Inflow distribution monitoring of long horizontal wells is a challenging issue. Input from such surveillance is needed to verify the clean-up of the well; to monitor the functionality of the completion solution; identify early water breakthrough; to calibrate the reservoir model, and to optimize the drainage strategy. These steps are crucial for increased oil recovery (IOR).
A dual lateral well equipped with unique chemical inflow tracers distributed across ten compartments has been installed in a marginal field development on the Norwegian Continental Shelf. The Hyme oil field development utilizes a 20 km subsea tie back to a platform where the inflow tracers are sampled. The monitoring efforts assess well performance from the clean-up, cross flow and back pressure in each lateral. Traditional wire-line conveyed production logging was not an option in the field's monitoring strategy due to lack of wire-line access to the reservoir zones. The multi-year life length of the deployed chemical inflow tracers enables monitoring of the well for a substantial period of time.
Tracer samples are acquired on a regular basis depending on monitoring objectives. In addition, a large number of samples were acquired after a shut-in period to catch the flow-induced transient responses of the different tracers. Parameters such as clean-up quality, cross-flow during shut-in and back-pressure in the two branches were interpreted from tracer appearance, including peak arrival timing and overall shape of the different tracer transient responses. The tracer transient monitoring technology enabled quantification of oil contribution from each compartment in each lateral. A history matching process was used to match the observed tracer signatures after a shut-in period using a transient inflow tracer model that has been experimentally verified by flow-loop experiments. The estimated inflow profiles show good agreement with expected result, based on the reservoir properties, and what was acquired from individual testing of the two branches.
The initial information gained since first oil has been valuable in understanding early production performance and updating transient wellbore and reservoir models for assessing well performance in relation to increasing field recovery without the need for interventions.