Determination of Fracturing Risk-Units base on seismic and micro-seismic

Abstract During hydraulic fracturing, unconventional oil and gas reservoirs often encounter risks, such as fracturing casing deformation, which affects the efficiency and effectiveness of fracturing. We can accurately identify the location of fracturing risks by using logging data and seismic data. However, we cannot avoid the occurrence of risks, and the location of deformation may be in the un-fractured stage, which is relatively far from the already fractured stage. In severe cases, it is necessary to merge or discard the un-fractured stage of the casing deformation, which will inevitably affect the fracturing effect and production. Therefore, it is particularly important to effectively divide risk units, optimize the sequence of fracturing in the stage, and reduce the impact of risk occurrence. In order to reduce the impact, the author proposes a method to determine risk-units. Firstly, before hydraulic fracturing, seismic data is used to interpret faults and determine risk-units based on the connectivity of faults. Then, during hydraulic fracturing, micro-seismic events are applied to explain artificial faults, optimize the connectivity of faults, and determine risk-units. Finally, based on the risk-units, determine the sequence of fracturing, the stage within the same risk-units should be subjected to hydraulic fracturing as the same batch, after all stages within the same risk-units are fractured, the stages of next risk-units can be carried out. The method proposed by this paper has been applied in zipper fracturing, which can effectively reduce the impact of casing deformation. After the application of this method, the deformation only occurs in the fractured stage or near the un-fractured stage, thus significantly reducing the impact on the un-fractured stage. However, due to the complexity of geological structure and stress transmission, the stages may also have mutual influence, located within different risk-units. Therefore, how to optimize the sequence of fracturing based on risk-units is a topic that needs further-deepening research. This paper innovatively proposes a method for determining fracturing risk-units based on seismic and micro-seismic data to optimize the sequence of fracturing in zipper fracturing, this is of great significance for improving fracturing efficiency, improving fracturing effectiveness, and increasing single well oil and gas production.