Experimental Study on Igneous Rock Abrasiveness

Igneous oil and gas reservoirs are hot spots in well drilling. But, drilling them is extremely difficult due to the highly abrasive nature of the rocks. So, drillability and abrasiveness of igneous rocks must form the basis of drilling optimizition design. The problem is, however, that igneous rock abrasiveness testing methods have not yet been formulated. So, in this paper, we describe the development of a rock abrasiveness measuring device used to test the abrasiveness of igneous rock samples with different lithologies. We also examined the relationship between the abrasiveness and their uniaxial compressive strength of igneous rocks, and mineral content. We found that under the conditions of rock sample rotary speed of 8 r/min, WOB of 800 N, and drill bit rotary speed of 198 r/min, the weight loss of grinding standard part of per unit volume broken rock within a certain time can be used as abrasiveness index to distinguish the abrasiveness of igneous rocks with different lithologies. The abrasiveness of igneous rocks shows a good power function relationship between uniaxial compressive strength and equivalent quartz content. The research results show that the abrasiveness prediction model based on the uniaxial compressive strength of igneous rock can predict the igneous rock abrasiveness very well and provide a theoretical basis for optimizing the drilling design for wells in igneous reservoirs.