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Africa (Sub-Sahara) Cairn Energy has flowed oil from its SNE-2 well offshore Senegal. Drillstem testing of a 39-ft interval achieved a maximum stabilized but constrained flow rate of 8,000 B/D of high-quality pay. A flow rate of 1,000 B/D of relatively low-quality pay was achieved from another zone.
Summary The brittleness index (BI) has major implications for hydraulic fracture studies and production toward optimized recovery in unconventional reservoirs. The paucity of brittleness studies in Mizoram and Upper Assam, located in northeastern India, motivates us to take up multimineral modeling and estimation of BI. Two commonly used BI estimation approaches, mineralogical and geomechanical, have been implemented to characterize the shaly sandstone in the study area. Laboratory analyses of the available drill-cutting samples and crossplots from well log data along with previous literature confirm the types of minerals present in the study area. With this mineralogical information, a new approach of BI log estimation from multimineral modeling is suggested here using conventional log data in the absence of core/drill cutting samples. A multimineral model for Mizoram and Upper Assam is developed by using bulk density (q), compressional sonic velocity (V p), shear sonic velocity (V s), lithodensity, and acoustic impedance (AI) logs to calculate volumetric percentage of minerals. Estimated mineralogical BI from well log data using four established models are compared and calibrated with X-ray diffraction (XRD)-derived BI to validate the proposed procedure. Most brittle zones having a BI 66% are demarcated for high Young's modulus (Y 60 GPa) and low Poisson's ratio (0.25) values in the Y vs. crossplot for the study area. The presence of brittle minerals estimated from both XRD and the multimineral model suffices the reason for the high brittleness of shaly sandstone in Mizoram compared with Upper Assam.
Quantitative identification of diagenetic facies is critical for favorable reservoir prediction. In this study, the diagenetic facies of the Chang-8 reservoir in the Zhenbei area of the Ordos Basin was investigated using an integrated analysis of casting thin sections, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Chang-8 reservoirs can be subdivided into five major diagenetic facies categories: 1) weakly-dissolved chlorite cemented facies, 2) moderately-compacted mineral dissolution-susceptive facies, 3) moderately-dissolved kaolinite-bearing facies, 4) moderately-compacted carbonate cemented facies, and 5) strongly-compacted tight sandstone facies. On the basis of the above analyses, the diagenetic facies were identified from well logs by involving the supervised-mode self-organizing-map neural network (SSOM) algorithm. Six wireline logs sensitive to the diagenetic facies characteristics were used as the model input, the diagenetic facies prediction model was built using SSOM. The prediction results of the diagenetic facies are in good agreement with the core analysis types, with a matching of 83.87%. Our work also sheds light on reservoir typing by linking the diagenetic facies with reservoir quality and oil testing data.
Section Membership Contest 2009 Date Established: 20 February 2000 http://connect.spe.org/bangladesh/home Ismail Hossain, Chevron Bangladesh Ltd Staff Liaison Erin O'Sullivan, Society of Petroleum Engineers Staff Liaison Jackie Hoffmann, SPE Middle East If you are a section officer, you may sign in to see more details.
Cairn Energy has flowed oil from its SNE-2 well offshore Senegal. Drillstem testing of a 39-ft interval achieved a maximum stabilized but constrained flow rate of 8,000 B/D of high-quality pay. A flow rate of 1,000 B/D of relatively low-quality pay was achieved from another zone. Drilled to appraise a 2014 discovery, the well lies in the Sangomar Offshore block in 3,937 ft of water 62 miles from shore. Drilling reached the planned total depth of 9,186 ft below sea level.
Baruah, Nabajit (Oil & Natural Gas Corporation) | Mandal, Dipak (Oil & Natural Gas Corporation) | Jena, Smita Swarupa (Oil & Natural Gas Corporation) | Sahu, Sunil Kumar (Oil & Natural Gas Corporation)
This paper examines the prospect of Gas Assisted Gravity Drainage (GAGD) process in improving recovery from a sandstone reservoir by injecting produced gas back into the crestal part of the reservoir. Besides recovery improvement, immiscible gas injection ensures near Zero Flaring strategy. The process has been found to be ideal in reservoirs with high permeability and reasonable dip to maximize oil production wherever a sufficient gas source exists. Based on the study, gas injection is recommended at the crestal part of the reservoir under study at the rate equivalent to the produced gas to maintain pressure, arrest gas cap shrinkage and improve recovery.
The continuous evaluation of electric submersible pumps (ESP) performance and its integration within the energy management system in the operation of Blocks 16 & 67 of Ecuador allowed to develop a specific procedure to assess the efficiency of ESPs in order to identify energy improvement opportunities. This procedure is summarized with the Significance Matrix, a tool that integrates ESP's field data such as production history and electrical measurements to estimate hydraulic and electrical power requirements, and a specific method for efficiency evaluation. The result of the Significance Matrix is the categorization of each ESP system as significant or nosignificant use of energy. The significant uses of energy are further analyzed to design an action plan that is prioritized through technical and economic assessment. The comparison between the Significance Matrix of December 2014 and November 2017 showed that the optimization of eight (8) ESP systems resulted in an average reduction of 49 BDPD in fuel consumption that can be translated to a decrease in greenhouse gases emission of 20 tCO2 per day.
