Abstract
The large quantity of batch wells typical in unconventional fields results in per well incremental optimisation gains compounding and significantly improving asset economics. A disposable, cost effective, fibre optic intervention system safely and efficiently provides high quality data to optimise completion design and hydraulic fracturing, calibrate reservoir models and inform future well design. CO₂ efficiency estimates and technology applications in unconventional fields including Vertical Seismic Profiling (VSP), cement cure analysis and hydraulic fracture optimisation are outlined.
The upper end of one or two bare fibre optic cables are fixed inside a light-weight pressure control cap, while the downhole ends are deployed along the wellbore as they unspool from a disposable probe which is pumped along horizontal sections. Distributed Acoustic Sensing (DAS) is used for seismic and micro-seismic fracture analysis, whereas Distributed Temperature Sensing (DTS) is used to monitor well and near wellbore fluids. The high-quality data is used both in real time and subsequent enhanced analysis with disposable fibre having been successfully deployed in over 200 unconventional wells. The high level of acoustic and strain coupling as well as the elevated sensitivity of disposable bare optic fibre produce high quality data, with recent studies favourably comparing disposable fibre data with that obtained by retrievable fibre optic intervention. When compared with well monitoring methods utilising Wireline or Coiled Tubing, the disposable fibre system is extremely light weight with a micro footprint, requires only one person to deploy, has static seals, and does not require a BOP. The result is a low risk, efficient, method of highly sensitive, complete wellbore, fibre optic sensing. The transportation weight saving, reduced survey time, power consumption and reduced personnel requirements result in significant operational CO₂ reductions.
Examples of unconventional well VSP, cement cure analysis, well integrity and fracture optimisation applications demonstrate efficiency gains and impact on asset economics. Unconventional field lifecycle applications of a new disposable fibre optic system are presented along with field optimisation and economic benefits. In addition, an example operation illustrating comparative CO₂ emissions for a hydraulic fracture monitoring application demonstrates disposable fibre CO₂ emissions at 8% of comparable wireline operations.
