Realizing Enhanced Drilling Efficiency by Implementing Air Hammer Technology in Extremely Hard Abrasive Rock Formations

摘要

Many techniques have been attempted to improve penetration rates in hard rock drilling. Problems faced while drilling hard and abrasive rock formations are not only restricted to poor penetration rate but also the Non Productive Time associated with Drill String Failures, Wellbore Instabilities, Higher consumption of Drill Bits, Excessive Trips, Out of Gauge Wellbores, Stuck Pipe and Fluid Losses due to Fractures etc. This Frontier area under study has rocks of Proterozoic age, which have Uniaxial Compressive Strength ranging from 10000-30000psi. Field evidence in this frontier onland area has established the benefits of implementing Air Hammer Drilling Technology by achieving spectacular Rate of Penetration, better Hole Geometry and eventually lower Cost per Meter. This is a technique in which the more common circulating fluids, water or mud, are replaced by highly compressible Air/Mist/Foam & Gas (preferably Nitrogen). This technology has been established as the most efficient method to drill through surface hard rock especially when sufficient Weight on Bit (WOB) is an issue. Air Hammer Drilling has demonstrated the most efficient way to drill these rock formations and shown the improvement in penetration rates in the order of 200%-500%. Huge savings on surface holes of 9 wells have been achieved with Air Drilling application as compared to Conventional Drilling in offset well#1. This also corresponds to lesser number of drilling days which in turn mean money saved. The enhancement in the rate of penetration in drilling hard rock formations is an opportunity to shrink overall well costs and Non Productive Time (NPT). So this technology is unquestionably ideal for drilling trouble free and cost effective hard top surface sections. The paper will also open vistas for planning future wells having Surface Hole Sections with very high compressive strengths for improving the penetration rate and reducing the overall drilling cost of well.