Reservoir heterogeneity characteristics of Yanchang Formation in Yanchang Region
MA Dong-sheng1,FU Chao-feng1,LI Ke-yong2,
(1.College of Earth Science and Resources,Chang'an University,Xi'an 710064,China; 2.Journal Center,Xi'an University of Science and Technology,Xi'an 710054,China; 3.Northwest Water Conservancy and Hydropower Engineering Co.,Ltd.,Xi'an 710077,China)
In order to study the reservoir heterogeneity characteristics of Yanchang Formation in Yanchang Region,from the macroscopic and microscopic aspects,according to the logging data,core observation,core analysis dataand mercury testing method,we discuss the influence ofparameterson reservoir heterogeneity.The results show that the rhythm of the particle size distribution has a certain control effect on the reservoir heterogeneity in the vertical direction.The site of particle size uniformity is better,the layer of the larger stratified structure density has poorer physical properties,the thinner the interlayer,the smaller the distribution,the more prone to vertical hydrocarbon migration,theinterlayer has on important influence on thedistribution of oil and gas in the vertical.The heterogeneity of the layers can be evaluated by the parameters such as permeability coefficient of variation,splitting coefficient and step difference.The interlayer acts as a barrier to fluid movement.The planar continuity and physical properties of reservoir sand bodies are important factors to control reservoir heterogeneity.The sandbody of delta underwater distributary channel constitutes the basic skeleton of oil-bearing sandbody in Yanchang Formation.The distribution of sand bodies in different phases shows different connectivity and heterogeneity.The secondary porosity formed by the primary porosity and the later transformation in the diagenetic process controls the full extent of the oil and gas entering the reservoir.We believe that the reservoir heterogeneity of the Yanchang Formation in Yanchang Region is characterized by the inhomogeneity of the factors such as grain size rhythm,stratified structure,interlayer,permeability,sand body geometry and pore structure.
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