bluuebunny/crossref_metadata_2025 huggingface dataset:
Gel Surface Filtration from Polymer Solutions During Gravel Packing
Authors: Torrest R. S. , Marcano F.
Published: December 2007

Gel filtration from hydroxyethyl cellulose polymer solutions at the inlet face of formation sand can rapidly build a low permeability layer that dominates system behavior. Laboratory experiments with dilute solutions show the nature of this build-up as well as behavior with subsequent water flow. Pressure response and fluid placement during gravel packing and pack quality may be strongly affected.
Compositional Simulation of the Block 31 Field and Surface Facilities
Authors: Ireland M. M. , Boiling J. D.
Published: December 2007

The Block 31 reservoir in west Texas was studied using a full-field compositional reservoir simulator coupled to a compositional facility model. The first-ever miscible EOR project, a vaporizing-gas drive, was initiated in 1949 and is still underway at Block 31. The objective of the study was to update past performance predictions of previous studies by Warner et al.1,2 and optimize future reservoir production.

A compositional model of both the reservoir and field facilities was required due to the complex fluid phase behavior and intricate coupling of reservoir performance with the surface facilities. The convergence pressure technique was used to model fluid phase behavior in the reservoir. Core and log data were used to construct a reservoir description of the multiple Devonian zones. Forty years of field history were then matched. The initial decline in reservoir pressure under primary drainage was matched by adjusting reservoir pore volume. To account for the large model grid blocks and match the rise in GOR after primary, the relative permeability to gas was changed. The oil, NGL, and gas production rates from the model were all within 3.0% of field values at the start of 1985.

To improve operational reliability and reservoir performance, predictions looked at replacing the 20 year old flue gas plant with an air separation plant producing nitrogen. Also, the construction of additional gas processing facilities to increase NGL production was investigated. The results showed the flue gas plant should be replaced to increase liquid reserves, but additional produced gas processing facilities were unnecessary. Additional insights gained into field operations are discussed including optimizing future gas sales, recognizing the importance of strict reservoir surveillance, and realizing the opportunities for improved sweep efficiency in the field.
Foam as a Diverting Technique for Matrix Sandstone Stimulation
Authors: Burman J. W. , Hall B. E.
Published: December 2007

It is often difficult to adequately treat the entire perforated interval in a damaged, gravel packed well. Foam was evaluated in the laboratory as a diverting technique for hydrofluoric acid treatments, and encouraging results led to field evaluation of foam diverting in 12 wells in the Gulf of Mexico. Generation of stable foam at low pump rates was aided by the use of a coil tubing unit, which further enhances treatment results by enabling the various fluids to be spotted at or below the perforated interval. Two different techniques were used in these treatments: staged foam injection and foam injection during the first third of the treatment. Production data was used to evaluate the foam diverting technique. Also, temperature logs were run before and after one treatment to provide further information on the benefits of foam. Advantages and disadvantages of foam diverting as well as treatment design procedures, laboratory data, and production data relating to foam diverting in matrix hydrofluoric acid treatments are presented in this paper.
A Novel Economical Approach for Accurate Real-Time Measurement of Wellbore Temperatures
Authors: Jones R. R.
Published: December 2007

A measuring device and technique are described for an accurate and economical determination of the bottom-hole circulating temperature (BHCT) in a well-bore while drilling, completing and/or at any time prior to cementing.

Accurate determination of the BHCT is very important during the drilling and completion of a well, and is crucial to effective cement slurry design and cement job results. Methods for this determination include a variety of tools, charts, tables, logs, mathematical computation, etc. Unfortunately, these methods are often expensive, require specialized equipment, interfere with normal operations, and are often applied when well conditions do not simulate those prior to cementing. Inaccurate temperature measurements attribute to poor cement slurry designs and poor cement job results usually due to improper slurry retardation. Data are presented to dramatize the effect of temperature on cement slurry design and application.

The device described is designed to be circulated in a wellbore at any time during normal completion operations whenever tolerances in the wellbore exceed 0.375 in. (0.952 cm). The approach provides real-time temperature data for the operator and requires no specialized equipment, nor costly, unnecessary delays in the well program. Case studies are presented in this paper to emphasize the ease of application, accuracy and economic feasibility of this novel approach.
Assessment of Variable Temperature in Gas Storage
Authors: Steele A. E.
Published: December 2007

The assumption of constant reservoir temperature is widely used in reservoir analysis and has generally been extended to Gas Storage Engineering. However, this assumption may not be applicable to all storage fields, particularly for those high rate fields that cycle large volumes of gas through a small number of wells. A study investigating storage reservoir temperature was initiated to determine (1) if there is a significant cyclic variation in gas temperature, and (2) if there is a long term cumulative heat effect from gas storage operations.

To evaluate cyclic temperature variations, electronic temperature surveys were run in several wells during both minimum and maximum content shut-in periods. A cumulative gross heat balance was performed for the reservoir to estimate the temperature effect of 20 years of gas storage cycling. The results indicate that variable reservoir temperature is possible.

