Application Of Hydraulic Fracturing Technologies To The Shallow Telisa Formation

Abstract

SPE Members Abstract This paper describes the changes that have been made to the stimulation treatments in the Telisa formation over the past year. The Telisa formation in the South Balam Field is a shallow (+/-600 feet), high permeability (10-100 md), laminated sandstone reservoir. The South Balam Field is located near the large Duri Field in central Sumatra. Hydraulic fracturing was initiated in the Telisa formation at South Balam Field in 1990. Due to the shallow depth of Telisa formation surface treating pressure are typically 400 to 600 psi. These low pressure make pressure analysis very difficult. In many instances only 100 psi of net pressure is seen during the treatments. It is difficult to measure fluctuations in net pressure using only surface data. This has prompted the use of bottom hole pressure recorders with surface read-out which are more accurate and have higher resolution. The pressure recorders are hung inside tubing approximately 100 feet above the perforations, which eliminates pipe friction during the treatment analysis. The treatment are pumped down the annulus. Minifracs were performed and analyzed using bottom hole pressure data to determine fluid efficiency, fracture closure pressure, and leakoff characteristics. Results of these tests have resulted in job modifications regarding pad and treatment sizes. History matching of treatment pressures, both post-frac and in real-time, have been performed using a hydraulic fracture simulator to determine created fracture geometries. Low level radioactive isotope tracer material was used to tag the treatments for determining the fluid and proppant distribution throughout the pay interval. The accumulation of this data indicates that hydraulic fractures in the Telisa formation are not horizontal, as expected for this shallow depth, but are vertical in orientation. Additional treatment changes which were incorporated to increase fracture conductivity include pumping higher proppant concentrations, pumping increased proppant sizes and using higher quality proppant. This paper indicates techniques and results which can be applied to other shallow high permeability sandstone reservoirs. Introduction The Telisa is the shallowest producing horizon in the South Balam Field, at an average depth of 600 feet, which is located approximately 50 km northwest of Duri Field in central Sumatra. Figure 1 is a structure map on top of the Telisa horizon. P. 277