Rock Bit Optimization Technology Used in Igneous Rock Strata in Malang Depression of Tuha Oilfield

The carboniferous reservoirs in Malang Depression of Tuha Oilfield were mainly composed of igneous rocks with low drillability and strong abrasion.It had high requirements on rock bits.In allusion to 7 major technical indexes including bit cost,drilling footage,penetration rate,pure drilling time,weight on bit,drilling velocity and drilling fluid density.Principal component analysis was used to optimize and evaluate the used bit types.In combination with the rock drillability grade,HJ637,HF637,HF637G bits are selected for igneous rock reservoir drilling.Field application shows that the penetration rate is boosted by 22.2%.