Modeling for reorientation and potential of enhanced oil recovery in refracturing

Reorientation of fractures and high production improvement are observed and illustrated by fields and theoretical researches. During the refracturing treatments, it is important to get familiar with the enhanced oil recovery mechanics of fracture reorientation and distribution of residual oil. Mechanisms of fracture reorientation are discussed in order to design the parameters of reoriented fractures in numerical simulation. To furtherly evaluate the oil recovery of different angles of reoriented fractures, geological and numerical models are simulated using data of the actual reservoir with rhombus inverted nine spot well pattern, different angles of reoriented fracture are designed for both corner and edge wells to obtain the enhanced oil recovery. Results show that potential of production increase is highly impacted by the well pattern and angles of fractures and meanwhile impacted by distribution of residual oil and formation properties. Oil enhancement potential is significantly different with fracture reorientation angles in refracturing treatment: cumulative produced oil for corner wells is symmetrical around the angle of 0o and reaches the highest at the angles of positive and negative 23o; for the edge wells, it is also symmetrical around the angle of 0o while reaches the highest cumulative oil at the angles of positive and negative 90o. The difference shows that optimal angles exist for reoriented fractures during refracturing design and with proper induced reoriented fractures, more oil will be recovered for field restimulation treatments.