Study of influence of unsteady two-phase inflow on water cut dynamics of horizontal wells with multi-stage hydraulic fracturing

In this paper the author tried to analyze observable features of water cut of horizontal wells with multi-stage hydraulic fracturing in case of non-stationary two-phase inflow inlow-ermeable undersaturated oil reservoirs of Western Siberia using flow simulations. The author developed filtration models, calculations under which show how integral dynamics of wells water cut under shaftand fissures of hydraulic fracturing change depending on the complex of parameters, such as: well type (directional with hydraulic fracturing, horizontal, horizontal with multi-stage hydraulic fracturing); type of stimulation; amount of fissures, technology of their formation, which determine parameters of the fissures near the well; features, volumes and type of drainable areas; stage of wells operation and operating practices; features of fluids and dynamic changes of relative permeability in the mixture.
Materials and methods
Simulation using approved flow simulation software with proper account for fluid flows in the presence of massive hydraulic fracturing for the example of typical area of the real inhomogeneous Jurassic reservoir of Western Siberia.
Results
Under actual data of wells operation on development objects of Western Siberia, the author determined and reproduced (withthe help of filtration modeling) the features of water cut of horizontal wells with multi-stage hydraulic fracturing in low-permeable undersaturated reservoirs. In initial intensive period of well operation, accumulation of more movable aqueous phase (in comparison with the stable period) takes place. Vertical phase inflow in fissures, which cross differently saturated interlayers, is unstable and changes depending on the complex of parameters.
Сonclusions
Water cut dynamics for horizontal wells with multi-stage hydraulic fracturing is determined mostly by water cut of fissures in case of elliptic flow and is caused by interference and decrease of flows between fissures, level of initial water saturation of reservoir, operation rate.