Strength Satety Analysis For Perforated Casing In High Temperature And High Pressure Deep Well

Outer pressure of the casing in HPHT (high pressure and high temperature) deep well isincreased with high ground stress and non-uniform in-situ stress. Then there is irsk for casing.Perforation completed, the holes influence the consistency of perforated casing. Ifunconventional cracks happen, the working life of the perforated casing will be decreased andthe safety will be affected. So the strength safety for perforated casing in HPHT deep wellwas analyzed in this paperThe perforated casing strength is decreased with the stress concentration near theperforations. The perforation parameters and stress concentration factor was analyzed byusing finite element analysis sotfware. There aer otfen cracks near the perforations. As aresult of cracks, the burst strength of perforated casing is decreased. The three-dimensionalmodel of perforated casing with hole edge cracks was established. The relationship betweencracks length and burst strength was analyzed by using ifnite element analysis.Atfer the drilling completion, the oil well may be tested and be put into production.Perforated casing is exerted non-uniform in-situ stress. Cosidering formation stress, finiteelement model was established by using ANSYS. In fact, need to take perforated casing-cement rocks-bonding rocks as a system. Acidiifcation was used to increase production atfercompletion. Considering the temperature loads, the hot structure coupling of perforatedcasing under acidification condition was analyzed in this paperBased on the above conclusions，allowable worn depth of casing and reasonableperofrated parameters under the non-uniform stress were deirved that can provide referenceof deep well casing string strength design.