Ekofisk is the oldest oilfield in the Norwegian North Sea on the Norwegian Continental Shelf (NCS). It is 300 kilometers (about 186.41 miles) southwest of Stavanger and 3,000 meters (about 9,840 feet) below the seabed. Ekofisk has been an important economic driver for the whole of Norway since coming onstream in 1971, with over three billion barrels of oil produced since then. With its large reserves, it has been in production for over 50 years after its discovery.
Enhanced oil recovery (EOR) is becoming increasingly challenging for securing oil supplies in mature oilfields. This was a long-standing challenge for our customer, a major operator in the Ekofisk field. They faced long-standing challenges with production log (PLT) data from the field, which often provided inconclusive results due to difficulties with interpreting PLT data from horizontal wells. These wells are characterized by drilling complexity, formation heterogeneity and multiphase flow challenges. They approached RESMAN for a more efficient method to acquire reliable reservoir data for production optimization.
RESMAN piloted an intervention-free and cost-efficient approach using inflow tracer technology, which was successfully developed and tested in a newly drilled horizontal field. Inflow tracers were used to acquire early time data and to enhance understanding of flow dynamics throughout the well life. They were permanently installed in the completion string to identify individual zone production by oil, gas and water. Additionally, intra-well tracers were injected into each zone during stimulation to better understand stimulation efficiency. Extensive sampling programs were executed during well start-up, clean-out, transient and post-transient production phases.
Traditional techniques for understanding where and how much oil and water are being produced require well intervention through production logging (PLT), which is costly and difficult to execute. This is particularly challenging in low permeability carbonates and chalk fields, which often require long multi-stage horizontal wells with complicated data analysis in each stage. Tracer technology offers a reliable and cost-efficient way to understand reservoir fluid flow pathways.