A New Comprehensive Hydraulic Fracturing Technology to Minimize Formation Damage in Low Permeability Reservoirs

Abstract

Abstract In low permeability reservoirs, hydraulic fracturing treatments are usually utilized to evaluate reserve quality in exploration wells or make producing wells economically. As we all know that the formation damage during a hydraulic fracturing job may reduce a well's production rate in a large degree, so, a new comprehensive hydraulic fracturing technology aiming to minimize formation damage is put forward in the paper. Compared with the past common hydraulic fracturing technology, it mainly contains 7 sections:1)the optimization of PAD volume;2)the optimization of polymer concentration used in fracturing fluid;3)the technology of high sand concentration and the optimized proppant pumping schedule(more than 10 stages) correspondingly;4)the optimization of pumping rate and increasing pumping rate step by step during last stages of proppant pumping;5)fracturing fluid additives selection and the optimization of breaker schedule;6)forced closure technique is performed at the moment of shut-in;7)the control of bottomhole flowing pressure during flow back of fracturing fluid and production stage in the case of stress sensitivity which is usually a main characteristic of low permeability reservoirs. After the study, four exploration wells belonged to a certain oil field of petrochina are hydraulically fractured using above technology system. The well A1 and A2 get an idea post-fracturing rate of 9.12m3/d and 11.44m3/d respectively, compared with 1.94 m3/d of their adjacent well A7. what's more, a new geology reserve has been determined up to 5,000,000 tons as a result of above 2 successfully fracturing treatment wells. Similarly, the well A5 get a rate of 16.82 m3/d compared with 0.78 m3/d of its adjacent well A6, and the well A3 get 30.57 m3/d compared with 25.7 m3/d of its adjacent well A4. Overall, the comprehensive hydraulic fracturing technology put forward in the paper has a great significance in evaluating reserve quality, sometimes it may even be used to find an undiscovered reserve. On the other hand, it may also increase economic benefit of a producing well in low permeability reservoirs.