|dc.description.abstract||Reservoir monitoring allows petroleum engineers to acquire a better understanding of the phenomenon happening inside a hydrocarbon reservoir under development; multiple methods exist currently to monitor a reservoir, depending on the data required and the studies the data is needed for. In naturally fractured reservoirs with a gas cap present, where the fracture network dominates the fluid flow from the reservoir to the production wells, it is of vital importance to be able to have a continuous surveillance of the behavior of the fluid contacts, in order to successfully plan and optimize the development of the reservoir. A well-documented monitoring methodology consists on installing permanent sensors at open-hole well completions, metering the pressure and temperature outside a production tubing designed to be in contact with all the fluids in the well. With the data gathered through these sensors, and basic knowledge of the reservoir fluid properties, the fluid contacts in the fracture network can be estimated at any time whenever data is available.
An alternate methodology is presented in this document, for those well cases in which the placement of permanent sensors at the well completion is not viable and therefore pressure data outside of the production tubing for the aforementioned well is not available. This thesis proposes two methodologies to calculate the fluid contact by performing a small-aperture orifice to the well completion design at the gas cap level, this modification allows to collect gas inflow pressure and rates data by introducing to the well surface-run tools; A derived mathematical expression is fed with the obtained data to estimate the conditions outside the production tubing at the gas cap level, such correlation is also presented as a series of dimensionless type curves; finally, with the estimated pressure conditions and the corresponding fluid properties, the position of the gas-oil contact is calculated. The methodologies presented can be adapted to different forms of fluid flow through orifices equations in case the reader prefers to use a different one to those selected here; the methodology has to be calibrated before being implemented in the field in order to reduce uncertainty.||en