| Abstract |
Injection well Nag-66, located southeast of the main Tiwi production field has been successfully forked by sidetracking at a depth of 861m (2828 7 and then reopening the original penetration. To our knowledge this is the first forked completion in a hot water-dominated geothermal field. The procedure called fof / identiaing a suitable interval of competent formation for initiating the fork, setting a bridge plug an& retrievable whipstock, milling a window through the 9-518ö casing, and drilling the sidetrack to I990 m (6526 Æ). Following drilling of the sidetrack, 7ö slotted liner was run into the sidetrack. The whipstock was then retrieved and the bridge plug was chased to bottom in the original hole. This relatively simple method was adapted j o m technology well-known in the oil and gas industry, and in barefoot forked geothermal completions pioneered by Unocal at The Geysers in California. Prior io this forked completion, Nag-66 had declined io an injection capacity of 7 kg/s (55 kph) of hot brine ai I. 0 MPa (150 psi@ wellhead pressure. Scale drillout improved the capacity of the original hole to 48 kg/s (380 kph). The sidetrack, tested separately, had a capacity of 40 kg/s (315 kph). The well in its final forked completion tested at 95 kg/s (750 kph). Thus, the operation was an economic as well as a technological success. This method should be applicable to production wells in addition to injectors, and will be most valuable in mature fields where right-of-way for new drilling locations is limited and existing wells are available for forking. Forking costs little more than a sidetrack and preserves the productivity (or injectivity) of the original hole. |