Cement placement in severe doglegs and its impact on well integrity: A numerical assessment

Hao Yu, Arash Dahi Taleghani, Zhanghua Lian

Research output: Contribution to conferencePaperpeer-review

3 Scopus citations


Horizontal drilling with hydraulic fracturing technology has played a critical role in shale revolution, while the integrity of the drilled wells have been a concern in some parts of the world. In the dogleg section of these directional wells, stiff straight casing strings should deform to fit the borehole trajectory, which lead to its complicated contact geometry in the hole. The severity of dogleg and casing properties may make the formed annulus space so complex that prevent full placement of the cement around the casing, which can endanger well integrity in some occasions. We have developed a three-dimensional large deformation finite element model (FEM) to simulate the dynamics of running a casing string into the dogleg section. The deformation of casing in presence and absence of friction reducer additives have been calculated by this model to determine the annulus geometry supposed to be cemented. Then, we utilized a computational fluid dynamics (CFD) model to simulate cement displacement. Different cement rheology, pumping rates and casing specifications are considered into the developed framework to investigate the impact of incomplete or non-symmetric cement placements on fluid migration or casing failure during the next stages of field development such as hydraulic fracturing and production. The obtained numerical results show the complicated contact geometry of the casing and borehole at the dogleg, which may worsen in casing strings with small thickness and large curvature doglegs. Results show that the magnitude of the stress developed along the casing can considerably increase due to friction. Complicated geometry of the annulus induced by casing deformation makes mud displacement by cement in the dogleg difficult. Continuous drilling mud pockets are formed due to the cement reverse flow.

Original languageEnglish (US)
StatePublished - 2018
EventSPE/AAPG/SEG Unconventional Resources Technology Conference 2018, URTC 2018 - Houston, United States
Duration: Jul 23 2018Jul 25 2018


OtherSPE/AAPG/SEG Unconventional Resources Technology Conference 2018, URTC 2018
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment


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