A thermally induced β-cyclodextrin/benzene derivatives gel and the potential application in fracturing temporary plugging

Four β-cyclodextrin (β-CD)/benzene derivatives gels were developed as temporary plugging agent for different formation temperature ranges. The gel was composed of β-CD as the host, benzene derivatives as the guest and 1,2-propylene glycol as solvent. The systems undergo a "sol-gel" phase transition when the temperature rises. By adding different benzene derivatives (toluene/phenol/benzoic acid) in the system, the gel temperature could be controlled between 70 and 130 ℃. And the gel turns into a solution again upon further heating. Further, FT-IR, X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to analyze the micromorphology and phase transformation mechanism of the gel. The results confirmed that the gelling process of the four systems mainly depends on non-covalent bond action. Furthermore, the degradation rate and the plugging and permeability recovery rate were tested. The results showed that the degradation rate of the four systems were finally greater than 98%, the plugging rate was greater than 85%, and permeability recovery value was more than 98%, which can meet the requirements of fracturing temporary plugging with the formation temperature of 70 ∼ 130 ℃.