Computational fluid dynamics study of lost circulation phenomenon in naturally fractured reservoirs

Abstract

Natural Fractures play an important role in oil and gas industry because of their capability of providing pathway for hydrocarbon flow in geologic formations. Fractures connect pores together, therefore, enhance the oil and gas production from a reservoir by increasing the permeability. On the other hand, presence of fractures makes a drilling operation challenging because drilling fluid got lost into them, which in turn increases the drilling cost. The aim of this paper is to carry out a Computational Fluid Dynamics (CFD) study of drilling fluid flow in natural fractures to improve comprehensive understanding of the flow in fractured media. The study was carried out by creating a three-dimensional steady state CFD model using Ansys (Fluent). For simplicity and validation purpose, the model defines fracture as an empty space between two circular disks. Moreover, it is considered that single phase fluid is flowing through fractures. By solving the flow equations in the model, correlations to determine the fracture width and invasion radius have been developed for specific mud rheological properties. Prior to onset of drilling and at the end of lost circulation, similar correlations can be developed by knowing rheological properties of drilling fluid which will be very much helpful to take an instantaneous action during lost circulation i.e. determining lost circulation material (LCM) particle size and also be useful in the well development stage to determine the damaged area to be treated.