A novel mode for “three zones” collaborative reconstruction of underground gas storage and its application to large, low-permeability lithologic gas reservoirs

Abstract

The difficult of reconstruction area selection, the unclear closed boundary and the low injection-production efficiency are the main problems restricting the gas storage reconstruction in large-scale low-permeability lithologic gas reservoir. In view of this, this paper proposes a new ‘three zones' cooperative building model which can provide a comprehensive selecting standard, delimit a stable closed boundary and optimize an efficient operation mode for the successful reconstruction of gas storage in this type of gas reservoir. Its application will create a precedent for the gas storage reconstruction in low-permeability gas reservoir and bring huge economic benefits. First, the multi-parameter comprehensive index evaluation rule of the reservoir under the constraint of “five facies” is established, and the overflow mode and volume of gas in the core area are calculated to define the reasonable range of the ‘three zones'. Subsequently, a mathematical model of fluid exchange between different zones under the new model is established to simulate and predict the dynamic indexes and fluid migration law in different zones. Finally, the operation safety of the gas storage is evaluated, and the applicability and advantage of the new model is confirmed.