Abstract
The paper describes the complete workflow applied for the future development of the Oglan Field in the Ecuadorian Oriente Basin in a sanding potential scenario. First, a sand prediction study evaluates a potential risk of sand production in a certain range of drawdown, identifying 1000 Psi as the critical one. Then, the conceptual evaluation of sand production mechanism is presented and discussed, in order to define the most suitable completion method for the production section.
The methodology is based on a Geomechanical characterization done over the Oglan 2Dir cores, which includes stress evaluation, and the definition of the geomechanical properties needed for the sand prediction model. The procedure integrates results from Scratch tests, Triaxial, Ultrasonic Tests, Geo-pressures and Log processing. Once the sand production potential was identified the evaluation of a suitable downhole sand control method becomes necessary; grain size analysis, sand sorting ratios, reliability, productivity are evaluated to identify the optimal sand control technique. Finally, a sand production comparison for Hollin Formation in Ecuador is performed.
The initial section of the paper will show the results of the sand risk integrated study which evidences a certain degree of strength heterogeneity in the Hollin formation. According to the stresses and strength information, the risk of sand production in open hole horizontal wells is not negligible for high drawdown values ≥1000 psi. The risk of sanding decreases for lower drawdown (in the range from 500 psi – to 1000 psi), but cannot be totally excluded due to rock strength heterogeneity. Critical DD of 1000 psi and Safety DD of 500 psi is finally concluded. A simulation in a vertical well was done with no sanding risk. This result is in agreement with the Oglan 2 dir well test, which did not observe sand production with a maximum DD of ~700 psi. Since the development of the field is planned by the drilling of horizontal wells the risk of sand should be Included in planning of the completion method.
No depletion has been considered through all the sand risk analyses, as strong aquifer support is believed to keep pressure almost at the virgin level. The effect of the water production in producing sand is considered since increasing water cut could increase the sanding potential. The second section describes the selection criteria used to evaluate different technologies for downhole sand control which involves sand failure characteristics, particle size distribution, well condition, reservoir and fluid characteristics, plugging risk, erosion risk and well productivity to identify the optimal downhole sand control.
This paper provides the complete workflow applied for sanding evaluation necessary for the development plan of the field. The results of geomechanical analyses and modeling showed indeed that the mechanical behavior of the Hollin reservoir in Oglan Field is somewhat different when compared to information available in the Oriente Basin literature, so the technical information detailed in the paper is useful for future development and correlations of nearest fields.
