Operational Decision Making Reaching New Frontiers with Real-Time Downhole Telemetry in the Russia's Arctic

Abstract

This paper presents the first experience of using a system for transmitting downhole data to surface (a telemetry system) based on wireless acoustic signal transmission during drill-stem testing (DST) in four carbonate reservoirs penetrated by an exploration well on Dolginskoye field in the Pechora Sea. Because no fluid would be recovered at surface during well testing, the job sequence program was optimized so that a full set of geological data could be obtained for each carbonate reservoirs in one trip. The purpose of a wireless acoustic telemetry system is to provide a communication link between downhole and surface equipment by means of acoustic signals passing through the well testing bottom-hole assembly (BHA) and enabling a two-way communication channel to be established so that bottomhole data can be received on surface in real time, and downhole equipment can be monitored and controlled. The system allows operators to adjust the well testing program based on bottomhole pressure data and to check whether sufficient amount of data has been collected for the well testing objectives to be achieved. Using a wireless acoustic telemetry system during dynamic well testing has many advantages compared to conventional testing with no downhole telemetry: bottomhole data can be received during job execution, operators have opportunity to monitor and analyze testing data and rely on a full set of representative data received in real time to make decisions for optimizing the job sequence program. The paper emphasizes the significance of receiving average formation pressure data during DST operations as it clarifies geological framework of the intervals under investigation and makes it possible to compare them with pressure data obtained by wireline tools when testing reservoirs with low porosity and permeability. The paper demonstrates a testing procedure optimization process which resulted in saving time on one well up to 36 hours and on other two wells – up to 24 and 48 hours, respectively, where acid treatments were considered unnecessary. For the first time, dynamic well testing were completed on the Russian Arctic shelf in four carbonate reservoirs without any fluid recovery on surface, under an optimized testing program. Considering a short navigation season, this technology is ideal for real-time bottomhole data transmission applications.