bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Successful Subsalt Exploration Example in the Precaspian Basin
Authors: Wang Zhen , Zheng Junzhang , Luo Man , Wang Yankun 
Published: March 2015

Abstract
M block in eastern margin of Precaspian Basin is the first CNPC 's risk exploration project in Central Asia & Russia, which has been prospected by many companies and no discovery was found. The main exploration difficulties are subsalt trap recognition's trouble caused by salt domes with giant thickness (greater than 1000m) which lead to subsalt target stratum's pull-up and false faults in the Permian and strong heterogeneous reservoir prediction in carbonate reservoir buried near 4000m. Technology was developed based on the difficulties, in the aspect of subsalt structural recognition, fine interpretation by multi-display methods, salt domes' margin identification using boundary detecting technique, time-depth conversion methods of raytracing procedure, forward modeling examining velocity field's precision, vertical seismic profiling (VSP) detecting local structural shape, palaeotectonic restoration analyzing trap's origin, prestack depth migration verifying trap's validation, salt dome's influence was wiped out continuously and strata's real shape was resumed which leads to the increase of drilling success ratio. In the aspect of carbonate reservoir prediction, favorable reservoir zones in Carboniferous strata were outlined based on the study of logging assessment, sequence stratigraphy, sedimentary facies, seismic inversion, fracture and petroleum detection, attribute analysis. At the same time, REI(reservoir evaluation index) and CI(cave index) indexes were initiated, and carbonate reservoir's logging assessment standard in this block was established that improves reservoir prediction's precision. In the aspect of comprehensive evaluation, 3 structural accumulating belts were divided after the study of reservoir types, which are west structural belt, central structural belt and east structural belt. The different belts' play was evaluated synthetically. The main and potential play was pointed out in different belts. The regular patterns about subsalt carbonate accumulating were generalized. Middle ramp region should be break through first is our bulk exploration deployment clue, and a big field with more than a hundred million tons reserves was discovered which is the biggest subaerial discovery since the Kazakhstan being self-governed and guarantees the abundant supply for the Central Asian pipeline.
Initialising Dynamic Reservoir Models for History Matching Using Pre-Production 3D Seismic Data
Authors: Niri Mohammad Emami , Lumley David 
Published: March 2015

Abstract
Stochastic reservoir modeling is a common practice in the energy industry, and is widely used for hydrocarbon reserves estimation, targeting new producer/injector locations, and production profile forecasting with flow simulators. Due to its high spatial coverage, 3D seismic data plays a critical role for defining the reservoir geometry, and for constraining physical property modeling. However, integration of 3D and time-lapse 4D seismic data into the reservoir model history matching process poses a significant challenge due to the frequent mismatch between the initial reservoir model, the reservoir geology, and the pre-production (baseline) seismic. Therefore, a key step in a reservoir performance study is the preconditioning of the initial reservoir model to equally honor both the geological knowledge and the baseline seismic data. In this study, we investigate issues that have a significant impact on the (mis)match of the initial reservoir model with the geological and geophysical data. Specifically, we address the following questions:Which of the common methods to stochastic litho-facies modelling produce reservoir models that best match the baseline 3D seismic data after seismic modelling?How are the results affected by the presence of noise in the observable data, and by the low vertical resolution of seismic data compared to logs?What is the effect of geostatistical variogram parameters on the results?How do these methods perform on object-oriented reservoir models?
The results of this study indicate that a method based on the probability of litho-facies distribution given by P-wave impedance in a stochastic modeling process yields the best match to the reference model, even in the presence of noise in the dataset. The effect of variogram parameters on the seismically-constrained litho-facies modeling process is also demonstrated.
Well Integrity Risk Mitigation vis-a-vis Revenue Potential: A Qualitative Model for Wellwork Prioritisation in Dukhan Field, Qatar
Authors: Singh Sanjay K. , Negron Jose , Al-Marri Nasser , Arijo Nasir Murtaza 
Published: March 2015

Abstract
Qatar Petroleum's supergiant Dukhan field located onshore Qatar has a mature well inventory of hundreds of wells. Mitigating well integrity risk without affecting crude oil production and water injection targets is critical to sustaining revenue streams from the field. This involves a large number of integrity repair wellwork with workover rigs. Performing such a wellwork campaign is time-intensive and without adequate prioritization has the potential of jeopardizing well integrity and causing safety/environmental issues besides adversely affecting the production and injection levels. This paper discusses a qualitative model that has been developed and used to prioritize repair wellwork in Dukhan field. The model is centered round integrity risk level and revenue potential of wells. A set of integrity parameters including status of surface and downhole barriers determines integrity risk level. Another set of reservoir management and well capability parameters determines revenue potential. Each of the wells is then assigned scores to reflect the risk level and the revenue potential. Cross-scaling of such scores defines the priority of a repair wellwork. Using the above approach for wellwork prioritization has been effective in mitigating integrity risk and maintaining revenue potential of the large inventory of mature wells.
The First Land Full Azimuth Seismic for Fractured-Cavernous Carbonate Reservoirs Exploration in Tarim Basin, Western China
Authors: Liu Yimou , Liang Xianghao , Zhou Yi , Liu Shiyong , Lin Shangwen , Wang Naijian 
Published: March 2015

