Study On Well Testing Method Of Shale Gas Well

The characteristics of shale gas reservoirs, the mechanisms of reservoir capabilities, migration and production mechanism for shale gas are analyzed in the present paper on the basis of researching literature. The absorption and desorption phenomena of shale gas that differs from conventional gas is studied and basic differential equation for shale gas considering its absorption and desorption phenomena is developed. Seepage Flow Mathematical Model of non-steady state and steady-state of vertical well, vertical fractured well and horizontal well is established (Laplace space) based on the result of point-source function of Ozkan. The type curve graph is drawn with the use of Stehfest numerical algorithm and some examples are analyzed.The main conclusions obtained are as follows:1) With special low porosity, low permeability, self-generating and self storage, absorption into the possession, concealment gather low yield or no natural capacity, long production cycle, a greater change in gas reservoir recovery of the Shale gas reservoirs, Gas in the shale has a special occurrence in the transport mechanism. After the four steps of blood pressure, desorption, diffusion and Darcy flow, the adsorption state of shale gas in the shale matrix porosity flow into the production well bore.2) Considering the adsorption and desorption properties of shale gas reservoirs, the basic differential equations for steady-state and non-steady-state diffusion of shale gas reservoirs are derived with Langmuir isotherm law and Fick diffusion law. The introduction of the adsorption and desorption coefficients makes the form of the seepage flow differential equation of shale gas the same as that of conventional natural gas.3) The proliferation of point source solution for steady-state and quasi steady-state Shale gas is derived. The infinite and circular closed boundary flow models of vertical wells, fractured wells, and horizontal wells in gas shale reservoirs are established and solved. The dimensionless well test model curve is drawn through Stehfest numerical algorithm and the sensitivity factors of these models are analyzed.4) The pressure dynamic features of non-steady-state and quasi steady-state vertical wells, fractured wells, and horizontal wells in infinite gas shale reservoirs are compared with that in circular closed boundary gas shale reservoirs.5) The established seepage flow numerical model is tested through examples.