bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tectonics, Stratigraphy, and Hydrocarbon Exploration in the Strait of Hormuz
Authors: Pauken R. J. , Hemer D. O. 
Published: December 2007

ABSTRACT
The objective of this study was to describe the little-known structure and stratigraphy of the Strait of Hormuz in terms of the better known stratigraphy and tectonic history of the Oman region. Four structural provinces surround the Strait of Hormuz: (1) the Zagros fold belt to the northwest (2) the Arabian Platform to the southwest, (3) the Makran Basin to the east and (4) the Oman Mountains to the south. The development of these structural provinces, over 260 Ha of geologic time, influenced the stratigraphy and structure of the Strait. This was the result of rifting and sea-floor spreading (opening of Neo-Tethys) in the late Paleozoic and early Mesozoic and a variety of tectonic events associated with the closure of Neo-Tethys and the northward motion of the Arabian Plate, from mid Cretaceous to Recent.
The stratigraphic section encountered in the Strait ranges in age from Infracambrian to Recent and is composed of four depositional sequences bounded by prominent regional unconformities. These include; Permian-Triassic rift sequence deposited during the opening of Neo-Tethys, a Jurassic-mid Cretaceous carbonate shelf sequence, a late Cretaceous orogenic sequence and Tertiary-Recent orogenic and post-orogenic deposits.
The most dramatic regional tectonic event was the closing of the Tethyan seaway during the late Cretaceous, illustrated by thrusting of the Hawasina nappes and obduction of the Semail ophiolites along the eastern Oman margin, south of the Dibba Zone. Structural development associated with this event is not easily recognized in the Strait. This is because of the overpowering structural effects of the younger Miocene compressional episode, the most important tectonic event recorded in the Strait.
Miocene structuring resulted in the formation of anticlinal and horst features associated with thrust faulting, resulting in a SSW-NNE structural grain paralleling the Oman Peninsula. These structural highs were subsequently eroded, producing a prominent angular unconformity which is easily identified on seismic sections. Some of the structuring was locally enhanced by diapirism of the underlying Hormuz Salt. Above this unconformity is a relatively flat-lying post-orogenic sequence of Miocene limestones, shales and sandstones which would constitute a potential seal for any hydrocarbon accumulations reservoired in the underlying structures.
Potential reservoir facies include fractured Middle Cretaceous to Lower Tertiary limestones present under the Miocene unconformity and thick, eastward-thickening, turbidite deposits of the same age. Numerous wells drilled in the Southern Arabian Gulf Basin, west of the Strait have encountered both oil and gas. The occurrence of oil and gas wells, along with numerous shows and undrilled structures indicate that this area should be given careful consideration for future exploration.
Horizontal Well Technology: Performance Evaluation and Technoeconomic Assessment
Authors: Singh R. S. 
Published: December 2007

ABSTRACT
Horizontal wells could turn out to be one. of the. most Important technological developments of the decade. What was considered an exotic way of drilling in early eighties, and mote ox less an extension of deviated drilling, now appears as a significant production technique.
The paper computes the productivity indices, Pls for both horizontal and veitical wells, the ratio of Pls E the replacement factors. Three variants have been cons-idered, viz drilling of vertical, short-radius and long radius horizontal wells in a fractured basement reservoir. Performance prediction and technoeconomic evaluation has been made for future.
Extensive literature review has been carried out and computations made. It is concluded that even though horizontal option appears to be beneficial, obviously there are cases when it not so. For the examples considered herein, long-radius horizontal well completions are found bettet than both vertical and short-radius horizontal well completions, but vertical welis seem to have an edge over the short-radius horizontal wells.
The Application of Local Grid Refinement to Simulate a Large Hydrocarbon Reservoir as an Alternative to a Two-Model Approach
Authors: Al-Towailib H. S. , Liu J. S. 
Published: December 2007

