Recent Advancements in Wireline Microfrac Operation to Facilitate Successful Formation Breakdown – Experiences from Middle East and North Africa

Abstract This study presents the results and insights gained from recent wireline straddle packer microfrac testing conducted in tight Paleozoic and Mesozoic reservoirs, as well as caprocks in the Middle East and North Africa. A primary challenge encountered was the high breakdown pressure, which exceeded the tool's limits. To address this issue, the pump-out method was extensively used to achieve successful breakdowns in these tight formations, which exhibited an average formation breakdown pressure gradient of up to 1.16 PSI/ft, surpassing the vertical stress gradient. The pump-out method was implemented when the first injection cycle failed to achieve breakdown within the tool’s pressure limit. We combined cyclic injection (hole pressurization) with pump-out (hole depressurization below mud hydrostatic) to successfully provoke breakdown. The back-to-back loading and unloading cycles created significant radial stress variations in the near-wellbore region, leading to fatigue and rock weakening. The pump-out technique works by destabilizing the mud cake, which allows fluid to infiltrate the formation and promotes pressure communication between the wellbore and any fractures that may have initiated. This study highlights the proven advantages of the pump-out method, which facilitated successful formation breakdown in impermeable and robust formations. The loading-unloading technique combined with pump-out has proven to be an effective approach for achieving successful formation breakdown without compromising the integrity of the tools used.