Elastic Properties of Deep Carbonate Gas Reservoirs

Deep carbonate reservoirs are characterized by crystalline structure, and their pore spaces are usually reformed by dissolution. We have collected over 80 carbonate samples from wells. Porosities, permeabilities and densities were measured by using standard techniques. We employed the pulse transmission technique to measure the velocities on dry and wet samples. Besides, by the means of XRD, TOC analysis, FESEM, and Micro-CT, we also obtained the imformation about mineral composition, bitumen content and pore structures. These samples generally can be divided into three types, including matrix-pore dolomite, dissolved-pore dolomite and vuggy dolomite. We analyzed the effects of porosity, pore structure, bitument content, fluid type on elastic properties. Different types of sample show great differences in pore geometry and pore connectivity, which influences the sensitivity of velocity to porosity and fluid type. If the residual bitumen is treated as water, the effect of pore structure on velocity-porosity relation and fluid sensitivity will be clearer.