Exploration and Application of Aftereffect Compound Perforation Technique in Low-porosity & Low-permeability Reservoirs in Offshore Fields

The requirements of low-porosity and low-permeability reservoirs to perforating technology are high in offshore fields. Conventional perforation technique has damage zone near the bore,which leads to increase flow resistance, decrease productivity and influence the exact analysis of formation testing in exploration wells. The aftereffect compound perforation technique combines conventional perforation and aftereffect body,which produces two-stage work to improve hole geometric shape. Perforating flow efficiency test and ground concrete target perforating test are carried out. Compared with conventional perforation technique, the flow efficiency of aftereffect compound perforationis increased by 38%, penetration depth increased by 17%, diameters increased by 22%, pore volume increased by 45%. There are obvious network-like micro-cracks formed around the pores which could recover formation permeability. The downhole dynamic test is used in the perforation to measure pressure, temperature, horizontal and vertical impact force. The result will supply the reliable assurance for the evaluation of perforating parameters optimization, string safety and wellbore integrity evaluation. The technique has been successfully applied in formation testing and completion of well M1. Notable effect of well evaluation and testing in low-porosity and low-permeability reservoirs has been obtained.