Relief Well Drilling Using Surface Seismic While Drilling (SSWD)

Abstract

Abstract Magnetic survey methods are used to locate the blowing wellbore when drilling a relief well. If no magnetic material is present in the openhole section of the blowing well, the last set casing shoe is the deepest possible intersection point. A deeper intersection point will increase the hydrostatic head, increase the frictional pressure drop and allow a lower density kill fluid to be used. A new potential method called surface seismic while drilling (SSWD), could make it possible to intersect the blowing well below the casing shoe. This method is not dependent of any casing or steel tubular present in the well to identify the relative wellbore positions. The SSWD method is based on a surface seismic source generator and a receiver array located on the seabed. Preliminary simulations indicate that it is possible to locate the wellpaths of the two wells on the seismic data. This method will allow real-time seismic monitoring of the well paths without interfering with the drilling operation. This can allow for more precise relative wellbore positioning. To investigate the benefits of a deeper intersection, a simulation model was prepared. A vertical offshore well consisting of 2000 meters of casing, and a 1000-meter openhole section were used. The well was killed dynamically by circulating seawater at high rates into the blowing wellbore. Compared to a casing shoe intersection, simulations show that a bottom hole intersection would reduce the flow rate and pump pressure by approximately 48% and 55%, respectively. The required kill mud weight was reduced by 24 %. The seismic method may also be used in conventional well killing operation to provide additional information of the position of the two wellbores and potentially reduce the time needed to drill the relief well. This paper presents the SSWD method and the potential improvements in relief well drilling and well killing.