The impact of including variable reservoir temperatures in gas storage engineering calculations may be significant for high rate (peaking) fields, which are frequently the critical fields in a storage system. Small variations in temperature will affect maximum storage content, pressure-content modeling and, most importantly, the conclusions of gas inventory analysis.
Inverse Modeling in Gas Reservoirs
Authors: Fasanino G. , Molinard J. -E. , de Marsily G. , Peleé V.
Published: December 2007

The distribution of permeability or transmissibility is of interest to the engineers for several reasons. These reasons may be related to design, operation, development or understanding of reservoir performance. In order to determine the distribution of the permeability, in general, several sources of information are available. These include: Transient tests in individual wells which give estimates of local permeability in the surrounding matrix,Longer term interference tests which relate to the influence of permeabilities around several observation wells,Geological information about the formation which involves statistically significant representation hereby referred to as ‘geostatistics’,And, finally, observations made during the operation of the field.

The first three items above relate to reservoir description while the fourth relates to reservoir performance.

The paper describes a procedure developed for determining the distribution of permeability by an inverse modeling technique.

The procedure combines the data from various sources of information listed above in a manner which compatibly reconciles local observations with spatially structured reservoir properties, and recorded pressure history.

It was implemented through a computer program cal led MAGHY (Modèle d'Ajustement de Grandeurs HYdrauliques). It applies to reservoirs or aquifers subject to the flow of slightly compressible liquids (oil or brine), or compressible gases in single phase, in two dimensions.

Two examples are included as application of the procedure. One involves an aquifer study where the flow field was in single phase liquid. The other presents validation of the procedure through a hypothetical case where a pre-determined permeability distribution was converged upon through the use of computer program implementing the inverse modeling technique. It was based on single phase gas flow.
Selective Plugging and Oil Displacement in Crossflow Core Systems by Microrganisms
Authors: Raiders R. A. , Maher T. F. , Knapp R. M. , McInerney M. J.
Published: December 2007

The ability of bacteria to divert fluid flow from a high permeability sandstone layer to a low permeability sandstone layer by selective plugging and the ability of these bacteria to recover residual oil was studied. A crossflow system consisting of two layers of Berea sandstone were placed in capillary contact. Pressures were monitored in oil-brine and brine saturated systems to determine pressure gradients within the layers and estimate flow behavior. A mathematical simulation model was developed and used to analyze the results.

Changes in crossflow patterns were observed in the systems. During the treatment process, up to 60% of the production from the system was from the low permeability layer. Injectivity into the low permeability layer increased by a factor of three from initial conditions, relative to constant flow into the high permeability layer The greatest decreases in permeability, and thus the largest increases in potential gradients, occured in the high permeability layer, due to preferential microbial growth. Estabilishment of a mobile gas phase by biogenic gas production also assisted flow diversion. Large amounts of gas were produced from the high permeability layer once permeability reduction occured.

These results extend the previously published data obtained using parallel cores not in crossflow, and show that preferential plugging and oil release from high permeability regions do occur in crossflow systems. Oil recoveries comparable to those achieved in earlier linear core experiments were observed in the crossflow experiment. Thus, microbial metabolism apparently improves flow patterns in laboratory crossflow experiments and leads to the recovery of residual oil from waterflooding.
A Method for Controlling Numerical Dispersion in Carbon Dioxide Flooding Simulation
Authors: Potempa T. C.
Published: December 2007

The phenomenon of numerical dispersion is due to the finite grid size in simulators. This effect can severely influence the results of simulations of displacement of oil by carbon dioxide. Mathematical techniques for controlling such spurious dispersion are described. The resulting scheme is compared to the industry standard upstream weighted finite difference method for gas drives which are: (a) immiscible, (b) have limited miscibility by a vaporizing gas drive mechanism, (c) exhibit developed miscibility, and (d) are fully miscible.

The results presented are of value for the following reasons. First, we discuss modifications that we have made to implement methods developed for mathematical model problems in a compositional simulator. Second, we have shown that such techniques represent an improvement from the state-of-the-art. Our particular contribution is the method by which we modify a central difference approximation to insure monotonie behavior. Third, we provide direct comparisons between the standard scheme and our modified scheme. Fourth, we show that, to obtain a specified level of numerical dispersion, at minimum a threefold reduction in computer costs is realized by our scheme with respect to the industry standard method. Last, we show that this estimate of benefit is conservative, as we can obtain up to a fiftyfold improvement in some cases.
Interference Well Testing to Predict Early Water Breakthrough in Naturally Fractured Reservoirs
Authors: Najurieta H. L. , Robles O. O. , Edwards D. P.
Published: December 2007

Secondary recovery projects in dual porosity reservoirs with high transmissivity fractures must be carefully managed to avoid early water break-through into producing wells. If water production does begin in an injector/producer system, the origin of the water channelling must be identified so that remedial changes can be made in the injection-production schedule.

