Shale Gas Reserves Assessment Method and Application Based on Uncertainty Analysis

Compared with the conventional oil and gas, the spatial distribution of the single well recoverable reserves within a shale gas block is more non-homogeneous, and the uncertainty faced in the reserve assessment is greater. So the uncertainty in the process of the shale gas exploration and production, data acquisition and reserve parameter assigning should be recognized deeply and correctly. And it is very important to enhance the rationality of recoverable reserve assessment results by integrating it into the shale gas reserve assessment. In this paper, the sources of various types of uncertainties and their mutual coupling relationships are summarized and concluded systematically through analyzing the uncertainty characteristics of the recoverable reserves of the shale gas in depth. On this basis, an uncertainty-based reserve assessment process for the shale gas was established. The core of this method lies in selecting appropriate analog well bin through geological zoning and engineering grouping, followed by Monte Carlo simulation to probabilistically assess Estimated Ultimate Recovery and quantify associated uncertainties. The new process and method were practically applied in several blocks of shale gas field in Fuling, Chongqing, China. It has been proved that the above methods can reasonably estimate the recoverable reserves of the shale gas and offer the uncertainty range of the reserve quantitatively at the same time, and thereby providing the technical support for exploration and development planning, listed reserve assessment and reserve asset trading of the shale gas block.