A study of influencing factors on fracture initiation pressure of cemented sliding sleeve fracturing

• The linear spring model was used to describe the first interface.
• The effect of valve azimuth on circumferential stress distribution was analyzed.
• The angle of ports was discussed.
• Put forward some measures to minimize fracture initial pressure.

As a new well completion technology of multiple-layer fracturing, the main concept of cemented sliding sleeve fracturing (CSSF) is to place sliding sleeve valves in the casing string and complete the well with normal cementing operations. The potential high fracture initiation pressure is a key issue to overcome with this technique. This paper mainly presents the theoretical and experimental studies on the influencing factors of CSSF on fracture initiation pressure, hoop stress distribution in the cement and formation near the wellbore was predicted with finite element analysis (FEA): 1. the linear spring element was used to simulate the cementing strength of the first interface between casing and cement; 2. the finite element model of CSSF was established under the condition of in-situ stress; 3. laboratory tests of the CSSF was conducted with the full-scale fracturing simulation experimental system. The results indicate that by improving the cementation strength of the first interface and reducing the ports orientation angle can reduce the fracture initiation pressure. Additionally, the length and the number of ports are the main influencing factors of the fracture initiation pressure. Increased the length and the number of ports can achieve the aim of reducing the fracture initiation pressure. The valve with slots turns out to be a better choice compared to the valve with fins.