A Leakage Factor–Based Technique for Evaluation of Lateral Sealing Capacities of Small–Displacement Faults

Summary Conventional sealing generally involves juxtaposition and faulted rocks. However, it is not appropriate to evaluate the lateral sealing properties of faults by analyzing the conventional sealing in hydrocarbon–bearing structures controlled by small–displacement faults. In this context, stress–related sealing is critical. In this study, a leakage factor–based analysis technique for stress–related sealing is proposed. It can establish the relationship between the normal stress, shear stress and the pore pressure experienced by the fault plane, obtain the leakage factor that reflects the sealing capacity of the fault plane, calculate the comprehensive stress state of the fault plane, and further effectively discriminate the fault sealing capacity. The Structure JZ in the Bohai Bay Basin is taken as an example. There are a series of fault block traps that are controlled by Fault 1 and associated faults. Specifically, fault displacements of traps in the south and north are relatively small. With use of the proposed technique, the stress–related sealing capacity of Fault 1 in the north reaches 0.78, which is higher than that in the south, 0.71. The good sealing capacity is validated by the subsequently encountered nearly 40 m oil layer in the drilling.