Discovering Insights from the First Horizontal Multistage Fracturing in TE Sand, KTB Field: Evaluation of Fracturing Design and Tracer Result

This study provides an extensive review and analysis of the first ever horizontal multistage fracturing (MSF) treatment to the TE formation in the KTB Field, Indonesia. The project represents a departure from the historical practice of only completing single-stage fracturing in directional wells, with the more holistic stimulation philosophy of using MSF to optimize reservoir contact and production performance in a low quality sandstone reservoir. The main objective of this paper is to review the effectiveness of the fracturing design approach which utilized progression in the proppant loading, volume efficiency, and tip screenout (TSO) design to ensure placement of the fracture effectively placed inside the wellbore at the end of the treatment, as well as validating this design using post fracture diagnostics with chemical tracers. Review of design progression across the eight stages to overcome deficiencies encountered during historical single-stage treatments which experienced high fluid leak-off and low fracture conductivity, as well as a stage identification tracer program utilizing liquid and particulate tracers to identify contribution of each stage as well as interwell communication. Comparison of pressure data, fracturing parameters and tracer recovery to understand the impact of stimulation design on production behavior at the stage level. The study aims to provide practical insights for application of MSF in future cases in similar tight formations. The T formation in the KTB Field is a low permeability, moderate porosity sandstone reservoir. Porosity and permeability values average around 24% and 40 to 150 mD respectively. The reservoir in this field is in Central Sumatra and has suffered from very poor connection even with the fairly good porosity. Hydraulic fracturing has proven vital to unlocking the productive capacity of this reservoir. The major development target, TE-2, is separated from a poorer quality interval T3 by a 10-ft thin shale stringer above. TE-2 is the primary stimulation interval; however fracture modelling and field history show that fracture growth into T3 often takes place during a treatment because of the poor sealing ability of the shale. The fracture gradient is seen to be reasonably consistent in the vertical section, and the stress contrast of around 800 psi allows for reasonable fracture containment.