In order to improve reservoir fluid recognition, the sensitivity of array resistivity response to the difference of the invasion properties in both oil-bearing layers and water layers is analyzed. Then the primary inv...In order to improve reservoir fluid recognition, the sensitivity of array resistivity response to the difference of the invasion properties in both oil-bearing layers and water layers is analyzed. Then the primary inversion is carried out based on the array resistivity log. The mud invasion process is numerically simulated based on the oil-water flow equation and water convection diffusion equation. The results show that the radial resistivity of a fresh mud-invaded oil-bearing layer presents complex distribution characteristics, such as nonlinear increase, increasing to decreasing and low resistivity annulus, and the resistive invasion profile of a water layer is monotonic. Under specific conditions, array resistivity log can reflect these changes and the array induction log is more sensitive. Nevertheless, due to the effect of factors like large invasion depth, reservoir physical and oil-bearing properties, the measured apparent resistivity may differ greatly from the actual mud filtrate invasion profile in an oil-bearing layer. We proposed a five-parameter formation model to simulate the complex resistivity distribution of fresh mud-invaded formation. Then, based on the principle of non-linear least squares, the measured array resistivity log is used for inversion with the Marquardt method. It is demonstrated that the inverted resistivity is typically non-monotonic in oil-bearing layers and is monotonic in water layers. Processing of some field data shows that this is helpful in achieving efficient reservoir fluid recognition.展开更多
Permeability is an important index in reservoir evaluation,oil and gas accumulation control,and production effi ciency.At present,permeability can be obtained through several methods.However,these methods are not suit...Permeability is an important index in reservoir evaluation,oil and gas accumulation control,and production effi ciency.At present,permeability can be obtained through several methods.However,these methods are not suitable for tight sandstone in general because the pore type in tight sandstone is mainly secondary pores and has the characteristics of low porosity and permeability,high capillary pressure,and high irreducible water saturation.Mud invasion depth is closely related to permeability during drilling.In general,the greater the permeability,the shallower the mud invasion depth,and the smaller the permeability,the deeper the mud invasion depth.Therefore,this paper builds a model to predict the permeability of tight sandstone using mud invasion depth.The model is based on the improvement of the Darcy flow equation to obtain permeability using mud invasion depth inversion of array induction logging.The influence of various permeability factors on the model is analyzed by numerical simulation.The model is used to predict the permeability of tight sandstone in the south of the Ordos Basin.The predicted permeability is highly consistent with the core analysis permeability,which verifi es the reliability of the method.展开更多
基金funded by the National Natural Science Foundation (41174009)National Major Science &Technology Projects (2011ZX05020, 2011ZX05035,2011ZX05003, 2011ZX05007)
文摘In order to improve reservoir fluid recognition, the sensitivity of array resistivity response to the difference of the invasion properties in both oil-bearing layers and water layers is analyzed. Then the primary inversion is carried out based on the array resistivity log. The mud invasion process is numerically simulated based on the oil-water flow equation and water convection diffusion equation. The results show that the radial resistivity of a fresh mud-invaded oil-bearing layer presents complex distribution characteristics, such as nonlinear increase, increasing to decreasing and low resistivity annulus, and the resistive invasion profile of a water layer is monotonic. Under specific conditions, array resistivity log can reflect these changes and the array induction log is more sensitive. Nevertheless, due to the effect of factors like large invasion depth, reservoir physical and oil-bearing properties, the measured apparent resistivity may differ greatly from the actual mud filtrate invasion profile in an oil-bearing layer. We proposed a five-parameter formation model to simulate the complex resistivity distribution of fresh mud-invaded formation. Then, based on the principle of non-linear least squares, the measured array resistivity log is used for inversion with the Marquardt method. It is demonstrated that the inverted resistivity is typically non-monotonic in oil-bearing layers and is monotonic in water layers. Processing of some field data shows that this is helpful in achieving efficient reservoir fluid recognition.
基金supported by the National Natural Science Foundation of China project(No.41504103 and No.41804097).
文摘Permeability is an important index in reservoir evaluation,oil and gas accumulation control,and production effi ciency.At present,permeability can be obtained through several methods.However,these methods are not suitable for tight sandstone in general because the pore type in tight sandstone is mainly secondary pores and has the characteristics of low porosity and permeability,high capillary pressure,and high irreducible water saturation.Mud invasion depth is closely related to permeability during drilling.In general,the greater the permeability,the shallower the mud invasion depth,and the smaller the permeability,the deeper the mud invasion depth.Therefore,this paper builds a model to predict the permeability of tight sandstone using mud invasion depth.The model is based on the improvement of the Darcy flow equation to obtain permeability using mud invasion depth inversion of array induction logging.The influence of various permeability factors on the model is analyzed by numerical simulation.The model is used to predict the permeability of tight sandstone in the south of the Ordos Basin.The predicted permeability is highly consistent with the core analysis permeability,which verifi es the reliability of the method.