skip to content

Laboratory for Scientific Computing

 
Schematic of drilling operation

In order to create stable and safe oil wells, cement is used to protect the drill casing. Due to the challenging environments found in wells, it is useful to simulate the cementing operation. This requires accurate simulation of multiple complex and viscous incompressible fluids over a wide range of length scales. A modelling tool has been developed to perform these simulations, using an existing Adaptive Mesh Refinement framework.

The challenge

When drilling an oil well, cement provides a barrier to unwanted hydrocarbon flow, isolates permeable zones in the foundation, and supports and protects the casing. Many challenges exist when displacing cement into position, and numerical simulation is often used to predict flow patterns and fluid interfaces. Due to challenging well conditions and non-Newtonian rheological models used to describe the nature of the fluids, highly accurate numerical solutions are difficult to obtain in an efficient manner. This constitutes a significant challenge for ensuring safe and efficient analysis of a vital drilling operation. Often the only option available is to use oversimplified models which are not accurate or precise enough to be applied in ever challenging well conditions, such as high pressure, high temperature, extended reach wells and wells with tight rock formation tolerances. More detailed simulations can be performed by commercial software, but, as a rule, they offer a generic platform for all kinds of flow which is not sufficiently tailored to the operational requirements of cementing and the timescales to perform usable simulations are far too long to meet operational time constraints.

The research

We address the aforementioned issues by building a new cementing simulation tool. In addition to revisiting the underlying mathematical formulation of the physical problem, the key challenges associated with the project are modelling of viscoplastic rheology; performing simulations in a low-speed flow regime; treatment of nontrivial, time-dependent geometries; capturing interfaces between displacing and displaced fluids accurately; and the achievement of fast run times through massive parallelisation and mesh adaptivity. The latter is necessary due to the disparate length and time scales of the problem at hand. Preliminary work in code development has focused on modelling of variable-density incompressible flow for viscoplastic fluids within a framework built for adaptive mesh refinement and massive parallelization called AMReX, developed at Lawrence Berkeley National Laboratory, California.



 

Publications

  • K. Sverdrup, N. Nikiforakis, A. Almgren: Numerical simulations of immiscible generalised Newtonian fluids. ECCM-ECFD Conference Proceedings, 2018.
  • K. Sverdrup, N. Nikiforakis, A. Almgren: Highly parallelisable simulations of time-dependent viscoplastic fluid flow with structured adaptive mesh refinement. Physics of Fluids, 2018.
  • K. Sverdrup, A. Almgren, N. Nikiforakis: An embedded boundary approach for efficient simulations of generalised Newtonian fluids in non-trivial domains. In preparation, 2019.