I n order to obtain oil from the earth’s subsurface, a path is needed for theoil to flow up to the surface through it. Therefore, drilling operation is implementedto make a hole that connects the subsurface or reservoir and the surface which iscalled an oil well. Drilling is done by creating a hole through layers ofhomogeneous and heterogenous rocks to reach the depth of the oil’s location whichis the reservoir. To do that, drill bit is used to drill the well. Drilling operationrequires huge amount of capital, for instance rig rent fee, drilling tools, andprofessionals involved in the drilling operation. With that being said, time is greatlyprecious and an efficient drilling operation is what companies expect to avoidunexpected expenses caused by drilling problems or inefficient drilling operation.Some aspects that need attention on the efficiency matter is the hydraulicsystem and the correct choice of drill bit. Drill bit performance will affect the rateof penetration of the drilling operation. Hydraulic system is important because italso affects the rate of penetration which will directly result in either fast or slowdrilling operation. Faster drilling operation results in less operational expenses,but safety is the main priority, therefore calculation is needed to be donebeforehand in order to obtain the optimum pumping flow rate.Calculations for hydraulic system will be done using BHHP and BHImethod. Choosing the right drill bit is also crucial, in order to be able to decidewhich drill bit will be used, calculations and analysis from the hydraulic systemwill be used to determine the drill bit choice. Choosing the drill bit could be doneby using a few methods such as specific energy method, cost per foot, and bitdullness. Those methods will be used to choose the right drill bit, so the drillingoperation could be done in the most efficient way and least capital consuming.This thesis with the title “Hydraulic Optimization and Bit PerformanceEvaluation Using Drilling SpeciFefic Energy Method for 12.5” Hole in “X” Wellon “Y” Field is intended to be used for future reference on hydraulic systemcalculations which is needed to determine the right choice of drill bit and also tobe used by the company for future drilling operations.