ABSTRACT

Polar oil and gas reserves are abundant and have important strategic value for oil and gas exploration and development. However, the natural environment in the high and cold regions of the polar region is harsh, and the existing low-temperature cementing systems develop very slowly below 0 °C, or even do not undergo hydration reactions, which is difficult to meet the needs of polar cementing work. In order to solve this problem, this paper has developed an ultra-low temperature early strength cementing material with rapid development by combining different cementing materials and adjusting their proportions and has studied its complementary additives and optimized the cement slurry formula. Finally, a set of ultra-low temperature early strength cement slurry system has been formed, which has adjustable thickening time, good rheology and normal thickening line shape. The strength reached 3.7 MPa at −5 °C for 24 h, meeting the technical requirements of cement slurry in polar alpine region.

INTRODUCTION

The Arctic region has 900×108 bbl of undiscovered oil and more than 47×1012 m3 of undiscovered natural gas, accounting for 13 % and 30 % of the world's unproven oil and natural gas reserves, respectively (Zhou, 2017). However, the natural environment in the polar region is harsh. Most of the oil and gas reservoirs are distributed in the permafrost region, where the formation ice content is up to 80 %. In the field cementing process, conventional cement slurry system is insufficient to meet the needs of polar cementing work (Xu, 2019; Zhang, 2020).

At present, the strength of oil well cement develops slowly under low temperature conditions (especially below 0 °C) and cannot adapt to the polar cementing operation. The ultra-low temperature cementing material is the key factor for the cement slurry to adapt to the low temperature cementing in the polar region.

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