The reservoir physical properties of low/ultralow permeability reservoir formation vary largely, in order to develop effectively, many well completion methods are required, among which perforation, compound perforation and dynamic negative pressure perforation are the most important well completion methods. The conventional testing technology can no longer satisfy the evaluation of low permeability and ultralow permeability reservoirs, such as the interpretation rate of conventional test data of low permeability and ultralow permeability reservoirs is generally less than 30%. At present, the commonly used well testing analysis software is based on the conventional Darcy flow model method of medium and high permeability reservoirs, the influence of starting pressure gradient, pressure sensitivity effect and the completion mode are not include in, which makes the error of test results large. In order to ensure the output and accuracy of the basic parameters such as formation pressure, permeability and skin factor, it is of great significance to study the influence of various perforation methods on the development of low permeability reservoirs, to realize the fine description of reservoir distribution characteristics and to accurately predict and evaluate the effect of measures, so as to formulate a reasonable development scheme.

Study on perforation mechanism of low permeability and ultralow permeability reservoirs

Based on the calculation of explosion flow field of fire and explosive, the explosive deflagration reaction rate equation and equation of state are analyzed for the special lithology of low permeability and ultralow permeability reservoirs.

Study on formation production optimization seepage theory

Based on the seepage equation of oil gas and water in low permeability and ultralow permeability reservoirs, combined with the high pressure physical parameters of fluid in the formation, the coupling problems of formation, hole and microfracture are analyzed, and the formation seepage equation based on perforation and micro fracture is established.

Perforation technology and parameter selection optimization method

Through the research and analysis of the influence of perforation parameter selection on productivity, according to the number and dosage of perforation bullet, combined with casing structure, cement ring properties, rock characteristics and fluid influence, the safety of wellbore is determined, and the optimal perforation scheme is provided according to the production or economic benefit by optimizing the parameters such as perforation gun type, bullet type, phase, pore density and so on. According to the optimal scheme, the formation productivity is predicted, which provides a theoretical basis for the optimal design of perforation parameters.