A semi-analytical model for quantifying the inter-well communication in water-bearing shale gas-condensate reservoirs

Abstract

The increased risk of well communication in unconventional reservoirs expands the requirement for effective techniques to quantify the strength of inter-well communication. This work develops a robust and practical semi-analytical model to interpret the parent-child well system communicating through the fracture hits in water-bearing shale gas-condensate reservoirs. The compartment concept is employed to simplify the parent-child well system, in which the fracture hit region (FHR) is applied to describe the communication between sibling wells. The improved distance of investigation (DOI) is derived to characterize dynamic drainage under the three-phase condition for the water-bearing shale gas-condensate reservoirs. The material balance equations (MBEs) for each phase (oil, gas, and water) in each region are coupled and solved simultaneously to obtain three-phase production. The average pressure and saturation in each region are updated during the iteration with adaptive timestep to reduce the effect of nonlinearity under three-phase condition. Furthermore, the genetic algorithm (GA) is introduced to realize the automatic history match and properties interpretation of the parent-child well system.The oil/gas production of parent well drops rapidly when the child well starts to produce indicates the fracture-drive interference. However, similar drop in water production rate sometimes doesn't take place due to higher water saturation caused by fracturing of the child well. By the production history matching of field data from southwest Canada, the water and oil saturation, half-length and permeability of fractures, matrix permeability and FHR parameters are interpreted, higher efficiency than the numerical simulations. The results demonstrate the practical application of the new model for reservoir and fracture properties from online production data of parent-child well system.