Abstract
Production and recoverable reserves of mature oilfields can be increased through the application of Production enhancement and optimization techniques. In the Napo reservoir, where an important percentage of the total production comes from highly depleted sands with moderate permeability and high clay contents, the implementation of hydraulic fracturing stimulation, with the simple objective of skin by-pass is generally accepted, however the production performance and decline after these conventional treatments is not optimal, due to subsequent fracture conductivity impairment caused by clay and fines migration issues, which is the primary formation damage mechanism. For this reservoir, with a clearly identified damage mechanism combined with moderate permeability and significantly low reservoir pressure gradients (down to 0.1 psi/ft) a fit-for-purpose strategy to successfully stimulate and obtain sustained production was required.
A xthorough multidisciplinary study and well screening was carried out to identify the best candidates. This task incorporated petro-physical, stratigraphic, completion and production history analysis, as well as enhanced Hydraulic Fracturing modeling for dedicated optimum fracture geometry and treating fluid selection. The study presented on this paper shows the workflow followed of the candidate selection, treatment design, execution and the post-job evaluation and validation methodology implemented on the campaign. Also, well testing before and after stimulation treatments had enabled the validation of the strategy, followed by production monitoring.
After 14 months of production it has been proven that this production enhancement strategy has achieved sustained production, with an average production increase of 350% and average post-frac skin values of -3. The post stimulation production conditions have had a positive effect on the run life of electro submergible pumps and the reduction of workover operations.
On Parahuacu and Guanta fields the achievement of a sustained production optimization through the application of a fit-for-purpose hydraulic fracturing strategy has unlocked the reservoir potential, quantifying an incremental production in excess of 390,000 bopd during 14 months after the hydraulic fracturing campaign. After 14 months of the campaign start-up, 990 bopd of incremental production associated to the Hydraulic Fracturing activity, Represents on average 30% the total field production, proving the effectiveness of this technique which is now part of the asset's production optimization strategy.
