Technical Research Of CO₂Foam Fracturing Technology

Fracturing has been developed rapidly and used widely as a main measures which can beused to increase production. CO₂foam fracturing fluid is a series of new fracturing fluid, whichis developed on the basis of common fracturing fluid. It has the characteristics of good stability,high viscosity, good sand carrying function, high low fluid loss, low cleanup ability and lowdamage.In this article, it is been included that CO₂foam fracturing fluid’s soaking mechanism andit’s rheological characteristics, and the increase production mechanism of CO₂foam fracturingfluid is also researched through the investigation of CO₂foam fracturing fluid ‘s physics andfiltration characteristics.In this article, it is been completed that the addition agent system of CO₂foam fracturingfluid optimize though the tests of laboratory and working site during we make up CO₂foamfracturing fluid. selecting FL-36as foam agent is not only because FL-36has the chrematisticsof good foaming and good soaking, but also because FL-36has low adsorptive with formationlithoplate; We choose domestic hydroxypropyl guar as steady foam agent of foam fracturingfluid; and potassium chloride as clay inhibitor of foam fracturing fluid whose concentration isdepend on reservoir clay relative content; and the technique that persulfate accompany withcapsule deemulsifier is been used in gel breaker system; First succeed create AC-8acidic crosslinking agent which resolving with water can cross link with multi-vegetable gum densifier. Wechoose high-grade DL-8as cleanup additive for the oil reservoir, and to the gas reservoir thepremier selection is DL-10.It has developed a variety of new fracturing fluid which could apply in different conditionslike different reservoirs or construction requirements: low-temperature small-scale neutral CO₂foam fracturing fluid series, mid-temperature small-scale weak alkaline CO₂foam fracturingfluid series; medium-high temperature crosslinking CO₂foam fracturing fluid series. It built aseries of test methods and had been proved that this kind of fracturing fluid is foaming easily andhas high foam stability, good rheological and and carrying functions, low fluid loss and rapid gelbreaking function. And it had proved that the adsorption characteristics to cores are inaccordance with the power-law model. The fluid is viscoelastic fluid with yield stress, Its acidiceffect of core damage is also low. In a word, CO₂foam fracturing fluid is a high quality, lowdamage fracturing fluid system, and has broad application prospects and good promotionalvalue.