Effects of the wellbore parameters of radial horizontal micro-holes on the gas reservoir production rate

•A coupling model to predict the conventional gas reservoir production rate.•A model to calculate the friction pressure drop of horizontal micro-hole gas flow.•We analyze the influences of the micro-hole parameters on the gas production rate.

Radial horizontal drilling technology can create several drainage micro-holes to improve the efficiency of fluid flowing from the reservoir into the wellbore, increase the single-well production rate and enhance the recovery of natural gas. This paper proposes a steady-state model to calculate the production rate of natural gas for radial horizontal micro-holes by coupling the reservoir inflow model and the wellbore flow model. The newly developed model calculates the friction pressure loss for gas flow in the radial horizontal wellbore. The influences of certain wellbore parameters on gas production rate have been analyzed, and a sensitivity study has been performed. The results show that the production rate increases as the wellbore length, the number of micro-holes, the included angle and wellbore diameter increase. However, the effects of the number of micro-holes, the included angle and the wellbore diameter are significant only within certain limits. Based on the degree to which the parameter positively affects the gas production rate, the wellbore parameters can be ranked as follows: wellbore length > the number of micro-holes > included angle > wellbore diameter > distance between the micro-hole and the lower boundary. The wellbore length and the number of micro-holes have the greatest influence on the production rate of multiple radial horizontal micro-holes. The models and results presented in this paper can provide the theoretical basis for the design of radial horizontal drilling in natural gas reservoirs.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (217 K)Download as PowerPoint slide