This paper shows that pressure interference testing between injection and producing wells, is a better method for locating problem injectors than the alternative technique using radioactive tracers.

Furthermore, information derived from interference tests can be used to prevent water break-through in water-flood projects.

Calculations of the interference response before and after break-through are shown in an example. A simple graphical method is used to illustrate water advancement.
Dimensionless Pressure of a Vertically Fractured Well Surrounded by Offset Wells
Authors: Stein M. H.
Published: December 2007

A superposition model was developed to study the effect of offset wells on pressure transient tests for vertically fractured wells. The principle of superposition was found to be a valid tool.

For the situation in which a vertically fractured well was surrounded by production wells, there was no difference in the portion of the data used for the analysis of pressure buildup data when the offset producers were shut-in and when they were left on during the buildup test. This result implies that for a fieldwide situation in which the offset wells are left on during the buildup test radial flow is not achieved and the formation flow capacity calculated from a semilog plot has to be corrected. There may be limitations to the accuracy of the correction factors in multilayer reservoirs.

Analysis of pressure buildup or falloff data for a pressure maintenance project with a vertically fractured well in the middle of a five-spot pattern can yield different results depending on the operation of the offset wells during the pressure transient test. For a fieldwide situation in which the offset wells are left on during the pressure transient test, radial flow might be achieved, in which case the formation flow capacity calculated from the semilog plot should not be corrected. If radial flow is not achieved either due to interference from offset wells or the test not being run long enough, the data can be type curve matched to determine formation flow capacity.
Predicting Uniaxial Compressive Strength from Log Parameters
Authors: Tokle K. , Horsrud P. , Bratli R. K.
Published: December 2007

Models for prediction of in-situ rock behaviour often suffer from lack of relevant input data, especially rock strength data. Rock mechanical testing of cores provides only discrete data points. This paper presents a method which produces a continuous plot of uniaxial compressive strength. The method is based on correlating standard log parameters with laboratory measured rock strength data. When a correlation has been established, it can be applied to new wells in the same field, giving a strength plot by computer processing of the necessary logs.

The method has been applied to two wells in a North Sea field, resulting in a statistically significant correlation. Proper depth adjustments between core depth and log depth are essential. It is further important that the lithologies of interest are represented among the core material.
Pipeline Transportation of High Pour Point New Zealand Crude Using Pour Point Depressants
Authors: Slater Grant , Davis Ann
Published: December 2007

The Petroleum Corporation of New Zealand Limited discovered New Zealand's first major oil field in 1980. Production is currently 1590 m3/d (10,000 bpd), which represents about 14% of the country's requirements.

The crude has a high pour point (32°C) and a high wax level (35%). A major factor in development of the field was the selection of appropriate technology to overcome transportation problems via a 40 km pipeline from the process plant to port storage with ground temperatures of 11°C (52°F). Technical and economic considerations resulted in the selection of a chemical pour point depressant rather than thermal cracking, dilution with condensate, or maintaining the crude oil temperature above its pour point.

Selection of a suitable pour point depressant was made using laboratory studies done by various prospective suppliers. Product performance was based on pour point and yield value for the crude using a simple simulation of pipeline cooling.

The first year of pipeline operation was essentially troublefree and the following key points were noted. The actual pipeline dosage rate was considerably lower than laboratory predicted rates. By careful experimentation during pipeline shutdowns of varying duration, it has been possible to devise a management plan which minimizes difficulties during start-up.

The paper discusses how the adoption of pour point depressant technology, in conjunction with pipeline design, has resulted in an essentially trouble-free system which enables the crude to be successfully transported by pipeline.
Drilling Performance in Turbodrilled and Rotary-Drilled Khuff and Pre-Khuff Wells in Bahrain Field
Authors: Alqassab M. H. , Fathalla M.
Published: December 2007

This paper discusses the performance of turbodrilling the Khuff and pre-Khuff wells in Bahrain field. Data obtained from these wells and earlier rotary drilled wells are analysed and compared in order to optimize the application of turbodrilling. Recommendations are made for selecting intervals best suited for turbodrilling.
New Techniques in Horizontal and Drainhole Drilling Optimization: Lehrte 41 Lateral Drilling Project
Authors: Prevedel B.
Published: December 2007

In order to optimize hydrocarbon recovery, more and more research work has been carried out in the last few years, especially in the field of drainhole drilling-, production-, and reservoir technology.

PREUSSAG's lateral drilling project Lehrte 41 in a partly by edge water drive depleted oil reservoir can be addressed as one step further towards an increased oil production especially with respect to current oil prices.

The objective of the workover operation in question was to bring the well back to an economical production by sidetracking and building up the angle of inclination to 120 deg with the Articulated Drillstring (ADS).

