Since gas hydrate exists in three different forms at the same time such as pore filling,particle support and separate stratification,the calculation method of hydrate saturation using traditional shaly sand formation ...Since gas hydrate exists in three different forms at the same time such as pore filling,particle support and separate stratification,the calculation method of hydrate saturation using traditional shaly sand formation interpretation models is equivalent to considering only the simple case that hydrate exists as pore filling,and does not consider other complex states.Based on the analysis of hydrate resistivity experimental data and the general form of the resistivity-oil(gas)saturation relationship,the best simplified formula of hydrate saturation calculation is derived,then the physical meaning of the three items are clarified:they respectively represent the resistivity index-saturation relationship when hydrate particles are completely distributed in the pores of formation rocks,supported in the form of particles,and exist in layers,corresponding quantitative evaluation method of hydrate saturation is built.The field application shows that the hydrate saturation calculated by this method is closer to that obtained by sampling analysis.At the same time,it also provides a logging analysis basis for the effective development after hydrate exploration.展开更多
Aiming at the problem of anisotropy inversion of tight sands, a new method for extracting resistivity anisotropy from array laterolog and micro-resistivity scanning imaging logging is proposed, and also the consistenc...Aiming at the problem of anisotropy inversion of tight sands, a new method for extracting resistivity anisotropy from array laterolog and micro-resistivity scanning imaging logging is proposed, and also the consistency of electric and acoustic anisotropy is discussed. Array laterolog includes resistivity anisotropy information, but numerical simulation shows that drilling fluid invasion has the greatest influence on the response, followed by the relative dip angle θ and electrical anisotropy coefficient λ. A new inversion method to determine ri, Rxo, Rt and λ is developed with the given θ and initial values of invasion radius ri, flushed zone resistivity Rxo, in-situ formation resistivity Rt. Micro-resistivity image can also be used for describing the resistivity distribution information in different directions, and the electrical characteristics from micro-resistivity log in different azimuths, lateral and vertical, can be compared to extract electric anisotropy information. Directional arrangement of mineral particles in tight sands and fracture development are the intrinsic causes of anisotropy, which in turn brings about anisotropy in resistivity and acoustic velocity, so the resistivity anisotropy and acoustic velocity anisotropy are consistent in trends. Analysis of log data of several wells show that the electrical anisotropy and acoustic anisotropy extracted from array laterolog, micro-resistivity imaging and cross-dipole acoustic logs respectively are consistent in trend and magnitude, proving the inversion method is accurate and the anisotropies of different formation physical parameters caused by the intrinsic structure of tight sand reservoir are consistent. This research provides a new idea for evaluating anisotropy of tight sands.展开更多
文摘Since gas hydrate exists in three different forms at the same time such as pore filling,particle support and separate stratification,the calculation method of hydrate saturation using traditional shaly sand formation interpretation models is equivalent to considering only the simple case that hydrate exists as pore filling,and does not consider other complex states.Based on the analysis of hydrate resistivity experimental data and the general form of the resistivity-oil(gas)saturation relationship,the best simplified formula of hydrate saturation calculation is derived,then the physical meaning of the three items are clarified:they respectively represent the resistivity index-saturation relationship when hydrate particles are completely distributed in the pores of formation rocks,supported in the form of particles,and exist in layers,corresponding quantitative evaluation method of hydrate saturation is built.The field application shows that the hydrate saturation calculated by this method is closer to that obtained by sampling analysis.At the same time,it also provides a logging analysis basis for the effective development after hydrate exploration.
基金Supported by the Scientific Research and Technological Development Project of CNPC(2019A-3608)
文摘Aiming at the problem of anisotropy inversion of tight sands, a new method for extracting resistivity anisotropy from array laterolog and micro-resistivity scanning imaging logging is proposed, and also the consistency of electric and acoustic anisotropy is discussed. Array laterolog includes resistivity anisotropy information, but numerical simulation shows that drilling fluid invasion has the greatest influence on the response, followed by the relative dip angle θ and electrical anisotropy coefficient λ. A new inversion method to determine ri, Rxo, Rt and λ is developed with the given θ and initial values of invasion radius ri, flushed zone resistivity Rxo, in-situ formation resistivity Rt. Micro-resistivity image can also be used for describing the resistivity distribution information in different directions, and the electrical characteristics from micro-resistivity log in different azimuths, lateral and vertical, can be compared to extract electric anisotropy information. Directional arrangement of mineral particles in tight sands and fracture development are the intrinsic causes of anisotropy, which in turn brings about anisotropy in resistivity and acoustic velocity, so the resistivity anisotropy and acoustic velocity anisotropy are consistent in trends. Analysis of log data of several wells show that the electrical anisotropy and acoustic anisotropy extracted from array laterolog, micro-resistivity imaging and cross-dipole acoustic logs respectively are consistent in trend and magnitude, proving the inversion method is accurate and the anisotropies of different formation physical parameters caused by the intrinsic structure of tight sand reservoir are consistent. This research provides a new idea for evaluating anisotropy of tight sands.
