| Title | Application of Modified Inflatable Packer to Repair Production Casing Leak in Big Hole Geothermal Well |
|---|---|
| Authors | Ali MUNDAKIR, Agus A. ZUHRO, Budi SETIAWAN |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Production Casing Leak, Big Hole Well, Workover and Well Repair, Wooden Plug, Modifired Inflatable Packer |
| Abstract | Continuity of steam which produced from the geothermal well is the most important thing in geothermal operation. There are several issue that can decrease the steam supply or even deplete it. Leaking of production casing is a common problem in geothermal operation, which usually caused by aquifer flow that enter the production casing. It can cause the cooling of reservoir temperature which lowering the steam flow, and in the end lowering the capacity of electrical energy generated. PT. Pertamina Geothermal Energy (PGE) as the leading geothermal company in Indonesia operates 5 fields with a total installed capacity of 617 MW. To meet the production capacity, a total of 166 production and injection have been drilled. Some of them are “Big Holes†that utilize 13.3/8†as the production casing. Until recently, a total of 22 big hole wells (about 13% of the wells) has been undergone well repairation due to leakage in production casing. The root cause of the leakage is mostly the casing configuration which used “tie-back†system. The system is basically divide cementing process of production casing into two steps to reduce hydrostatic pressure for each step. A receptacle is then used to connect between the first stage and the second stage of the production casing. After several years in operation this tie-back type of connection was found as the cause of the leakage in production casing. Workover and well repair operation was then done to solve the leakage. The work was done by first applying bridge/wooden plug on the top of production perforated liner 10.3/4†to isolate its reservoir zone. The operation then continued by cementing plug and/or squeeze job to fill the leakage in the receptacle of production casing. After that, bridge plug and wooded plug will be drilled or pushed until the bottom of the well. These Conventional Workover and Well Repair operation normally takes around 25 days and costs about USD 2 Million due to long working day of the operation. There is also a big risk in which its reservoir zone is getting plugged by cement used during the squeeze job. In this case, it will decrease or even deplete the well production capacity. To avoid the risk, PGE has initiated to use a “Modified Inflatable Packer†to repair the production casing leakage in well HLS-C1 of Hululais Geothermal Field of Indonesia in 2018. The Modified Inflatable Pakcer was installed just below the casing leak point, then that packer is released and pulled out to surface after the leaking has been shut. This method remove the use of bridge plug or wooden plug including the operation to drill and push that plug. This operation also eliminates the risk of plugging reservoir zone that cause decreasing well production capacity. Its also reduced the cost by shortening the operation time. The workover on well HLS-C1 was completed in 10 days with the cost of USD 770K. Moreover, its production capacity remains the same based on the well testing that done afterward. |