After reaching total depth, the well was cased with standart slotted tubings and the top formation successfully cemented

Oil production was resumed with a surface rod pump and showed a significant increase.
Optimized Operations Significantly Reduced Drilling Time and Cost in Gulf of Suez October Field
Authors: Khalaf F.
Published: December 2007

This paper discusses the improvements in the drilling techniques and procedures that optimized the drilling operations in Gulf of Suez October Field. The improvements include all aspects of the operation: the drilling plans, the drilling procedures, the drilling equipment, the support services, and the supervision. Optimization greatly increased penetration rate, improved hole stability, and reduced time of all operations. With these results, the last group of wells were drilled almost three times faster than the early wells, and at half of their cost.
Evolution of Bahrain Field in Relation to Western Arabian Gulf Basin
Authors: Samahiji J. A. , Chaube A. N.
Published: December 2007

The Bahrain Field, on the edge of the stable Arabian Platform, is a prominent salt related anticline. Growth analysis indicates active growth in the Triassic – Lr Jurassic, Up Cretaceous (Turonian and Maestrichtian) and early Tertiary Hydrocarbon localisation is noticed at many levels in Paleozoic, Jurassic and Cretaceous. Likely source intervals are Lr Khuff for Khuff gas and the Oxfordian-Kimmeridgian Hanifa – Lr Jubaila for Mesozoic oils. Hydrocarbons were emplaced in the present trap in Up Cretaceous – Tertiary. With tectonic breaching of the Hith seal, these remigrated from Jurassic to the numerous Cretaceous intervals. Periods of growth and oil migration conform to those postulated for the region.
Reservoir Geological Modeling of the Arab D Reservoir in the Bul Hanine Field, Offshore Qatar: Approach and Results
Authors: Munn D. , Jubralla A. F.
Published: December 2007

The Bul Hanine Arab D reservoir is the most important of offshore Qatar in terms of oil production potential. In 1980 contrary to earlier predictions, water-breakthrough occurred along discrete intervals of the reservoir in a crestal well. This led to the establishment of an integrated in-house study team in order to develop a consistent reservoir model and subsequently investigate various future development policies.

The reservoir geological model used during this study was constructed by subdividing the reservoir into rock/pore-type layers (fifty-two in total), for which sets of petrophysical parameters could be defined (porosity versus permeability relationships, capillary pressure curves, formation resistivity factors and resistivity index). In particular the development of the porosity/permeability relationships has led to a greatly improved permeability profiles in the uncored wells.

Several significant uncertainties (such as the special core analysis data, the inter-well geological heterogeneity and faulting/fracturing) remain to be investigated, using the developed detailed reservoir geological layering, during the history-match and prediction phases of the planned simulations.
Synchronous Deformation of the Neoautochthonous Sediments of the Northern Oman Mountains
Authors: Warrak M.
Published: December 2007

The D3 structures deforming the neoautochthonous sediments in the southern part of the Northern Oman Mountains, are shown to be synchronous folds that developed contemporaneously with sedimentation. During their development, these folds tended to form highs associated with basins behind them, that migrated in time and space from east to west over Oman foredeep
Limestone Reservoir Development: A Simulation Approach
Authors: Al-Aruri A. D. , Sarkar P. R.
Published: December 2007

Kuwait Oil Company, KSC (KOC) has many oil producing reservoirs among which LL-X is a limestone. Despite the enormous volume of oil-in-place, very little has been produced uptil now due to the tight nature of the producing horizons and poor aquifer communication. In view of the rock heterogeneities, suspected crestal fracturing, complex fault pattern, areal and vertical variation of fluid properties, a detailed reservoir simulation study was warranted to design the optimum exploitation strategy. Consequently, simulation study was made on a model with 10962 cells. The optimum prediction scheme with five-spot pattern waterflood pattern was selected after screening a score of scenarios based on techno-economic evaluation. This paper highlights some important aspects of the study with the results obtained.
Effect of Internal Pressure and Cement Strength on the Resistance of Concentric Casing Strings
Authors: El-Sayed A. H. , Khalaf F.
Published: December 2007

Some solutions have been suggested to avoid failure of casing particularly opposite massive salt bodies.The most effective of these solutions has been the use of multiple cemented casing strings. It has been found that dual cemented-casing strings have a collapse resistance superior to the sum of the collapse resistances of the casing strings composing this system. But, these results do not include the effect of the internal pressure.

