Interference Analysis of Shale Gas Horizontal Wells Considering Magnetic Azimuth Correction

Abstract

ABSTRACT: In order to analyze the interference risk of shale gas horizontal wells, a model is established to analyze the interference domain in shale gas horizontal wells. With this model, the borehole uncertainty and the fracturing interference domain can be coupled reasonably. To reduce borehole uncertainty and further reduce the interference domain, the multi-station analysis (MSA) is employed to correct the magnetic azimuth of the shale gas horizontal wells. The interference domain of a shale gas horizontal well was studied. With magnetic azimuth correction, the semimajor axis of ellipse of borehole uncertainty (EOU) decreases from 23.10 m to 19.48 m (lateral) at the measure depth of 5671.60 m. And the edge length of the interference domain decreases from 206.20 m to 198.96 m. The results show that, magnetic azimuth correction based on MSA can reduce the interference domain and interference risk. And this analysis method can provide a theoretical reference for avoiding interference in shale gas horizontal wells. 1. INTRODUCTION In order to achieve long-term stable production of shale gas fields, infill and adjustment wells are deployed to reduce the well spacing in shale gas fields. With the well spacing reduced, the overall benefit is improved. But it also leads to earlier well to well interference. Interference will result in many drillings technical problems, such as complex and frequent overflows and leakages. Therefore, interference analysis has always been the focus and hot issue in shale gas development. The interference domain is determined by fracturing interference domain and the borehole uncertainty. Numerical simulation method is usually employed to calculate the fracturing interference distance. A discrete fracture model is proposed for multi-scale flow in large-scale fractured tight oil reservoirs (Fang et al., 2017). On the basis of this model, a method for analyzing the well spacing of shale gas horizontal wells based on the integration of geology, engineering and economy is established (Yong et al., 2020). Numerical simulation shows that the cross section of the fracturing interference field in the direction of wellbore extension can be approximated as an ellipse ( Liu et al., 2018; Zhou et al., 2021). Actual drilling data of Fuling shale gas field in the Sichuan shows that the semi-major axes of the ellipse can be approximated to 80m and 50m (Gu et al., 2020; Liu, 2020).