The particular foamed cement formulation by acid for oil/gas wells cementing jobs: an experimental approach

Abstract

Foamed cements are coarse dispersions of a base cement slurry, a gas (usually air or nitrogen), a foaming surfactant and other materials A new foamed cement, designed for oil/gas well liners and casing cementing jobs, was formulated. Ultra-lightweight cement pastes (such as foamed cements) are appropriate for formation damage prevention in fractured and depleted reservoirs. In this work, foamed cements were prepared at high shear rates using a foaming agent primarily composed of sodium lauryl ether sulfate, boric acid and a retarder (JR120). This formulation was called FBJ. The samples were subjected to tests for density, rheology, free water, settling, thickening time, compressive strength (CS), fluid loss, porosity and permeability, along with microscopic photography and computed tomography scanning. Compared with other drilling cements, the FBJ was found to have one of the lowest densities (1200 kg/m3), a CS of 8963 kPa and a thickening time of about 3 h. The rheology of the FBJ improved under high-pressure and high-temperature conditions. Examinations of the set FBJ also showed that the pores were not interconnected, the porosity of the FBJ was greater than 73% and 28% of the FBJ was matrix. Moreover, cement permeameter tests indicated that the permeability of the FBJ was just 0.0109 mD (1 mD ≈ 1  × 10−12 cm2). All of these results show that the formulated FBJ has acceptable properties for oil/gas wells cementing applications.