With the increased importance of achieving zonal isolation in the shallow riserless sections of deepwater wells, it has become critical to understand the results of the cement placement. Riserless cementing job design has historically been a static process largely independent of the drilling parameters, particularly in these large-diameter boreholes.
Variable borehole shape and quality affects the wellbore cleaning, wellbore stability while drilling and the smooth operation of the casing run. Borehole quality can also compromise cement placement efficiency and mud displacement mechanics. It has become increasingly important to develop a greater understanding of the impact that borehole size and the identification of borehole degradation have in cementing design and placement, to increase the likelihood of achieving zonal isolation objectives.
Caliper tools provide an explicit method that uses physical measurements to evaluate not only wellbore quality but also formation characteristics. Caliper measurement is used to optimize the cementing design by adjusting key parameters such as cement slurry volumes, centralization, pre-flush volumes, and fluids pump rate, so that effective mud removal and optimized cement placement are achieved.
A review the current practices of field measurements and observations to understand and detect cement returns in the deepwater drilling environment and also the applications and key learnings from the engineering workflow led to new development of tools to improve the understanding of the cement volumes required for these particular top hole sections.