Horizontal Shale Oil Production Wells Experience Hydraulic Fracture Choking Effect Under Closure Stress

The choke effect of hydraulic fractures on a horizontal shale oil well during production is shown using a coupled matrix–fracture–wellbore flow simulation model. The effect is the consequence of a significant loss in hydraulic fracture conductivity near the wellbore due to fracture closure stress. A consequence of the choke effect is that the fluid pressure in the fractures is maintained high enough to keep gas in the solution. The gas leaves the solution only after the choke region is passed when the oil with its solution gas begins the flow in the wellbore, and when it abruptly experiences a steep pressure gradient. This phenomenon has a long period of producing a constant gas–oil ratio (flat GOR) as its signature. The influence of the choke effect on the wellbore flow regimes is also investigated in the hydraulic-fractured horizontal section of the reservoir. During horizontal pipe flow, a distributed–intermittent flow sequence develops from the toe to the heel of the shale oil well over the production time. However, in the presence of the hydraulic fractures, a sequence of distributed–intermittent–transient–segregated flows develops. This indicates that the choke has the potential to affect the flow regimes in the horizontal section.