A water-controlled acid fracturing method suitable for carbonate reservoirs

Abstract

The invention provides a water controlling and acid fracturing method suitable for a carbonate reservoir. The method includes the steps that sliminess water prepad fluid is injected into stratum at the displacement of 1.0 m<3> / min-3.0 m<3> / min; the displacement is increased to 3.5 m<3> / min-4.5 m<3> / min, and gelled fracturing fluid is injected to the stratum; the gelled sand-carrying fluid is injected into the stratum at the displacement of 3.5 m<3> / min-4.5 m<3> / min, and meanwhile precoated sand with the mesh being 70 to 140 is injected into the stratum according to the sand ratio of 4%-6%; the gelled fracturing fluid or the sliminess water prepad fluid is injected into the stratum at the displacement of 3.5 m<3> / min-4.5 m<3> / min; gelled acid is injected into the stratum at the displacement of 3.5 m<3> / min-4.5 m<3> / min, when the injection volume is the sum of the volume of an oil pipe and the volume of a shaft on the lower portion of the oil pipe, the displacement is increased to 5.0 m<3> / min-6.0 m<3> / min, and gelled acid is injected continuously; replacement liquid is injected into the stratum at the displacement of 4.0 m<3> / min-5.0 m<3> / min. By means of the water controlling and acid fracturing method, extension of the downward fracture is controlled effectively, the water cut rising speed is lowered, and water control and oil production enhancing of the carbonate reservoir are achieved.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development, in particular to a water-controlling acid fracturing technology suitable for carbonate rock reservoirs. Background technique [0002] Some blocks of the Ordovician carbonate reservoirs in Tahe Oilfield have entered the medium and high water-cut development period, the oil-water interface has risen, the water-avoidance height has decreased, and some wells have produced high water-cut after acid fracturing measures. In view of this situation, Conventional acid fracturing has the following problems: 1. For fracture-vug reservoirs with small thickness, water-avoidance height less than 30 meters and no good interlayer, conventional acid fracturing effect is poor, and the proportion of water layers after stimulation is high, up to 28.9% %. 2. For stress-sensitive ultra-deep carbonate rocks (≥5,400 meters), the construction process is very likely to cause sand plugging, and the te...

AI Technical Summary

Problems solved by technology

[0002] Some blocks of the Ordovician carbonate reservoirs in Tahe Oilfield have entered the medium and high water-cut development period, the oil-water interface has risen, the water-avoidance height has decreased, and some wells have produced high water-cut after acid fracturing measures. In view of this situation, Conventional acid fracturing has the following problems: 1. For fracture-vug reservoirs with small thickness, water-avoidance height less than 30 meters and no good interlayer, conventional acid fracturing effect is poor, and the proportion of water layers after stimulation is high, up to 28.9% %

2. For stress-sensitive ultra-deep carbonate rocks (≥5,400 meters), the construction process is very likely to cause sand plugging, and the termination of sand addition will result in a decrease in the effective sand concentration in the fracture, and the fracture height cannot be effectively controlled. It is easy to communicate with the water layer. At the same time, the water-blocking effect of the artificial interlayer of coated sand is poor, which eventually leads to aggravated water flooding after fracturing or invalid transformation

[0008] Although some studies and discussions have been carried out on the coated sand fracturing technology in the above literatures, none of them can fundamentally solve the specific problems existing in some blocks of carbonate reservoirs

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