Modelling Well Inflow Potential in Three Dimensions Using Computational Fluid Dynamics

Abstract

Abstract Conventional well inflow modeling fails to capture the complexity of flow in to wells from asymmetric near wellbore permeability distribution. In order to simulate flow in to horizontal wells with varying degrees of damage along the well and around the circumference a complex numerical model is required. Computational fluid dynamics enables fluid flow in to the well to be modeled. Along a horizontal well the magnitude and depth of mud cake, filtrate invasion and formation damage will vary. Longer exposure times at the heel of a well and lower drawdown at the toe will lead to different formation damage, clean-up and inflow patterns along the well. In addition, gravity can have a profound effect on damage distribution at the base, middle and top of the well. Thicker mud cakes will tend to develop at the base of the well and whilst there may be more erosion on the low side, this will only serve to compound the damage by leading to deeper mud invasion. Inevitably, formation damage will have an asymmetric distribution along and around the well. Asymmetric models of fluid flow in to horizontal wells have been created to reflect the damage heterogeneity. Results of the models have shown that even in homogenous reservoirs, the vast majority of inflow in to the well is derived from the high side of the heel of the well. Modeling shows the potential impact of consistent chemical clean-up and of inflow control along the horizontal well. By fully capturing the magnitude and impact of damage in conventional wells using computational fluid dynamics, the value of well drilling and completion options such as underbalance drilling and hydraulic fracturing can be evaluated. This paper presents the first use of complex three dimensional computational fluid dynamic models to predict and mitigate against asymmetric formation damage in horizontal wells.