Alkali-Resistant and pH-Sensitive Water Absorbent Self-Healing Materials Suitable for Oil Well Cement

Abstract

Oil well cement microcracks cause formation fluid channeling, compromising oil and gas extraction safety. Superabsorbent polymer (SAP) can absorb water and swell to prevent fluid channeling. In this study, an alkali-resistant and pH-sensitive SAP was prepared based on the properties of oil well cement slurry. The preparation of the SAP was optimized, including monomer ratio, cross-linking agent dosage, and monomer concentration. The pH sensitivity and alkali resistance of the SAP were evaluated. The results revealed that the SAP exhibited good pH sensitivity, with the absorption rate in water being 2.18 times that of cement slurry filtrate (CSF) at 95 °C. Furthermore, the FTIR spectrum showed that the SAP had a stable molecular structure. The secondary absorption rate in water of the SAP after soaking in CSF was not different from the original absorption rate. Styrene–butadiene latex (SBL) can be used to adjust the SAP’s absorption rate. The SAP’s absorption rate had a good exponential functional relationship with SBL dosage. The SBL dosage can be determined by the functional relationships to prepare a SAP with the required properties.