MULTIFACTORIAL STATISTICAL ANALYSIS OF FACTORS INFLUENCING THE EFFICIENCY OF ACID FRACTURING

Abstract

Background Highly productive terrigenous strata of Western Bashkortostan, which contain residual oil reserves, have been largely developed, and they reduce the rate of oil production, increase water cut in well production, which leads to an increase in the oil production cost and contributes to an increase in the stock of wells with difficult operating conditions. All these factors make it necessary to carry out geological and technical measures at the wells in order to restore the production wells capabilities. The statistical analysis use in assessing the reasons for the decline in the success of geological and technical measures allows us to establish the level of technological processes influence on the acid fracturing effectiveness, and thereby contribute to its optimization, as well as to predict its effectiveness. Aims and Objectives Determination of the following statistical dependencies: o the value of additionally produced as a result of acid fracturing of oil from the total accumulated production in the well; o the effect time of the total well time; o an increase in the productivity coefficient of the well from a number of geological, physical, and energetic characteristics of the formations and technological parameters of acid fracturing. Results As a result of the multifactorial analysis of the well and reservoir geological, technical, technological and energy parameters, affecting the acid fracturing efficiency, it was established that when selecting candidate wells, it is necessary to choose wells with pressure in the drainage zone lower than 30 % of the initial reservoir pressure. It was revealed that the optimal value of the dimensionless conductivity coefficient is 4. The salt-acid solution optimal specific consumption for the conditions of the Tournaisian stage of oil fields in Western Bashkortostan is 2.9-3.3 m3/m. The water cut of well production should not be more than 50 %, since a further increase in water cut leads to a significant reduction in the ratio of cumulative production as a result of acid fracturing to total cumulative oil production. The distance to the oil-water contact should be at least 15-20 m, since with a decrease in this distance, the ratio of production accumulated as a result of acid fracturing to the total accumulated oil production due to a possible breakthrough of water decreases.