State Key Laboratory of Oil Gas Reservoir Geology and Exploration

Chengdu, China

State Key Laboratory of Oil Gas Reservoir Geology and Exploration

Chengdu, China

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Ren J.,State Key Laboratory of Oil Gas Reservoir Geology and Exploration | Guo P.,State Key Laboratory of Oil Gas Reservoir Geology and Exploration | Wang S.,Petrochina | Bi B.,Petrochina | And 2 more authors.
Natural Gas Industry | Year: 2013

In the development of abnormally high-pressure gas reservoirs, the reservoir rock generally exhibits the characteristic of stress sensitivity. For such stress-sensitive reservoirs, the permeability modulus changes with the stress if the effective stress is of a large variation range. Therefore, the productivity formula based on the constant permeability modulus is unlikely to accurately evaluate the productivity of such gas reservoirs. In view of this, a productivity calculation model was established considering both the variable permeability model and high velocity non-Darcy flow effect according to the permeability rule of abnormally high-pressure gas reservoirs; The Newton-Raphson method was adopted for solving the model. The study results and case analysis showed that the stress sensitivity has the effect of reducing the production of abnormally high-pressure gas reservoirs. Particularly, the production decreases heavily when the FBHP (flowing bottomhole pressure) is low. Thus if the traditional calculation method based on the constant permeability modulus is adopted, the evaluated productivity will probably provide unreliable basis for assessing the stress-sensitive effect on the gas well production. Moreover, the high velocity non-Darcy flow effect will reduce the productivity of abnormally high-pressure gas reservoirs, and the reduction becomes severer with the decrease of FBHP. Therefore, the effect of such factors as the variable permeability modulus and the high velocity non-Darcy flow effect on well productivity should be considered in the development of abnormally high-pressure gas reservoirs.

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