A method of controlling the direction of propagation of injection fractures in permeable formations

摘要

The invention relates to a method of controlling the production of oil or gas from a formation ( 1 ) comprising that a first and second drilled production well ( 105, 110 ) are formed next to each other that extend essentially horizontally, that, at the drilled production wells, a further drilled well ( 115 ) is formed that extends between the first and the second drilled production well ( 105, 110 ), that the production of oil or gas is initiated, and that, while oil or gas is being produced, a liquid is conveyed to said further drilled well ( 115 ) and out into the formation ( 1 ) for a first period of time TSUB1/SUB. The invention is characterised in that the pore pressure of the formation is influenced during the period TSUB1 /SUBwith the object of subsequently controlling the formation of fractures along a drilled well, typically across large distances in the reservoir. Such influence is accomplished partly by production in adjacent wells, partly by injection at low rate without fracturing in the well in which the fracture is to originate. Injection at low rate presupposes that an at least approximated determination is performed of the maximally allowable injection rate ISUBmax /SUBfor the period TSUB1 /SUBin order to avoid fracturing ruptures in said further drilled well ( 115 ) when liquid is supplied by the injection rate I for the liquid supplied to the further drilled well being kept below said maximally allowable injection rate ISUBmax /SUBfor said first period of time TSUB1 /SUBwhen the relation sigma'SUBhole,min/SUB=sigma'SUBh /SUBhas been complied with.