Well Engineering for Oman Deep Gas: Planning and Drilling the Deepest Well in the Sultanate of Oman

摘要

As part of ongoing gas exploration efforts, Petroleum Development Oman (PDO) is currently executing a fast-track four well drilling campaign targeting deep, high temperature and potentially high pressure prospects (CITHP>10,000 psi, BHST >170° C),using under-balanced drilling in the Fahud Salt Basin in the Sultanate of Oman. In early 2009, a co-located, ring-fenced multi-disciplinary team including two Well Engineers was set-up. The objective was to spud the first well before the end of 2009 and complete the four well campaign within two years. This paper describes the process followed to progress well designs, procure materials and get the rigs and people in place in only 8 months from project kick-off to spudding the first well. Recognized industry standards indicate that such projects typically take more than 18 months to deliver. Using PDO's experience in deep gas exploration it was possible to standardize well components and only introduce additional items where unavoidable. To further accelerate the project, the two campaign rigs were upgraded with Top Drive Systems and 7500 psi mud circulating capability. The paper goes on to present the drilling challenges and learnings gathered from the first two wells. , Both wells were a technical success and delivered within the planned time and cost. The deepest well at 7145 m AH set Sultanate of Oman records for total depth and bottom-hole temperature. The key challenges faced were downhole tool reliability, directional control in a long slim hole reservoir, drill string dynamics, short planning interval, just in time material delivery and bit and downhole drive optimization. Significant future time and cost reduction is expected to be possible by applying the key learning’s on future wells.