Utilizing Expandable Casing Clad Enabled Short Radius Sidetrack in Wells with Casing Leaks

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractShort radius re-entries are very common in Saudi Aramco. Short radius is the fastest and generally most cost effective way to deliver reentry wells whenever vertical wells are converted into horizontal wells. A casing leak across Arab-C formations is a common problem in some onshore fields. Arab-C formation is a high-pressure water bearing zone. Arab-C is located right above the cap rock of the pay zone. When leaks develop, water starts to flow from the high pressure zone to the pay zone (downhole cross flow) and the well will stop producing oil. This paper will describe the use of expandable casing clad to repair wells with casing leaks across the high-pressure zone. In such wells, the leak was located across Arab-C in production liner. Then, the leak was squeezed off with cement. After that, the casing window was milled below the leak and a short radius curve section was drilled without penetrating the pay zone (Arab-D). Next, the expandable casing clad was utilized to enable drilling the low-pressure pay zone with low mud weight.Utilizing this technique enabled Saudi Aramco to drill short radius sidetracks while insuring integrity of the well, provide Geosteering in the pay zone and facilitate the option to run flow control/isolation systems. By drilling such wells as short radius re-entries, long radius sidetracks with open hole expandable liner option were avoided. Consequently, significant rig time and cost savings were achieved. After the success of this technique, short radius drilling was still carried out with wells that had casing leaks, and the leaks were stopped.