Abstract: A method of determining the presence of hydrocarbon-filled natural fractures with sufficient lateral extension in a well in which stimulation by hydraulic fracturing is intended to be carried out. Following perforation of an interval, a fluid is pumped into the well and a pressure response trace is collected. The fluid is pumped at a rate which is lower than the pump rate for the intended frac job and the data collection rate is higher than the data collection rate for the intended frac job. Characteristic elements are identified in the pressure response trace whose value and combination indicate the presence or absence of hydrocarbon-filled natural fractures with sufficient lateral extension in the interval.

Abstract: A method of increasing hydrocarbon production by hydraulic fracturing in shale formations by using an a-seismic process of cyclic injection of cooled aqueous fluid at a low rate with shut-in periods to induce tensile failure in the formation and create a fracture network of high and very high conductivity fractures with sufficient lateral extension in a completed well. A final single cycle of aqueous fluid and proppant is used in which the volume of proppant has been determined from measurements of the downhole pressure. Further fracture parameters being: volume of the very high conductivity fractures, lateral extension of the very high conductivity fractures, surface of the very high conductivity fractures and estimation of the global fracture network shape are determined and analysed after each injection cycle.