一种新型的低成本低密度水泥浆体系

A New Low Cost and Low Density Cement Slurry System

南海油田的深水浅层疏松砂岩地层温度低,地质疏松,常伴有浅层气,导致该地层会有水泥浆抗压强度低、二界面胶结质量差等生产技术问题。现场为保证安全施工,通常采用高性能材料来提高固井质量,而使固井成本太高。因此针对这些问题,基于紧密堆积理论以及大量实验研究复配出一种低成本低密度混材DHC-20,并优选其他外加剂的种类,优化其配比,成功建立了一套适应于深水浅层疏松砂岩地层的低成本低密度水泥浆体系。该水泥浆体系密度范围在1.4~1.7g/cm^3,满足沉降稳定性要求,流动性好,24h抗压强度大于12MPa,48h抗压强度大于14MPa,并且比用低密度水泥浆体系成本降低20%,实现了降本增效。

The deepwater shallow unconsolidated sandstone formation in Nanhai Oilfield is characterized by low formation temperature and loose formation and shallow gas,which results in low compressive strength of cement slurry and poor quality of binder bonding.In order to ensure the safety on site,it is necessary to use the high-performance admixtures to improve the well cementing quality,which leads to a high cost.Due to the above is-sues,a low cost and low density blend DHC-20 has been selected through a large number of experiments according to the compact packing theory;then the selection and quantity of other admixtures are optimized;finally,a low cost and low density cement slurry system is established which is suit-able for the deepwater shallow unconsolidated sandstone formation.The new cement slurry system has a density ranging from 1.4g/cm^3 to 1.7g/cm^3 and satisfies the sedimentation stability requirement with a good mobility;its compressive strength is greater than 12MPa after 24h,and greater than 14MPa after 48h;the cost also reduces by 20% compared with that of in-use cement slurry system,therefore the cost decrease and benefit increase is achieved.