Currently considerable part of new oil and gas fields put into production, features structurally complex low permeable reservoirs. Under complex Arctic climatic conditions, Yamal in particular, development of gas-condensate deposits seems to be especially difficult and capital intensive task. To increase projects commercial efficiency, productivity of each gas well needs to be maximized. Classic solution here is to drill vertical well (VW) with fracture. Under complicated conditions especially when developing offshore fields, where drilling unit costs are considerably higher than in already developed oil and gas bearing regions of Russia, horizontal or sub-horizontal wells (HW) with multiple fractures can be more efficient.
To evaluate process efficiency under conditions of Urengoiskoe gas-condensate field, a high resolution sector reservoir model for a single well was built. The model was used to calculate production parameters for various bottomhole design variants: vertical well with fracture, horizontal well with several transverse or longitudinal fractures.
In this sector model, each fracture was explicitly simulated, and in number of models minimum width of a cell containing fracture was 5 to 10 mm, which correlated with real fracture width.
Analytical calculations and simulation results, considered in this paper, are indicative for a number of typical effects for gas-condensate wells, which should be given a notice:
Generation of condensate bank in bottomhole formation zone, leading to well productivity decline;
Inertial effects in fracture (Forchheimer effect) caused by high gas filtration rate and also resulting in well productivity decline;
"Straightening’ of relative permeability curves in the areas with high fluid velocity.