Novel Expandable Cement System for Prevention of Sustained Casing Pressure and Minimization of Lost Circulation

Abstract

Sustained casing pressure (SCP) is a common issue in the oil and gas industry. There were several solutions applied to contain it either by mechanical means or by injecting high-performing cement slurries. There are some limitations associated with these solutions such as volume loss, mechanical failures, limited expansion, exact spotting, and material deterioration with time. In this study, a novel expandable cement system contains a novel silicate aqueous alkali alumino silicate (AAAS) and zinc (Zn) metal slurry, and class G cement is introduced as an expandable solution to prevent annulus flow between the casing and formation. The silicate-based admixture reacts with the Zn metal slurry to generate hydrogen gas that results in the expansion of the cement slurry. The reaction and expansion can be controlled by optimizing the quantities of silicate systems and metal slurry. The expansive properties of the silicate system can be utilized to formulate a cement mix for plugging off the annulus flow. Cement slurries with different percentages such as 3, 5, and 8% by weight of water (BWOW) of AAAS silicate and Zn metal slurry were prepared and tested for their expansion. Several laboratory tests such as expansion, consistency, viscosity, and unconfined compressive strength were performed to assess the percentage expansion. The expansion was tested in the plastic tube as well as in expansion molds. The cement slurries were cured at 50 °C temperature in a water bath. It was observed that metal slurry upon reaction with AAAS silicate resulted in cement expansion by several percentages. The cement expansion was reduced by 16% at 8% BWOW concentration of AAAS silicate as compared to the expansion gained at 3% BWOW concentration. Further, the temperature triggers the expansion of cement slurry. The consistency and viscosity were impacted by the addition of AAAS and metal slurry. The application of expandable slurry can help in preventing the annulus flow and eliminating the safety issues associated with SCP. The expansion solution can be applied in loss circulation zones.

Preparation and Performance of Microencapsulated Sealing Material for Coal Mine Gas Drainage

“…Li et al 39 developed a new inorganic borehole sealing material with high density and expandability, offering good adhesion to overcome the disadvantages of traditional sealing material, such as poor pore sealing, considerable air leakage, and low extraction concentration. Murtaza et al 40 studied a novel expandable cement system, and the G-grade cement as a swellable solution to prevent annular flow between the casing and the formation was introduced, with the thought that the swellable solution could be applied in the leakage zone. Wang et al 41 investigated the air leakage mechanism, discussed the effects of time, active support pressure, and drainage pressure on air leakage, and then proposed a double-expansive (DE) material as the sealant.…”