| Title | Successful Big Hole Well Workover-Relining Experience in Well KN3B Mindanao Geothermal Productton Field (MGPF) |
|---|---|
| Authors | Lorena C. M. Daco-ag, Benson Ma. G. Sambrano, Miguel B. Esberto, Rosella G. Dulce, James E. Jumawan, Elvis V . Zerna and James B. Nogara |
| Year | 2007 |
| Conference | PNOC-EDC Geothermal Conference |
| Keywords | |
| Abstract | Well KN-3B is the highest steam producer among all production wells Mindanao Geothermal Production Field (MGPF), and the first large diameter well (13 3/8" production casing) drilled in the field. A shallow obstruction was discovered in the well in 1999. In 2000, solids consisting of sand to pebble sized rock fragments were found in the separators and brine line. Solids carry over from Nindanao-2 (M2) production wells in Pad C (which include KN-3B) and Pad F were suspected as the reason for the declining acceptance of the injection well KN1RD. Consequently, this resulted to excess brine disposal problems. Some of the solids were determined as originating from a damag3d open section of well KN3B since diorite rock fragments were identified from the solids recovered Diorites are unique to the formation encountered by KN-3B during drilling in 1993. Although output of the well did not deteriorate due to these problems, the operational safety of the well and its components were believed to be at risk and needed to be addressed. Repairs to the well will likely help solve the solids problem in M2. After a series of discussions and assessments, workover-relining was recommended and implemented beginning April 29, 2006. A downhole viewer (DHV) survey was conducted prior to repair to evaluate the nature and location of damage. The workover involves milling of casing bulges and relining of the 13-3/8" production casing by a 9 5/8" perforated liner and 9 5/8" casing, and the relining of the 9-5/8" production liner by a 7" perforated liner. The workover was completed on June 13, 2006. Completion tests indicated a significant improvement in injectivity compared to that from the post drilling completion test. Initial bore output measurements indicated an increase in mass flow. Subsequent flow measurements show an improvement back to pre-WO levels. The volume of solids trap was reduced 34 to 60% after the work-over. |