Techbits: Hydraulic Fracturing's Progress Reviewed in Workshop

Abstract

Techbits Approximately 110 professionals converged on Cartagena, Colombia from 11 to 13 August for SPE's Applied Technology Workshop (ATW) titled "Hydraulic Fracturing in the Americas." The international audience, representing the US, Canada, Mexico, Argentina, Venezuela, Brazil, Colombia, Romania, and Indonesia, shared the latest information on how hydraulic fracturing has been applied to improve hydrocarbon recovery during various stages of field life. Two full days of discussion included 21 high-level fracturing topics divided into six subtopics, including high-permeability and low-permeability fracturing, unconventional reservoirs and horizontal well fracturing, fracture design and diagnostics, and advances in fluids and proppants. The ATW's first session on high-permeability fracturing featured discussions by representatives of Schlumberger, Halliburton, and Ecopetrol-ICP. Highlights of the session included an explanation of how the microannulus between cement and rock favor fracture initiation and propagation, and that a wide propped width is required to provide high fracture conductivity and offset embedment. The leakoff areas above and below a perforated interval help contain fracture height growth and facilitate tip screen out and it is important to consider the cool down temperature profile for proper design of fracturing fluids. Packerless multistage CT fracturing in Argentina using hydra-jet technology is performing well in high-permeability formations and in tight gas sands. Frac design in Colombia includes a procedure for selecting candidates considering reservoir and geomechanical data. Also, organic preflushes have shown excellent results when performed prior to main frac treatment. The second session on low-permeability fracturing considered experiences in the East Kalimantan in Indonesia and the Burgos Basin of Mexico. At East Kalimantan, poroelastic hysteresis is severe, and special considerations need to be taken in fracturing these poroelastic sensitive formations. The main considerations are to follow a rigorous planning schedule and demand high-quality services for fracturing operations. Also, an analysis of the history of fracturing in the area is a must before designing new fracturing jobs. Use of microemulsion technologies has showed good results in the Burgos Basin. Another parameter for success includes getting proper values for rock permeability, closure pressure, and rock mechanical properties from minifrac tests. Flowback tests using chemical tracers showed that the recovery of fracturing fluids after a treatment is in the range of 5–20% of the total injected fluids. In a session discussing the fracturing of unconventional reservoirs, experiences from the Barnett Shale were presented. The speakers recommended accounting for the shale's network of natural fractures, and considering a switch to clean fluids when encountering high pressure due to the large increase of sand concentration near the mouth of the fracture. A return of more than 30% of water is a bad sign for the fracturing job.