Application of Thixotropic Early-setting Expanding Cement Slurry in Cementing Liner String in Block TAMBOCOCHA, Ecuador

Block Tambococha, as an important part of the famous "ITT" project, is located near the center of the Amazon tropical rainforest in Ecuador. The major reservoir NAPOM₁ is a high porosity high permeability reservoir with buried depth of about 1 500 m. Poor liner cementing job quality has been met previously. To resolve this problem, the composition of the cement slurry was modified by changing the density of lead slurry and the consistency of the cement slurry, reducing the concentration of filter loss reducers and latex, and adding early strength thixotropic additives into the slurry. The cement slurry with modified composition had its thickening time, initial and final gelling time slightly shortened, while the gel strength was increased, and the gel strength of the cement slurry developed faster than the gel strength of the cement slurry prior to modification. Eight times/wells of application of this improved cement slurry gave 100% success rate of cementing job, more than 95% of the liner cementing job had high quality. The use of the cement slurry with modified composition resolved the problems encountered during cementing operation, such as active in-situ oil and water in the reservoirs and shallow oil bearing zones, providing a sound technical support to subsequent liner cementing operation.