement-off bottom, tapered 7" solid x 4½" slotted and 3½" simple slotted liner. Also, it describes the new advanced completion techniques such as:- –Single overshot completion.–Deviated horizontal dual completion with the elimination of 7" liner.–Dual lateral dual completion.–Selective dual completion with cement inflated formation packers.
Horizontal Completion Options in Reservoirs With Sand Problems
Authors: Restarick Henry
Published: December 2007

Economic efficiency in today’s oil and gas industry requires careful consideration of all horizontal openhole completion criteria during the completion design stage. This paper will review the scenarios that can limit the success of openhole horizontal completions and will focus on problems inherent to sand-producing reservoirs and their management using 1) prepack screens available today and new screen design innovations, 2) recent 90-degree short- and long-radius screen bend tests that determine flexibility characteristics, 3) mechanical fluid-loss control systems, 4) circulation options available to the operator for openhole cleaning 5) and new innovations in zonal isolation with sliding sleeve circulation devices that address sanding problems.

Case histories of several unique completions that proved to be successful in controlling premature water breakthrough and sand problems in fractured reservoirs will be presented, followed by a summary of the important considerations for openhole horizontal completion design.
Determination of Horizontal and Vertical Permeabilities Using Multiprobe Wireline Formation Tester in Layered Formations
Authors: Ayan Cosan , Kuchuk Fikri J.
Published: December 2007

A new interpretation technique is described for determining the horizontal and vertical permeabilities and the porosity-total compressibility product using a multiprobe wireline formation tester. The multiprobe tester (tool) provides the capability to conduct controlled local production and interference tests along an openhole. It also permits flexible configuration. In this paper, we describe a three-probe configuration that consists of a sink, a diametrically opposite horizontal observation probe, and one vertically displaced observation probe. Pressure measurements from two observation probes are used for the estimation of unknown formation parameters. In layered and heterogeneous formations, this configuration allows one to test interlayer communication and to determine individual layer properties. The interpretation technique is applied for the estimation of the layer horizontal and vertical permeabilities and the porosity and total compressibility product for a carbonate formation in an offshore field in Abu Dhabi.
Applications of a New Multi-Resistivity & Imaging Tool in The Middle East.
Authors: Chardac Jean-Louis , El-Sayed Hussein
Published: December 2007

A new measurement-while-drilling (MWD) multi-resistivity tool has been introduced in the Middle East. It measures five resistivities, four of them focused, and a gamma ray.

The four focused resistivities all have the same very high vertical resolution, and different depths of investigation. The deepest measurement uses a ring electrode which measures resistivity all around the borehole, allowing a measurement even when the tool is sliding. The other three focused measurements are made with button electrodes which are azimuthally sensitive.

The true formation resistivity is recorded by the deepest measurement before invasion becomes severe. Button resistivities, thanks to their different depths of investigation, identify zones where invasion starts, and allow invasion diameter computations in favorable conditions.

Images of the formation resistivity at three different depths of investigation are produced. This enables geological features, including dips, fractures and their orientation to be studied. The combination of resistivities with three depths of investigations produces an image of the invasion profile around the borehole.
Effect of Microporosity in Carbonates: Introduction of a Versatile Saturation Equation
Authors: Petricola M. J. C. , Watfa M.
Published: December 2007

The giant carbonate reservoirs in the Middle East are free of clays (e.g. Mishrif, Thamama and Arab reservoirs to mention but a few). This blessing for the interpreters is more than counter-balanced by a host of other parameters that make shaly-sand interpretation look like child play.

The pore geometry in carbonates introduces variations in the cementation factor m (porosity exponent) and the saturation exponent n. It is also believed that most of the carbonates exhibit mixed wettabilities, with the micropores, which retain the original formation water, being water wet, and the macropores, which are invaded by the migrating oil in the majority of cases, being oil wet. There are ample log evidence to suggest that in some cases the presence of microporosity dominates the resistivity measurements, giving apparent saturation computations that are inconsistent with the production data(e.g. dry oil production from zones with computed Sw greater than 70%). At the least, a dual porosity model would be needed to describe the system in full. However, in the absence of data to solve for a dual porosity system, the parameters m and n are normally manipulated to obtain saturation values that are closer to the observed test results.

