Fiber-Optic Revelations From a Multistage Openhole Lateral Fracturing Treatment

Abstract

Fiber-optic measurements are being applied more and more in unconventional reservoirs. Coiled tubing (CT) fiberoptic real-time telemetry can be used to perform distributed temperature sensing (DTS) and distributed acoustic sensing (DAS) providing valuable insight into how fracturing treatments have performed. Changes in vibration during pumping operations can indicate which zones are taking fluid. Fluctuations in observed temperature during pumping can indicate which zone(s) accepted fluid, and warm backs after pumping can determine the qualitative volume of injected fluid that went into each interval.Typically, fiber-optic cables are permanently installed on the outside of casing to monitor the fracturing treatment, other injection operations, and/or production profiles. This methodology presents many risks during installation and well operations, such as pinching, tearing, or perforating the cable or loss of coupling, resulting in poor data resolution. Additionally, once the cable is installed, it is restricted to the specific well or wells installed, hence it cannot be used in other wells or applications as it is a permanent component of the completion. As a result, the technical and commercial value of this technique requires high scrutiny, close supervision, and consideration based on the risk and cost versus value. The case study presented in this paper demonstrates an alternative approach. CT fiber-optic realtime telemetry was used to observe fluid flow along an openhole lateral drilled in an unconventional formation.The study well was produced for a period of time prior to the fracturing operation and the well was then stimulated in a continuous treatment utilizing degradable particulate and fiber material for diversion. Injection tests were performed prior to the fracturing operation allowing the real-time measurements to determine where depleted zones were and what type of rate needed to be pumped for fluid to flow further down the lateral. This allowed for the job to be modified to better target-stimulate the well. Various diversion recipes were pumped both prior to and in between proppant-laden fracturing treatment stages to encourage stimulation along a greater portion of the lateral. CT fiberoptic real-time telemetry was initially deployed to measure the well under static conditions to determine productive zones along the lateral prior to stimulation. It was then used to determine the relative success of each diversion stage during the stimulation treatment.The diagnostics provided by the CT fiber-optic real-time telemetry allowed for a better understanding and optimization of the diversion recipes than other methods. Results presented in this paper show the lessons learned and best practices moving forward for diverting in openhole fracturing treatments. These lessons learned may also be applied to refracturing treatments. Furthermore, CT fiber-optic real-time telemetry can be used in other wells to fine-tune diverter and fracturing fluid recipes.