No abstract

No abstract

When designing a hydraulic fracturing intervention, the selection of the interval to be perforated is critical in order to maximize oil production and to avoid unwanted gas/water breakthrough from neighboring layers.While on new wells the perforation interval can be selected carefully analyzing logs and CBL, it can be challenging to design a workover where the HF targets a zone that is right in the middle of a large existing perforated interval (125 meters).Leaving exposed too many perforations during a fracturing treatment could result in operational issues such as early screenout and/or uncertainties on the fracture initiation point. Zonal isolation could be obtained by cementing part of the perforations but this would mean in permanently losing part of the level. This paper will describe a successful workover carried on a shut-in oil well, onshore Congo, where a single stage fracturing treatment was performed leaving exposed only few meters of the existing perforations and without permanently losing the remaining intervals.This result was obtained using a multi-stage ball drop frac completion setting the packers across the perforated interval. The downhole equipment was able to withstand the treating pressure during the fracturing treatment and production was obtained through the frac sleeves.This workover resulted in a significant oil production from a well that never produced until that moment.

When production facilities are not equipped with a solid control device, proppant flowback becomes an issue throughout the entire productive life of a screenless multi fractured well. The challenge of minimizing proppant flowback is even more critical when dealing with offshore horizontal wells with ESP systems installed. A wide selection of proppant flowback prevention additives is now available in the industry: most of them work either chemically or mechanically. At low formation temperature (150 F), the effectiveness of some additives such as resin coated proppant or fiber can be limited due to the temperature activation. This paper will describe a successful strategy of proppant flowback control which was implemented in a multi stage fracturing treatment on a horizontal well in M- field, offshore Congo. It is the combination of resin coated proppant, enhanced by a chemical activator and inert fibers that provides double mechanism to eliminate proppant flowback issues during well production and sustaining life of ESP. Success in this multi stage fracturing treatment has resulted in oil production from a pay zone that has never been produced due to poor petrophysical characteristics. This document will describe: proppant flowback control additives selection process, placement strategy, hydraulic fracturing design and well execution considerations for multi stage fracturing treatments.