A Novel Approach to Time-Lapse Logging in Producing Horizontal Wells Using Logging While Tripping (LWT) Technology - A Case Study Review in a Middle East Reservoir

Abstract

Naturally flowing horizontal oil producers typically suffer from increasing Water-Cut within 5 to 7 years of commencing the production. This paper will describe the application of Logging While Tripping (LWT) technology in identifying water-producing sections and hence isolate them effectively by installing Adaptive Inflow Control Devices (AICD) in the permanent completion. This paper will describe the method of deployment of LWT technology which can measure resistivity, caliper, density, neutron porosity, and gamma-ray in the open hole lateral section from inside the drill pipes. LWT logging tools are pumped down inside the drill pipes and locked into place in the LWT collars and data will then be acquired while tripping out of the well with virtually no extra rig time required. This paper will also describe how this technology can be used in time-lapse logging to be compared with the original saturation profile at well day 1 and identify new water sweep sections in the horizontal oil production wells. This approach has been applied in more than 10 horizontal wells in the Middle East; timelapse logs have been successfully used to install AICD devices and improve oil productivity. Results from some wells shall be presented. The study showed that with LWT, it became possible to monitor the horizontal/deviated producing well’s water saturation with the following advantages when compared with the conventional method:Using LWT reduced well intervention time by not less than 200% and hence it also significantly reduced the overall well intervention cost and all the associated non-productive time (NPT) and lost-time incidents (LTI).Measuring time-lapse saturation with deep resistivity tools with a depth of investigation of 50-60 inches; which is greater than the conventional sigma saturation tools of 15-17 inches.Measuring time-lapse porosity to observe the effect of acid treatments if any.Caliper data was used to avoid sections of the borehole where the AICDs most likely will not achieve isolation.Virtually zero risk during logging since the radioactive chemical sources are kept safe inside drill collars and can be retrieved in case of stuck pipes. Ultimately, using LWT achieved its objective of identifying water sweeping sections, resulting in a successful and economic reduction of water. This paper illustrates a case study for the first time for the successful implementation of LWT in water zonal isolation by time-lapse logging. The paper will open the door for a wider range of LWT applications in high-risk wells delivering significant optimizations and improvements to the well intervention operations.