Real-Time Drill Bit Tracking with Passive Seismic Data at Grane, Offshore Norway

Abstract

Summary Passive seismic data acquired with the permanently-deployed reservoir monitoring (PRM) system at Grane have been used to monitor drilling operations in real time. The aim is to support better well placement by reducing the position uncertainty while drilling, and hence reduce the risk of drilling infill wells too close to existing producers. The well position derived from conventional magnetic and gyro MWD measurements has an error that accumulates with measured depth and can become relatively large in the lateral direction for long horizontal wells. In contrast, by analysing drilling noise recorded by an array of seismic sensors, one obtains independent measurements of the well position, not suffering from accumulation of error. First tests at Grane indicate that the lateral position uncertainty of the well path can be reduced significantly for the longest horizontal wells. For PRM-equipped fields, passive seismic drilling monitoring thus offers a complementary method for real-time well positioning at minimal extra costs and can be used for decision making during drilling operations.