ABSTRACT:

Hydraulic fracturing technology has evolved greatly in recent years. However, still there exist many uncertainties in fracture diagnosis and fracturing design. Even though Distributed temperature sensing (DTS) has received growing acceptance with its real-time temperature monitoring capability, few models are applicable for the quantitatively interpretation of DTS data, which limits its commercial prospect. The objective of this research is to establish a new workflow that can provide high-resolution quantitative fracture diagnosis by DTS. A fully coupled wellbore/reservoir model is established to simulate the temperature behavior along the wellbore during the shut-in period and production stages. Thermal Embedded Discrete Fracture Model (Thermal EDFM) is integrated with discrete wellbore model to analyze the fluid flow and heat conduction inside complex fracture network. Full physics production analysis is conducted to diagnoses more detailed fracture parameters such as fracture half-length, height and fracture conductivities. By incorporating thermal EDFM into our workflow, the simulator is capable of handling complex fracture networks consist of both hydraulic fracture and natural fracture at field scale. The ultimate goal of this research is to have a deeper understanding of field operation effectiveness and provide improvement for future fracture and well spacing design.

1. Introduction

Flow profiling by temperature field is not a fresh topic in recent years. Trace to the 1960s, Ramey et al. (1962) first proposed the analytical model to qualitatively build up the flow profile based on wellbore temperature distribution. However, due to technical limitations, the temperature measurement device cannot provide the required stable high-resolution temperature data. Thus, these techniques did not attract much attention at that time.

Optical-fiber Distributed Temperature System is recently becoming a more compelling measure device because of its non-intrusive and high-resolution temperature measure capability. While conventional temperature logs can only provide a snapshot of the temperature profile at a specific time, DTS can provide short-term as well as permanent real-time temperature monitoring along the whole wellbore without any intervention on the well operation. The application of DTS includes water and gas breakthrough detection, injection and production fluid profile monitoring. Brown et al. (2000) first introduced the application of DTS on reservoir surveillance in Wytch Farm. This novel new approach has shown its great potential in evaluating well performance. Michael et al. (2001) introduced the application of DTS in conjunction with remotely operated hydraulic Interval Control Valve as a simple and cost-effective method to provide intelligent production management in multi-layer wells.

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