致密气藏超长水平段低摩阻水泥浆固井技术

Low Friction Cement Slurry Cementing Technology in Ultra-long Horizontal Section of Tight Gas Reservoir

长庆油田致密气藏超长水平段固井,存在裸眼段长、环空间隙小、流动摩阻压耗大和施工压力高,易发生漏失造成固井质量差和后期环空带压等一系列复杂问题,严重影响后续开采和单井产量。为此开发了低摩阻低密度水泥浆和低摩阻高强韧性水泥浆,来提高水泥浆的流动性,降低流动摩阻压耗、施工压力和漏失风险。低摩阻低密度水泥浆采用耐压性能优良的空心玻璃微珠做为主要减轻材料,提高体系的耐压性能,入井后保持较高的结构圆整度,有效降低摩阻压耗。低摩阻高强韧性水泥浆在常规高强韧性水泥浆的基础上,引入实心玻璃微珠和复合高效增强剂,在保证水泥石力学性能的基础上,提高了水泥浆的流动性能,降低了水泥浆的摩阻压耗。室内模拟实验表明,低摩阻低密度水泥浆较常规低密度水泥浆范宁摩阻系数由0.0593降低至0.0295,降低50.25%;低摩阻高强韧性水泥浆较常规高强韧性水泥浆摩阻系数由0.070降低至0.0414,降低40.86%。前期先导性试验应用表明,使用低摩阻水泥浆摩阻压耗降低明显,有效降低施工压力。采用低摩阻水泥浆并进行低摩阻高强韧性水泥浆分段梯度携砂设计,助力致密气藏5256 m超长水平段固井施工顺利完成,固井质量合格,为长庆致密气藏超长水平段固井提供有力的技术支撑。

Cementing of ultra-long horizontal section of Sulige Tight Gas Reservoir in Changqing Oilfield has long open-hole sections, small annulus gaps, high flow friction and pressure loss, high construction pressure, and easy leakage, resulting in poor cementing quality and later annular pressure. A series of complex issues have seriously affected subsequent mining and single well production. Therefore, low friction low density cement slurry and low friction high strength and toughness cement slurry are developed to improve the fluidity of cement slurry and reduce the flow friction pressure consumption, and reduce the construction pressure and the risk of leakage.Low-friction low-density cement slurry adopts hollow glass beads with good pressure resistance as the main reducing material to improve the pressure resistance of the system, and maintain a higher roundness of the structure after entering the well, effectively reducing the friction and pressure loss.Low-friction high-strength and toughness cement slurry is based on conventional cement slurry, introducing solid glass microspheres and composite high-efficiency reinforcing agents to improve the fluidity of the cement slurry and reduce friction pressure loss on the basis of ensuring the mechanical properties of the cement stone.The experimental results show that the Fanning friction coefficient of low-friction and pressure-resistant hollow glass microbead cement slurry is reduced from 0.0593 to 0.0295, which is 50.25% lower than that of conventional low-density cement slurry. The friction coefficient of low friction high strength toughness cement slurry is reduced from 0.07 to 0.0414, 40.86% lower than the conventional high strength toughness cement slurry. The preliminary pilot test shows that the low friction cement slurry can reduce the friction pressure and the construction pressure effectively. The adoption of low-friction cement slurry and the segmented gradient sand carrying design of low-friction high-strength and high-toughness cement slurry helped the cement construction of 5256 m ultralong horizontal section in tight gas reservoir to be successfully completed, and the cementing quality was qualified, providing strong technical support for the ultra-long horizontal section in Changqing tight gas reservoir.