Publications

Sisi-Nubi is a gas condensate field located in East Kalimantan, lying roughly 25 km offshore of the modern Mahakam delta. Seven hydraulic fracturing jobs were done in the field, targeting Sisi Main Zone which is the lowest reservoir in Sisi-Nubi, characterized by low permeability sand-shale intercalated layers. Post fracturing job evaluation shows that high well production corresponds to extended vertical fracture growth which by passing the shale layers to connect several sand bodies. The best fractured well was put on production in mid 2010 and it can produce up to 30 MMscfd. This successful fracturing produces from two markers contain thick laminated sand accumulation. Methods are exists for fracture height evaluation, the most common one is radioactive tracers with Gamma Ray Tool as radioactivity detector which has been implemented in 2 fractured wells in Sisi-Nubi. However, determining fracture height with stand alone gamma ray in the absence of tracers is possible for ceramic or man-made proppants (clay based) since they have relatively high gamma ray compared to reservoir sand. This approach also been applied in Sisi-Nubi and brings a clear clue in estimating the fracture height. The advantages of this approach are less cost, no need for dedicated run and eliminating operational constrain linked to radioactive source handling. The data acquisition itself can be obtained from any routine well interventions in combination with gamma ray tool run during well life. This paper demonstrates the impact of extended vertical fracture growth in the production of Sisi Nubi fractured wells and describes a simple method of using stand alone GR to estimate fracture height without radioactive tracers.