摘要 :
Oil and gas well drilling planning is the main task of any drilling engineer. In order to overcome this task, it is required to maintain the wellbore pressure between the maximum value that does not fracture the formation and the ...
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Oil and gas well drilling planning is the main task of any drilling engineer. In order to overcome this task, it is required to maintain the wellbore pressure between the maximum value that does not fracture the formation and the pressure of the fluids within the formations, because, as the wellbore pressure exceeds the fractures' pressure, formation damage occurs, which will consequently result in lost circulation problems. Meanwhile, if the well pressure is less than the formation fluids pressure it leads to other drilling problems such as the kick problem and possibly blowout. The maximum well pressure that does not fracture the formations is called the fracture pressure and the formation fluids pressure is called the pore pressure. Therefore, pore pressure and fracture pressure are considered as the most crucial parameters for drilling engineering planning and for launching new wells. Another significant parameter for well planning is the detection and estimation of an abnormal pressure depth. This is when the formation pressure is higher than the normal pressure at a specific depth. There are many methods for determining pore pressure, fracture pressure and abnormal pressure depth and their values. These methods can be divided into two categories: predictive methods and verification methods. In this paper, the predictive method involves determining or estimating the above-mentioned parameters prior to drilling operation using seismic data, especially equivalent to matrix stress. This is applied to two case studies: an African sandstone reservoir in Libya and the South Texas Frio Trend, based on seismic data recorded for interval transit times vs. depth. The results showed that; first, for the African sandstone reservoir, Libya, the oil filed the abnormal pore pressure located deeper than 6000ft, which is the main indicator for specifying that the maximum depth has an abnormal pressure. Second, for the South Texas Frio Trend, the abnormal pore pressure was located at deeper than 8000ft. In the last section, based on the pore and fractured gradient, the casing sets are selected.
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摘要 :
Oil and gas well drilling planning is the main task of any drilling engineer. In order to overcome this task, it is required to maintain the wellbore pressure between the maximum value that does not fracture the formation and the ...
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Oil and gas well drilling planning is the main task of any drilling engineer. In order to overcome this task, it is required to maintain the wellbore pressure between the maximum value that does not fracture the formation and the pressure of the fluids within the formations, because, as the wellbore pressure exceeds the fractures' pressure, formation damage occurs, which will consequently result in lost circulation problems. Meanwhile, if the well pressure is less than the formation fluids pressure it leads to other drilling problems such as the kick problem and possibly blowout. The maximum well pressure that does not fracture the formations is called the fracture pressure and the formation fluids pressure is called the pore pressure. Therefore, pore pressure and fracture pressure are considered as the most crucial parameters for drilling engineering planning and for launching new wells. Another significant parameter for well planning is the detection and estimation of an abnormal pressure depth. This is when the formation pressure is higher than the normal pressure at a specific depth. There are many methods for determining pore pressure, fracture pressure and abnormal pressure depth and their values. These methods can be divided into two categories: predictive methods and verification methods. In this paper, the predictive method involves determining or estimating the above-mentioned parameters prior to drilling operation using seismic data, especially equivalent to matrix stress. This is applied to two case studies: an African sandstone reservoir in Libya and the South Texas Frio Trend, based on seismic data recorded for interval transit times vs. depth. The results showed that; first, for the African sandstone reservoir, Libya, the oil filed the abnormal pore pressure located deeper than 6000ft, which is the main indicator for specifying that the maximum depth has an abnormal pressure. Second, for the South Texas Frio Trend, the abnormal pore pressure was located at deeper than 8000ft. In the last section, based on the pore and fractured gradient, the casing sets are selected.
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摘要 :
In engineering, the pore pressure parameter is a useful factor. However, the expression of the compressibility coefficient of pore fluid, which is needed in calculating the parameter, is still not acceptable. Based on the pore wat...
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In engineering, the pore pressure parameter is a useful factor. However, the expression of the compressibility coefficient of pore fluid, which is needed in calculating the parameter, is still not acceptable. Based on the pore water pressure, the definition of compressibility coefficient is proposed. The difference between pore air pressure and pore water pressure is considered according to the effect of surface tension. In order to simply the expression, introduced are two parameters: parameter TR which deals with the influence of surface tension; parameter Φ which is used to reflect the status of pore air. The expression of compressibility coefficient derived can be extended to the application on unsaturated soils with lower degree of saturation. Then, the pore pressure parameters for K0 loading and isotropic loading are presented. Finally, the formula is validated with the experimental results from field and laboratory tests reported in the literatures, and the agreement is good. The pore pressure parameter is not constant during loading, as should be indicated.
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摘要 :
In engineering, the pore pressure parameter is a useful factor. However, the expression of the compressibility coefficient of pore fluid, which is needed in calculating the parameter, is still not acceptable. Based on the pore wat...
