Numerical Computation of a Circulating Drilling Fluid

Abstract

Deeply buried reservoirs are one of the main options to extend the oil & gas reserves and to keep on satisfying the growing need of energy. In this context, the ability to determine the temperature profile of the mud while drilling is a crucial issue from the design of a well to the control of the rheological properties of the mud. The present work is a study of the heat transfers occurring between the mud and the formation while circulating in a well. Firstly, a model, based on an empirical Nusselt law, was built and implemented in a numerical software. Secondly, we compared the results found with the numerical software with field data, which was made possible thanks to the collaboration of Total. Introduction The estimation of the "peak oil" relies on the knowledge of the identified and recoverable oil & gas reserves. Currently, the producing countries still estimate their reserve to contain enough oil & gas for another 40 years of production. Several ways exist to keep this estimation and postpone the "peak oil", among which is the production of deeply buried reservoirs. This is a challenge the producing oil companies will have to take up. Nevertheless, the deeper the drilling, the bigger the pressure and thermal constraints are. High pressure and high temperature mandate the development of new technologies such as drilling fluid which is able to keep its rheological properties. The mud has to maintain its efficiency in:–removing the cuttings from the well–stabilizing the borehole to prevent any collapse of the well–cooling down, cleaning and lubricating the bit–controlling the fluid loss–suspending the cuttings in case of a pump stoppage In this context, it is important to be able to assess the temperature of the drilling mud and to make predictive calculations of the mud temperature while drilling. This information would be priceless for the mud engineer, mud logger, drilling engineer, etc., to help to choose the right composition of mud at the right time (E. Gao et al. 1998 and B. Corre et al. 1984), especially when the temperature reaches the threshold when MWD tools do not work anymore. That's the reason why we worked on building a model which correctly represents the heat exchange phenomena between the mud and its environment. Ultimately, the goal is to be able to accurately predict the temperature profile of the mud all along the well with potential applications in real time monitoring or well design. State of the Art Showing the level of interest in the topic, there have been a number of papers which have been written about the mud temperature when circulating in a well.

Multiphase Flow Modeling of Surface Equipment in Managed Pressure Drilling Operations

“…A general dynamic model for multiphase flows was developed by Peterson et al [2] that could be utilized in a real time drilling environment. Peysson et al [4] formulated an advanced thermal model and conducted numerical computations for drilling operations for HPHT situations. A detailed CFD study for multiphase flow is presented by Chinello et al [12] for annular flow.…”