This paper discusses the influence of a high internal pressure (alone, or combined with external pressure) and the cement properties on the collapse resistance of cemented concentric strings. The resistance of the system depends on the quality of the cement. A low quality cement will continue to creep after setting and will not contribute much to the system under combined pressure loads. The application of an internal pressure that corresponds to normal pressure gradients reduces the tangential stress and increases the collapse resistance of the system by 25% over the same system without internal pressure.
Field Desalting of Wet Crude in Kuwait
Authors: Chawla M. L.
Published: December 2007

Production of wet crude had been a growing field problem in Kuwait. The need to treat wet crude was felt for quite some time. Application of right technology and installation of proper desalting facilities were needed to solve this problem. Thus it was decided to install electrostatic desalting plants progressively in Kuwait's oil fields. By the end of 1986, 14 plants, (6 conventional (AC) and 8 dual polarity (AC/DC)) with a total capacity of over 750,000 STB/D of treated crude have been installed.
Accurate Estimation of Water Saturations in Complex Carbonate Reservoirs
Authors: Amin A. T. , Watfa M. , Awad M. A.
Published: December 2007

Large errors in the computed values of water saturations in the uninvaded zone (Sw) and invaded zone (Sxo) will occur if some of the parameters used in the interpretation are treated as constants. In particular, the application of constant values of the Archie factor (m) in the saturation equations has been found to introduce major errors.

A method was developed to calculate a " variable m " using resistivity and electromagnetic propagation logs. This method evaluates in detail the mixing in the invaded zone between the invading filtrate and the formation water. This allows representative values of the fluid properties in the invaded zone, such as resistivity and electromagnetic propagation time, to be obtained and used in the interpretation. The computed results using this technique were verified in water bearing zones, tar zones, zones with production tests and by comparison with core analysis.

Examples of well data are included where comparisons were made between the more conventional interpretation method, using constant values form and fluid properties, and this new interpretation method. The validity of the assumptions made, particularly with regards to the potential mismatch in the depth of investigations of the various measurements, were analysed in detail. This method has now been tried on a large number of wells, and has been shown to improve the accuracy of the computed values of saturations over the conventional method.
Variable Salinity Aquifer and its Effect on Reservoir Performance
Authors: Ghoniem S. A.
Published: December 2007

This work deals with a reservoir which have shown substantial variation in produced water salinity with location and time. Water dumping and variation in salinity within aquifer can be responsible for this phenomena. Using production data, well completion details, cased hole logs, and initial reservoir pressures, it was concluded that upper water dumping took place after production had started from the reservoir under investigation. Thus, initial open hole logs are considered dependable.

Representative initial open hole logs showed qualitative and quantitative variations in the aquifer salinity towards the East which confirms the initial production data. A technique was developed to calculate precisely the water cut from saturation profiles of some selected wells (calculated from open hole logs at various salinities). This technique, which was first checked at locations where the data were correctly specified, proved that the best match between calculated and observed water cuts for the selected wells was obtained at the highest tested salinity (23000 ppm NaCl). Therefore it is wise to calculate the original oil in place of such reservoir at the highest salinity (23000-28000 ppm NaCl) observed in the initial stage of production from reservoir. Geochemical analysis of produced water showed clear evidence of the presence of meteoric water in the reservoir aquifer. Therefore, complexity in the behaviour of salinity of produced water is attributed to the hydrodynamic factors.
Dual-Burst Thermal Decay Time Logging Overview and Examples
Authors: Olesen J-R. , Mahdavi M. , Steinman D. K. , Yver J. P.
Published: December 2007

The Dual-Burst TDT* (TDT-P) tool is a 11116 -in. diameter pulsed neutron, dual detector tool system that uses a new method of analyzing the decay of a burst of fast neutrons in the downhole environment. The method provides an accurate measurement of the neutron capture cross section of the formation by employing a physically realistic model of the decay, which accounts for neutron diffusion effects, rather than displaying the decay as a sum of exponentials from the formation and borehole. Intrinsic sigma is computed directly from the decay curve instead of by using correction charts. The model is evaluated using over 2,500 data obtained in well characterized laboratory test formations. The benefit of the method is that the formation cross section is independent of the fluid in the borehole as well as independent of the neutron diffusion characteristics of the formation, characteristics which vary with lithology.

Selected results over the data base are discussed and compared to the results of a two-exponential processing over the same data. The insensitivity of the formation capture cross-section determination with the diffusion model to variations in borehole characteristics as well as tool geometry and, more importantly, timing is demonstrated.

Middle-Eastern log results are presented; they include TDT-P versus TDT-M comparisons, showing the variable effect of diffusion for different cases; an example of the insensitivity of formation sigma to borehole fluid characteristics. Results from a two component (formation and borehole) diffusion processing to invert the data, featuring a level by level fit of the diffusion coefficients to the measured data, are presented and compared with the results from a fast, real-time, wellsite computation using a single component model and diffusion coefficients predetermined from external input of lithology and borehole geometry.
Evaluation of Empirically Derived PVT Properties for Egyptian Oils
Authors: Saleh A. M. , Mahgoub I. S. , Asaad Y.
Published: December 2007