Abstract
Ordovician carbonate reservoirs are the very important yet difficult targets in the oil and gas exploration and development of Tarim basin, western China. The main task (also main challenge) of seismic is to image and predict the storage spaces of carbonate reservoirs-the secondary dissolved caves, holes and fractures, which are buried in more than 6500m deep. The target formations are usually in very low signal-to-noise ratio due to the seismic attenuation and the caves and fractures are small and aligned in random directions. Narrow azimuth and conventional wide azimuth seismic fail to image and identify the fractured-cavernous reservoirs accurately, leading to many drilling failures. Here, the effects of some key acquisition parameters such as bin size, fold and aspect ratio on carbonate reservoirs imaging accuracy are carefully examined using seismic forward modeling and new analysis methods. A high-density full-azimuth seismic acquisition was carried out based on the above analysis and the results show that small bin size has the advantage to imaging the ultra-deep carbonate reservoirs and the fracture prediction results from full azimuth data well agree with that from imaging well logging data. A set of well drillings based on the full azimuth data have been proved to be successful.
Reliable Fracture Characterisation and Value Addition Through Special Core Reorientation: Kuwait Case Study
Authors: Alenezi A.M. , Narhari S.R. , Al-Ajmi N.H. , Pattnaik C. , Rao J.D. , Al-Ateeqi K.A. , Staffelbach C. , Anis Abdel-Hamid Anis , Chakravorty S. , Barbe J.F. 
Published: March 2015

Abstract
Reliable fracture characterization is essential for efficient field development of tight carbonate reservoirs. A comprehensive campaign of core based fracture analysis was carried out on more than 7,000ft of deep tight carbonate (over 14500ft TVD and 3pu avg. porosity and 0.1 mD avg. perm) cores of Kuwait, spread over a number of wells covering a large area of over 1000sq km.
The aim of the study was to provide inputs for a detailed structural analysis of the area, with the help of reorientation of cores focusing on the geometrical and structural characteristics of each well. The reorientation procedure used a special core Goniometry process, which permits a totally hands-free 3D digitization of all planar and linear features. Reorientation of the cores is established using either the deviation data from the wells or through comparison with image log data.
In addition to the detailed integrated description of type, size, aperture and filling of fractures, a porosity/permeability model was generated after calculation of fracture frequency. By calculating the orientation and value of the permeability vectors, an indication of optimum direction of drilling was established for each well/area.
The natural fracture network obtained with open, partially-open and cemented fractures, together with induced stress-release fractures analysis, contributed to a better understanding of tectonic history and present-day stress in the studied area. A field synthesis map highlighted the main direction of all types of fractures and an actual stress map was worked out by compiling all directions of the maximum horizontal stress observed in the wells and oriented by the petal and centreline induced fractures.
The integration of the results with analyses of image log data, well log correlation data and seismic data provided critical information about the reservoir properties.
A Type Curve for Carbonates Rock Typing
Authors: Wibowo A.S. , Permadi P. 
Published: March 2015

Abstract
Rock typing for heterogeneous carbonates is still a standing problem. The present work was directed to investigating the relationship between microscopic geological characteristics of carbonates and architecture of the pore systems in the effort to develop a better method for carbonates rock typing. Eight carbonate reservoirs with complete core analysis data of 1,838 core plugs were used in this work. Six carbonate data sets were utilized in developing the method and the rest two were used for verification.
The well known Kozeny's equation was employed to provide the relationship between pore geometry and the structure. It can be shown that these pore attributes contain only permeability and porosity. A comprehensive analysis was then carried out by plotting pore geometry against pore structure on log-log graphs (PGS cross-plot) and identifying microscopic geological features of every core plug employed. Results for each carbonate data set show that the data points divides into six to thirteen clusters, each cluster has its own similarity in the microscopic geological features, the fitting line drawn on each cluster has very high correlation coefficient, the space between two closest fitting lines is all practically the same, and interestingly all the fitting lines tend to converge to a single point. A mathematical analysis done confirms the existence of this point, leading to the construction of a type curve. The rest two carbonate data sets perfectly verify this type curve.
This work differs from the previous ones in that the present work honors both geological and engineering aspects equally and reveals that certain diagenetic processes have produced certain pore architecture as exhibited on the PGS plot. This paper overall provides a better understanding about rock type definition, a tool to identify the effects of diagenetic processes on rock properties, and a type curve for easy rock typing.
Unlocking the Potential of Complex Marginal Reservoir in Highly Mature Oil Field, XiJiang24 South China Sea
Authors: Donghong Luo , Zhenghe Yan , Xiaofei Gao , Zhihua Rao , Yu Du Ding , Halomoan Parlindungan Monris , Bisain Amarjit Singh , Yang Liu , Azwar Olivia 
Published: March 2015

