Use of a Transient Cuttings Transport Model in the Planning, Monitoring and Post Analysis of Complex Drilling Operations in the North Sea

Abstract

Inadequate hole cleaning during a drilling operation may result in immediate problems such as excessive torque or pack-off situations, or it can lead to delayed problems such as while running in hole with a casing/liner or a completion string in a leftover cuttings bed. It is therefore desirable to provide quantitative information about hole cleaning conditions: at the planning stage, while drilling or when investigating incidents. Because the ability to transport cuttings particles varies with their position in the borehole and the current drilling parameters, hole cleaning modelling is a history-dependent problem. The precise modelling of the movement of solid particles during a drilling operation gives the possibility to estimate whether they are in suspension in the drilling fluid, settling on the low side or being eroded from a cuttings bed. These estimations may be confirmed through the change of the active volume or by the increase of downhole pressure, when PWD (Pressure While Drilling) measurements are available. A transient cuttings transport model has been used for planning and monitoring an ERD (Extended Reach Drilling) well drilled in the North Sea. The model has been used to compare the expected performance of different mud systems on both hydraulic and mechanical limits that could be expected prior to drilling. For another challenging drilling operation, the model has been used to post analyze the sequence of actions that led to problems while running in hole with a liner. Here also, the observations tended to confirm the predictions made by the hole cleaning model. Furthermore, an active use of such an advanced hole cleaning model may help determine the time required for circulation procedures prior to pull out of hole. This can help reduce the flat time associated with circulation procedures and at the same time decrease the duration by which the hole stays open thus reducing the risk of hole instability.

Study of the cuttings transport in stable foam drilling

“…Based on the basic equation (Ozbayoglu et al, 2002(Ozbayoglu et al, , 2003Avila et al, 2004;Mirhaj et al, 2007;Taghipour et al, 2014;Cayeux et al, 2016), and considering the above basic assumed conditions, the cuttings transport models for various hole sections are obtained based on the mass and momentum conservation.…”