Method for predicting water content and water yield of coal seam

Abstract

The invention discloses a method for predicting a water content and a water yield of a coal seam. The method comprises: (1), calculating a water yield parameter and a water yield of a pure coal seam; (2), constructing an integrated evaluation parameter of water yields of stand stones at a top bed and a bottom bed; (3), calculating a water yield of coal seam drainage; (4), calculating total moisture of the coal seam; (5), calculating a water content of the coal seam; and (6) calculating water contents of the stand stones at the top bed and the bottom bed of the coal seam. According to the invention, a relationship between the water yield and the logging value at the initial stage of the coal seam draining is analyzed and a method for predicting the water yield of the draining of the pure coal seam by using logging data is established; under the circumstance that water-contained sandstones exist in a short-distance range of the coal seam, a water yield calculation model of joint water yields of the coal seam and the water-contained sandstones is provided; on the basis of the coal petrography experiment, a method for calculating the water content of the coal seam by using logging data is established and a total water content of the sandstone layer of the top bed is provided; and with the water content and the water yield of movable water, the water yield cycle of the draining process can be predicted preliminarily.

Description

【Technical field】 [0001] The invention belongs to the field of exploration and development of coal bed methane, and in particular relates to the calculation of coal bed water content and the prediction of water production in the process of coal bed methane extraction. 【Background technique】 [0002] Coal seams contain varying amounts of water. Coalbed water is not only an important factor affecting the enrichment of coalbed methane, but also plays an important role in the output of coalbed methane as an objective medium. The dynamic change of reservoir pressure caused by its output directly affects the desorption process of coalbed methane. The vast majority of coalbed methane drainage needs to pump out the water in the coal seam to reduce the pressure of the coal seam below the critical desorption pressure, and the coalbed methane in the coal seam is desorbed and then discharged along the cracks. Only a very small part of the coal seam is opened and the free gas is directl...

AI Technical Summary

Problems solved by technology

[0003] The development of coalbed methane is an emerging industry in recent years. There are literatures about coalbed methane drainage production capacity evaluation software, but due to different drainage methods and the influence of coal seam geological factors, the reliability cannot meet the needs

However, the prediction method of water production in the process of coalbed methane drainage is basically blank.

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