Impact of Wellbore Completion Type on Fracture Initiation Pressure in Maximum Tensile Stress Criterion Model for Tight Gas Field in the Sultanate of Oman

Abstract

Abstract A detailed geomechanical study has been performed for a tight field in the Sultanate of Oman. This study included computation of fracture initiation pressure (FIP) applying the boundary element method (BEM) and maximal tensile stress (MTS) criterion using 3D numerical modeling. The goal of the present work is to numerically simulate the effects of wellbore completion type on FIP with arbitrary wellbore position and finding the conditions that correspond to the lowest FIP. The model is based on the BEM. Since the equations and correlations are not empirical and not field-specific, the model is applicable to a wide range of conditions. The data used for this project were from different zones and blocks of a tight gas-bearing sandstone field in the Sultanate of Oman. The amount and quality of available data allowed comprehensive model development. The model is built for the four blocks of the main field, but can be applied to the other blocks and fields. Two horizontal wells parallel to each other 400 m apart have been recently completed with different completion types, which allowed reasonable comparison of actual and modeled breakdown pressures for open and cased holes. Two vertical wells in different blocks have been completed with openhole sections with subsequent placement of hydraulic fractures. Discussion on the effectiveness of this completion type over the typically used cased and cemented completions in regards to breakdown pressure and overall well efficiency is provided. Some practical applications of the study include input for the decision on the completion type in vertical and horizontal wells.