Publications

An energy operator in Indonesia planned an exploration well that required two divergent hole opening sections: A 12 ¼” x 13 ½” hole section; and a 10 ⅜” x 12 ¼” hole section, to be able to add 11 ¾” liner between the 13 ⅜” and 9 ⅝” casing to address the subsurface uncertainties that are typical of an exploration well, and as such a new generation of Bi-Center bit was utilized. This project required the application of multiple innovative approaches: 1) The opening tool has to pass through the minimum or ID of the wellhead and casing; 2) Possess the capacity to be inserted into BHA design such as rotary or using mud motor; 3) The necessity to efficiently drill the cemented shoe track; 4) The minimization of rat hole needs to be eliminated to optimize and ensure cementing of the casing. Simultaneous drilling and hole enlargement were conducted in a way that achieved the intended objectives in a cost-efficient and effective manner. Before the project, a pre-job planning exercise was performed to ensure that the Bi-Center bit could pass through the maximum tool size allowance in conjunction with mud motor BHA. The 12 ¼” x 13 ½” Bi-Center bit was successfully drilled and enlarged to the programmed target depth, with a total interval length of 453 m and a satisfactory ROP. There were no issues while tripping the BHA through the wellhead wear bushing, the casing, and subsequently drilled the cement shoe track, float equipment, and casing shoe.The next section of the well experienced a successful run of the 10 ⅜” x 12 ¼” Bi-Center with a respectable ROP and the bit was graded in good dull condition after it was pulled out of the hole. Both the 11 ¾” liner and 9 ⅝” casing strings were successfully deployed to the bottom and demonstrated that the Bi-Center bits provided satisfactory hole quality.