A simultaneous injection fracturing method for large-scale hydraulic fracturing of vertical wells

Abstract

The invention discloses a large-scale hydraulic fracturing oil casing simultaneous injection fracturing method for a vertical well, which comprises the following steps: 1. establishing a communication channel between the wellbore and the reservoir; Until the formation of fractures in the reservoir; 3. Inject the pre-fluid without sand into the reservoir through the tubing, and inject the sand-carrying fluid into the reservoir through the oil casing annulus. The pre-fluid and the sand-carrying fluid are mixed at the bottom of the well and enter The fracture formed in step 2, until the proppant is completely laid in the fracture; 4. Inject the displacement fluid into the fracture through the oil casing co-injection, and the amount of the displacement fluid is greater than the volume of the wellbore. The efficiency of large-scale reservoir stimulation is improved, which facilitates the connection of large-scale reservoirs, increases the displacement of prefluid injection, increases the scale of stimulation, reduces sand plugging at the bottom of the well, and improves the efficiency of proppant placement.

Description

technical field [0001] The invention belongs to the field of oil and gas field exploitation and reservoir transformation, and relates to a large-scale hydraulic fracturing oil casing simultaneous injection fracturing method for vertical wells. Background technique [0002] Hydraulic fracturing is one of the main measures used in the industry today for the modification of oil and gas reservoirs. For unconventional oil and gas reservoirs, large-scale hydraulic fracturing such as volume fracturing and fracture network fracturing technologies are used more and more frequently. Large-scale hydraulic fracturing is mainly characterized by large displacement (pred fluid) and large sand volume (proppant). However, the conventional injection method is limited by the inner diameter of the tubing and the friction between the liquid and the inner wall of the tubing. The injection displacement is small and it is easy to form sand piles and sand plugs at the bottom of the well, which rest...

AI Technical Summary

Problems solved by technology

However, none of these methods can simultaneously solve the three major problems of displacement limitation, bottom hole sand plugging, and tubing inner wall damage.

[0004] Patent application number: CN201410423439.5 provides a double-sealed single-card volume fracturing string, specifically an oil pipe, and the end of the oil pipe is connected with a packer, a check valve, an eye pipe and a guide centralizer at one time. The packer and A pilot injector is connected between the tubing; a second packer, a third packer and an annulus injection valve are connected in series on the tubing, the second packer is located above the pilot injector, and the third packer is located on the Above the second packer, the annulus injection valve is located above and close to the third packer, which mainly overcomes the existing general double-seal and single-clamp segmental fracturing technology which is only applicable to tubing injection fracturing construction , the fluid friction is large, and the construction displacement is difficult to provide. The tubing and casing inject liquid flow at the same time to realize the layer-by-layer volume fracturing construction of oil wells and horizontal wells from bottom to top

However, the disadvantage is that this method is suitable for horizontal wells, and this method does not solve the problems of sand plugging at the bottom of the well and damage to the inner wall of the tubing.

[0006] To sum up, in the process of large-scale hydraulic fracturing of vertical wells, the existing valves, pipe strings, and methods can solve some difficulties, but cannot simultaneously solve the three major difficulties of displacement limitation, bottom hole sand plugging and tubing inner wall damage. solve