A New Method for Quantitative Evaluation of Perforation Damage in Sandstone Targets

High speed metal jet in perforating operation penetrates the oil and gas reservoir and forms a compaction zone near the hole, which causes damage to the porosity and permeability of the reservoir and seriously affects the productivity of oil and gas wells. At present, the traditional experimental methods are mainly used to evaluate the perforation damage. These methods are only a general qualitative and quantitative evaluation of single perforation technology or perforation target compaction zone damage, but they do not analyze and evaluate the damage characteristics and damage degree of sandstone target after perforation from point, line, surface, axial and radial perspectives of perforation channel, and have not compared the damage degree of sandstone target perforated by different perforation technology and charge type conditions. Therefore, a new method for quantitative evaluation of damage degree of sandstone target under different perforating technology or charge type is proposed, which can realize the multi-dimensional perforation damage characteristics of macro plane (point, line, surface) and along the axial and radial direction of perforating channel. Through the experimental study of four groups of perforating charges or perforating technology, the zonal characteristics of perforating target permeability zone are defined, and the quantitative evaluation of sandstone perforation compaction damage degree is realized. It is revealed that negative pressure perforation can reduce the damage rate and thickness of the compacted zone. There is a strong linear relationship between perforation depth and compaction zone area, perforation depth and average compaction thickness. The deeper the perforating charge penetrates, the greater the permeability damage rate of the compacted zone, and it shows logarithmic relationship. The new method has important engineering guiding significance for understanding the damage mechanism of perforated sandstone, quantitative evaluation of damage degree, improvement of perforating technology, optimization of perforating charge and suggestion of reducing perforation reservoir damage.