Study on Parameters Optimisation of Fracturing Stages & Perforation Clusters in Luzhou Deep Shale Gas Horizontal Wells Based on Integrated Drilling and Logging Data

Abstract

Abstract Considering the high temperature environment and high operation cost, only a small number of deep shale gas horizontal wells in Luzhou would conduct logging in horizontal sections. If the neighboring wells were rather far away, it would be difficult to accurately obtain the reservoir heterogeneity along the lateral; therefore, most completions were designed geometrically, with little or no guidance for the location optimizations of fracturing intervals & perforation clusters. In such a case, it was most likely to occur a low opening rate of perforation clusters in the same stage, resulting in a poor stimulation effect. For the first time, this paper proposed a novel optimization method for the fracturing parameters of horizontal sections based on integrated drilling & logging data. Firstly, the available data type was evaluated. If the logging data was missing, geometrically designed stages and clusters would be relocated based on drilling data; otherwise, it could be easily accessible by logging data. Then, when relocating, the drilling data (torque, drilling pressure, mechanical drilling speed, etc.) were used to calculate the rock mechanical specific energy (RMSE) along the lateral. Next, the RMSE values were calibrated with the indoor rock mechanics experiments to establish a standard classification of Luzhou deep shale rock hardness. Finally, based on the principle of similar rock hardness, the perforation clusters in the same fracturing stage were re-positioned to ensure their locations at the same or adjacent rock hardness level. The above design method was applied and verified in Luzhou deep shale gas wells, the results demonstrated that, after the geometrically distributed segments & clusters were adjusted and relocated, their positions had a high matching rate of 85.47% with the optimized design of fracturing segments & perforation clusters using logging data. What's more, the VideoLog technology was utilized to observe the erosion of the perforation holes after fracturing, 9 out of 11 perforation clusters effectively opened, with an opening rate of up to 81.8%. Compared to the previous geometrically fracturing design with only 2 out of 10 perforation clusters effectively opened, it was a 124.7% improvement. In addition, the shape and size of the opening perforation holes were the same after erosion, which indicated that the hardness of the rock at the locations where the perforation holes were arranged was nearly the same, resulting in almost all clusters simultaneously opening & initiating. Therefore, this method can effectively compensate for the blindness of the segment & cluster parameters design caused by the lack of logging data, ensure the effective opening efficiency of perforation clusters in the same stage, and maximize the uniformity and effectiveness of reservoir stimulation.