Prediction of casing critical buckling during shale gas hydraulic fracturing

Abstract

Casing deformation during volume fracturing in shale gas horizontal wells is caused by both existing and induced stresses. These stresses jointly alter and compound the stress field around the casing leading to inefficient well stimulation as planned, lack of access into the well for recompletion, future workovers and present imminent danger of well integrity. Using two simulation scenarios, casing structural integrity was investigated in both radial and axial configurations under the mechanics of a combine system-casing, cement and formation rock. Results obtained show that time dependent rock slippage -creep during stimulation lead to an increase transverse displacement and corresponding stresses on the casing. In addition, the effect of combined loading results in significant increase in both displacements and stresses that can cause radial and axial permanent failure of the casing. This explains the lack of access in the casing during multi-stage hydraulic fracturing and future well intervention and recompletions and increased current understating of the downhole dynamics and casing structural integrity during volume fracturing.

Multi-criteria material selection for casing pipe in shale gas wells application

“…Also, based on study conducted by Jacobs (2020) and Mohammed et al (2020) established the casing to buckle at very low shear rates, hence a minimum shear strength of 13 MPa was applied to modify the selection. As a result, Fig.…”

“…Although the API standards guidelines such as API Spec 5CT, API Spec 5C2 and 5C3 have proved to be adequate reference materials for casing materials in conventional oil and gas wells but inadequate for unconventional wells such as shale gas wells (Hay and Belczewski 2003). The challenges however posed by unconventional wells are numerous and entirely different from conventional wells (Casero and Rylance 2020;Mohammed et al 2020). The study of Gouveia et al (2020) on the current search for oil and gas shows that the casing is being increasingly exposed to unconventional reservoirs, i.e.…”

An application of FEA and machine learning for the prediction and optimisation of casing buckling and deformation responses in shale gas wells in an in-situ operation

“…The numerical modelling in this study is an advancement of the previous work by Mohammed et al (2020). The objective is to predict critical displacement, von Mises stresses and the applicable safety factor in order to establish robust design for the casing as a function of hole dimeter, cement mechanical properties (Elastic modulus and Poisson's ratio), surface and downhole temperatures, slip plane angle and casing geometry.…”

“…In addition, Haghshenas et al (2017) and pointed out that casing deformation is due to imposed additional load by fracture slip and weak bedding plane through the wellbore in the process of hydraulic fracturing. The studies of Mohammed et al (2020) and Yin et al (2018) show that creep load (slippage) lead to an increase of transverse displacement and stresses on the casing.…”

Failure Analysis of Tubing Collapse in a Gas Well

“…Shokry and Elgibaly [8] developed a well design optimization through the elimination of intermediate casing string. Mohammed et al [9] investigated the structural integrity of casing under radial and axial configurations using two simulation scenarios. Zhang et al [10] proposed a new model to describe the buckling morphology of a pipe string in a 3D curved wellbore.…”