This paper evaluates the most frequently used empirical gas and oil PVT correlations for application in Egypt. Correlations are used to determine values for bubble point pressure, oil formation volume factor at saturation pressure, solution gas oil ratio, oil and gas formation volume factor and oil viscosity. Often, these properties are required for oil field computations when there are no experimental or laboratory measurements available. When only oil and gas gravities and reservoir pressure and temperature are available, it is imperative to use published correlations for making accurate estimates of the fluid's physical properties. A review of the correlations used, along with the statistical accuracy of these correlations when compared to Gulf of Suez and Western Desert field data, is provided in this paper.
Performance of a Pilot Cyclic Steam Stimulation Project in Kuwait
Authors: Milhem M. M. , Ahmed K. N.
Published: December 2007

The heavy oil sand reservoir of Kuwait containing a viscous, low API oil occurs at a shallow depth of about 422 feet subsea. Its reservoir temperature and pressure are generally low because of the shallow depths involved. The heavy oil reservoir has not been produced till now by the primary techniques. Primary recovery is expected to be low mainly due to lack of a natural driving mechanism.

Various studies were made to find out ways and means to recover the heavy crude oil from the shallow deposits in Kuwait. The viscosity, temperature behaviour of Kuwait heavy oil is such that its viscosity is reduced by a factor of more than 100 when the temperature is increased to 300° F which suggests that the oil might be produced successfully with thermal recovery processes. Other favourable conditions for such a process are the shallow depth of the accumulation and the relatively high oil saturation. In view of their size and favourable characteristics, Kuwait's heavy oilfields are obvious candidates for the application of thermal recovery methods. It was concluded that injection of limited amounts of steam might be a very effective method for stimulation of heavy-oil wells. To obtain an early answer on the suitability of thermal process a pilot project of four wells for steam stimulation was initiated in an area near light oil production facilities. This helped in transportation of produced crude. The other favourable factors for selecting the pilot area are:

Net pay thickness is the highest in the known area, The oil viscosity is moderate compared to other areas, Nearer to fresh water station. This is required as water needs to be transported by road tankers.

The pilot project was initiated with simplest design and was handled with in-house expertise with minimum input from outside consultants, to achieve the following objectives:

To determine the applicability of thermal recovery process for Kuwait's heavy oil deposits, To determine optimum steam injection rates, To observe reservoir response under different conditions of steam injection, To obtain information for future implementation of large scale project, To gain operating experience under local conditions and to determine problem areas.

The first steam injection was started in September 1982. This paper describes the performance until the end of September 1986. The operating practices and well performances are discussed in some detail.

In view of the favourable results obtained so far, steam soak projects have been expanded considerably since the start of this project. Presently another pilot of the same size as the one under discussion is underway. Further extension in the two pilot areas is being programmed.
Combustion Reaction Kinetics in Limestones Containing Heavy Oils
Authors: Bagci A. S. , Kok M. V. , Okandan E.
Published: December 2007

Experimental results on combustion reaction kinetics for 12.6, 17.8 and 26.4 API gravity crudes from three different oil fields in Turkey are presented. Reaction experiments were carried out in limestone pack using Camurlu (asphaltenic), Raman and Garzan crude oils. In this subject area very limited data exist and no references can be cited for limestones containing crude oils. From this point of view, the results of this study will supply data to an area where not much is reported.

During this work, experiments were conducted in a stainless steel reaction cell under non-isothermal conditions, where linearly increasing temperature at a rate of 1 °C/min was obtained by using a temperature controlled heater. Constant air rate, 1.5 lt/min was used and the behaviour of samples at 25 and 50 psig pressures were investigated. The cell temperature, the amounts of O2, CO2, CO gases, air injection rates and pressures were measured.

Results showed that there were three reaction regions for combustion of crude oil in porous media when data were analyzed by the method proposed by Fassihi et al. Arrhenius constant, reaction rates and activation energies were calculated using Weijdema's reaction model. The molar CO2/CO ratios were found to become constant at high temperatures. The activation energies were calculated for each reaction region defined as low temperature oxidation (LTO), fuel deposition and high temperature oxidation (HTO). The atomic H/C ratios decreased while temperature was increasing.

Finally combustion reactions occuring in a limestone environment is compared with a sandstone environment for 17.8 API oil at 25 psig pressure. It was observed that considerable differences were obtained in atomic H/C, molar CO2/CO ratios and activation energy in HTO region.
Water Injection Performance: Case Study and Related Spontaneous Injectivity Improvement
Authors: El Sheemy M. M.
Published: December 2007

This Case Study examines the water injection performance in two land oil fields. Both produce from layered limestone reservoirs and employ raw water from deep aquifers for injection. The study findings indicate that well injectivity behavioral patterns can be influenced by injection zone permeability, initial well damage, injection water source aquifers as well as operating parameters of the surface injection system. They also show that spontaneous well injectivity improvements do occur and could be attributed to the injection water characteristics.
Reservoir Delineation with VSP and Well Log Data
Authors: Rodrick D. L. , Poster C. K.
Published: December 2007

A prospective Mishrif reef defined by surface seismic data was drilled, but the predicted porosity was not encountered. Acquisition and study of vertical seismic profile (VSP) data including complex trace attribute processing and waveform modelling, indicated that higher reefal porosity was developed farther updip. This prediction was confirmed by side-track drilling.
The Evolution of Khuff Completion
Authors: Al-Khayat S. A. , Mohammed M. F.
Published: December 2007

This paper reviews the changes and improvements in the design of Khuff Well completions in Bahrain; functions of the components will be emphasized and their performance evaluated.