This study simulates the effects of microporosity on the computed values of saturations. A dual porosity system is assumed, with a range of parameters for the two pore systems. The interaction between the macro and micro pore systems was also varied using different mixing laws. The results demonstrate that the presence of micropores can have a large effect on the computed values of saturation. A tool that measures microporosity will be invaluable in carbonates, with such a measurement becoming a standard service like the density-neutron combination.
Intelligent Scraping Experience Using Ultrasonics in Two 60"/56" Dual Diameter 100 km. Seawater Transmission Pipelines in Saudi Arabia.
Authors: Bird A. F. , Chu K. S.
Published: December 2007

Saudi ARAMCO’s two 60"/56" (1524/1422 mm.) diameter Seawater Injection Pipelines used for secondary oil recovery stretch from the Seawater Treatment Plant across the Arabian Desert for a distance of approximately 100 kilometers.

Both lines were put into operationin mid 1978 using over the ditch Plicoflex tape wrap as a means of protection against external corrosion. A significant portion of both pipelines (32 km. of each line) runs through Subkha (salty moist) areas. A series of test hole evaluations in 1989 indicated moderate to severe external corrosion particularly in Subkha which necessitated sleeving and external coating application.

In 1991 a series of leaks, four (4) in total over a period of two (2) months occurred in Pipeline #2 due to external corrosion. This suggested that the line(s) were in urgent need of at least partial replacement or major rehabilitation. Prior to making a final decision on partial replacement it was decided to run an Intelligent Scraper in both pipelines to ascertain both internal and external pipeline conditions. An Ultrasonic Scraper the largest of it’s kind in the world, similar to what was used in the Alyeska Pipeline was developed and successfully run in both pipelines in February 1993.

This paper discusses the pipeline history, test hole evaluations, Intelligent Scraping experiences, field evaluation for anomaly verification, and repair of approximately 120 locations as identified by the Intelligent Scraping run. The Intelligent Scraping evaluation played a major role in the cancellation of partial pipeline replacement with cost savings estimated at $30 MM.
Use of Fine Gridding in Full Field Simulation
Authors: Greaser G. R. , Doerr T. C. , Chea C. , Parvez N.
Published: December 2007

A full field 3D simulation study was completed for a large Saudi Arabian oilfield located in the Arabian Gulf. The subject field produced from a highly layered Arab D carbonate reservoir which exhibited a strong water drive. The objective of the study was to determine future platform locations and timing with respect to water encroachment. The large areal extent (13×23 km) and highly layered nature of this reservoir necessitated use of coarse grids in order to obtain a reasonable model size. The coarse grid model was constructed with 86,000 grid cells. Using the coarse model, prediction studies showed an advantage to future platform development with horizontal wells. However, these results were suspect since it was thought that the coarse cell model may not properly model water coning and encroachment around the horizontal wellbores. To improve the modelling of water movement, fine grid numerical simulation techniques were investigated. This paper discusses the use of sector and local grid refinement modelling techniques with commercially available software. Fine grid simulation studies were conducted for a proposed new platform. The fine grid simulation studies showed significantly different results compared with the coarse model predictions. The fine grid simulation results will be discussed, the two fine grid simulation techniques will be compared, and reasons presented why performance differences exist. Performance of the fine grid models on an Unix RISC based workstation is included.
An Advanced Kick Simulator for High Angle and Horizontal Wells - Part II
Authors: Vefring Erlend H. , Wang Zhihua , Rommetveit Rolv , Bach Graham F.
Published: December 2007

This paper presents additional simulation results of gas kicks in high angle and horizontal wells using the advanced kick simulator described in Part I. We place emphasis on the removal of gas bubbles from three potential traps in a horizontal well, i.e., (i) upward inclined section, (ii) local tops in the trajectory, and (iii) washout sections. Operational implications are also discussed based on the simulation results. The critical parameters are noted for operational considerations.

