Research And Analysis Of New Multi-stage Fracturing Sleeves

A growing number of low permeability reservoir promotes the horizontal well fracturing technology developing rapidly domestic and abroad. As an important equipment of fracturing technology, fracturing sliding sleeve is developing rapidly in China. After years of development, the domestic horizontal well staged fracturing technology mainly has two technologies:the ball fracturing technology and coiled tubing with BHA technology. There is already existing intelligent sliding sleeve based on RFID. Still use a lot of foreign production in domestic oilfield fracturing sliding sleeve tool, the need to strengthen fracturing technology research of sliding sleeve is urgent.This paper analyzed sliding sleeve domestic and foreign, proposed a new ball activated fracturing sleeve. The fracturing sleeve tool can meet basic requirements of the fracturing sliding sleeve, which can be opened, closed and sealed. In addition, the tool is a combination of two types of fracturing sliding sleeve, achieve in all reservoir fracturing with the same diameter ball. After fracturing, tools for milling ball seat are not needed, and the fracturing ball will automatic flow back. The specific research contents arc:(1) Researching and analysis on fracturing sliding sleeve domestic and overseas, and designing the structure of new fracturing sliding sleeve. From research report we found that two kinds of sliding sleeve now are used in oil and gas industry, one is ball activated fracturing sliding sleeve, the other is tubing with BHA, and both of them has its drawbacks. Depend on this research, we design a new structure of ball activated fracturing sliding sleeve. We have four plan, and we chose the best through analysis results. In this plan, the seat have six sub-seat which can calculate the balls passed across, and activate or closed the ball seat. Besides, we design the spring and shear pin and analyzed the strength of this parts.(2) Analyzing the key point of the sliding sleeve, and getting the optimal structure parameter. Fracturing sliding sleeve works in hostile environment down the well with high pressure. So the key part of the sliding sleeve needs to be analyzed. When fracturing, both ball seat and fracturing ball bear a high pressure differential that require deep research about ball and seat under this high pressure. Though we can get the better sealing surface and the optimal parameter of the cone angle. The results of analysis about the inner sleeve under 70MPa static pressure show that the strain of the sleeve would not block the motion of inner sleeve in the fracturing sliding sleeve.(3) Analyzing the corrosion rate to the fracturing hole. The fracturing fluid contains much proppant. With high flow rate, the fluid with sand leads to the erosion in the internal sliding sleeve?The differential pressure existed between in an outside of the sleeve after that the fracturing hole opened. Every sliding sleeve have six fracturing hole. Corrosion in fracturing hole results in bigger size hole that weaken the intensity of the sleeve and the sealing performance. The results show that erosion rate can meet the requirement of fracturing in every single zone.(4) Analyzing the seal of ball seat. When fracturing the well, ball seat is contacted with inner sleeve and fracturing ball, and formed a seal between them. Building a calculation model with inner sleeve and fracturing ball, and analyzing the contact pressure as well; Designing a new structure between two sub-seat, and analyzing the sealing property.