无氯低温早强剂及其在浅层水平井固井中的应用

Chloride-free and Low Temperature Early Strength Agent and the Application in Cementing of Shallow Horizontal Well

摘要:

基于水平井在低渗油藏开发方面的巨大优势，采用水平井已成为开发延长油田东部浅层油藏稳产增产的一项重要技术。由于该区域水平井具有井内温度低、垂深浅、后期压裂易产生水平缝等特点，要求水泥环有高的强度和密封性。通过室内试验筛选出一种新型的无氯复合型早强剂M59S，与水泥中的铁离子、铝离子形成促凝早强的复合络合物，可大幅缩短低温下水泥水化时间，提高水泥石早期强度，辅之以其他外加剂形成了一套低温早强水泥浆体系。经室内性能评价，该体系稠化过渡时间短，浆体稳定性好，析水为0，失水量＜40 mL/30 min，流变性能良好，20 ℃常压养护水泥石48 h抗压强度＞20 MPa，能够满足低温浅层水平井固井的施工及技术要求。该低温早强水泥浆体系在延长东部浅层水平井中应用，固井效果良好。

Abstract:

Based on the great advantages in low permeability reservoir development, horizontal well has been an important part of the development of shallow reservoir in Yanchang oilfield. For the characteristics of low temperature, shallow vertical depth and the horizontal seams creating in post fracture in this region, high strength and good sealing are required for the cement sheath. Through laboratory tests, a new type of chlorine-free composite M59S was selected, which was put with iron ion and aluminum ion in cement to form an early strength complex to greatly shorten the cement hydration time at low temperatures and improve the early strength of cement stone. A set of low temperature early strength slurry system is formed assisting by other additives. By the laboratory performance evaluation, this slurry system has a short thickening transition time, good stability and rheological characteristic, zero water precipitation and water loss less than 40mL. The compressive strength of cement stone reached more than 20MPa with ordinary pressure curing in the condition of 20℃ for 48h. The construction requirements of low temperature horizontal well cementation were satisfied. This low temperature early strength slurry system has good cementing effects in its application for shallow horizontal wells in the eastern part of Yanchang oilfield.