Repeated fracturing method for low-yielding and low-efficiency old oil well

Abstract

The invention discloses a repeated fracturing method for a low-yielding and low-efficiency old oil well, and relates to the technical field of repeated fracturing and production-increasing. The method comprises the steps that numerical simulation is conducted to obtain the reservoir remaining oil distribution characteristic according to the reservoir microscopic characteristic, the production performance analysis and the site parameter obtained by testing; a crustal stress field prediction model is established under the development condition of a single well or a well net to obtain the crustal stress field state before repeated fracturing is conducted; a reconstructed reservoir is obtained based on the reservoir remaining oil distribution characteristic; a reconstructed crustal stress field is obtained according to the crustal stress field state before repeated fracturing is conducted; the penetration of artificial fractures of the reservoir is optimized to promote generation of the stress interference between the fractures, and the spreading directions and the complexity of the fractures are changed to obtain a reconstructed underground seepage field; artificial complex fracture net seepage channels are established under the reconstructed reservoir, the reconstructed crustal stress field and the reconstructed underground seepage field to form a fracture control matrix unit; and full-scale water injection is conducted on the reservoir to improve the driving pressure difference of seepage of fluid in the fracture control matrix unit to the fractures.

Description

technical field [0001] The invention relates to the technical field of repeated fracturing stimulation in the development of oil and gas fields, in particular to a repeated fracturing method for low-yield and low-efficiency old oil wells. Background technique [0002] As an important measure to stabilize production and improve development benefits of developed oil and gas fields, refracturing has received great attention in recent years. In the past, the reconstruction of refracturing technology mainly focused on filling and perfecting old fractures, and assisted partial fracture diversion technology, thus forming conventional refracturing and diverted refracturing technologies. The conventional refracturing technology mainly refers to re-propping the original fractures to solve the problems of insufficient initial fracturing scale; while the re-fracturing technology is mainly used to seal the original fractures and open new fractures. [0003] The reasons for low productio...

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Problems solved by technology

[0003] The reasons for low production and low efficiency of old wells in developed oil and gas fields can generally be divided into three categories: first, unbalanced water injection development, manifested as high water cut in the middle and late stages of development, affected by reservoir heterogeneity and fractures, and unbalanced oil well efficiency; First, water injection development is ineffective, which is reflected in the poor physical conditions of reservoirs and fluids, continuous low production after commissioning, and it is difficult to establish an effective displacement pressure system; third, horizontal well depletion development, which is mainly characterized by relatively low initial production and rapid decline, water injection development Cannot achieve effective displacement

For the first two types of old wells, the adaptability of conventional refracturing technology becomes poor: Many old wells in the first type have undergone multiple rounds of refracturing, the water cut rises rapidly after fracturing, the validity period is short, and the oil increment of a single well is increasing. The lower the lower; the first refracturing of the old wells in the second category will have the characteristics of low single well production, stable water content, and short validity period; while the refracturing technology for the third category of horizontal wells is still in the exploratory stage

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