Coalbed Methane Well Fracturing Operation Retrieval Of Rock Mechanics Parameters Of Production And Pressure Prediction

Coalbed methane as an important component part of the unconventional resource with the advantages of shallow depth of drilling, less investment risk and costing and fast return has become the most active in the field of unconventional resource production, so it is much accounted of many countries producing coal. Hydraulic fracturing is the most ordinary measurement used to stimulate the wells and plays an important role in exploitation and production of coalbed methane.Parameters of rock mechanics are important for coadbed methane production and design, whose values could be attained from core trixial stress testing in lab or well logging. In this paper, a new method to calculate the parameter values of rock mechanics is provided by deducting the data of surface pressure during treatment. In this model, the relation about bottom hole pressure and rock mechanics nearby is as the mainline and fracture creation and extension is the core fraction. Firstly, the special mechanism about fracturing this type of rock is analyzed ground on the characteristic of ingredient pore, cleat development and a new model for fracturing fluid leak-off is also made coupled with leak-off control mechanism depending on the pressure. Because the ingredient has stronger sensitivity and the leak-off mechanism in which is different from that in conventional resource. On the basis of authors'study, two-dimensional numerical model for fracture extension in ingredient is established and a model for flowing in wellbore which could calculate the real time bottom hole pressure is also set up. For fitting the relation about bottom hole pressure during treatment and coalbed characteristic using interation, the values of young's modulus and poisson's ratio about ingredient for the section of wellbore which is stimulated are worked out. It shows the credibility of this new way by examples. This method can be used in not only real time analyzing in the coal rock frac, but evaluating and analyzing after frac. It provides a new tool for research the mechanics parameters of the coal rock by fracturing treatment information.Predicting the coalbed methane production after fracturing accurately is the key to exploitation of coalbed resource. Based on the theories and methods of many subjects such as oil-gas geology and mechanics of flow through porous media, the mechanisms of coalbed methane generation, storage, migration and production are studied, also a simplified geologic model of coalbed container rock is established in this paper. The mathematical model to simulate the water-gas two phase flow in the coalbed container rock under the condition of two dimension, non-equilibrium adsorption and quasi steady state is set up and the solution procedure of the model is deducted in detail used the method of IMPES. In virtue of computer technology, the simulation software for predicting the coalbed methane production is also developed. Finally, as the example of HaCan X Well, the regime prediction of production is run and the factors which effect the coalbed methane production after fracturing are also simulated and calculated using the model established in this paper. The result of the simulation proves the simulation model given in the paper is correct and credible. Hydraulic fracturing increase the pressure drop from matrix to the bottom hole. It will has an effects on the desorption & diffusion necessarily. But it hardly can be seen in the literature. In this paper, the desorption & diffusion data in the calculation is collected and analyzed by the charts firstly. The result of the simulation proves the simulation model given in the paper is correct and credible.