ENHANCEMENT OF THE COMPLETION EFFICIENCY OF PERFORATION TUNNELS IN PETROLEUM WELLS

摘要

The objective of perforating is to maximize well productivity by establishing good connectivity between the wellbore and formation. The conventional method of perforation - perforation by shooting (PS) cannot achieve expected wellbore productivity due to a region of reduced permeability around the perforation tunnel. In this study, it has been established that permeability is decreased in the range of 30%-75% due to the implementation of the PS technique compared to the openhole completion. As a result, a new perforation technique - perforation by drilling (PD) has been proposed in this paper. To simulate a perforated completion, cylindrical sand samples (0.0572 m OD) consolidated with cement with varying porosity were prepared. These samples were perforated (0.0136 m ID) by the PS, PD and Casting techniques. Perforations created by the Casting techniques are considered the ideal, openhole perforation tunnel. Fluid flow rates and differential pressure across the perforated samples were measured for three different types of samples using "Geotechnical Digital System" triaxial testing set-up. Fluid flow rates with changing differential pressure and finally pressure build-up data with time indicates the PD technique can achieve better wellbore productivity compared to the PS technique. Results indicate that at 100 kPa differential pressure the PS, PD and Casting techniques can achieve 0.20 mL/s, 0.65 mL/s and 1.00 mL/s fluid flow rates respectively across a sample.