Full scale gas kick experiments in horizontal wells have been performed. We will discuss the experimental set up and test parameters. The test data are being analysed.
Waterflooding in a System of Horizontal Wells. (Analytical Reservoir Model. Offshore Case)
Authors: Bedrikovetsky P. G. , Magarshak T. O. , Shapiro A. A.
Published: December 2007

An approximate analytical method for the simulation of waterflooding in a system of horizontal wells is developed. The method is based on an advanced stream-line concept. The essence of this new method is the exact solution for the 3D two-phase flow problem in the system of coordinates linked with the stream lines under the only assumption of the immobility of stream lines. A software based on this approach was developed for IBM-compatible PC. It allows us multivariant comparative studies of immiscible displacement in systems of horizontal, vertical and slant wells. The simulator has been used in order to optimize geometrical parameters of a regular well system and to predict recovery in conditions of Prirazlomnoye offshore oil field.
Study of the Hydrodynamic Pattern in a Sedimentary Basin Subject to Subsidence
Authors: Jacquin C. , Poulet M.J.
Published: December 2007

The structure of a sedimentary basin is modelized, assuming that this basin is subject to subsidence and has the following characteristics:

shaped like an inverted cone with a circular base having a radius of 300 km, depth in the middle varying from 0 to 3,000 m during an evolution lasting 150 million years and during this evolution, successive deposits of sand and clay strata occurred with gradual expulsion of water from the clay as the result of burial.

This basin structure is used to study the hydrodynamic conditions that have occurred in the different sedimentary strata. The main conclusions of this study are as follows.

Fluid circulations through the clay are quite complex because the direction of flow has usually reversed itself, with this reversal occurring earlier or later following the moment of deposition of clayey material. This leads to an evaluation vs time of the cumulative amounts of water, respectively, running upward (W2) and downward (W2) over a 1 sq cm horizontal surface associated with the clay deposited in a given place at a given moment. The circulation of water through clay causes fluid overpressures compared with the hydrostatic pressure. The vertical distribution and the order of magnitude of these overpressures agree with standard observations made on actual sedimentary basins. The circulation of water through sandy horizons occurs at very low speeds of between about 1 and 10 mm/year, but the volumes of water involved are large (from 10(12) to 10(13) cu m for a period of between 40 and 150 million years).

These results may provide useful indications for studying some of the phenomena governing the formation of petroleum accumulations, i.e., diagnesis and hydrocarbon migration.

Introduction

Hydrocarbon displacement phenomena inside stratigraphic series (primary migration in the source rock and secondary migration in permeable layers where traps are located) cause permeable layers where traps are located) cause the sizable accumulations making up exploitable oil fields. The leading mechanisms assumed to be behind these displacements are displacement of hydrocarbons in a dissolved or emulsion state in water and displacement of continuous oil and gas phases (or possibly oil dissolved in gas) by gravity or aquifer movement.
Relationship Between the Ratio of Formation Exposure Length to Formation Thickness and Ultimate Oil Recovery From Horizontal Wells
Authors: Boukadi F. , Bemani A.
Published: December 2007

This paper discusses the relationship between the ratio of exposed formation length to oil-bearing formation thickness and ultimate oil recovery from horizontal wells.

Horizontal technology is usually chosen as the best practical solution to improve the ultimate oil recovery and cope with the water and gas coning problems encountered in many oil fields. The intent being to reduce the water production, to minimize the cost of the required treatment of water at surface, and reduce the gas production to limit the consequent energy reduction. Horizontal wells drilled and tested have given confidence to the use of the technique in future operations in different fields in the Middle East and particularly in Oman. Nevertheless, the immediate effects of raised oil output is not to be at the expense of possible lower optimum recoveries. For that reason, numerical sensitivity analyses on reservoir parameters, such as the ratio of exposed formation length to formation thickness at various maximum allowable liquid rates, have been carried out. Recommendations on the water coning horizontal drilling implementations and ways for reducing water coning effects are outlined and thoroughly discussed for various reservoir thicknesses.

Adequate horizontal drilling with a suitable maximum production rate will then be recognized as a fairly better technique for reservoir management.
Geologic Controls On Wettability of Carbonate Reservoirs, Abu Dhabi, U.A.E.
Authors: Marzouk I. , Takezaki H. , Miwa M.
Published: December 2007

Wettability is one of the most important rock properties that controls fluid saturation distribution and fluid flow behavior. It will have significant impact on original oil-in-place, reservoir performance, ultimate oil recovery and accordingly, field economics.

