To remain economical, mature offshore oil fields require unique, time-efficient and cost-efficient drilling and completion operations for each well. This paper is a case study of a rapid selection method for determining the operational process for each offshore oil well candidate and its application in the Zhaodong oilfield.

In mature oilfields, maintaining production requires drilling and completing sidetrack wells. There are 3 key steps to rapidly selecting the most suitable drilling, completion and operational strategy for each well. First, review historical production data and operational costs to set production targets for each well. Second, evaluate the potential drilling and completion operations both technically and economically to achieve the target. Third, optimize the selected operations based on prior field application and production results.

This process was applied with newly sidetracked wells in the Zhaodong oilfield. The wells were either completed using a multi-zone cased hole fracturing technique or an open hole completion technique, per the selection process. One candidate well completed with the multi-zone fracturing technique had a daily production rate of 134 tons of oil, and another candidate well completed with an open hole technique had a production rate of 236 tons of oil. These two wells were the most prolific in the Zhaodong oilfield.

Using relatively basic engineering work integrated with simple economic calculations, this methodology is far less complicated and costly than computer simulation modeling for the operator. The performance in the Zhaodong oilfield reinforces this methodology used for selecting the proper candidate and completion process, providing more value and confidence for offshore operators.

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