Method for predicting permeability of carbonate rock acid fracturing self-supporting cracks

Abstract

The invention discloses a method for predicting permeability of carbonate acid fracturing self-supporting cracks. The method comprises the following steps: collecting basic parameters of carbonate acid fracturing self-supporting cracks; collecting a rock sample to simulate a reaction process of the acid rock, and acquiring a Young modulus and Poisson modulus and a poisson ratio of carbonate rock dissolved by acid; establishing an equation of crack width variation under acid fracturing self-supporting crack stress sensitivity; establishing a gas effective viscosity prediction model consideringthe stress sensitive effect and confined space effect of carbonate acid fracturing self-supporting cracks; and establishing a dynamic prediction model for the permeability of the carbonate acid fracturing self-supporting cracks considering the stress sensitive effect and the influence of the viscosity variation in a micro-nano scale confined space of the self-supporting crack for the gas, acquiring a prediction result of the permeability of the carbonate acid fracturing self-supporting cracks. The prediction model is closer to the actual formation conditions, thereby facilitating accuracy forpredicting the permeability of the acid fracturing self-supporting cracks.

Description

technical field [0001] The invention relates to the field of oil and natural gas exploration and development, in particular to a method for predicting the permeability of carbonate rock acid fracturing self-supporting fractures. Background technique [0002] my country is rich in carbonate rock oil and gas resources, among which marine carbonate rock oil and gas resources are about 385×10 8 t oil equivalent, lacustrine carbonate rock oil and gas resources are about 45×10 8 t oil equivalent, the average proven rate is only about 11%; carbonate rock resources have become an important field of exploration and development in my country. Exploration and development experience at home and abroad show that acid fracturing is a key technology for the effective production of heterogeneous carbonate reservoirs. Acid fracturing is to non-uniformly etch the crack surface by acid liquid to form acid-etched cracks with a certain conductivity. The permeability of acid-etched fractures i...

AI Technical Summary

Problems solved by technology

However, the conductivity of acid-fractured self-supporting fractures in carbonate rocks has the following characteristics: the acid solution will significantly reduce the rock strength during acid fracturing, and the influence of rock strength on the permeability of acid-fractured fractures cannot be ignored; When the fractures are small, the gas slippage effect in the acid fracturing fractures cannot be ignored, and the slippage effect increases as the fractures become smaller; when the gas flows in the micro-nano scale acid fracturing micro-fractures, the viscosity will significantly affect the fracture permeability; During the production process, the decrease of pore pressure leads to the increase of reservoir effective stress, which significantly reduces the permeability of fractures

Current acid fracturing fracture permeability prediction methods cannot measure the impact of the above factors

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