Cross-Flow Detection and Prediction in Multi-Layered Oil and Gas Reservoirs

In vertical wells in homogeneous reservoirs, the complete formation produces uniformly. But in wells perforated at multiple zones, high permeable zones are depleted faster, causing cross flow in future from low permeable zones, to the depleted high permeable zones. The cross flow can be detected by production logging using flowmeter data in flowing and shut-in conditions, and also temperature data in shut-in conditions. In multi-layered gas producing wells, production with high rate from layers having different permeability and skin values causes non-uniform depletion in drainage area of different producing layers. Also JT cooling affects sandface temperature and causes local cooling around fluid entry points. Therefore although layers might have same static pressure, spinner and temperature data in shut-in conditions look like cross flow, which is only a pressure and temperature stabilization, and not a real cross flow. In these cases, if shut-in time duration was long enough, the apparent cross flow would not be seen.This paper shows application of production logging in detection and prediction of cross flow in multi-layered reservoirs.

Keywords:

Cross flow , production logging , layer pressure , and multi-layered reservoir