Combination of turbodrill and impregnated diamond bit to enhance ROP in drilling of wellsin piedmont zone, Tarim Basin

Piedmont zone in the Tarim Basin is one of key zones for hydrocarbon exploration and development in the Tarim Oilfield. With consideration to high abrasiveness and high drillability of the piedmont zone, low footage per bit, significant bit consumption, low ROP, high drilling costs and other challenges, the combination of turbodrill and impregnated diamond bit was introduced. It was used in 2 wells (well Bozi-102 and well Keshen-2-1-14) drilled in the piedmont zone. According to the drilling data, in Well Bozi-102, the combined assembly achieved a total footage of 704 m, with drilling time of 407.5 h and average ROP of 1.73 m/h, and in Well Keshen-2-1-14, the combined assembly achieved a total footage of 146.8 m, with drilling time of 71.75 h and average ROP of 2.05 m/h. Compared with PDC bits and roller bits deployed in identical formation in neighboring wells, the proposed assembly can enhance ROP by 2-4 times, average footage per bit by 3-10 times, and average drilling time by 1.7-2.5 times. Relevant test results show that the combination of turbodrill and impregnated diamond bit can effectively enhance ROP in drilling of wells in piedmont zone, the Tarim Basin, as a powerful technical support.