Gas Reservoir Performance in Abnormally High Pressure Carbonates
SPE Gas Technology Symposium
Traditionally, it is believed that the production index curve (PIC) of abnormally high-pressure (AHP) gas reservoir is a curve with sectional downward bend. But the traditional view often contradicts with what is observed in production practice. To solve the contradiction, this paper carries out depletion production experiments with long-core displacement on AHP gas reservoirs in Miocene Huangliu Formation, Dongfang (DF) area of Yinggehai Basin. The cores were collected from two wells in the
... two wells in the study area, and temperature and pressure of the local formation were used in the experiments. Two sets of experiments were conducted, one without aquifer and the other with different aquifer volumes. The results analysis shows that: (1) The PIC of water-drive gas reservoir is generally a smooth convex, which eventually intersects the cumulative gas axis at the dynamic OGIP point; The PIC convexity is positively correlated with aquifer volume. (2) The AHP gas reservoir is a special gas reservoir with finite aquifer, and the traditionally view that the PIC of the AHP gas reservoir with sectional downward bend is incorrect. (3) Piston-like displacement features were observed in the experiments. The larger the aquifer, the more the energy retained in the gas reservoir, and the higher the recovery ratio at the same abandonment pressure. It is concluded that, to push up the recovery ratio, balanced development should be pursued in water-drive gas reservoir to ensure stable uplift of gas-water contact.