One of the main challenges in production enhancement in mature fields is finding the optimum method to develop different reservoirs under the best exploitation strategy. Ecuador's Eden Yuturi is a mature field where nearly 15% of the field's production comes from a highly laminated, low permeability reservoir with viscous oil properties. The development of this layer requires hydraulic fracturing to economically produce the wells.
Hydraulic fracturing was implemented in Eden Yuturi in 2011. The fracturing technology has evolved since then. In 2019, the channel-fracturing technique was introduced, where proppant is pumped in pulses to achieve a heterogeneous placement within the reservoir, creating infinite-conductivity channels. The hydraulic fracture conductivity generated by open channels is higher than a conventional proppant pack. In conventional fractures, flow through proppant is described by Darcy's law; however, for an open fracture channel, the Navier-Stokes equation is applied, implying that effective permeability is 100 times higher.
Based on lessons learned for the past 6 years, some of the best practices include: perforating the entire reservoir in cluster, aggressive fracture designs averaging approximately 60,000 lbs of 20/40 proppant pumped, using resin-coated proppant to reduce proppant flowback and using ESP pumps with more robust stages that are well suited to handle solids production and viscous oil.
For the frac design, conductivity is increased from 3,500 md-ft to more than 500,000 md-ft with the channel fracturing technique. The associated dimensionless fracture conductivity increased from 2 to 50, and the resulting fracture width increased by 400%. As a result, the average fractured well productivity index increased by two-fold, resulting in higher production rates from 300 to 500 BOPD, ensuring the required volume to be economic as they decline smoothly, reaching cumulative volumes beyond 300,000 bbl of oil per well. This has enabled the Asset to increase reserves in the last campaigns by 2.5 MMbbl.
This result leads the NOC to better optimize their development strategy. Nearly 10 MMbbl are estimated to be recovered from this reservoir. Hydraulic fracturing has made the economic exploitation of this tight layer a reality since the reservoir was previously considered an uneconomic target. Through this aggressive strategy, Eden Yuturi Field has become the pioneer in economically exploiting laminated reservoirs in Ecuador.