Abstract
An oil & gas operator in XiJiang block offshore South China has shifted the development of highly mature oil fields that have been producing for 17 years toward the remaining undeveloped marginal reservoirs using a horizontal well drilling program.
The main targets of the new development campaign are the remaining thin oil column reserve in attic locations of the reservoirs as well as the unproduced thin laminated reservoirs in the area. Upon understanding the uncertainties and challenges associated with drilling horizontal wells in these complex reservoirs, an innovative drilling approach was initiated for accurate horizontal placement in thin sands, channel sands, and thin oil column reservoirs with strong bottom-water. The approach includes the integration of an advance multifunction formation evaluation Logging-While-Drilling (LWD) tool that provides real-time formation evaluation and structural interpretation along with a bed boundary mapper LWD tool with the ability to map multiple key boundaries that are the prerequisite parameters that must be identified during the execution stage and which include the water contact and top and bottom of the reservoir structure simultaneously in distance.
Outstanding outcomes have been observed by implementing this new approach in the complex target reservoirs. The approach was applied to multiple challenging wells, each of which has produced from 2,000 to 6,000 BOPD with very low water cut, far exceeding the set production goals of 1,500 to 2,000 BOPD. These are very promising development economics in the oil fields that have 90% to 95% water cut on average.
The successful implementation of the new development strategy in highly mature oil fields will lead to sustained and extended production, increasing the ultimate recovery and well economics. The approach provides an example of using integrated technology solutions to overcome the challenges in complex target reservoirs.
Non-Hyperbolic Moveout Multi-Parameter Anisotropic Tomography
Authors: Panizzardi J. , Bienati N. , Gentile E. 
Published: March 2015

Abstract
Application of anisotropy has proved to be mandatory for the improvement of imaging quality, at the point that nowadays the introduction of TTI anisotropy has become a standard for PSDM projects. These advancements pose new challenges to migration velocity analysis, and the time domain approaches commonly used for the estimation of anisotropic velocity parameters are no longer enough to satisfy imaging accuracy requirements.
A depth-domain estimation technique is proposed, which is completely based on PSDM and on the classic CIG (Common Image Gather) flattening principle.
One of the key aspects is the use of a robust automatic non-hyperbolic moveout picking algorithm, which is applied on the depth migrated CIGs and provides the correct description of the complete residual moveout: this allows the joint tomographic inversion of two anisotropic velocity volumes, which are able to properly account for the non-hyperbolic residual moveout behavior at both short and long offsets. The method has general validity and it can be applied to any imaging project; it is also particularly stable when applied to multi-azimuth acquisitions.
This approach can obtain a good anisotropic focusing velocity if the data contains sufficiently large offsets, although still one or more wells are needed to constrain vertical velocity.
Seismic Attributes and Advanced Computer Algorithm Method to Predict Formation Pore Pressure: Paleozoic Sediments of Northwest Saudi Arabia
Authors: Nour Abdoulshakour , AlBinHassan Nasher 
Published: March 2015

Abstract
Oil and gas exploration professionals have long recognized the importance of predicting pore pressure before drilling wells. Pre-drill pore pressure estimation not only helps with drilling wells safely but also aids in the determination of formation fluids migration and seal integrity. With respect to hydrocarbon reservoirs, the appropriate drilling mud weight is directly related to the estimated pore pressure in the formation. If the mud weight is lower than the formation pressure, a blowout may occur and, conversely, if it is higher than the formation pressure, the formation may suffer irreparable damage due to the invasion of drilling fluids into the formation. A simple definition of pore pressure is the pressure of the pore space fluids in excess of the hydrostatic pressure. The cause of abnormal pore pressure includes quick burial of unconsolidated sediments before dewatering, hydrocarbon formation in the pore space of rocks, mineralization such as smectite-illite osmosis, tectonic movement of sediments and other geological processes that result in overpressure.
Geoscientists and engineers have used various techniques to predict abnormally high formation pore pressure from seismic data. These techniques primarily employ the empirical relationship between seismic velocities and formation density. Consequently, many investigators have shown the sensitivity of seismic velocities to other factors such as lithology, gas and pore fluid content, which reduces the reliability of purely velocity-based methods in predicting abnormally high formation pressure (Young and Lepley, 2005). In this study we will focus on using an advanced pattern recognition computer algorithm, called Support Vector Machine (SVM) and attribute data from seismic and wells to the prediction of formation pore pressure in the lower Paleozoic Qalibah formation of northwest Saudi Arabia.
Deepwater Production Improvement Through Proactive Reservoir Management and Conformance Control
Authors: Masoudi Rahim , Karkooti Hooman , Jalan Shlok , Arif Anndy , Chan Keng S. , Othman Mohamad B. , Burford Steve , Bee Philip 
Published: March 2015