In general, there have been three basic completion designs. Early wells have 5" liner Cemented across the Khuff zones with 5" tubing tied back from the liner to the surface. Subse quent wells were completed with 7" casing with a mechanical set seal bore packer and 5" tubing anchored to it. The latest group of wells are equipped with hydraulic set packers and the tubing is tied back through a floating seal assembly to allow for movement.

All designs use various configurations of landing nipples below and above the liner or packer seal assembly. Early designs also utili zed a sliding side door sleeve (circulating device) above the seal assembly. The later designs incorporate a landing nipple below a perforated pup in the tail section for flowing bottom hole pressure measurements.
Mixed Integer, Linear Programming Model for Multireservoir Strategic Planning
Authors: Saif M. A. , Kumar R. , Shanyoor M.
Published: December 2007

This paper outlines the features of a Mixed Integer Linear Programming Model developed for multireservoir strategic planning and its practical application to Kuwait Oil Company (KSC) in arriving at an optimum production/ development policy involving a number of reservoirs over medium and long time periods (5-20 years). The input data to the model consist of a number of production/development plans ''profiles", generally from simulation studies of each reservoir. The model chooses one profile of each reservoir such that the overall cost of production and development are minimised and all other constraints are fulfilled.
Lekhwair Pilot Waterflood, North Oman
Authors: Willetts J. M. , Hogarth R. A. M.
Published: December 2007

The Lekhwair field contains light, slightly undersaturated oil in two low permeability limestone reservoirs. Soon after being brought into production in 1976 the likely benefits of pattern waterflooding were recognised, but despite encouraging results from studies, there was still considerable concern regarding the sustainability of injection. A pilot waterflood with six inverted five-spots was therefore put on stream in October 1984. Injection is progressing without serious declines in injectivity, and pilot operations are proceeding very satisfactorily.

Injection water breakthrough into producers was not expected for towards ten years. Hence, a monitoring programme, utilising two observation wells drilled close to injectors, has been designed to obtain earlier results. Induced gamma ray spectrometry and induction logging tools have been used to distinguish between the low-salinity injection water and oil. Long-life radioactive tracers have been injected and frequent gamma ray logging is also monitoring the passage and depth profile of the flood front. Although sweep is still progressing at the observation wells, logging has shown already a recovery efficiency of 42%.
Practical Limitations in Obtaining PVT Data for Gas Condensate Systems
Authors: Eyton D. G. P.
Published: December 2007

This paper examines the accuracy of laboratory generated PVT data for gas condensate reservoir fluids. Although there are recognised difficulties in obtaining representative samples from such reservoirs, there are also significant uncertainties in the results of laboratory studies performed using the samples. The largest uncertainties are associated with the measurements of small liquid volumes, dewpoints and chemical compositions. Reservoir engineers should be aware of these uncertainties and should weight PVT data accordingly, when used as input parameters to reservoir models.
Analysis and Phase Behavior of Khuff Gas System in Bahrain Field
Authors: Al-Mahroos F. M. , Tjoa G. H.
Published: December 2007

Khuff gas is the most important resource in Bahrain. About 90% of Bahrain's total energy needs, including power generation either for public utility or for industry, depends on the Khuff gas. In addition, it is used currently as a feed-stock to the petrochemical and refining industries, and for injection and artificial lift in the Bahrain oil field. A good knowledge of the phase behavior of the Khuff system is important to predict reservoir performance and future processing needs. This performance and future processing needs. This knowledge is also necessary to study multiple contact, partially miscible oil recovery projects in the partially miscible oil recovery projects in the Bahrain oil field which involve injection of the Khuff gas into the Mauddud and the Arab reservoirs.

In 1985, the Bahrain National Oil Company (BANOCO) launched a program to sample and analyze the Khuff gas. The objective of this program was to determine any lateral or vertical variation in Khuff fluid composition (Khuff formation covers 66,000 acres and consists of 2100 ft. thick dolomitic carbonate), to conduct laboratory experiments that are required for studying the phase behavior, and using the laboratory data to construct a mathematical model of the Khuff system based on the Peng-Robinson Equation of State.

