Accurate Inflow Profile Prediction of Horizontal Wells Using a Newly Developed Coupled Reservoir and Wellbore Flow Equations

Abstract

Despite their widespread use, horizontal wells continue to underperform compared to our expectations. This is mainly due to lack of our understanding and ability to predict accurate inflow profile as a result of pressure drop along the wellbore. Standalone inflow equations do not calculate accurate inflow profile. In order to get the best performance from a horizontal well, a uniform inflow profile achievement is important. This cannot be addressed unless the inflow profile is quantified.In this work we describe coupling of some analytical reservoir flow models with wellbore flow models for predicting accurate inflow profile of long horizontal wells. S. D. Joshi and Babu-Odeh inflow equation options have been implemented in this coupled solution. Continuity equations are used to calculate pressure drop in the wellbore. A coupling algorithm has been proposed which converges reasonably quickly giving accurate picture of the inflow profile. Results obtained from this work have been compared with some published work which is encouraging. Also results of a few case studies have been discussed which show the effect of a few completion/ fluid parameters on pressure & flux profile of these (horizontal) wells. The ultimate goal of this work is to come up with a stand-alone computer program which will be able to model not only the inflow performance relationship of these wells, but also will be able to come up with detailed inflow profiles along the completed interval of horizontal wells for various completion options with varying parameters. IntroductionHorizontal wells are increasingly becoming more important means of developing oil and gas fields, driven by need for reducing number of wellheads and industry's quest for means to increase volumetric sweep for thin reservoirs and/or reservoirs with viscous crude. However, horizontal wells production performance and reservoir sweep efficiency have not been as good as what they have been touted for. One of the reasons for this mis-match has been our inability to achieve a uniform inflow profile along long completion intervals, therefore suffering from coning and uneven reservoir sweep. This is turn is partly caused by design engineers difficulty in predicting inflow profile under various wellbore and near wellbore reservoir parameters.Inflow equations and normal reservoir simulators do not calculate accurate inflow profile of long completion intervals; they rather take a simplistic approach of a single point wellbore/reservoir interface. However, literature describes a few advanced well modelling coupled with reservoir flow models.Penmatcha and Aziz (1998) proposed a reservoir/wellbore coupling method using an analytical 3-D reservoir model and a semi-analytical wellbore model. While this is a quick way to predict inflow profile (pressure and flow), it does not incorporate reservoir and near wellbore rock property variations.Ozkan et al. (1999) described another semi-analytical approach of reservoir/wellbore coupling using equations and correlations. Vicente and Sarica (200...

Pressure Transient Behavior of Horizontal Well with Time-Dependent Fracture Conductivity in Tight Oil Reservoirs

“…Many previous studies considered the horizontal wellbore as an infinite wellbore; however, it has been shown that wellbore pressure drop exists in the production [53,54]. We investigated the effect of horizontal wellbore pressure drop on pressure behavior as shown in Figure 21, which shows that the effect of considering wellbore pressure drop is negligible.…”