Using Embedded Discrete Fracture Model (EDFM) and Microseismic Monitoring Data to Characterize the Complex Hydraulic Fracture Networks

摘要

Microseismic monitoring is widely used in petroleum industry to image the created hydraulic fracture networks. In this technology, the recorded seismic information during hydraulic stimulation is analyzed to locate the rock deformation and to characterize the failure mechanism. Over the last few years, various approaches have been proposed to calibrate the corresponding discrete hydraulic fracture networks (DFN) with the measured microseismic pattern to study long-term reservoir production. However, due to complexity of the problem and the limitations of reservoir simulators, the direct application of such complex DFNs has been highly restricted. Instead, the spatial extent of microseismic cloud has been often used as a direct measure to assess the efficiency of the treatment. Such interpretation techniques without further modeling and simulations of hydrocarbon production and pressure drainage fail to represent an accurate view of connectivity and complexity of the fracture system. In this paper, we present a recently developed Embedded Discrete Fracture Model (EDFM) to capture the realistic geometry of fractures. In EDFM, each fracture plane is embedded inside the matrix gird and is discretized by the cell boundaries. Using EDFM, we study a series of reservoir simulation examples, in which the complex hydraulic fracture networks calibrated by microseismic monitoring are considered. We investigate different DFN realizations in both planar and complex fracture configurations. We explore the impact of network geometry and fractures properties on the overall performance of the reservoir. The simulation results indicate that the efficiency of well treatment is strongly controlled by fractures connectivity and the distribution of conductivity within the network. When the spatial extent of microseismic cloud is fixed, by changing the degree of connectivity, a wide range of production response is observed. For instance, when the interconnection between the fracture planes is weak, the observed drainage volume is much smaller compared to the one predicted by microseismic monitoring. On the other hand, taking into account the role of aseismic deformations (such as tensile openings) improves the cumulative production. Even in the case of bi-wing hydraulic fracture planes, it is displayed that neglecting the effect of small-scale fissure openings may lead to underestimation of stimulation efficiency. Although the microseismic monitoring depicts a preliminary view of the induced fracture network, more information can be obtained through numerical simulation of fluid transport inside the facture system. Modeling the complex DFNs shows that an accurate production forecast can be achieved using simulation models rather than direct application of total stimulated reservoir volume. Integrating the Embedded Discrete Fracture Model (EDFM) and the microseismic data provides a robust and efficient approach to investigate different DFN realizations.