ABSTRACT
In the process of oil and gas well drilling and completion, under the action of positive pressure gradient or self-absorption, drilling and completion fluid solid phase particles block the reservoir pore and form the filter cake. The filter cake plays a vital role in reservoir protection, and is closely related to the oil and gas well productivity from cake formation to remove. The filter cake is always expected to be thin, tough, with low permeability and easy to remove. Many scholars made a lot of research from the filter cake layer structure, space truss structure, pore structure and the structure of fractal structure of filter cake. However, the researches on the structure of the filter cake are mainly conducted qualitatively at home and abroad, while the quantitative research progress is slow. At the same time, the research on the relationship between the filter cake structure and its performance is also relatively weak. In recent years, with the wide application of horizontal wells, it has called widespread attention on how to effectively remove filter cake in order to improve the oil and gas well production capacity at home and abroad. The widely-used filter cake removal technology mainly includes natural clear, mechanical removal, chemical removal and biological removal technology currently. Among them, the biological removal technology is developed in recent years as a new type of filter cake removal technology. With the further development of mud cake removal technology and downhole filter cake removing circumstance with increasing complexity, a single filter cake removal technology cannot completely meet the requirements. The filter cake removal technology is developing in the direction of the composite to clear, in order to obtain ideal filter cake removal effect.