Improved DTS profiling model for horizontal gas wells completed with the open-hole multi-stage fracturing system

The fiber-optic distributed temperatrue sensor (DTS) has been used for flow profiling in horizontal multi-stage fractured wells, and several reservoir/wellbore coupled thermal models were developed. Although these theoretical models are applicable only to some specific scenarios, the industry has realized the great potential of DTS for production prediction in unconventional resources. This paper presents a DTS flow profiling case for a horizontal multi-stage fractured well in tight gas reservoirs with open-hole packer completion scenarios by applying a newly improved theoretical model. In this paper, we extended the conventional semi-analytical wellbore-fracture-reservoir coupled flow/thermal model which have been developed for cased, perforated, and multi-stage fractured wells, by considering the special feature of the openhole packer completion scenario. Since the formation fluid flows first through the fracture into the open-hole annular space between the formation and the production liner, and then flow along the annular space until meeting the frac port on the production pipe, a simulation sub-region was added for representing the open-hole annular space, which helps to understand the flow and heat transfer inside it. The presented model successfully simulated the two-segment flow regime caused by the simultaneous flow and heat transfer in the annular space and the production pipe. In each stage, the DTS temperature data possibly show double drops due to the Joule-Thompson cooling effects at the fractures and frac ports if their locations are not consistent. With the improved model, the synthetic cases were firstly used for studying the temperature characteristics and the effects of gas production rate and frac port location. Then the DTS monitoring data during a three-rate production test in a horizontal multi-stage fractured well in the Erdos Basin of China was simulated and analyzed. The open-hole packer completion was taken into account in the simulation and the gas rate prediction is satisfactory.