Khuff gas wells 311, 359, 361, 369 and 372 were selected for sampling to provide optimum areal and vertical coverage of the three main Khuff intervals KO, KI and KII. Prior to sampling, the wells were conditioned by flowing at a flow rate of ±25% of the AOF potential during an extended period of time. This relatively low production period of time. This relatively low production rate was maintained to avoid any liquid drop-out in the formation which would lean out the samples. The sampled wells were flowed through a three phase separator at an average pressure of 1000 psig, in which gas and liquid rates were measured every hour to verify that the production rate remained stable during the test. The standard sampling procedure was to fill the liquid sample cylinders to full separator pressure and the gas sample cylinders to 60 – 75% of the separator pressure to prevent condensation in the sample container. The separator gas sampling manifold was provided with a side line to measure on-site the H2S and CO2 contents of the Khuff gas by using Kitagawa stain tubes. The sample cylinder pressure and temperature were recorded for all liquid and gas samples. The opening pressure of the sample cylinders were measured at the laboratory to verify that no leakage had occurred in transit.
Compositional Simulation Studies as Aid to Development of Gas-Condensate Reservoirs at Adhi Field, Pakistan
Authors: Abid M. S. , Mateen K.
Published: December 2007

The Adhi field has two main producing horizons, Tobra and Khewra. Both are gas condensate reservoirs with reservoir pressures just above the dewpoint pressures of reservoir fluids. Because of structural complexity, high drilling cost and retrograde nature of reservoir, fluids, compositional simulation1 study was undertaken to examine the behaviour of field under various depletion and cycling recovery schemes. The paper describes the application of compositional simulation to evaluate the relative advantages of various production strategies in a gas-condensate reservoir. The paper also discusses the problems associated and limitations of a compositional radial model in matching the short-term test data for a well with flowing bottom hole pressure below the dewpoint pressure of reservoir fluid.

Use of well test derived permeability in the single-well model resulted in considerable condensate accumulation, sharp decrease in well deliverability and rapid rise in separator Gas/Oil ratio (GOR) not indicated in the actual well performance. Prediction runs show that gas cycling would yield an additional 3.5 percent of initial-oil-in-place (IOIP) in 18 years of production.
Evaluation of Tubing-Conveyed Perforators in Gulf of Suez Fields
Authors: Ghazali S. M. , Khalaf F.
Published: December 2007

Gulf of Suez Petroleum Company (GUPCO) introduced in 1984 the technique of perforating underbalance with a tubing conveyed gun. The early results of the first runs were very encouraging.

Since then, tubing conveyed perforation has become standard practice for nearly all new completions, workovers, and drill stem tests. The tubing conveyed perforating system has reduced completion time, reduced formation damage, and maximized well production.

This Article presents Gupco's evaluation of the tubing conveyed perforation (TCP), discusses the operational aspects of this technique, and the results of its application.
Stimulating Multilayered Carbonates in the Upper Zakum Field
Authors: Al-Tamimi Y. K. , El-Mzien N. Y.
Published: December 2007

The purpose of acid treatments fall into two basic categories: Matrix Acidizing and Fracturing Acidizing.

In Matrix acidizing the acid flow is confined to the formation 's natural pores and flow channels at bottom hole pressure less than fracturing pressure. The purpose is to increase the permeability and porosity of the producing formation.

In Fracture Acidizing the acid is injected through natural or induced formation fractures at pressure usually exceeding the fracture pressure of the formation. This type of stimulation enlarges or creates flow channels from the formation to the well bore.

In both types of acidizing, effective stimulation depends upon permeating the producing formation with an extensive network of channels, to enable hydrocarbon to flow from the reservoir rock to the well bore.

A review is made hereafter, to assess various methods as applied to stimulate complex, multilayered carbonates, in the Upper Zakum field, Offshore Abu Dhabi in the U.A.E.

The review also include a resume of a mini-frac, that was carried out to gather fracturing parameters under in-situ conditions, the objective being to investigate the possibility of creating a contained fracture without creating communication between the adjacent Thamama horizons.

Conclusions suggest that good primary cementing is essential to effective stimulation of multilayered reservoirs. Further work is needed on the feasibility of achieving good cement bond along thin 0.6-1.8m (2-6ft) of interbeds.
Current Challenge to Industry Viability: International Perspective - How to Manage the Present Without Destroying the Future
Authors: Rutman G.
Published: December 2007

Preliminary remarks

I represent an international petroleum company which is somewhat unique to the industry:It is, in part, a Government-owned company, and it is not AmericanIt's a youngster, being only 10 years old in its present form, as compared to some of yours that have been operating for over a century.

Consequently, the views I am about to give you will not always be obvious, nor - I fear - directly applicable to American companies, given that taxation, Government regulation, and import duties often are our major problems.

Having been brought up on a Cartesian diet, it seems to me impossible to believe that management of the present could destroy the future of the oil industry, especially since the latter is in any case an unknown. I shall attempt to demonstrate to you that there is a unity between past, present and future.

To give you a common thread, and also to take account of changing customs in this aspect of life, I propose to illustrate my remarks with a few snapshots from the family album.

1. Some historical perspective

The considerable instability of the present leads me to delve into the distant past, to find other situations that suggest this current period of difficulty is only a growing pain that eventually will pass.