Real-Time Downhole Monitoring Of Hydraulic Fracturing Treatments Using Fibre Optic Distributed Temperature and Acoustic Sensing

Abstract

In order to make commercial and development decisions effectively and more rapidly, new appraisal and testing technologies are needed to maximize early data collection and subsequent subsurface understanding as quickly as possible. For Unconventional Gas and Light Tight Oil (UGLTO) projects, some of this critical data can be derived from hydraulic fracture stimulation and inflow profiling activities. For UGLTO projects, achieving an optimum hydraulic fracture stimulation is a continuous endeavor beginning as early as possible; and balancing the cost of completion vs. production performance is critical as the completion/stimulation is a large cost component of the well and heavily influences production rate/ultimate recovery. The fast paced development and introduction of new completion technologies requires diagnostic technology that can help us understand stimulation effectiveness, assess new completion technologies, and evaluate which zones are the most productive. One emerging technology, fibre optic distributed sensing has the potential of providing key insights during both the hydraulic fracturing and initial flowback. The passive nature of fibre optic sensors allows intervention-free surveillance, which makes fibre-optic technology an effective platform for permanent sensing in producing wells. Until recently, the oil & gas industry fibre optic sensing technology has focused mainly on temperature (DTS) profiling along the wellbore. In 2009, it was first demonstrated how fibre optic distributed acoustic sensing (DAS) can also be used for downhole applications. Where hydraulic fracture diagnostics based on DTS alone in the past sometimes yielded ambiguous results, the combination of both acoustic and temperature sensing provides a step-change improvement in the ability to perform real-time and post-job diagnostics & analyses of the stimulation. The different horizontal well case studies presented in this paper will illustrate how the combination of DTS and DAS has the potential to enhance the monitoring, assessment, and optimization of openhole and limited entry designed hydraulic fracture stimulation treatments.

Interaction of Multiple Hydraulic Fractures in Horizontal Wells

“…Observations from substantial amounts of field data show that generally 25% or more of the fractures placed are ineffective. In fact, recent fracture stimulation surveillance with advance technologies such as microseismic monitoring and fibre optics temperature and strain sensing [4][5][6] have shown that multiple fractures do not grow and develop in the same way. Some of the fractures are pre-maturely 'terminated' during the treatment.…”

Temperature-Prediction Model for a Horizontal Well With Multiple Fractures in a Shale Reservoir

“…A major limitation of this method is that these measurement can provide only what happens to the fracture at the wellbore, and it does not provide any information about the fracture when it is father than about 1 to 2 ft from the wellbore (Cipolla and Wright, 2002). Radioactive tracer and production logging techniques are grouped into this method, and recently, the application of the DTS and distributed acoustic sensing technology is examined for the fracture diagnostics in both of quantitative and qualitative analysis (Hoang et al, 2012;Huckabee, 2009;Molenaar et al, 2012;Sierra et al, 2008;Tabatabaei and Zhu, 2012).…”

“…Sierra et al (2008) and Huckabee (2009) applied the DTS data to diagnose the fracture stimulation and evaluate well performance. For shale reservoirs, Gonzalez and Chokshi (2012) presented the DTS application, and recently the DTS technology is used with distributed acoustic sensing techniques for fracture diagnostics in shale reservoirs (Molenaar et al, 2012). …”

Laboratory evaluation of distributed coaxial cable temperature sensors for application in CO2 sequestration well characterization

“…Fiber-optic-based downhole temperature, pressure, strain, and acoustic sensors for petroleum industry application are currently available. [16][17][18][19][20] However, some of their inherent drawbacks need to be addressed when they are considered as an alternative to conventional electronic transducers. Robustness and longevity of the system are the major concerns.…”