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In engineering, the pore pressure parameter is a useful factor. However, the expression of the compressibility coefficient of pore fluid, which is needed in calculating the parameter, is still not acceptable. Based on the pore water pressure, the definition of compressibility coefficient is proposed. The difference between pore air pressure and pore water pressure is considered according to the effect of surface tension. In order to simply the expression, introduced are two parameters: parameter TR which deals with the influence of surface tension; parameter Φ which is used to reflect the status of pore air. The expression of compressibility coefficient derived can be extended to the application on unsaturated soils with lower degree of saturation. Then, the pore pressure parameters for K0 loading and isotropic loading are presented. Finally, the formula is validated with the experimental results from field and laboratory tests reported in the literatures, and the agreement is good. The pore pressure parameter is not constant during loading, as should be indicated.
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摘要 :
The waves induce a sequence of cyclic shear stresses in the soils below the seafloor and progressively increase the wave-induced pore pressure. There are two different mechanisms accounting for the wave-induced pore pressure, name...
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The waves induce a sequence of cyclic shear stresses in the soils below the seafloor and progressively increase the wave-induced pore pressure. There are two different mechanisms accounting for the wave-induced pore pressure, namely residual and oscillatory natures of the pore pressure, depending on the way that the pore pressure is generated. In this study, the ratio of total wave-induced excess pore pressures caused by body force (seepage force) was analyzed, with increasing number of wave cycles using a two-dimensional model. The possibilities of seabed failure caused by liquefaction or shear failure were evaluated in the seabed around a breakwater. In addition, the effectiveness of blocks covered on the seabed was evaluated.
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摘要 :
The waves induce a sequence of cyclic shear stresses in the soils below the seafloor and progressively increase the wave-induced pore pressure. There are two different mechanisms accounting for the wave-induced pore pressure, name...
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The waves induce a sequence of cyclic shear stresses in the soils below the seafloor and progressively increase the wave-induced pore pressure. There are two different mechanisms accounting for the wave-induced pore pressure, namely residual and oscillatory natures of the pore pressure, depending on the way that the pore pressure is generated. In this study, the ratio of total wave-induced excess pore pressures caused by body force (seepage force) was analyzed, with increasing number of wave cycles using a two-dimensional model. The possibilities of seabed failure caused by liquefaction or shear failure were evaluated in the seabed around a breakwater. In addition, the effectiveness of blocks covered on the seabed was evaluated.
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The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated so...
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The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated soil were also summarized. The consolidation theory of unsaturated soils have well applicable future, but the theory is not mature and need the investigators' further research.
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摘要 :
The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated so...
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The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated soil were also summarized. The consolidation theory of unsaturated soils have well applicable future, but the theory is not mature and need the investigators' further research.
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摘要 :
The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated so...
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The consolidation theory and test results of unsaturated soils were summarized in detail in this article, which include the recent development. And some existent difficulties and problems for consolidation theory of unsaturated soil were also summarized. The consolidation theory of unsaturated soils have well applicable future, but the theory is not mature and need the investigators' further research.
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The Mahakam Delta has been developed for more than 40 years and many wells have been drilled to develop the area and to increase production.The Tunu,Bekapai and Peciko Fields are located in the Median Axis of the Mahakam Delta and...
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The Mahakam Delta has been developed for more than 40 years and many wells have been drilled to develop the area and to increase production.The Tunu,Bekapai and Peciko Fields are located in the Median Axis of the Mahakam Delta and collectively have contributed a large volume of production.In the current context of mature fields,there are many drilling problems found,i.e.kick and lost circulation issues due to the reservoirs becoming more depleted,but on a positive note,isolated high pressure still exists.This complexity makes pore pressure and stress analyses in the research area essential in order to support the massive drilling and production activities in this area.The result of well data analysis shows that there are three pore pressure patterns in the study area,i.e.normal pressure,low over pressure and high over pressure.The analysis of cross-plot of sonic and density logs shows that low overpressure is generated by loading mechanism,while high overpressure is generated by non-loading mechanism.The loading mechanism is caused by relatively rapid sedimentation in the study area,while the non-loading mechanism is caused by kaolinite to illite transformation and gas generation.The analysis of pore pressure(Pp)and minimum horizontal stress(Shmin)shows that there is coupling relation,especially in the Tunu Field.This relation is proven by the increase in the hydraulic fracture value starting at the top of overpressure and by the presence of a lost circulation zone that coincides with the presence of a depleted reservoir zone.The coupling ratio of AShmin/APp in overpressure zone shows a relatively low value.This condition indicates that the overpressure is more the cause,rather than the effect of the increase in Shmin in that zone.This analysis will help to increase the understanding of pressure behavior in Mahakam fields,thus helping with a suitable well design strategy for further development and to unlock the remaining field potential.
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