Pore effect of dolomite reservoirs based on burial dissolution simulation: A case study of the Lower Cambrian Xiaoerbulake Formation in the Tarim Basin

Burial dissolution is one of the important factors which control the development of dolomite reservoirs, but its effect on porosity is still not clear, which restricts the evaluation and exploration of burial dissolution dolomite reservoirs. This study took arene dolomites, stromatolite dolomites and thrombolite dolomites of the Lower Cambrian Xiaoerbulake Formation in the Tarim Basin as an example, used 0.2% acetic acid solution instead of organic acids of burial environment, carried out dissolution simulation experiments of dolomite reservoirs in the condition of high temperature and high pressure. The results showed three different samples' porosity was improved in different temperatures and pressures, but their permeability increased exponentially. The reservoir space of arene dolomites changed from pores to pores and vugs, while the reservoir space of stromatolite dolomites and thrombolite dolomites changed from pores to pores and solution fractures. It implied that organic acid had a strong solubility to dolomites, and the initial pore structure controlled the final reservoir space type. With the dissolution from homogeneous to heterogeneous, the vugs and solution fractures developed heterogeneously, and reservoir connectivity was partly improved. So, burial dissolution is of great importance in reforming the permeability of dolomite reservoirs.