Geologic controls on wettability is a subject of increasing interest, which will lead to better understanding of the origin, distribution and prediction of this important rock property. The Thamama carbonate reservoirs, which are the main producing reservoirs in Abu Dhabi, U.A.E., are the prime target of this paper.

Geological and Petrophysical studies of core samples indicated unique phenomena, which could not be explained by the conventional theory of wettability. For example, review of the "Amott" wettability measurements generally indicated oil wet character in the oil zone, mixed wet in the transition zone and water wet in the water zone. Fresh core resistivity measurement showed variable saturation exponent "n" with changing water saturation of the same sample. Other examples are discussed in this paper.

In order to explain these phenomena, careful examination of geological and petrophysical properties such as pore throat size distribution and petrographie image analysis, were conducted, which confirmed close relation between wettability and rock type especially the pore system. The pore system proposed in this study is based on the pore throat size. Accordingly, the pore system of the Thamama reservoirs is classified into; Macropore throats (more than 4 microns), Mesopore throats (4-0.3 microns) and Micropore throats (less than 0.3 microns). Micropores are always filled with water (Swi). Mesopores are filled with either oil or water depending on the oil column thickness. Macropore are easily filled with oil above the free water level (FWL).

Based on the above observations, a wettability distribution model is proposed and the following new concepts are introduced: True Wettability, represents stabilized condition of grain surfaces in a water/oil system under conditions where oil can contact the rock surfaces. True wettability of the Thamama carbonate reservoirs is considered to be oil wet.Wettability Change, represents the oil accumulation process in a virgin water filled reservoir. Before oil accumulation, wettability was originally water wet, after oil accumulation wettability changed to oil wet if grain surfaces contacted with oil.Apparent Wettability, which is the measured wettability, represents the distribution of oil and water in the different pore spaces. It will depend on micropore throat percent and oil column thickness.

Several geological and petrophysical evidences and examples were discussed in this paper.
Petrophysics and Seismic Wave Technology: Applications in Exploration, Formation Evaluation, and Reservoir Characterization
Authors: Klimentos T.
Published: December 2007

One of the most important issues in reservoir characterization is heterogeneity. Reservoirs are more heterogeneous than researchers have believed in the past. Reservoir heterogeneity can be created by complex sedimentary and diagenetic processes and then modified by a sequence of tectonic changes. The petrophysical and seismic properties of reservoirs may vary significantly from one well to another or even at a distance of a few meters. Therefore, if one could predict such rock property variations in space, it would be very beneficial to reservoir characterization and planning of appraisal and production wells. Moreover, front movement in a water flooding may be monitored by studying the different seismic response between water and hydrocarbon saturated rocks.

In this paper a new method for predicting the spatial variation in rock and fluid properties is presented along with laboratory results and a case study. Various models of porosity, permeability, pore-fluid, and lithology are created to predict the corresponding P- and S- wave velocities and acoustic impedances. The best fit between synthetic seismic and sonic models would indicate the most probable reservoir model.

This method could be useful in (1) Reservoir Characterization: Predicting the spatial variation in rock and fluid properties of a reservoir. This is essential for accurate reservoir characterization and planning of appraisal and production wells; (2) Formation Evaluation: Modeling porosity, permeability and pore-fluids near the wellbore in conventional and horizontal wells; and (3) Seismic Exploration: Direct detection of hydrocarbon bearing rocks in areas for which little subsurface information is available.
Lithological Variability of Electrical Parameters in a Sandstone Sequence
Authors: Amabeoku Maclean O. , Mimoune Kissami , Al-Nufaili Subhi
Published: December 2007

Electrical parameters are the constants in the Archie equation and variants thereof, to calculate water saturation, original oil-in-place, and residual oil saturation from resistivity well logs. The applicability of these parameters in reservoir calculations are, in many cases, reservoir specific. It is, therefore, imperative that determinations of these parameters in the laboratory should be done at conditions that reflect, as closely as possible, those prevailing in the reservoir, with respect to temperature, pressure, and fluids. The formation factor, cementation exponent, and saturation index vary with lithology as well.

The lithofacies identified in this sandstone sequence include clean sandstone, shaly sandstone, and sideritic sandstone. X-ray diffraction analysis shows the mineralogical composition to be clays, ankerite, siderite and quartz.

