In most shale gas reservoirs in the US, horizontal wells are drilled through the “reservoir” before being hydraulically fractured at a series of discrete zones and placed on production. The subsequent zonal gas production rates have proved highly variable and inconsistent with what are considered to be homogeneous shale gas reservoirs that have been stimulated in the same way. Developing better models and optimizing completion and stimulation techniques for the next well requires identifying which zones worked well, and which zones did not, in the last well. This leads us to the need for production logs. Production logs in shale gas wells are normally recorded 30 to 60 days after the stimulation process has finished. In addition to the produced shale gas, the production log must contend with semistagnant water trapped in the lateral section because of the wellbore trajectory. This paper looks at the wavy stratified and slug flow regimes that are expected in most horizontal shale gas wells and at one possible choice of sensor measurements and sensor distribution for a shale gas production-logging toolstring. In the case of production logs in horizontal gas wells, a number of interpretation steps need to be taken before the raw acquisition curves can be presented as a multiphase flow profile with zonal contributions. This paper shows examples of the workflow, together with snapshots of the holdup and velocity profiles across the vertical pipe diameter and the resulting flow profiles.
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