Production Logging Application in Fuling Shale Gas Play in China

Abstract Production logging play an important role on dynamic production monitoring and post-fracturing evaluation in shale gas horizontal wells, the technique can realize the rules of gas production and water flowback, in addition, understand the downhole dynamic production. However, the applications of production logging in shale gas play are not mature and still face many technical difficulties and challenges in China. This paper proposed the technical roads and methods for production logging in shale gas well in Fuling oilfield based on the analysis of technical difficulties. At first, this paper discussed the optimization of downhole tools transmitted, the coiled tubing is more suitable than tractor for conveying the downhole tools, then analyzed how to determine the coiled tubing diameter, and provided coiled tubing mechanics simulation in a shale gas well. Secondly, we analyzed the selection of well control equipment, mainly focus on the optimization of pressure index of BOP. Thirdly, we analyzed the characteristics of array logging tools that produced by Schlumberger and Sondex, and illustrated the array tools have the potential risks that blocked and destroyed by debris of bridge plug, thereby the borehole cleaning is needed before testing. At last, we researched the calculation principle of flow rate with array tools and analyzed the data interpretation process according to the status of shale gas well and the principle of gas and water mix flow. One case well in Fuling shale gas play shows that it is feasible to use coiled tubing conveyed array tools for production logging in shale gas well. The testing data interpretation results demonstrate the reliability of data interpretation method and the significance of production logging. For the case well, one half (6 stages out of 11 stages) fractures produce gas and the other half contribute nothing. The productive fractures also present different performance and the most predominant fracture contribute 36.47% of the total production. By production logging, not only fracture contribution to total production rate can be obtained, the flow regime and dynamic liquid level can also be determined. The production logging can be helpful for downhole fluid dynamic analysis and production optimization, and it may partly help the design of horizontal laterals and fractures scenarios.