Sand control flowback technology after fracturing in shale gas horizontal wells

Abstract

The invention discloses a sand control flowback process after fracturing of a shale gas horizontal well. A 2mm oil nozzle is used to open and drain the shale gas horizontal well that has been fractured, and record the change of the wellhead pressure. If the pressure drop rate is lower than 0.05MPa / h, it will be increased to 3mm oil nozzle drainage; after 72 hours of well opening and drainage, take measures according to whether gas is seen: if no gas is seen, calculate the pressure in the bottom hole fracture according to the wellhead pressure, if If the pressure in the fracture is greater than the formation closure pressure in this area, continue to use the 3mm nozzle to drain until the formation is closed; if the pressure in the fracture is lower than the formation closure pressure in this area; Under the condition of sand, when the pressure drop rate is lower than 0.2 MPa / h within 12 consecutive hours, increase the oil nozzle step by step by 1mm to the test working system, and obtain the test production of the well. This method judges the fracture closure degree, gas-liquid ratio and wellbore flow state in real time during the flowback process, optimizes the flowback system in real time, and effectively controls the wellbore sand production in the early stage of flowback.

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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