Drilling techniques in exploration of oil and gas, adopted around the world, involves optimization of controllable variable during drilling operations. The drilling optimization procedures, involves better understanding of operational as well as equipment parameter on ROP (Rate of Penetration). The objective of optimization is to estimate a reasonable rate of penetration to reduce drilling time, cost and consequently early discovery of oil and gas.

In this case study, optimum penetration rate of Kohat/Potohar region, where drilling is extremely problematic due to subsurface conditions specifically for muree and Kuldana formations, are obtained by two methods-mathematical & comparative. Comparative method uses cost per foot, specefic energy and rae of penetration with respect to depth comparison charts and give optimum drilling parameters while for mathematical model, BYM penetration model has been preferred to adress several drilling factors by using past drilling data of wells of Kohat region. Important parameters like ECD, Pore pressure gradient, evaluation of tooth wear and jet impact forces calculation are made for examining inter-relationship of controllable factors. At last a statistical approach of multiple regression analysis are made by using Matlab.Results of Matlab are further employed in determination of optimized parameters. Outcome from analysis are used to compare results with comparative approach and obtain optimum values of drilling rate, RPM and WOB for respective formations. Based on these approaches, potential risks can be mitigated which help to boost drilling performance and provides effective parameters for drilling of future wells in Kohat region.

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