D rilling is an activity to obtain oil and gas also geothermal source. Drillingcan be done not only onshore but also offshore. Nowadays, drilling is important inthe oil and gas industry to find reserves in the reservoir. The formation ofgeothermal drilling usually is igneous rock. In general, many geothermal fieldsencountered fractures cause loss circulation zone in drilling. In drilling, overcomeloss circulation zones make drilling more effective and efficient. aerated drillingmethods are known to reduce common problems in geothermal drilling such as losscirculation and stuck pipe. The principle drilling of aeration is to inject air into thefluid of the drilling fluid to reduce the bottom hole pressure on the borehole lowerthan formation pressure that make an underbalanced drilling. The conventionalmethod of Aerated drilling is gas law method which is still not very accurate toanalyze aeration drilling to prevent stuck pipe and loss circulation. So there arestill many drilling problems such as stuck pipe and loss circulaton despite usingaerated drilling techniques. The well profile and casing data on”BP” well is hole26” use 20” casing to the depth of 405 meters, hole 17” use 13 3⁄8 casing to thedepth of 1264 meters, hole 12 ¼“ use 10 3⁄4 casing to depth of 1466 meters, andhole 9 7⁄8 use 8 5⁄8 casing to depth of 2016 meters. The method used in thisresearch is guo-ghalambor method which is corrects aeration drilling and bottomhole pressure in th wells accurately. The guo-ghalambor method corrects the twophase in drilling system called moody friction between the liquid phase of thedrilling fluid and the gas fase for injection in the drilling fluid. This researchanalyze in route 12 ¼ and 9 7⁄8. In route 12 ¼ there is loss circulation problem in1581 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 1800meters to overcome the problem it optimizes the gas injection of 1600 SCFM gasand 740 GPM mud rate. Injection and analysis results drilling hydraulics output.The output of 12 ¼ route are ECD, ESD, Annular Static Pressure, and AnnularDynamic Pressure. The hydraulics output results less than formation pressure aswell as on route 9 7⁄8 it makes underbalanced drilling in the well. Optimization ofaeration drilling is based on the limitations based on operationg window of gasliquid ratio window method. The limits contained in the operating windows in Guo-Ghalambor found in the recommendation operating range. the limits used in thegas liquid ratio window are the line between the collapse line and the balance lineand there are loss circulation, collapse, and poor cutting transport. Aerated drillinguse guo ghalamabor method is effecvtive to overcome loss circulation problem.