| Title | Prevention and Control of Calcite Deposition in Two-Phase Header: the Bacman-2 Botong Experience |
|---|---|
| Authors | Jimmy J. Fragata, Ramonito P. Solis, Romerico C. Gonzalez, Edwin L. Bondoc, Fidel S. See Leonardo J. Llenarizas, Amador R. Josef, and Liberato S. Virata |
| Year | 2003 |
| Conference | PNOC-EDC Geothermal Conference |
| Keywords | |
| Abstract | A liquid removal system (LRS) was installed along the two-phase branchline of well OP-5DA, which is composed of a modified 610-mm diameter oversized drain pot (ODP) and a 457-mm diameter standard drain pot (SDP). The objective is to prevent calcite deposition inside the header by collecting and draining OP-5DAÆs liquid component before it mixes with well OP-6D fluids at the 610-mm diameter two-phase line header. Prior to the installation of the LRS, massive calcite deposited six meters in length from the mixing point and fully blocking the 610-mm header within a ten-month period. The calcite deposits of about 1.63 m│ gave an equivalent calcite deposition rate (CDR) of 0.163 m│/month. With the LRS installed, about 52% reduction in the CDR or 0.084 m│/month was observed after pipe inspection. Further revisions on the LRS and its operation led to a significant decline in CDR by 83% or 0.027 m│/month as compared with that without LRS. Previous physical and chemical simulations show that the cause of calcite deposition inside the header is due to mixing of incompatible fluids from OP-5DA and OP-6D. OP-5DA high-enthalpy two-phase fluid is supersaturated with respect to calcite, while that of OP-6D is pure steam and superheated by as much as 16░C. As these fluids mix, further boiling occurs resulting to voluminous calcite deposits formed at the mixing point in the header. Removal of OP-5DA liquid component with an ODP was chosen to be an economical solution among the options. |