ABSTRACT
Simulation of a large hydrocarbon reservoir that interacts with other producing reservoirs through a common aquifer with a single regular fine-grid model can be very difficult if not entirely impossible. Such a model will require a very large number of cells in order to account for all interactions among the producing reservoirs and still provide enough resolution in the window area being studied. Due to the limitations in computer hardware that can handle the enormous resources required by the model and the solution algorithm, this task is found to be impractical.
A two-model approach has been used to overcome this difficulty. In this approach, a coarse-grid, areal model of all reservoirs and the aquifer and a fine-grid, three-dimensional model of the window area of interest are used. The two models are run alternately to feed each other with reservoir rates and boundary conditions while the convergence of boundary conditions is maintained. This approach is found to be resource intensive and requires excessive human effort.
This paper discusses the application of the local grid refinement approach as an alternative to the two-model approach to simulate a large hydrocarbon reservoir. The local grid refinement approach involves use of only one model of the reservoir and its associated aquifer system. It allows a finely gridded multi-layer model of the reservoir of interest to be imbedded into a coarsely gridded, single-layer areal model of its associated aquifer system. Consequently, the number of cells is reduced significantly and it becomes practical to simulate the large hydrocarbon reservoir and its associated aquifer system in one model.
For this purpose, therefore, a locally refined grid model was constructed and initialized using data from the already existing models used in the two-model approach. History match runs were made successfully. If compared with the two-model approach, the LRG model history match results are favorable.
The LRG model approach is found to be more advantageous than the two-model approach in terms of eliminating the inaccuracies, the excessive resources, and the intensive human efforts associated with the two-model approach. The simulation results has proved that this approach is feasible and more efficient than the two-model approach. Therefore, the use of this approach will greatly simplify the simulation of the large hydrocarbon reservoir and its associated aquifer system.
Geology and Hydrocarbon Potential of the Tihama Basin, Republic of Yemen
Authors: Doornenbal J. C. , DeGroot P. F. L. , Saif S. M. , Schroot B. M. 
Published: December 2007

ABSTRACT
The Tihama basin at the west coast of Yemen was studied to gain a thorough understanding of its geology and hydrocarbon potential. Literature, field data, ten deep exploration wells, five shallow stratigraphic tests and a selection of seismic data were studied, resulting in stratigraphic correlation profiles and structural sections. The study comprises a compilation of exploration data gathered by different companies since the early 1950's. A gross structural and sedimentological model for the area was the result of the study. The Miocene to Recent sedimentary suite can be divide into three units: the Pre-Evaporite, the Evaporite and the Post-Evaporite Groups. The area can be divide in six different structural elements according to the location relevant to the spreading axis of the Red Sea and to the central part of the Miocene salt basin. Potential traps abound in the Pre-Evaporite and the Evaporite Group. In the Post-Evaporite Group the hydrocarbon potential is questionable because of lack of seal. Throughout the study area the quality and degree of maturation of the source rocks appear to be highly variable.
The Western Rub' Al-Khali Infracambrian Graben System
Authors: Dyer R. A. , Husseini M. 
Published: December 2007

ABSTRACT
A major Infracambrian graben system is observed along regional seismic reflection profiles in the Western Rub' Al-Khali of Saudi Arabia. This graben system was formed coincident with the development of salt basins in Oman and the Arabian Gulf, and the Najd fault system of the Arabian Shield. Evident structural elements include the northwest-southeast trending Najd faults, and the more commonly recognized north-south trends.
The sediments deposited in the grabens can be divided into three units based on seismic character. The inferred basal unit is relatively free of seismic reflections and has an indefinite basal seismic reflector. The middle unit contains parallel seismic reflections marked by high comparative amplitude and continuity. The upper unit represents an eroded wedge characterized by low internal seismic reflectivity.
The three units are correlated with the Infracambrian Huqf Group of Oman and the Jubaylah Group of the Najd system of the Arabian Shield. Specifically, the basal unit is interpreted to correspond to the coarse clastics of the Abu Mahara. Formation at the base of the Huqf Group and the Robutain Formation of the Jubaylah Group. The middle seismic unit is interpreted as carbonates and marine clastics, equivalent to the Khufai, Shuram, and Buah Formations of the Huqf Group and the Muraykhah Formation of the Jubaylah Group. The upper seismic unit is interpreted as the clastic facies equivalent of the Ara Formation salt of the Huqf Group.
The carbonates of the Huqf Group of Oman are the proven source rocks of oil fields in the Ghaba and South Oman Salt Basins, and therefore the middle seismic unit of the Western Rub' al-Khali graben system may also be regarded as a potential source rock. The faulting associated with the graben system is terminated by a major unconformity which separates the syn-rift sequence from the post-rift sandstones of the Saq Formation of Saudi Arabia.
Sabkha vs. Salt Basin Model for the Arab Formation Understanding in the Umm Shaif Field, U.A.E.
Authors: Lapointe P. A. 
Published: December 2007

ABSTRACT
The Arab Formation forms the principal oil reservoir of the Upper Jurassic sequence in the Middle East. Previous studies (1) carried out on the cores of the Umm Shaif field, Abu Dhabi offshore areas, led to nine distinct sabkha cycles, assuming that a "giant" sabkha system was prevailing during the lower Arab to the top of the Hith deposition covering a very largely extended area.
Recent regional and detailed field studies provided new information and highlighted some comments on this sedi-mentological model.
A revised model is therefore suggested, based upon the contemporaneous deposition of marine gypsum in deeper inter algal mounds or bioclastic shoal areas (shallow water evaporites) and restricted more basinal areas (intrashelf basin, relatively deep water evaporites). The sabkha fades could however appear during relative sea level fall onto small areas
Non-Darcy Flow Behavior in Partially Penetrating Gas Wells
Authors: Erarslan S. , Ayan C. , Lee W. J. 
Published: December 2007

