T The RRAD07 geothermal field is located in the Bengkulu Province,Indonesia. The well that has been drilled is a directional well with total depthtarget of 5915 ftMD. The analysis that has been done to obtain the optimizationresults on the AD10 well which had problems with loss circulation whendrilling with the Aerated method. Optimization is done using the Guo-Ghalamborequation, to do the calculation of the Bottom Hole Pressure (BHP) which includesthe pressure on the borehole during static conditions (Annular Static Pressure), thepressure on the borehole during dynamic conditions (Annular Dynamic Pressure),Equivalent Circulating Density ( ECD) and Equivalent Static Density (ESD)). Thedrilling cutting removal calculation includes calculating kinetic energy with theminimum kinetic energy required for drilling fluid to lift the cuttings from thebottom of the drill hole is 3 lb/cuft and determining the success of theoptimization scenario selected by the Gas-Liquid Rate Window (GLRW) method.Drilling at depth of 4354 ftMD using a liquid injection flow rate of 720 GPM andan air injection rate of 800 scfm occurs partial loss circulation. Optimization isdone using 4 optimization scenarios. Optimization scenario 1 is the actual drillingdata that has been done. In the optimization scenario 2 with a liquid injection flowrate of 440 GPM and an air injection flow rate of 1100 scfm based on GLRWgraph analysis, the condition of "Poor Cutting Transport" condition was caused ata depth of 4191 ftMD obtained kinetic energy of 2.6 lb / cuft less than theminimum kinetic energy of 3 lb / cuft so that the drill cuttings at a depth of 4191ftMD are not raised above the surface and will accumulate. Optimizationscenarios 3 and 4 by increasing the air injection flow rate by 1100-1250 scfm andliquid injection flow rate by 720 GPM from the GLRW graph analysis results show the condition of "Good Working Area". This condition shows precisely theoptimization scenario chosen, this is evidenced by the creation of underbalancedconditions (static and dynamic annular pressure has been lower than rockformation pressure) and kinetic energy in optimization scenario 3 of 14.75 lb /cubf and optimization scenario 4 of 15.36 lb / cubf is greater than the minimumkinetic energy of 3 lb / cuft so that the removal of drill cuttings from the bottom ofthe drill hole can be lifted up to the surface optimally. In the optimization scenario5 with an air injection flow rate of 1500 scfm and a 720 GPM liquid injectionflow rate, GLRW graph analysis shows the condition of "Collapse" of thiscondition indicates that the large injection flow rate given will make the formationof the borehole formation collapse when drilling takes place.At a depth of 4606 ftMD using a liquid injection flow rate of 700 GPMand an air injection rate of 1000 scfm, Total Loss Circulation occurred.Optimization is done using 4 optimization scenarios. Scenario 1 is the actualdrilling data that has been carried out. In the optimization scenario 2, 3, 4 and 5 byincreasing the air injection flow rate by 1100-1500 scfm and the liquid injectionflow rate by 680-800 GPM. Optimization scenarios 2, 3, 4 and 5 show that goodunderbalanced conditions have been created and there is no loss of circulation ofthe "Good Working Area" on the GLRW chart. The calculation results of thekinetic energy depth of 4606 ftMD in the optimization scenario 2 is 13.2 lb / cuft,optimization scenario 3 is 14.9 lb / cuft, optimization scenario 4 is 16.3 lb / cuftand optimization optimization scenario is 18.9 lb / cuft. The results of thecalculation of kinetic energy is greater than the minimum kinetic energy of 3 lb /cuft so that the removal of the drill powder can be lifted up to the surfaceoptimally. In the optimization scenario 5 point optimization scenario is locatedclose to the condition "Collapse" so that the optimization scenario 5 is notrecommended in the optimization selection at a depth of 4606 ftMD.