THE INFLUENCE OF THE NEW TECHNOLOGY OF FIXED SURFACE PERFORATION ON CASING STRENGTH¹⁾

The surface perforating process in unconventional reservoirs can effectively reduce the cracking pressure of hydraulic fractures and increase the drainage area near the well-bore. The influence of the technology on the casing strength is an important research issue. Based on the theory of the fluid - solid coupling , a stress-coupling model of the formation-cement-perforation casing is established. With the model being reduced to a bare casing to be compared with the API standards, the effectiveness of the model is tested, and it is found that the constraints of the strata under the casing pressure can withstand an increased internal pressure of 1.48\sim2.16 times. On this basis, the relations of the casing size, the perforation diameter and the perforation phase angle with the casing pressure bearing capacity are obtained. The results show that when the diameter of the casing is smaller, the thickness of the casing is thicker. Calculations show that the bearing capacity of the casing is higher when the azimuth angle of the spiral perforation is 45^\circ and the angle between the fixed plane perforations is 30^\circ, the pressure bearing capacity of the casing is higher. With the same parameters, the perforating process of the fixed perforation is slightly lower than that of the casing caused by the spiral perforation.