ABSTRACT
In this study, the combined and separate effects of partial penetration, skin factor and non-Darcy flow were studied. Flow tests were simulated using a single phase numerical model, which also incorporates non-Darcy flow effects. IT-flow factors calculated from the model were compared with the values obtained from existing methods. A new equation to predict the IT-flow factor in presence of wellbore damage and partial penetration is presented.
The new equation successfully predicted the IT-flow factors, whereas, the common method gave underestimated values. The IT-flow factors from well tests were used to calculate the velocity coefficients using the common methods. In presence of partial penetration and wellbore damage, these values were found to be overestimations.
Further Investigation on the Analytic Solutions for Finite-Conductivity Vertical Fractures
Authors: Azari M. , Wooden W. O. , Coble L. E. 
Published: December 2007

Abstract
The analytical solutions1 based on the tritinear2 fracture flow model are used to further study effects of linear skin on the fracture, fracture to formation height ratio, wellbore and fracture storages, fracture to formation hydraulic diffusivity ratio, and phase segregation on the pressure profile of finite-conductivity, vertically fractured wells.
The analytic solutions for the constant-rate and the constant-pressure cases for both infinite and bounded reservoir conditions in conjunction with a unique asymptotic approach to pseudoradial flow are used to produce the corresponding type curves. The combined solutions provide all the possible flow regimes encountered in pressure transient testing of any finite-conductivity, vertically fractured formations. They present wellbore and fracture storage, early-time unsteady-state fracture linear, bilinear, skin on the fracture dominated, formation linear, pseudoradial, and pseudosteady state flow periods.
On the Interpretation and Design of Horizontal Well Tests
Authors: Temeng K. O. 
Published: December 2007

Abstract
The paper discusses several issues related to the interpretation of transient pressure tests on horizontal wells. Horizontal well type curves incorporating the effects of wellbore storage and skin are used to aid in the diagnosis of and estimation of parameters from test data. Issues addressed in this study include the identification of flow regimes. validity of Horner graphs. and analysis of multirate tests. An example interpretation is discussed to illustrate concepts.
It is shown that for other than the most ideal situation, the early radial flow behavior will not be evident. In tests with short flow or buildup periods, it is possible for wellbore storage and skin effects to mask both the early radial and linear flow periods. Where early radial flow is present, it is shown that as long as flow length is very long compared to shutin time, a Horner plot may be used to compute formation parameters.
In the general case. type curve matching procedures provide adequate means for estimating the desired parameters from the well test.
New Correlations for Time Lags and Pressure Response Amplitude in Pulse-Test Analysis
Authors: El-Khatib N. A. F. 
Published: December 2007

ABSTRACT
The equations for pulse test analysis by the tangent construction method are formulated in a general way to account for the possibility of the time lag exceeding the pulse or shut-in periods. The equations are solved for the dimensionless cycle period and response amplitude for a wide range of the relative time lag for the first four cycles and at different pulse ratios between 0.1 and 0.9. Cases with difficulties in solving the equations are discussed and their physical and mathematical interrelations are explored. A single set of correlation curves for the dimension-less cycle period is presented for all cycles while a seperate set of curves for the dimension-less response amplitude for each of the first four cycles is needed. The significance of using correlations for the three time lags is discussed.
Status and Scope for EOR Development in Oman
Authors: Al-Adawy M. S. , Nandyal M. 
Published: December 2007

ABSTRACT
In view of a significant STOIIP (3000+ million m3) of medium/heavy oil (less than 31° API), EOR development in Oman has been and remains a major strategic option in its challenge to increase recovery and to meet long term production requirements.
The initial EOR Development Programme (1980-89) of which results are highlighted in this paper was based on a series of pilots and tests to gain experience and reduce uncertainties prior to embarking on wider EOR application. The processes tested included Steam and Polymer Flooding in the Marmul field. Steam Soak in five South Oman heavy oil fields and Hot Water Injection in the Qarn Alam field. A wide range of reservoir types, oil characteristics and reservoir drive mechanisms have been covered in this test programme.
Results on Polymer Flooding and Steam Soak were rather encouraging and presently small-scale follow-up projects are being pursued in the Marmul and Amal (Eastern High) fields respectively.
Due to geological complexities and reservoir heterogeneities in the Al Khlata sands of the Marmul field pilot area, Steam Flood performance was rather poor and performance extrapolation to other reservoirs is difficult. However, scope exists for those fields with thick, well connected homogeneous sands, with
Steam Soak considered as a precursor to Steam Flood.
The Hot Water Injection Test performed in the unusual oil-wet fractured carbonate reservoir in Qarn Alam, did not provide the predicted wettability reversal for field-wide application. Processes to accelerate gas-oil gravity drainage mechanism in this reservoir are currently being evaluated.
The initial programme has provided the necessary operating/technical knowledge to enable new projects to be better defined. Thus, an overview of future EOR scope taking into consideration the current oil economic climate is developed and presented.
Gas Saturation Monitoring in North Oman Reservoir Using a Borehole Gravimeter
Authors: Adams S. J. 
Published: December 2007

