According to a recent study (Trudel et al. 2019), in Northern British Columbia, around 28.5% of wells have been reported to have a surface casing vent flow. Well leakage primarily occurs when there is an inadequate cement bond in the annulus, between the casing and the open hole. The leakage rates of the wells varied by the operators, while one operator had a significantly lower leakage rate compared to the rest. A case study is conducted to analyze how a robust cementing practice can lead to a better cement quality, consequently leading to a lower leakage rate.A few common cementing practices analyzed in the study are: I) cementing in stages versus continuous single-stage cementing II) the effect of pumping excess cement on the displacement efficiency III) the effect of centralizer placement on the displacement efficiencyFrom the selected groups of wells exhibiting leakage and without, field data are gathered including the wellbore schematic, fluid properties, and centralizer specifications. The cement displacement is simulated for the whole length of the well using the two-dimensional gap averaged model of annular displacement flow by Maleki &amp; Frigaard (2017), while the centralizer placement and the resulting eccentricity of the casing are simulated with the stiff-string method as described in Gorokhova et al. (2014). The simulation results are correlated with the cement bond log for each well. In the paper, the effects of different cementing practices on displacement efficiency are presented, highlighting the fact that excess cement pumping can gradually decrease the residual mud channel in the annulus and increase the displacement efficiency. In addition. the comparison of the cementing parameters that result in wells exhibiting leakage and without is presented.

Comparison of Common Cementing Practices Affecting Cement Displacement Efficiency in Northern British Columbia

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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