Adjei Stephen, Elkatatny Salaheldin, Abdelfattah Ahmed Mohsen
Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Department of Architecture, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2020 Nov 30;5(49):32094-32101. doi: 10.1021/acsomega.0c05174. eCollection 2020 Dec 15.
The use of lightweight pozzolanic aggregates as partial replacement of cement results in low-density cement systems. Such systems ensure effective zonal isolation in zones where low equivalent circulating densities are required. However, low pozzolanic materials, such as fly ash and ground granulated blast furnace slag (GGBFS), have poor early-age strength development and long set times, especially when used in high volume, that is, exceeding 50% by weight of cement. The objective of this study is to develop a lightweight oil- and gas-well cement recipe with enhanced properties employing the synergism that exist among fly ash, GGBFS, and silica fume. The experimental work was per laboratory procedure outlined by American Petroleum Institute. Portland class G cement and the aluminosilicate materials were admixed in water to form a 13.5 ppg slurry. Chemical admixtures were used to facilitate the dissolution of reactive components in the pozzolanic materials and the hydration process. The experimental investigations were done at 150 F and an ambient pressure of 1500 psi. The newly developed lightweight recipe exhibited excellent rheological and mechanical properties, having a wait-on-cement time for about 4 h and a 24 h sonic strength of 3116 psi, at 150 F and 1500 psi. The thickening time was approximately 4 h (70 Bc). This slurry will be ideal in zones that would require a low hydrostatic slurry column and rapid gel strength development.
使用轻质火山灰质集料部分替代水泥可形成低密度水泥体系。此类体系能在需要低当量循环密度的区域确保有效的层间封隔。然而，低活性火山灰质材料，如粉煤灰和粒化高炉矿渣（GGBFS），早期强度发展较差且凝结时间长，尤其是在大量使用时，即超过水泥重量的50%时。本研究的目的是利用粉煤灰、GGBFS和硅灰之间存在的协同作用，开发一种性能增强的轻质油气井水泥配方。实验工作按照美国石油学会概述的实验室程序进行。将G级波特兰水泥和铝硅酸盐材料在水中混合，形成13.5磅/加仑的水泥浆。使用化学外加剂促进火山灰质材料中活性成分的溶解和水化过程。实验研究在150°F和1500 psi的环境压力下进行。新开发的轻质配方表现出优异的流变性能和力学性能，在150°F和1500 psi条件下，其候凝时间约为4小时，24小时声速强度为3116 psi。稠化时间约为4小时（70 Bc）。这种水泥浆对于需要低静水泥浆柱和快速形成胶凝强度的区域将是理想的。