ABSTRACT
Following partial implementation of gas/oil gravity drainage as the primary recovery process in the Natih Field, Petroleum Development Oman undertook a gas saturation monitoring campaign to determine its effectiveness. Evaluation based on thermal decay tool measurements produced secondary gas saturations lower than anticipated from material balance considerations.
It was reasoned that the limited depth of investigation of the nuclear tools may have been insufficient to sample formation representative of the reservoir. In order to resolve this uncertainty a number of wells were surveyed using the borehole gravimeter as a deep reading formation density tool. Comparison with original porosity measurements obtained using conventional devices enabled quantitative gas saturations to be evaluated. Confidence in the method was obtained by additionally running the tool across the same formation in a gas reservoir.
Results indicate that the gravimeter can be used to quantify gas saturations to within a 15% range. The gravimeter has proven effective in situations where conventional neutron and thermal decay gas monitoring tools are limited by their depth of investigation.
The accuracy of the method is constrained by the control of distance between discrete gravity stations, the borehole and cable noise and the confidence with which the reservoir porosity is known. In low porosity systems the accuracy is degraded.
As a consequence of the higher gas saturations evaluated using the Borehole Gravimeter, implementation of full scale gas/oil gravity drainage in the Natih Field will continue.
Using Electrical Logs To Obtain the Saturation Exponent (n) in the Article Equation
Authors: Watfa M. 
Published: December 2007

ABSTRACT
The saturation exponent (n) is an essential parameter that is required to solve the Archie Equation and obtain saturation values. This equation gives correlations between resistivity, porosity and saturations. When core measurements of n are unavailable, its value is assumed constant (usually 2). However, under certain conditions, this assumption of a constant value could lead to large errors in computed saturation values.
This paper presents a technique whereby electrical logs are used to solve simultaneously for n and the water saturation values Sw and Sxo in the uninvaded and invaded zone respectively. This technique combines open hole log values which are sensitive to saturation, namely the deep reading resistivity Rt, the shallow resistivity Rxo, and the electromagnetic transit time tpl, together with the through tubing cased hole measurement of the formation capture cross-section (Σ). Essentially four equations are used to solve for Sw, Sxo, n and the porosity exponent (m) at every log sampling point.
A data-base containing log data from 22 wells was constructed from the Upper Jurassic Arab Formation. This is a carbonate reservoir with anhydrite. The porosity distribution in sections of this formation is known to be heterogeneous, with the presence of vugs and fractures. The results of this study showed that the Arab Formation is water wet, and the computed values of n are consistent with the range of values obtained from core measurements. The n values were found to increase with increasing dolomitization, and were shown to be independent of both the pore type and of the porosity exponent m. The results presented demonstrates satisfactorily that this technique, under particular conditions, can give accurate computed values for n at downhole conditions.
Determination of Residual Oil Saturation From Time-Lapse Pulsed Neutron Capture Logs in a Large Sandstone Reservoir
Authors: Syed E. U. , Salaita G. N. , McCaffery F. G. 
Published: December 2007

ABSTRACT
Cased hole logging with pulsed neutron tools finds extensive use for identifying zones of water breakthrough and monitoring oil-water contacts in oil reservoirs being depleted by waterflooding or natural water drive. Results of such surveys then find direct use for planning recompletions and water shutoff treatments.
Pulsed neutron capture (PNC) logs are useful for estimating water saturation changes behind casing in the presence of a constant, high-salinity environment. PNC log surveys run at different times, i.e., in a time-lapse mode, are particularly amenable to quantitative analysis. The combined use of the original open hole and PNC time-lapse log information can then provide information on remaining or residual oil saturations in a reservoir.
This paper reports analyses of historical pulsed neutron capture log data to assess residual oil saturation in naturally water-swept zones for selected wells from a large sandstone reservoir in the Middle East. Quantitative determination of oil saturations was aided by PNC log information obtained from a series of tests conducted in a new well in the same field. The tests involved detailed comparative studies between four PNC tools and three different wellbore fluids. Two sets of transforms developed from the above tests provided a means for converting old PNC log data to more current and accurate measurements.
Utilizing time-lapse PNC data, residual oil saturations (ROS) were calculated in swept zone(s) for 22 selected wells. An assessment of the uncertainty in derived ROS values was also made.