A self-excited oscillation bottomhole sand mixing tool and method

Abstract

The invention relates to a self-excited oscillating bottom-hole sand mixing tool, which includes a tool body. A cavity is provided in the middle of the tool body, and one end of the cavity is open and the other end is closed. The cavity is formed from the opening end of the cavity from the left The upstream nozzle, the shock chamber, the downstream nozzle and the pressure-guiding sandblasting chamber are arranged in sequence from the right. The diameters of the shock chamber and the pressure-guiding sandblasting chamber are larger than the diameters of the upstream nozzle and the downstream nozzle. There is a pressure-guiding sandblasting hole communicating with the outside of the tool body. The downhole sand mixing tool can make the high-concentration sand-carrying fluid vibrate while flowing, and realize the rapid and uniform mixing of the high-concentration sand-carrying fluid and the annulus liquid under the action of vibration after flowing into the oil casing annulus. The original surface adjustment of sand concentration is transformed into bottom-hole adjustment, which achieves real-time adjustment of sand concentration, improves the effect of reservoir transformation, solves the sand plugging accident caused by the inability to change the sand concentration in time, and improves the construction quality and efficiency.

Description

technical field [0001] The invention belongs to the technical field of multilayer and multistage fracturing in oil and gas fields, and in particular relates to a well bottom sand mixing tool and a sand mixing method with self-excited oscillation function. Background technique [0002] Research results at home and abroad show that volume fracturing for low-permeability oil and gas reservoirs can effectively improve the contact surface between the fracture network and the reservoir, increase the stimulated volume of the reservoir, and thus increase the single well production. The main feature of volume fracturing is "large displacement and large fluid volume". It is necessary to use casing injection or simultaneous injection of oil pipe and oil casing annulus for fracturing construction. Since the oil pipe and oil casing annulus are injected simultaneously, the construction risk is small. , has been widely used. At present, there are three main problems in fracturing when the...

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Problems solved by technology

At present, there are three main problems in fracturing when the tubing and the casing annulus are injected simultaneously: 1. The sand-carrying fluid injected from the tubing cannot be mixed quickly and evenly with the liquid injected into the casing annulus, resulting in uneven sanding in the fractures , affecting the effect of reservoir stimulation; 2. The sand-carrying fluid injected into the formation is injected from the wellhead after the ground is adjusted. In the fracturing process, once the pressure is abnormal and the sand concentration needs to be adjusted, it can only be operated at the wellhead. The sand-carrying fluid needs to pass through a tubing volume from the wellhead into the formation, which has a certain hysteresis and is prone to sand plugging; 3. If sand plugging occurs in the final stage of fracturing (when the sand concentration is the highest), a large amount of proppant is deposited at the bottom of the well, Heavy workload for sand washing and plug removal

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