Casing structural integrity and failure modes in a range of well types - A review

Abstract

This paper focus on factors attributing to casing failure, their failure mechanism and the resulting failure mode. The casing is a critical component in a well and the main mechanical structural barrier element that provide conduits and avenue for oil and gas production over the well lifecycle and beyond. The casings are normally subjected to material degradation, varying local loads, induced stresses during stimulation, natural fractures, slip and shear during their installation and operation leading to different kinds of casing failure modes. The review paper also covers recent developments in casing integrity assessment techniques and their respective limitations.The taxonomy of the major causes and cases of casing failure in different well types is covered. In addition, an overview of casing trend utilisation and failure mix by grades is provided. The trend of casing utilisation in different wells examined show deep-water and shale gas horizontal wells employing higher tensile grades (P110 & Q125) due to their characteristics. Additionally, this review presents casing failure mixed by grades, with P110 recording the highest failure cases owing to its stiffness, high application in injection wells, shale gas, deep-water and high temperature and high temperature (HPHT) wells with high failure probability. A summary of existing tools used for the assessment of well integrity issues and their respective limitations is provided and conclusions drawn.

Hydraulic Fracturing‐Induced Seismicity

“…Hydraulic communication could be slightly restricted in extent, only causing nearby aseismic slip that subsequently triggers more distant seismic slip (Eyre, Eaton, Garagash, et al, 2019). Anecdotal evidence of well bore shearing and deformation could be related to this mechanism (Mohammed et al, 2019). However, asserting or refuting this conjecture will require pad‐scale in situ measurements of strain and displacement, complemented by lab experiments using pressures above the fracture gradient (Gischig et al, 2019).…”

Risk assessment of corroded casing based on analytic hierarchy process and fuzzy comprehensive evaluation

“…There are various types of corrosion, some are very common and can be seen in day-to-day life, while the others are rarely seen except in very specific combinations of material and environments. As one of the most common corrosion forms on casing, pitting corrosion seriously affects the strength and service life of casing (Cerit 2019;Mohammed et al 2019). Therefore, based on the corrosion test results and previous works (Guo et al 2015;Li et al 2017;Sun et al 2017), in this paper, the corroded casing model is established with a shallow spherical shape.…”

“…To simplify the calculation reasonably, the operation pressure in casing equals wellhead pressure plus hydrostatic pressure (20 MPa). The steel grade of casing is N80, whose yield strength is 552 MPa, diameter is 177.8 mm, thickness is 10.36 mm, Young's modulus is 206 GPa, Poisson ratio is 0.3, and density is 7800 kg/m 3 (Mohammed et al 2019;Wen et al 2010;Han et al 2014). The calculation conditions of pitting corrosion are given in Table 3.…”

Probabilistic assessment of API casing strength in serviceability limit state

“…Additional torsion and bending effects, not assessed in this work, can stand out in some scenarios. Mohammed et al (2019) provide an overview on the structural integrity aspects and failure modes of casing systems, in different well types.…”