Well logging via coiled tubing fiber optic infrastructures and its application in shale gas wells

Staged fracturing of horizontal wells by composite bridge plug is the main development mode of domestic shale gas wells. Due to the particularity of wellbore trajectory and well depth configuration caused by optimized fast drilling of shale gas wells, some plug debris still remaining in the wellbore after the plug is drilled out and the complexity of multiphase-flow in horizontal section, the well logging technology for conventional producing profile cannot meet the requirement of shale gas wells. In view of large numbers of shale gas wells, it is urgent to evaluate the drilled and completed wells and fracturing effectiveness in order to guide further fracturing. Gas producing profile logging was carried by FSI (fluid scanning imaging logging instrument) technique, in which optical fiber goes through the coiled tubing with fluid scanning imaging tool hanging below. This technique can obtain real gas and fluid producing profiles and gas and fluid production of all perforation clusters and effectively evaluated the effectiveness of all staged fracturing. In line with the characteristics that production logging is mostly carried out after drilling out the bridge plug in shale gas wells and there is a lot of metal debris in wellbore, so strong magnet was used to remove the debris and drift the well prior to logging, which could improve logging success rate. This method of fiber-optic well logging through coiled tubing has a good prospect of application in shale gas wells.