Evaluation of Aerated Drilling Effectivity on “BP” Well in Gbk Geothermal Field Use Guo-Ghalambor Method

Abstrak

The formation of geothermal drilling usually is igneous rock. In general, many geothermal fields encountered fractures cause loss circulation zone in drilling. In drilling, overcome loss circulation zones make drilling more effective and efficient. Aeration drilling methods are known to reduce common problems in geothermal drilling such as loss circulation and stuck pipe. The principle drilling of aeration is to inject air into the fluid of the drilling fluid to reduce the bottom hole pressure on the borehole lower than formation pressure that make an underbalanced drilling. The conventional method of Aerated drilling is gas law method which is still not very accurate to analyze aeration drilling to prevent stuck pipe and loss circulation. So there are still many drilling problems such as stuck pipe and loss circulation despite using aerated drilling technique. The well profile and casing data on "BP" well is hole 26" use 20" casing to the depth of 406 meters, hole 17 use 13^3/8 casing to the depth of 1264 meters, hole 12^1/4 use 10^3/4 casing to depth of 1466 meters, and hole 9^7/8 use 8 ^5/8 casing to depth of 2016 meters. The method used in this research is Guo-Ghalambor method which is corrects aeration drilling and bottom hole pressure in the wells accurately because Guo- Ghalambor method corrects the two phase in drilling system called moody friction between the liquid phase of the drilling fluid and the gas phase for injection in the drilling fluid. This research analyze in route 12^1/4 and 9^7/8 in route 12^1/4 there is loss circulation problem in 1581 meters to overcome the problem it optimizes the gas injection of 1600 SCFM and 780 GPM mud rate. In route 9^7/8 there is loss circulation problem in 1800 meters to overcome the problem it optimizes the gas injection of 1600 SCFM gas and 740 GPM mud rate. Injection and analysis results drilling hydraulics output of Route 12^1/4 are ECD. ESD, Annular Static Pressure, and Annular Dynamic Pressure. The hydraulics output results less than formation pressure as well as on route 9^7/8 makes underbalanced drilling in the well.

Optimization of aeration drilling is based on the limitations based on operation window of gas law method and gas liquid ratio window method. The gas liquid ratio window is more accurate and more preferably applied in the field when doing drilling operations because the parameters are simple than gas law method.