An experimental program has been conducted to determine these electrical parameters at reservoir conditions using native crude oil on two of the lithofacies identified in the reservoir. This paper discusses results of these measurements. The results are grouped by lithology so that a regime of application can be defined. The importance of this lithological grouping is that different parameter values and lithology flags (or indicators) can be programmed into the water saturation calculation scheme to refine the well log determination of water saturation from Archie-type equations.
Development of a Modified Capillary Pressure J-Function
Authors: El-Khatib Noaman
Published: December 2007

Capillary pressure curves are represented by the equation Pc=a / (Sw-Swi)b. It is shown that for the Leverett J-function to produce a single correlation, the tortuosity, the irreducible water saturation and the saturation exponent b must be the same for the different formations. A modified capillary pressure function J* is introduced that incorporates the tortuosity and irreducible water saturation in its definition. The modified function is correlated with the normalized saturation SD so that all curves will have their vertical asymptotes at a single point SD=0. The modified function represents a significant impro- vement over the original one since it is now sufficient to have the value of the saturation exponent b be the same for two samples to get the same correlation. This was verified by analyzing data from the literature and comparing the two correlations. A modified linear regression by means of weighted least squares method is used to fit the experimental capillary pressure data. Data sets from different sources were analyzed. It was found that a good single correlation can be obtained for samples from the same formation but the correlations were different for different formations.
Factors Affecting Injectivity Decline
Authors: Al-Hamadah A. M.
Published: December 2007

Reservoir pressure support for a large portion of a giant field is maintained by peripheral sea water injection. The temperature of the injected seawater is significantly lower than the reservoir temperature and also lower than the previously injected water obtained from aquifers. Therefore, a decline in injectivity is expected as a result of higher water viscosity due to lower injection water temperature.

This paper presents actual data collected from power water injection wells in two areas of the field, both before and after the start of seawater injection. This data has shown a significant decline in injectivity after conversion to seawater in only one area. The quality of the injected water and other related factors will be reviewed to determine the reasons for this behavior that apparently contradicts what was expected. The paper also discusses the actual effects that cold seawater injection has on pressure falloff behavior.
A New Technique To Analyze Simultaneous Sandface Flow Rate and Pressure Measurments of Gas Wells With Turulence and Damage
Authors: Nashawi I. S. , Al-Mehaideb R. A.
Published: December 2007

Most of the problems associated with conventional gas well tests are related to the nonlinearity of the equations describing real gas flow, the presence of the rate dependent (non-Darcy) skin, and the long shut-in time periods required to collect the data for the analysis in tight reservoirs in which the wellbore storage period can be excessively long.

This paper presents a new pressure buildup technique that reduces the wellbore storage effects, eliminates the long shut-in periods experienced with conventional tests by using afterflow rate and pressure data, and most importantly provides a direct method to estimate non-Darcy skin. The proposed technique uses normalized pseudo-functions to avoid the nonlinearities of the governing equations and involves using two different plots. The formation permeability is obtained from the slope of the first plot. The mechanical and non-Darcy skin factors are obtained respectively from the slope and intercept of the second plot. A field example and two simulated cases are presented to illustrate the application of the new technique.
Calculation of Well Productivity in a Reservoir Simulator (II)
Authors: Chen G. , Tehrani D. H. , Peden J. M.
Published: December 2007

Conventional simulators calculate the well productivity using Peaceman's equation[1] for equivalent block radius and the well block pressure. This is generally acceptable for most vertical and horizontal wells. However, no formulation is available for slanted wells. Even for vertical and horizontal wells in which block aspect ratios are far from unity or where the well completion interval is short or the well is located close to a reservoir boundary or other wells, the existing formulations can give erroneous answers. In our previous paperi[2], a novel method was introduced for calculating very accurately the productivity of wells of any deviation (0-90°) fora homogeneous reservoir. In this paper, we present a more general solution for general well position and applicable to multiple wells and heterogeneous reservoirs. A novel method is presented to convert the heterogeneous model to an anisotropic but uniform permeability model before applying the new analytical technique, in conjunction with a numerical simulator. The analytical model developed for this purpose is coupled with a numerical simulator to produce the necessary parameters needs for simulation of well performance in a conventional simulator. The results will have a wide field application for horizontal, vertical and deviated wells.