Managed Pressure Drilling Brings Added Value to Production Casings Cementing Operations Increasing Success Rates and Quality in HPHT Fractured Narrow Window Wells

Abstract

The oilfields in study are important assets for the National Oil Company and represent 14% of the total oil production of the country. Two wide different and drastically challenging scenarios can be found: HPHT wells with a narrow mud weight window; and highly depleted wells in fractured carbonates. In both cases, the cementing job in production casings is historically classified as very difficult as a direct consequence of high frictional pressure losses due to the small annulus and deep wells configuration which causes loss circulation problems. A close analysis of the offset wells identified the use of MPD as a possible partial solution to mitigate the usual loss circulation scenario.This document describes the successful implementation of the MPD technique as a supplemental aid for cementing jobs, eliminating cement losses, avoiding formation damage, reducing mud losses by also offering additional safety to this kind of operations. In the last two years MPD has been used in a number of cementing jobs in HPHT wells and also in low pressure wells; with equivalent circulating densities as high as 1.65 sg. in both single phase and multiphase drilling fluids MPD applications as low as 0.29 specific gravity.Paper will also detail recommended operational procedures and recommended practices to integrate the MPD technique along with conventional cementing operations. The annulus between the 5" liner and the 7" liner 38# is very small, this condition associated with a narrow mud weight window, makes quite impossible to do a successful cementing job without the aid of the MPD technique.