Analysis of Efficiency of Horizontal Drilling in Low-Permeability Reservoirs at the Fields of LLC LUKOIL-Western Siberia with Oil-Based Drilling Fluids

Abstract

Abstract The rate of hard-extractive oil reserves in Western Siberia increases every year. Majority of new fields and developed objects, have low permeability reservoirs with deteriorated reservoir properties. LUKOIL-Western Siberia actively implements various technologies to improve the efficiency of hard-extractive reserves deposits development, increasing the rate of oil extraction in the company and oil cost reduction, including:horizontal well drilling with multi-zone fracturing;multilateral horizontal well drilling with 2-5 branches;new types of drilling fluids (including oil-based). This study reveals the estimation of the oil-based drilling fluids efficiency for productive formation drilling in horizontal multilateral wells. The study also gives the comparative analysis of technical and economic parameters of drilling and indicators of operation (productivity) for multilateral wells drilled in oil-based and water-based solutions, as well as horizontal wells drilled with water-based solutions, with multi-zone fracturing. Drilling fluids have least negative impact on oil and gas reservoirs characteristics; they have high temperature resistance, inertness against clays and salts, good lubricity. However, the cost of such drilling fluids is quite high, they are flammable and dangerous for environment. International and Russian experience of oil-based mud usage indicates the increase of technical and economic parameters of drilling, due to the differential sticking risk reduction, reduction of drilling loads due to the lower friction coefficient, which generally contributes to the penetration rate and commercial drilling speed. Furthermore, lack of negative effects of the hydrocarbon-based fluids on clay minerals within the collector, and least filtration leads to primary opening quality improvement. Test results for the oil-based muds at productive formation opening on the fields of LLC "LUKOIL-Western Siberia" showed a 30% penetration rate increase in experimental wells, compared to neighboring, drilled with basic water-based muds. While drilling the horizontal section with hydrocarbon-based fluids there was no unproductive time associated with drilling fluids. Average experimental multilateral well produced oil flow rate higher by 30%, compared to the results obtained in horizontal wells with multi-zone hydraulic fracturing. Average oil production rate in multilateral wells drilled with oil-based fluids was higher by 20% than that of multilateral wells drilled on standard water-based solutions.