Fine Anatomy of Reservoir Structure and Evaluation of Gas Storage Space in Deepwater Sublacustrine Fan Sandstone Reservoir—Take Jidong PG2 Gas Storage as an Example

In order to calculate the effective storage space, the target area is to reconstruct the gas storage in the deep-water sublacustrine fan sandstone reservoir. The production data show that the reservoir is pan-connected vertically, but the logging curve presents the characteristics of multilayers. Therefore, it is urgent to implement the reservoir structure problem to accurately characterize the gas storage space. Taking Jidong PG2 gas storage as an example, on the basis of the sedimentary background study, based on the continuous coring description of centimeter level, combined with seismic and well logging data, the reservoir structure was dissected to identify the types of interlayers, deepen the formation mechanism of interlayers, describe the internal interlayer distribution law, establish a three-dimensional model of interlayer spatial distribution, and realize the characterization of interlayer spatial structure. The spatial and temporal evolution of sedimentary facies and the distribution characteristics of sand bodies were defined, and then the pore volume of different facies zones was calculated to evaluate the gas storage space. The research results show that there are three types of interbeddings. The interlayer is mainly distributed in the area where the sand body is not developed, such as the side margin of the channel. The interbeddings are small in scale and present a banded discontinuous distribution, and the overall longitudinal connectivity of the reservoir is good. The reservoir as a whole is a set of multi-stage superposed thick massive sublacustrine fan main channel, braided channel and channel edge sedimentary sand body. Due to the intermittent hydrodynamic difference in the development of multi-stage channel, the logging response characteristics have the characteristics of multi-interlayer. The massive sublacustrine fan reservoir is labyrinthian and connected up and down. The research results have important guiding significance for subsequent effective reservoir space evaluation and similar reservoir research.