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

Abstract

The goal of the present work is to numerically simulate the effects of wellbore orientation on fracture initiation pressure (FIP). These simulations support the study of FIP sensitivity to arbitrary wellbore position and finding the orientations that correspond to the lowest FIP. A 3D numerical model of the fracture initiation from a perforated wellbore in linear elastic rock is used to model FIP. This model is based on the boundary element method (BEM) and maximum tensile stress (MTS) criterion. The data used 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. Since the equations and correlations are not empirical and not field-specific, the model is applicable to a wide range of conditions. Some practical applications of the study include selection of the optimum perforated intervals intended for fracturing stimulation in deviated or almost horizontal wellbores where different parts of lateral sections are not exactly aligned with principal stresses. Drilling wells in a particular direction to the principal stresses for the specific reason to reduce the FIP has not been tested to date and is a subject to further discussion.• Stronger completions • Revised (reduced) safety margins for the pressure during fracturing • Use of heavy brine for formation breakdown • Different (so called hybrid) fracturing schedules

Initiation and propagation of cracks in problems of petrothermal energy

“…The simulation is carried out for the reservoir parameters of Depth Khulud field in West Lower Amin formation located at the depth 5000 m [10,11].…”

“…The formation lies at a great depth (up to 5 km) and characterized by high compressive stresses (100-180 MPa) with big contrast. The pressure predicted by the 3D fracture propagation model has been compared with initiation pressure calculated for the same parameters [10,11].…”

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

“…A catalog of parameters has been derived from the existing mechanical earth model and used as an input data set in the model (Briner et al 2015b). Wellbore and perforation tunnel dimensions were fixed into a single set of parameters.…”

“…Rock stress state equations, along with BEM, FIP, and fracture initiation criteria theoretical background are defined in greater depth by Alekseenko et al (2012a) and Briner et al (2015b).…”

“…They included two geomechanics projects: one based on a model fully coupled with the fluid flow, described by Briner et al (2015c), and the other one utilizing a maximum tensile stress (MTS) criterion model as highlighted by Briner et al (2015aBriner et al ( , 2015b. The current work was performed using the latter model.…”