The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform
Desheng Zhou - One of the best experts on this subject based on the ideXlab platform.
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Borehole Failure Resulting From Formation Integrity (Leak-Off) Testing in Upper Marine Sediments Offshore
Journal of Energy Resources Technology-transactions of The Asme, 1998Co-Authors: Andrew K. Wojtanowicz, Desheng ZhouAbstract:This paper presents the results ofa theoretical study, supported with the finite element analysis, into potential loss of external integrity around a casing shoe resulting from leak-off testing (LOT) in upper marine sediments (UMS). Three types of possible failures from LOTs were considered: vertical Fracture, Horizontal Fracture, and a channel outside cemented annulus. It is proved in the paper that vertical Fracture is the most unlikely failure of the three. The other two types offailure can be distinguished by different values of propagation pressures. Although Horizontal Fractures are initiated at low pressure in the plastic zone around the wellbore, they cannot propagate beyond the plastic zone until wellbore pressures exceed overburden pressures. Annular channels, on the other hand, may propagate upwards at pressures lower than overburden pressure. The paper shows that these channels are initiated at pressures equal to the contact stress between cement and rock and their propagation pressures are on average 3.5-fold greater than contact stress. It is also explained how to identify the UMS with high risk of annular channeling during LOTs.
Andrew K. Wojtanowicz - One of the best experts on this subject based on the ideXlab platform.
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Borehole Failure Resulting From Formation Integrity (Leak-Off) Testing in Upper Marine Sediments Offshore
Journal of Energy Resources Technology-transactions of The Asme, 1998Co-Authors: Andrew K. Wojtanowicz, Desheng ZhouAbstract:This paper presents the results ofa theoretical study, supported with the finite element analysis, into potential loss of external integrity around a casing shoe resulting from leak-off testing (LOT) in upper marine sediments (UMS). Three types of possible failures from LOTs were considered: vertical Fracture, Horizontal Fracture, and a channel outside cemented annulus. It is proved in the paper that vertical Fracture is the most unlikely failure of the three. The other two types offailure can be distinguished by different values of propagation pressures. Although Horizontal Fractures are initiated at low pressure in the plastic zone around the wellbore, they cannot propagate beyond the plastic zone until wellbore pressures exceed overburden pressures. Annular channels, on the other hand, may propagate upwards at pressures lower than overburden pressure. The paper shows that these channels are initiated at pressures equal to the contact stress between cement and rock and their propagation pressures are on average 3.5-fold greater than contact stress. It is also explained how to identify the UMS with high risk of annular channeling during LOTs.
Zheng Zhong-b - One of the best experts on this subject based on the ideXlab platform.
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Study on Fracture Horizontal and vertical wells pattern in ultra-low permeability reservoir
Journal of Shaanxi University of Science & Technology, 2014Co-Authors: Zheng Zhong-bAbstract:The rational well pattern for Fracture Horizontal and vertical wells in ultra-low permeability reservoir has been studied by using typical geologic model and numerical simulation methods for a certain oilfield.Using non-uniform encryption local grid and the same connectivity method for Fracture grid processing.Compare and analyze the development effect of six well patterns,Fractured vertical injector and Fractured Horizontal producer pattern,Fractured Horizontal injector and Fractured vertical producer pattern,Horizontal injector and Fractured Horizontal producer pattern,vertical injector and Horizontal producer pattern,vertical injector and vertical producer pattern,Fractured vertical injector and Fractured vertical producer pattern,at different well interval and array spacing,to choose the rational well pattern.The results show that the rational well interval and array spacing is 200m×160mand the rational well pattern which could receive a anticipated development effect is Fractured vertical injector and Fractured Horizontal producer pattern.
Zhou Desheng - One of the best experts on this subject based on the ideXlab platform.
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Well Integrity Mechanism, Failure, and Testing in Shallow Marine Sediments.
LSU Digital Commons, 2000Co-Authors: Zhou DeshengAbstract:The leak-off test (LOT) is an in-situ method for testing casing shoe integrity in a well. It is used to evaluate the cement and formation integrity relative to the well plan specifications. The results determine whether any remedial cementing or corrective actions are required and are a basis for planning future wells in the area. Typical analysis of LOTs assumes an elastic wellbore and involves identification of linear trends on the recorded plots. However, LOTs recorded in shallow marine sediments (SMS) are inherently nonlinear and their analysis is a problem. Starting from the analyses of shallow soil properties, LOT plots, and leak-off pressure data, the dissertation presents the results of a theoretical study (analytical and numerical-finite element analysis) into potential for damage to cement integrity at the casing shoe resulting from leak-off test in SMS. Stress, strain and displacement around the open hole are analyzed before and during LOT. Three types of possible failures from LOTs were considered: vertical Fracture, Horizontal Fracture, and cement parting. It is proved that vertical Fracture is the most unlikely failure of the three. Although Horizontal Fractures are initiated at low pressure in the plastic zone around the wellbore, they cannot propagate beyond the plastic zone until wellbore pressures exceed overburden pressures. Cement parting, on the other hand, may propagate upwards at pressures lower than overburden pressure. The study identifies two factors, related directly to drilling technology, that control critical pressure of cement parting: contact stress and drilling fluid penetration. It is shown in the study that changes in cementing and drilling practices can improve casing shoe integrity and reduce the need for remedial cement squeezes. A general pressure-volume model of a LOT is presented including volumetric effects of wellbore expansion, mud loss into the rock, and propagation of both cement parting and plastic Fracture. Software entitled LOTUMS was developed to simulate LOTs in SMS. A method is also proposed to identify the mechanisms controlling LOT results using known overburden pressure and the shape of LOT plot
Wang Wenjun - One of the best experts on this subject based on the ideXlab platform.
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Optimization method of hydraulic fracturing Horizontal wells with extra-low permeability in Daqing Aonan oil reservoirs
Journal of Liaoning Technical University, 2009Co-Authors: Wang WenjunAbstract:According to the specific feature of hydraulic fracturing Horizontal wells oil reservoirs with extra-low permeability,mathematics models and optimization of matrix-Fracture-Horizontal well coupling flow with kickoff pressure gradient,matrix-Fracture ellipse flow,Fracture nonlinear flow for hydraulic fracturing Horizontal in extra-low permeability oil reservoirs are found.Some coupling flow models considering well pattern construction is set up.Some factors are analysis,such as Fracture length,Fracture distribution,Fracture numbers,Horizontal length,Fracture distance,Fracture conductivity,etc.The numerical simulation results show that the models and optimization method of hydraulic fracturing Horizontal wells with extra-low permeability are good and an application of theory models has substantiated.The optimization design is applied in extra-low permeability oil reservoirs.The test is very well in Daqing Aonan oil field.
