Abstract: The deep (>3500m) shale gas is enriched in Wufeng Formation--Longmaxi Formation in Luzhou Area, southern Sichuan. In order to ensure the goal of increasing and stable production of shale gas, it is necessary to realize the three-dimensional production of L$_1$ submember shale gas. The data of core, logging and production are used to study the reservoir characteristics, quantitative evaluation of reservoir quality and simulation of fracturing height of deep shale gas formations in the study area. Combining with quantitative evaluation of reservoir quality and simulation of fracturing height, an intelligent optimization and benefit evaluation method of double-layer targets for deep shale gas horizontal wells is established. The results show that: 1)the overall physical properties of Long-1 subsection become worse from deep to shallow, L$_1^1$—L$_1^3$ layer is dominated by first-class desserts, and L$_1^4$ layer is dominated by second-class sweet spot, with a thickness of more than 40 meters; 2)the intelligent optimization method of horizontal well target in deep shale gas reservoir can quickly obtain two sets of information such as optimal depth, sweet spot quality, fracturing height and target benefit evaluation ($Q$) of horizontal well; 3)the plane dominant area of the first set of target benefit evaluation is consistent with the current high production well area, considering the target benefit evaluation $Q$ value of L$_1^4$ small layer and the actual production of the second set of target horizontal wells that have been established, we predicted that the second set of targets in the deep shale gas reservoir in southern Sichuan has a certain development value and potential, and defined the dominant areas on the two sets of target planes. The study provides a basis for large-scale realization and production prediction of double-layer targets in deep shale gas reservoirs.

Key words: deep shale gas, double-layer target, horizontal well, reservoir quality, fracturing height, target selection