In-place Foam Fracturing Fluid System

During the fracturing for low pressure and low permeability gas reservoirs, there are some main problems in conventional hydroxypropylguar - organic boron cross-linking system: Firstly, the water-lock damage to low pressure and low permeability gas formations by filter liquor; Secondly, the reason for alkali-sensitive damage in alkali-sensitive reservoirs is that conventional hydroxypropylguar - organic boron cross-linking fracturing fluids were cross-linked under alkaline environment, while the permeability of reservoirs is reduced greatly; Thirdly, the formation pressure is low, and the energy of flow back is not enough, at present, the main measure in oil fields is "injecting with liquid nitrogen", but this technique increased the cost of fracturing, making great troubles in operating, and leaving the liquid nitrogen also is a big problem.According to problems above about the fracturing for low pressure and low permeability gas reservoirs, it is necessary to study a new kind of fracturing fluid, it can not only product a large quantity of gas to increase the pressure and flowback feature; but also be cross-linked under tart environment to avoid alkali-sensitive damage; at the same time, it has the good point which are low filtration, low residue, high sand-carrying capability and can lower the damage made by fracturing fluid to cores greatly.This paper introduces thermogenesis into the guar gel fracturing fluid to become in-situ simu-foam fracturing fluid system, this kind of fracturing fluid can produce self-generate gas, cross-link under tart environment, have simu-foam structure, and unify them, it also has good ability of flowback, lower the filtration greatly, so induces the damage to reservoir made by fracturing fluid.Under the well-understanding of geological specially characterize of low pressure and low permeability reservoirs and analyzing the damage of low pressure and low permeability reservoirs, the main work of the text including following:(1) The screening out and estimation of self-generate gas system under the geologic condition: aim at the character and engineering demand of the low pressure and low permeability reservoirs, sieve the self-generate gas system under the geologic condition, proceed the systematically research on the generation gas amount, generation gas speed and the effect factor, select the kind, dose and the catalytic condition of generation gas agent.(2) The research- manufacture and estimation of new model thickening agent: aim at the character of the low pressure and low permeability reservoirs and reaction condition of the self- generate gas system, research and manufacture new model thickening agent, make sure that match the self-generate gas system, and do some estimation to the new model thickening agent.(3) The screening out and estimation of the additives of the in-situ simu-foam fracturing fluid system: aim at the character of the low pressure and low permeability reservoirs, sieve the additives of the cross-linking agent, gel broken agent, pH regulator agent, clay stabilizer, aided flowing back additive, corrosion control agent match the self-generate gas...