Formation damage mechanisms in tight carbonate reservoirs: The typical illustrations in Qaidam Basin and Sichuan Basin, China

Abstract

Formation damage has become a major obstacle to the efficient drilling and economic development for tight carbonate reservoirs with multiscale pore system and plenty of sensitive minerals. This paper critically reviews the potential formation damage mechanisms associated with mineralogy and pore structure, and discusses the common formation damage of tight carbonate reservoirs. Reservoir mineralogy is closely related to fluid/stress-sensitivity damage, formation damage mechanisms of which including mineral dissolution and precipitation, swelling and dispersion, fine detachment and migration, deformation and creep are summarized, and linked to mineral compositions of carbonate reservoirs in Qaidam Basin and Sichuan Basin. Pore system of tight carbonate reservoirs consists of nano-intercrystal, micro-intergranular and oomoldic, and nm-to mm-scale dissolution pores and microfractures, resulting in the diversity of formation damage. Formation damage dependent on pore structure of carbonate reservoirs dominantly refers to fluid sensitivity, phase trapping, solid invasion and stress sensitivity. The commonly-known formation damage including fluid sensitivity, phase trapping and stress sensitivity of tight carbonate reservoirs is discussed in Qaidam Basin and Sichuan Basin. This review provides significant sights into the relationship between formation damage mechanisms and mineralogy and pore structure of tight carbonate reservoirs, and addresses the future work direction for formation damage control of tight carbonate reservoirs.