Formation Pressure Estimation and Its Impact On Well Design: A Case Study From The Greater Dolphin Area

摘要

Pore pressure studies have been a key consideration in well design; both from a drilling design and well deliverability perspective. In the drilling of an exploration opportunity, and in the absence of direct pressure measurements, pore pressure estimation becomes even more critical in the delivery of a safe, cost effective and potentially productive well. In a previously drilled key well in the Greater Dolphin Area there were no direct pressure measurements taken through one of the tested zones where there is potential for an updip accumulation. To fully appreciate this exploration opportunity, pore pressure estimation is required for both well design and subsequent well cost assumptions. Given the lack of pressure data for this prospect, pressure uncertainty ranges, supplemented by analogue well data feeding into a geomechanical model were utilized for well design. The geomechanical study defined the appropriate mud weight windows and guided the casing design. This pore pressure analysis also fed into the estimation of production rates and safe operating drawdown envelopes which are critical to the delivery of highly productive wells. Assumptions on the well design and the expected production rate provided the basis of drilling duration and cost and thus the economic viability of pursuing the prospect. Through this uncertainty management, this exploration opportunity, if deemed viable, can be included in future development programs and if successful, add to the gas reserves of the Greater Dolphin Area.