Investigation and Modelling of Slurry Performance of Ordinary Portland Cement Blended with Metakaolin and Sawdust-ash for Oil Well Cementing

Abstract

Oil well Cementing involves placing a special compound of cement grout formulated from constituents with relative weight
to that of cement in the annulus between the casing and the adjacent rock formation to strongly join the casing to the
formation. One of the challenges usually encountered during deep drilling, especially in a High-Pressure-High
Temperature (HPHT) environment, is the sustenance of wellbore integrity in terms of serviceability over long operation
period. In this study, the viability of optimizing slurry performance using Sawdust Ash (SDA) and Metakaolin (MK) as a
blend to Ordinary Portland Cement (OPC) allows combinations and percentages replacement of the Ordinary Portland
Cement (OPC) with Metakaolin for 10%,12.5% and, 15% while Sawdust ash at 0%, 5% 10% making up for 10 to 25% of
both pozzolan incorporation to modify the properties of ordinary Portland cement, and providing an efficient, cheaper oil
well-cementing material. Materials for the study were synthesized and characterized based on physical, chemical, and
pozzolanic properties. The slurry and mechanical properties were studied based on the mix formulation generated from
design of experiment (DOE) using two domains three interactive factors (23) level factorial model following the
specifications of (API SPEC 10A and 10B). Metakaolin blend with OPC alone at 15% was detrimental to rheology
performance but incorporating Sawdust Ash up to 10% with Metakaolin at both low and high blend (10% and 15%)
improved the slurry and mechanical performance; yielding an optimal blend sample of (75%OPC, 15%MK, 10%SDA).