Abstract
Abstract In this experimental study, two different cementitious materials including (i) a class of expansive cement that is currently used for P&A operations, and (ii) a non-cement-based naturally occurring rock, known as geopolymer are selected to examine the hydraulic bond strength and shear bond strength. Clean machined steel and rusty corroded steel were selected to represent the casing. The test samples were cured at 90 °C, which is considered as bottom-hole static temperature (BHST), and under elevated pressure of 17.2 MPa for one week. The hydraulic sealability of the barrier materials tested up to 3.4 MPa of differential pressure. The results indicated that additives used in slurry preparation have an impact on the hydraulic sealability of the material. Additionally, the rusty corroded streel provided a better hydraulic sealability comparing to the clean machined steel for the same cementitious material. The shear bond strength test was performed by running the push-out test. According to the present test observations, no correlation was found between the shear bond and hydraulic bond strength of different barrier materials. The geopolymer showed the lowest shear bond strength, while it provided the highest hydraulic sealability.
Highlights
In drilling operation and well construction, a cementitious slurry is pumped into the wellbore and placed behind the casing
The Ordinary Portland cement (OPC)-based system is brittle in nature and may show a weak performance at downhole condition by forming radial cracks when it is subjected to an excessive load [3,4,5]
Researchers and technology providers continuously attempt to improve the quality of set cement and the cementing operation by either new cementing techniques or introducing alternative cementitious materials for the situations that OPC has limitations [6,7]
Summary
In drilling operation and well construction, a cementitious slurry is pumped into the wellbore and placed behind the casing. The cyclic change in pressure and temperature over the lifespan of the well implies a lot of compaction and tension of the cementitious barrier materials. Such condition requires sufficient flexible cement system with high tensile strength to Young’s modulus and compressive strength to Young’s modulus ratios. Researchers and technology providers continuously attempt to improve the quality of set cement and the cementing operation by either new cementing techniques or introducing alternative cementitious materials for the situations that OPC has limitations [6,7]
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