Stratified fracturing method suitable for sandstone oil and gas reservoirs

Abstract

The invention provides a stratified fracturing method suitable for sandstone oil and gas reservoirs. The stratified fracturing method comprises the following steps that fracturing fluid is pumped intoa reservoir containing N layers, and each layer is sequentially fractured according to the sequence of minimum horizontal principal stress of a single layer section from small to large; the sum of the induced stress and the minimum horizontal principal stress generated in the single layer section which is fractured to be open is greater than the fracture pressure of a single layer section which is not fractured to be open; the N is selected from natural numbers between 2 to 5; and after all the N layer sections are all fractured to be open, fracture formation and sand addition are carried outfor all the fractured layer sections in a unified mode. According to the stratified fracturing method, on the premise of not increasing the cost of fracturing equipment, fracturing materials and thelike, the induced stress generated in fracturing construction is fully used for realizing multi-layer stratified fracturing, and the fracturing degree and fracturing reconstruction effect of each layer are improved to a maximum extent.

Description

technical field [0001] The invention relates to the technical field of oil and gas reservoir hydraulic fracturing stimulation, and more specifically relates to a layered fracturing method suitable for sandstone oil and gas reservoirs. Background technique [0002] Multi-layer fracturing of vertical wells in sandstone oil and gas reservoirs generally adopts layered fracturing technology. Compared with conventional general fracturing technology, layered fracturing can not only effectively avoid construction risks, but also greatly improve the degree of reservoir fracture and avoid support. It has many advantages, such as the ineffective support of the agent, saving the cost of fracturing materials, shortening the construction operation cycle, reducing the operation cost, and short production cycle. [0003] In recent years, layered fracturing technology has developed rapidly, and layered fracturing technologies for different reservoirs and processes have basically been formed....

AI Technical Summary

Problems solved by technology

[0005] Layered fracturing method of the pitching method: Although the requirement for the stress difference of the pitching method is enlarged to more than 3MPa, the pitching method is blind. For example, which layer will be crushed first cannot be accurately predicted, and the support profile cannot be effectively controlled; the number of pitching balls is designed There is uncertainty; in addition, the mutual interference of the fracture expansion of the two fracturing before and after the pitching, and the gel breaking of the previous fracturing fluid (the fracturing fluid in the fracture first breaks the gel first), resulting in the fracture of the previous fracturing The large proportion of internal proppant settlement, the unreasonable support profile, and the increased filtration damage of the reservoir by the fracturing fluid filtrate all affect the post-fracturing production to varying degrees

[0006] Packer mechanical layered fracturing method: Although the packer method can ensure that all layers are decompressed, the fracturing by the packer method generally has the problem of over-displacement and is difficult to overcome, resulting in an unsatisfactory fracture support profile. Seriously affect the production after fracturing; in addition, the packer method has the risk of tool entry failure and sand stuck pipe string

[0007] Due to the characteristics of each layered fracturing technology, each technology has its own applicability, but there are also some limitations, so it is still necessary to continuously improve and develop layered fracturing technology

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