Busch, Alexander (Norwegian University of Science and Technology) | Islam, Aminul (Statoil) | Martins, Dwayne W. (Neptune Energy Norge AS) | Iversen, Fionn P. (International Research Institute of Stavanger) | Khatibi, Milad (University of Stavanger) | Johansen, Stein T. (SINTEF Materials and Chemistry and Norwegian University of Science and Technology) | Time, Rune W. (University of Stavanger) | Meese, Ernst A. (SINTEF Materials and Chemistry)
Summary In oil and gas drilling, cuttings-transport-related problems are a major contributor to well downtime and costs. As a result, solutions to these problems have been extensively researched over the years, both experimentally and through simulation. Numerous review articles exist, summarizing not only the research history but also the qualitative effect of individual case parameters such as pump-flow rate, pipe rotation, and rate of penetration (ROP) on cuttings transport. However, comparing different studies is challenging because there is no common reference defined in the form of a typical and representative set of case parameters. To develop relevant and accurate cutting-transport models, it is critical that both experiments and models are targeting flow cases relevant for respective drilling operations. Development of a clear understanding of the industrial-parameter space, as well as establishing benchmarks, will help achieve a more-concerted effort in development of models and corresponding laboratory experiments. Other industries have established research benchmarks, such as the "NREL offshore 5-MW baseline wind turbine" (Jonkman et al. 2009) in wind-power research, providing a standardized set of case parameters and profiles, readily available for use to researchers worldwide, and resulting in straightforward benchmarking and validation as well as faster establishment of projects. For application to the modeling of cuttings-transport phenomena, we propose a methodology for deriving a well-defined and standardized set of geometrical, operational, and environmental case parameters describing various operating points of drilling operations and procedures as well as simplified problems. The methodology is exemplified with an 8.5-in.-section Applying this methodology before any cuttingstransport study may enable a better definition of industry-relevant case parameters. In Part 2, we will apply and discuss the derived parameter sets in the context of nondimensional numbers for assessment of scalability. Introduction The study of hole cleaning has been a major concern for several decades in the drilling industry. Inadequate hole cleaning can lead to stuck pipe, fractured formation, high rotational torque, premature bit wear, and decreased ROP, and can further cause problems during logging, casing, and cementing operations. It was reported that 70% of lost time in drilling was associated with stuck pipe (Massie et al. 1995) and one-third of the stuck-pipe problems were caused by inadequate hole cleaning (Hopkins and Leicksenring 1995). Wellbore inclination can significantly influence cuttings-transport efficiency. For angles greater than 30, particles may settle on the low side of the annulus, significant changes may occur in cuttings-fluid-flow patterns, and cuttings dunes or beds may build up. The cuttings beds or dunes formed at inclination angles between 30 and 60 are not stable and may result in cuttings avalanches.
Pore pressure prediction is essential part of wildcat well planning. In India, Tripura sub – basin is characterised by huge anticlines, normal faults and abnormally pressured formations. These factors push the wildcat well planning in this area into wide margin of uncertainty. Pore pressures were predicted from seismic velocities by using modified Eaton’s method over the synclinal and flank part of Atharamura to understand the pressure succession towards the anticline. These predicted pore pressure on the flank part lead to a reasonable match when plotted with offset well measured pore pressures. To reduce the uncertainty fracture pressure were established by various methods such as Hubbert & Willis method and Matthews & Kelly method from predicted pore pressures. But the fracture pressures were predicted with available horizontal stress correlations due to lack of Poisson’s ratio curve for the study area. The mud pressure required to drill the well is calculated using median line principle and hence drilling mud window is established by assuming virtual tight conditions. The plot of Equivalent Circulation Density (ECD) versus depth suggest that well can be drilled with two casing policy. But it is found that adding one more casing pipe will ensure the safety of well. Casing pipes were designed on the basis of collapse pressure, burst pressure and tensile load. Finally a well plan which includes pore pressure, fracture pressure, drilling mud policy, casing policy, kick tolerance graph were proposed to give clear picture on well planning on the top of the anticline in pore pressure point of view.
Khambra, Isha (Schlumberger) | Kumar, Ajit (Schlumberger) | Verma, Vibhor (Schlumberger) | Agrawal, Gaurav (Schlumberger) | Sarma, Rajiv (Oil India Ltd.) | Baruah, Neelimoy (Oil India Ltd.) | Prasad, C. B (Oil India Ltd.) | Bora, Pradyut (Oil India Ltd.)
The Upper Assam Basin is a matured Petroliferous situated in the northeastern part of India (
The major challenges faced in these reservoirs are high resistivity zones within sands, thereby creating an ambiguity due to very fresh water environment and a complexity in evaluation of the developed prospects between the hydrocarbon bearing and water bearing sand; Low shale density and sand matrix density contrast; Presence of gas across the sands is not effectively evident, especially in the secondary gas cap reservoir scenarios; changing reservoir dynamics due to production from decades, led to an uncertainty in identifying the current fluid contacts and last but not the least identification of mobile oil that could not be produced by existing wells under production from 60-70 years and have been left undrained. Therefore, in order to cater these challenges of old reservoirs and diminishing few unresolved uncertainties involved in redevelopment of the brown fields, reservoir saturation monitoring was carried out successfully in 50 wells in various fields which added immense value both technically and economically.
This paper has the detailed discussion about how this technique proved to be very beneficial and led to the substantial hydrocarbon gain in old wells. The reservoir saturation monitoring was carried out mainly in old wells which helped in taking the informed decision of identifying the sweet spot for hydrocarbon production. It has also helped in overcoming the uncertainty involved in the open-hole data interpretation (especially low resistivity and density contrast). This approach resulted in better understanding of the reservoir characteristics which led to ascertain potential reserves that can be characterized as the "Reserve growth".
The results of this approach also corroborated with the dynamic simulation models of various fields and enhanced the confidence on the predictive field development planning. Last but not the least it also contributed in achieving the annual hydrocarbon production target, considering other economic benefits, it led to reduced rig time spent for workover during the well life with low operational cost.