Sand control flowback process after shale gas horizontal well fracturing

Abstract

The invention discloses a sand control flowback process after shale gas horizontal well fracturing. A 2mm oil nozzle is adopted for carrying out well opening liquid discharge on a fractured shale gashorizontal well, the well opening pressure changes are recorded, and if the pressure drop rate within continuous 10 hours is lower than 0.05MPa / h, the oil nozzle is increased to a 3mm oil nozzle for draining; after well opening draining is carried out for 72 hours, and measures are taken according to whether gas breakthrough appears or not; if gas breakthrough does not appear, according to the well opening pressure, the pressure in the well bottom seam is calculated, and if the pressure in the seam is larger than the closing pressure of the regional stratum, the 3mm oil nozzle is continuouslyadopted for draining until the stratum is closed; if the pressure in the seam is smaller than the regional stratum closing pressure, at the moment, the stratum is closed, if gas breakthrough appears,the oil nozzle is directly increased to a 4mm oil nozzle for draining, on the premise that the sand production does not appear in the stratum, when the pressure drop rate is lower than 0.2 MPa / h within continuous 12 hours, the oil nozzle is increased stage by stage with 1 mm as the unit to the test work system, and the well test yield is solved. According to the method, in the flowback process, the crack closing degree, the gas and liquid ratio and the well cylinder flow state are judged in real time, the flowback system is optimized in real time, and the shaft sand production rate at the flowback primary period can be effectively controlled.

Description

technical field [0001] The invention relates to the technical field of oil and gas well fracturing flowback testing operations in the field of oil and gas field exploration and development, in particular to a sand control flowback method after staged fracturing of shale gas horizontal wells. Background technique [0002] Domestic shale gas development generally adopts staged fracturing of horizontal wells. After the fracturing is completed, it is necessary to use the energy of the formation itself to drain liquid. Only when a certain flowback rate reaches a certain flowback rate can the test and production conditions be met. However, sand production often occurs during the flowback process after fracturing. After sand production, the formation energy is insufficient to carry the proppant in the horizontal wellbore out of the well, resulting in the sand-buried perforation section, the fluid flow channel is blocked, and the fluid drainage rate decreases rapidly. Seriously affe...

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Problems solved by technology

The above two methods have the following difficulties: the difficulty of method ① lies in the accurate judgment of whether sand is produced in the formation and the control of the flowback rate; method ② for horizontal wells using large-diameter bridge plugs, since the large-diameter bridge plug has been placed in place after fracturing Placed in the horizontal section, and the diameter is generally between 65-76mm, there is a certain difference from the inner diameter of the casing (110-115mm), that is, the horizontal wellbore has multiple diameter reductions at the bridge plug seat, if The sand produced in the formation will accumulate at the reduced diameter. After the coiled tubing is run in, it will not be able to pass through the large-diameter bridge plug smoothly and the flushing will not be in place.

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