Effect of sand lens size and hydraulic fractures orientation on tight gas reservoirs ultimate recovery

Abstract

Low permeability and complexities of rock formation in tight gas resources make it more complicated to predict well production performance and estimate gas recovery. To produce from the unconventional resources in the case that formation rock is not sensitive to damage caused by liquid invasion, hydraulic fracturing is the most common stimulation treatment to improve the production to the excepted economically rate. In term of reservoir geometry, tight sand formations are normally stacks of isolated lenses of sand bodies that are separated by shale layers. Each sand lens varies in shape and size and acts as a trap for original hydrocarbon accumulations. The sand lenses parameters such as length and width can play important role in controlling gas recovery from hydraulically fractured tight gas reservoirs. This study shows the effect of drainage pattern of the lenticular sand bodies on production performance and ultimate gas recovery in tight gas formations. Analytical and numerical simulation approaches are used in order to understand the effect of hydraulic fracture parameters and also attribution of sand lens size and shape to the drainage pattern and gas recovery in hydraulically fractured tight sand gas reservoirs. The results highlighted that in tight gas with massive hydraulic fractures, sand lens size in the direction perpendicular to hydraulic fracture wings has the major impact on gas recovery. Sand lens size in the direction parallel to hydraulic fracture wings does not have significant effect on gas recovery. When the sand lenses are isolated and small in size, from a single-well-enhancement perspective, the gas recovery will increase significantly by performing massive hydraulic fracturing through isolated lenses.