Method for measuring gas and water relative permeability curve through coal-bed gas well production data

Abstract

The invention discloses a method for measuring a gas and water relative permeability curve through coal-bed gas well production data. Average reservoir pressure and average water saturation are obtained with a material balance method, and therefore changes between absolute permeability and relative permeability can be obtained; changes of irreducible water saturation are predicted through the relation between irreducible water saturation and porosity; the absolute permeability and the relative permeability generated after end points are calibrated are coupled in the same state, a domain average effective permeability dynamic prediction model can be obtained, and an effective permeability curve can be obtained. The method solves the problem that in a laboratory, the relative permeability curve can not be accurately measured easily. Compared with the prior art, the positive and negative effect of a coal reservoir can be well reflected, the gas phase effective permeability can be effectively improved, and a powerful basis is provided for accurately predicting a gas and water output law of a coal-bed gas well and predicting future yield of a producing well.

Description

technical field [0001] The invention relates to a measurement method for the development of coal bed gas, in particular to a method for measuring the gas-water phase permeability curve by using the production data of the coal bed gas well. Background technique [0002] In recent years, the commercial development of CBM in high coal-rank reservoirs in the Qinshui Basin of China has achieved success. However, weak research on coalbed methane development technology is still a key factor restricting the further development of China's coalbed methane industry. Coal reservoir permeability is one of the important contents of coalbed methane development evaluation, and relative permeability curve is a true reflection of the entire drainage process of coalbed methane wells from single-phase water flow to single-phase gas flow. The gas-water relative permeability of coal reservoirs not only strongly affects the gas production rate, but also can determine whether the coalbed methane w...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for measuring the gas-water phase permeability curve using the production data of coalbed methane wells, which overcomes the current technical shortcomings of large errors in the measurement of gas-water relative permeability in coal reservoirs. The positive and negative effects of layers, based on the special properties of high coal rank coal reservoirs and the production data of coalbed methane wells, under the same state, the absolute permeability and relative permeability are coupled to establish an effective permeability model, which is important for accurately quantifying the positive and negative effects Significant, can also provide a more reliable forecast basis for production

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