| Carbonate rock dissolution refers to the process and results of interaction between flowing erosive fluid and
carbonate rocks. Carbonate rock dissolution may take place at surface, burial and deep burial conditions. Dissolution
simulation of carbonate rock is to reproduce the process and results of carbonate rock dissolution under simulating
formation environment, which is an important method to study the favorable conditions and distribution rules of scale
dissolution of carbonate reservoir. Since 1930s, many carbonate dissolution experiments have been conducted by
researchers in China and abroad. The technology of dissolution simulation of carbonate rock mainly goes through three
stages: surface dissolution of rock under relative low temperature and low pressure, surface dissolution of rock under
high temperature and high pressure, and internal dissolution of rock under high temperature and high pressure. The
CNPC key laboratory of carbonate reservoir has designed the high temperature ＆ high pressure dissolution dynamics
simulation apparatus, and developed the carbonate dissolution simulation technology which consists of functions of rock internal dissolution, rock surface dissolution, visual and analysis in situ under high temperature and high pressure.
Experiments of temperature window and pore evolution pattern of carbonate rock burial dissolution were done by using
the high temperature ＆ high pressure dissolution dynamic simulation apparatus. The results of experiments with highsalinities fluid show that the dissolution quantity of carbonate rock has the characteristics of slow declining- slow risingfast declining. Because of the action of two opposite ionic effects in high-salinities fluid, 80~110 ℃ is the favorable temperature window for carbonate rock burial dissolution. The comparative dissolution simulations of five types carbonate rocks of interparticle pore, intercrystalline pore, dissolved pore - dissolved vug, oolite moldic pore and
growth-framework pore, indicate that the connecting pore is the prerequisite and favorable place for the occurrence of buried dissolution, and the difference of internal fabric of carbonate rocks will further increase the complexity of
reservoir space in the combination of pores, vugs, and fractures. |
