Microstructural analysis of strain-resistant cement designed for well construction

Introduction. The efficiency of oil and gas well construction depends largely on the stage of casing cementing and is completed by checking the quality of its fixing by various methods, most often by geophysical methods. The necessity of highquality cementing and ensuring the quality of technical conditions in the subsequent years of oil and gas well operation is the main task. Materials and methods. Microstructural features of cement slurries and cement stone were analyzed with advance methods. The essential technological properties were developed according to the requirements of GOST 1581-96 and API standards (API spec.10B). Class G cement (PCT-I-G) was used for all formulations. Polypropylene fiber and expanding additive СMA were used to increase impact resistance and to ensure tight contact with the confining surfaces of the obtained plugging stone. Microstructural analysis of the obtained cement stones and developed plugging mortars was carried out by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results and discussion. The results of the study showed that the expanding additive in tandem with polypropylene fiber works effectively to ensure the integrity of the cement ring. Conclusion. Microstructural analysis of plugging stones showed a tight bond between polypropylene fiber and cement stone at a concentration of – 0.25%. The expanding additive is fully hydrated and the obtained cement stone has no expansion cracks at 7 days. The developed grouts with a water-cement ratio of 0.44 showed high compressive strength.