Abstract
This paper presents an experimental investigation on geopolymer cement formulations for enhancing oil-well integrity. Fresh slurry properties, mixability, density, free-water, and rheology were determined for possible field applications. The compressive strength and expansion characteristics were studied for the durability and integrity of the well system. Mix formulations complied with the requirements of API RP 10B-2. All formulations showed homogeneous mixability, rheological properties, the plastic viscosity (PV), and yield point (YP) were increased from 48 cP to 104 cP and 3.8 N/m2 12.4 N/m2, respectively, with the increase of the dosage of elastomeric type expandable material (R additive). The highest compressive strength of 15 MPa was obtained using 10% R additive in the mix-blend after 60 days of curing. Increasing the amount of R additive provides the optimum strength at 10.4 MPa with design 2, 3, and 4. The linear expansion was increased to about 1% at 60 days with 20% and 25% of the R additive dosage. Design of Experiment (DOE) was performed for setting three factors: curing time (A), curing temperature (B), and concentration of R additive (C) to optimize the linear expansion (response).
Highlights
Cementing in oil wells is a primary process that creates a cement sheath to build and maintain zonal isolation, supports the casing, and protects it against external corrosion
This study aimed to develop the geopolymer binder formulation using fly ash as the base material for enhancing the well system’s integrity
Note: All ingredients are the percentage by weight of the mixture—Solid Blend (SB) was fixed to 65%, and Alkaline Solution was fixed to 35% Fly ash, slag, and R additives are % by weight of SB Expandable Material is Styrene-butadiene rubber-R
Summary
Cementing in oil wells is a primary process that creates a cement sheath to build and maintain zonal isolation, supports the casing, and protects it against external corrosion. The mixing procedure described by API RP10B-2 [1] recommends shearing of the cement system for 15 s at 4000 rpm or for 35 s at 12,000 rpm in a Warring blender It usually applies 5.9 KJ/kg of energy to the cement slurry. By adding a small dosage of a suitable type of dispersant, the cement system’s rheological properties can be controlled to the desired level. The experimental analysis included investigating the cement slurry properties in the fresh and hardened state, such as density, mixability, rheology, free water, static stability, fluid loss, compressive strength, and cement expansion. To control such properties, effects of the addition of chemical admixtures were included in the scope.
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