Method for determining dynamic reserves in inner and outer zones of multi-stage fractured horizontal wells in shale gas

Abstract

The invention discloses a method used for determining shale-gas multistage-fracturing horizontal-well interior-and exterior-zone dynamic reserves. The method includes: establishing gas-well binomial productivity equation through gas testing materials, and calculating actual flowing bottomhole pressure (FBHP) through production data and gas-well structure parameters; respectively establishing matter balance equation of a fracturing transformation zone and a non-fracturing transformation zone for a multistage-fracturing horizontal well in considering of adsorption gas desorption and abnormal high pressure influence; respectively setting the dynamic reserves of the fracturing transformation zone and the non-fracturing transformation zone, adjusting the dynamic reserves by combining with the matter balance equation of the fracturing transformation zone and the non-fracturing transformation zone, interporosity flow equation between the fracturing transformation zone and the non-fracturing transformation zone and the binomial productivity equation, and determining the fracturing horizontal-well interior-and exterior-zone dynamic reserves. With the method, testing of average formation pressure by well shutdown is not needed during use, influence of adsorption gas desorption and abnormal high pressure as well as fracturing recombination zones can be considered, and the dynamic reserves of the fracturing transformation zone and the exterior non-fracturing transformation zone can be respectively determined.

Description

technical field [0001] The invention belongs to the technical field of shale gas exploration and development, and in particular relates to a method for determining the dynamic reserves of shale gas in the inner and outer regions of a multi-stage fracturing horizontal well. Background technique [0002] The evaluation method of dynamic reserves of shale gas wells is quite different from that of conventional gas wells, mainly reflected in: (1) The geological characteristics and development techniques of gas reservoirs are different. Shale gas reservoirs are self-generated and self-storage gas reservoirs with extremely low permeability. Volume fracturing is needed to “artificially create reservoirs”. The production and recoverable reserves of gas wells are limited by fracturing, and the dynamic reserves of a single well are related to volume fracturing. . (2) The seepage characteristics are different. Due to the extremely low matrix permeability of shale gas reservoirs, it is...

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Problems solved by technology

[0007] When this method is applied to calculate the dynamic reserves of shale gas wells, there are mainly the following problems: first, the influence of the desorption and diffusion of adsorbed gas in the shale matrix cannot be considered when calculating the dynamic reserves of gas wells; Pressure recovery unstable well test to explain the average formation pressure; third, it is impossible to distinguish the dynamic reserves of the fractured stimulation area and the dynamic reserves of the surrounding unfractured stimulation area

[0008] Based on the calculation methods of dynamic reserves of shale gas wells at home and abroad, there is currently a lack of effective and accurate calculation methods for dynamic reserves of shale gas wells, and it is impossible to distinguish the dynamic reserves of the fractured area from the dynamic reserves of the non-fractured area

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