Abstract
Deep water fields are commonly subject to high development cost, challenging topside and subsurface issues and uncertainties. The level of heterogeneity, compartmentalization, fault intensity, reservoir connectivity, pressure and flow communication across the field, sand/fine production, wellbore stability are commonly less well understood at the time the development decision is made. The reservoirs may also consist of very thin beds to thick blocky sands and the reservoir properties can vary significantly both laterally and vertically throughout the field.
Pressure maintenance and water/gas injection can be part of the selected development strategies from day one. Due to the high uncertainties and development cost, both producers and injectors might be pragmatically commingled across various reservoirs with no additional sandface control and operational flexibility. Reservoir management strategies may rely on field/reservoir level voidage replacement ratio (VRR) control with no additional selectivity and control on water/gas injection. This strategy combined with the above mentioned uncertainty issues can potentially lead to injection conformance issues and reduced recovery factor due to sub-optimal sweep efficiency at the sand by sand levels. A deep water example has been studied in this work showing the conformance issue and uneven pressure distribution confirmed by different PLT campaigns and MDT pressure surveys for various reservoirs under VRR control.
In this paper, the above challenges and reservoir management (RMP) requirements combined with the concerns of the optimized water flooding in a complex deep water field in Malaysia have been studied and discussed. The application of the proposed guidelines and strategies for proactive reservoir management and conformance control showed potential for significant improvement in sweep efficiency optimization and hydrocarbon recovery improvement in this deep water field.
Sampling While-Drilling Goes Where Wireline Can't: Case Studies Illustrating Wireline Quality Measurements in Challenging Borehole Environments.
Authors: Sanchez Francisco Galvan 
Published: March 2015

Abstract
In the early 2000s, formation pressure while-drilling tools were introduced that can obtain formation pressure data, even in highly deviated wells and extended-reach drilling. In the past two years this LWD technology has evolved with the addition of downhole fluid sampling and fluid analysis. LWD Sampling and Testing can now be performed in challenging environments that cannot be performed with wireline tools such as horizontal or highly deviated wells. The limitations of wireline deployment in these wells are due to the cumulative frictional resistance of the wireline, the toolstring components and the borehole where it is run. Although several technologies exist to mitigate the risks, such as fly wheels, wireline tractors or pipe-conveyed options, operators prefer to eliminate the risks and costs associated with them by utilizing LWD technology.
The first part of this paper describes the new sampling and testing service that was designed for the LWD environment. This service has several closed-loop control systems for pressure testing, mobility determination and for pumping during the sampling and cleanup operations. In-situ fluid analysis is achieved with the use of sensors that measure optical refractive index, sound speed, density and viscosity. Downhole fluid samples are retrieved with the use of single-phase tank technology.
The second part of this paper details case studies of field tests that were performed for a major operator in Trinidad and for an IOC in the Netherlands. In Trinidad the service successfully performed pressure testing, real time fluid analysis and recovered three single phase samples while drilling a 300ft section at 70° deviation. On a dedicated logging run in the Netherlands the service first accurately took 25 formation pressure points and clearly identified three distinct gradients. The customer targeted four zones of interest and acquired 11 samples, six single phase samples in the oil zone, three single phase samples in the water zone and finally three single phase samples in the gas zone. This pressure testing and sampling operation was all executed in a 1307 m tangent section at 73° inclination. The service was utilized to determine the presence of moveable fluids in the reservoir for a horizontal development well for a customer in Norway. The tool was positioned at a sampling station with a mobility of 1.8 mD/cP and after almost 5 hours of pumpout at that station, it successfully acquired the first sample, after another 4 hours of pumpout at the same station the tool acquired the second sample.
In both cases the LWD sampling and testing service was chosen over wireline to mitigate the risks of sticking during the sampling and pressure testing operation. These field tests demonstrated that the LWD service is capable of taking wireline-quality measurements in extremely challenging borehole environments.