Reducing Drilling Risk and Cost through Integration of Seismic and Real-time Well Data

There is always uncertainty involved in drilling a well, arising from incomplete knowledge of the subsurface. Before drilling starts an earth model in the vicinity of the well is normally produced using available information relating to geology, rock properties, stresses, pressures and temperatures from surface seismic data and nearby well data. Based on the earth model a drilling plan is made, including the well’s trajectory, casing points and other specifications. However, the model is often quite uncertain because there is a lack of information in the vicinity of the well, and this uncertainty can lead to increased drilling costs and environmental and safety risks. A recent development that can reduce drilling uncertainty combines surface seismic data with LWD log information to produce a more reliable picture of geology and pressure distribution ahead of the drill bit. Tests of this method indicate that it is effective for reducing uncertainty about subsurface structure (e.g. fault location uncertainty) and providing better estimates of pore pressure. A blind test is shown demonstrating the accuracy of pore pressure predictions made using this method.