Abstract
The drilling of development wells in sand stringers involves very thin and sinuous targets. These targets are the channel sand stringers and contain a substantial amount of hydrocarbons. Optimal well placement is a requirement for these very thin reservoirs in order to drain them in a cost effective manner.
Conventional well placement has met with limited success in stringers and the production can be expected to be low from these stringers. A technology driven approach of detecting the formation changes early during drilling was needed. These changes, when addressed, can be translated into maximizing reservoir contact, limiting well-bore tortuosity thus enhancing optimal production.
Due to the uncertainty that is inherently present in the distribution of the channel sands, the prediction of the azimuth of channel meander can now be confidently solidified with new deep and directional electromagnetic measurements (EM) tool. This is a technology which uses directional EM through the use of tilted and transverse current-loop antennas. By detecting the upper and lower conductive shale boundaries the wells have been steered in this very challenging environment of channel sands.
This technology has proven to be a major success in the development of the sand stringers by improving the Net to Gross ratio by more than 50% and hence the longevity and producabilty of the stringer wells as compared to conventional well placement LWD techniques.