This paper discusses the outcome of a hydraulic fracturing concept in a complex commingled water flood field with dense infill well spacing. The objective was to prove this concept of fracturing in a graywater flood field to improve oil production and increase the recovery factor.
A mature oil field in the central Sultanate of Oman is facing production decline. The flank part of the field is not meeting the expected production even with water flooding. The main challenge is how to communicate between the injector wells and the producer wells. The 5-spot patterns are not showing effectiveness in the flank area. The heterogeneous reservoir complexity and tightness are the main factors for that. The water zones are very close to or imbedded in between the reservoirs.
A careful candidate selection exercise was conducted from the field's 140+ wells. Factors assessed included spacing between producers and injectors, multiple commingled reservoirs, proximity to the Oil Water Contact (OWC), and petrophysical parameters.
A successful fracturing trial in one of the wells, located in the southern part of the field and five kms away from nearest oil producer, was followed with a selection of fracture candidates inside the main field. The method of selection was to gather all well data and select criteria to narrow the list to those wells with a higher success probability to help prove a new concept of fracturing in the middle of water injectors and oil producers by controlling fracture length propagation and height containments. A candidate was selected and the fracturing design was manipulated with different scenarios to overcome challenging oil water contact and control fracture propagation to avoid nearby producers and water injectors. The fracture was design selected and the operation successfully implemented, which resulted in a contained fracture confirmed by the low water cut, salinity results, and the radioactive tracer. One lesson learned from the first fractured well was that the pump design should be optimized to sustain a new production profile after the fracture treatment. Triple production resulted from the initial production stage and a fracturing proposal was prepared to follow the success of the operation.