Xinjiang Petroleum Geology ›› 2022, Vol. 43 ›› Issue (3): 324-328.doi: 10.7657/XJPG20220309

• RESERVOIR ENGINEERING • Previous Articles     Next Articles

Establishment and Application of a Combined Production Decline Prediction Model for Tight Sandstone Gas Well

LI Xiaofeng(), XU Wen, LIU Pengcheng, YUE Jun   

  1. a. PetroChina Changqing Oilfield Company, Research Institute of Exploration and Development, Xi'an, Shaanxi 710018, China
    b. PetroChina Changqing Oilfield Company, National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields, Xi'an, Shaanxi 710018, China
  • Received:2021-11-26 Revised:2022-01-21 Online:2022-06-01 Published:2022-05-26

Abstract:

The Permian fluvial sandstone gas reservoirs in the Sulige gas field are tight and contain effective sand bodies that are mostly isolated or banded. After gas wells are put into production, reservoir fluid stays consistently in an unsteady flow state, and it is late to reach the boundary-dominated flow state. In this case, the traditional Arps production decline analysis method is not sufficient for field application. This paper analyzed the causes for the poor adaptability of the Arps production decline analysis method. On this basis, the variation law of the decline exponent of wells in tight gas reservoirs was identified by numerical simulation, and the relationship between the decline exponent and the flow period of fluid in gas wells was clarified. Finally, it was proposed to use the channel linear flow model to predict the production in the unsteady flow period and the Arps model to predict the production in the boundary-dominated flow period. For the gas wells in the unsteady flow period, the critical point time to attain boundary-dominated flow is determined by the theoretical formula; in the boundary-dominated flow period, the time of inflection point deviating from the linear flow is the critical point time. The field application shows that the proposed combined production decline model is accurate and effective in predicting the decline characteristics and indicators of gas wells.

Key words: Sulige gas field, tight gas reservoir, decline exponent, flow period, linear flow, boundary-dominated flow, decline prediction, combined model

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