NB/T 11105-2023Technical specification of coalbed methane numerical simulation (English PDF)

3.1 Coalbed methane numerical simulation

Based on the geological understanding and development rules of coalbed methane, special software (called numerical simulator) is used to simulate the desorption and expansion of coalbed methane in coal reservoirs.

According to the distribution, gas-water seepage and production, the obtained reservoir parameters and production data (or test production data) are fitted and matched, and then the gas-water production, gas-water production, and Dynamic changes of pressure and coal reservoir parameters.

3.2 Dynamic forecasting

On the basis of acceptable historical fitting accuracy of coalbed methane well drainage data, under a certain development mode, the daily water production of coalbed methane wells can be predicted.

The process of developing dynamic indicators such as gas production, daily gas production, cumulative water production, cumulative gas production, coal reservoir pressure, remaining gas content, recovery degree, etc.

4.1 Basic process of CBM numerical simulation

The basic process of CBM numerical simulation is shown in Fig. 1, including the following process.

a) Collection, collation and analysis of basic data;

b) Model establishment. according to the main problems faced in different exploration and development stages, formulate reasonable research objectives, and establish single well and well group or block model;

c) Initialization. check the balance of the established CBM model;

d) Sensitivity analysis. it is used to determine the sensitivity of different gas reservoir parameters to the objective function within a specific range of values, and it is used for subsequent historical simulation. Provide a basis for the adjustment of joint parameters;

e) History matching. under the premise of production data, by fitting indicators such as gas production, water production, pressure, etc:, the model calculation and actual gas