ThruBit Logging Saves Time and Reduces Stuck Pipe Risk in Very Challenging Downhole Conditions

摘要

Generally, highly deviated and horizontal wells, with challenging borehole conditions, are logged using the Tough Logging Conditions (TLC) technique, which allows the logging tools to be run pipe-conveyed utilizing the drill pipes. This method however, takes considerable time up to two days per run and has many inherent operational risks such as stuck pipe, long open hole exposure time and potentially, wellbore deterioration. Also, in case of an obstruction in the open hole or in the presence of a logging tools failure, the TLC logging assembly must be pulled out of hole and a conditioning trip may be required before continuing with the logging operations. The ThruBit logging technique eliminates and mitigates most of the TLC operational risks saving rig time. At section Total Depth (TD) and before running casing or an open-hole lower completions such as a Multi-Stage Fracturing (MSF) string, the ThruBit logging is performed through a combined reaming or dummy Bottom Hole Assembly (BHA) and consist of special ThruBit tools such as a portal bit, an hang off sub, and a flapper float valve. The ThruBit logging tools are run on wireline, pumped outside the portal bit, and hanged on a hang-off sub; the cable is then unlatched and retrieved after powering up thus confirming that the ThruBit logging tools are functioning. The logging data is finally recorded in the ThruBit logging tools memory while pulling out of hole. The ThruBit logging technique was performed successfully across interbedded formations: a detailed operating procedure was developed to minimize stationary time to account for the differential sticking risk. It allowed to save three days of rig time and it shorten the time between drilling the section and running the lower completion, thus reducing the risks related to open hole exposure time. ThruBit logging is a true game changer in acquiring the formation evaluation logs in challenging downhole conditions, reducing stuck pipe risks and saving time.