Application of Hybrid Silicate as a Film-Forming Agent in High-Temperature Water-Based Drilling Fluids

Ying Li; Maosen Wang; Xianfeng Tan; Yinghui An; Huanan Liu; Ke Gao; Mingyi Guo

doi:10.1021/acsomega.1c02725

Application of Hybrid Silicate as a Film-Forming Agent in High-Temperature Water-Based Drilling Fluids

ACS Omega. 2021 Jul 26;6(31):20577-20589. doi: 10.1021/acsomega.1c02725. eCollection 2021 Aug 10.

Authors

Ying Li¹, Maosen Wang¹, Xianfeng Tan^{2

3}, Yinghui An¹, Huanan Liu⁴, Ke Gao¹, Mingyi Guo¹

Affiliations

¹ College of Construction Engineering, Jilin University, Changchun 130021, China.
² Faculty of Engineering, China University of Geosciences, Wuhan 430074, China.
³ Lunan Geo-Engineering Exploration Institute, Shandong Province, Jining 253015, China.
⁴ School of Prospecting and Surveying, Changchun Institute of Technology, Changchun 130012, China.

Abstract

Effective control of shale swelling and lost circulation using drilling fluid is considered the dominant strategy for maintaining borehole stability, especially drilling operations in deep oil and gas wells. In this work, a hybrid silicate that contains lithium silicate and potassium methyl silicate (PMS) was employed as a film-forming additive to reduce shale hydration and filtration loss in the high-temperature drilling fluid. Scanning electron microscopy (SEM) results revealed that a dense quartz crystal film coating on the shale can be formed in a hybrid silicate solution when the temperature exceeds 150 °C. The in situ-formed film on the shale surface with a thickness of 60-130 μm was composed of fibrous crystalline silica. Furthermore, the aqueous hybrid silicate exhibited enhanced hydration inhibition ability by preventing water invasion of the formation. Aqueous hybrid silicate with a concentration of 0.5-3 wt % lithium silicate and 0.1-0.2 mol/L PMS was first chosen to obtain the optimum concentration according to the hydration inhibition ability and film formation characteristics. The hybrid silicate was added into a drilling fluid formulation applicable in high-pressure and high-temperature conditions, and the rheological characteristics and filtration properties were investigated. The results confirmed that drilling fluids with the addition of hybrid silicate can mitigate variation of viscosity and yield point before and after aging at 180 and 220 °C. Besides, the filtration behavior was also improved by adding hybrid silicate into the drilling fluid. A lower filtration loss was observed at the concentration of 1.0 wt % lithium silicate and 0.2 mol/L potassium methyl silicate, which showed 63 and 50% HPHT fluid loss reduction for unweighted and weighted formulations at 205 °C and 3.5 MPa, respectively. In addition, the drilling fluid featured stable rheological and filtration properties and excellent shale hydration inhibition characteristics when exposed to high temperatures, making it a promising candidate for drilling in deep oil and gas wells.