Study On The Technology Of Temporal Turnover Volume In Dense Reservoir

As the global consumption of oil and gas resources growing, more and more attention has been shifted to the development of unconventional tight oil and gas resources. In our country, such as Xinjiang, Sichuan and Changqing oil field are widely distributed with tight sandstone reservoir and tight carbonate reservoir. Because of its poor physical property and complex geological conditions, the exploitation of tight reservoirs is difficult, costly and high-risk. The key for economic and effective development of tight reservoirs is stimulation. But conventional fracturing can only form symmetrical fractures, which have limited stimulated volume, cannot release the tight oil and gas resource sufficiently. Thus, it is necessary to apply volume stimulation technology, future achieving three dimensions stimulation of the reservoir. But for some challenging reservoirs with the characteristics of super-thick, super-deep, super-HTHP and high horizontal stress difference, ordinary stimulation technology have limitation, explore new stimulation technology is very necessary. This paper proposes a new idea:use degradable particle and fiber temporarily plugging the fracture, increasing pressure in the wellbore or fracture, to achieve hydraulic fracture reorientation interlaminar, in-fracture and near wellbore. Generate multi-fracture in the longitudinal direction, communicate natural fracture network or form branch fracture on the transverse direction, improving the stimulation volume of tight reservoir significantly. Specific contents are as follows:(1) In this paper, a method of combination theoretical research and experimental research is used to study the temporary mechanism and rule of particle and fiber in fracture. Bridging Particle dosage and filling particle dosage calculation model have been established to optimize the dosage of plugging particle.(2) According to the correlation theories of elasticity and rock mechanics and interaction criteria between hydraulic fracture and natural fracture, this paper studies hydraulic fracture reorientation mechanism and reorientation condition interlaminar and in-fracture respectively. Different reservoir or different reorientation mode have different reorientation mechanism, condition and influence factor.(3) This paper proposes a new fracture reorientation technology-near wellbore reorientation technology, expounds the idea and mechanism of this technology in detail. Establish a calculation model of breakdown pressure for oriented perforating well, analysis the relationship between the breakdown pressure and the perforated angle, horizontal stress difference.(4) Considering the shape of arbitrary fractures, underground stress and fluid pressure distributed in fracture, a mode for specifying stress intensity factor of arbitrary fracture is set up. The propagation criteria and direction for mixed-type fracture are presented. The modes and computation procedures to determine the fracture propagation path and reorientation radius is also provided. (5) On the basis of simulations and laboratory experiments, the paper improves technical ideas of temporary plugging reorientation volume stimulation and gives specific implementation process. Selecting typical well, we carried out on-site verification for temporary plugging reorientation volume stimulation technology.This paper proposes a multi-stage plugging method combined with particle and fiber, establishes a new volume stimulation technology aiming at achieving "interlaminar, in-fracture and near wellbore" composite reorientation. The study provides a new technology for the efficient exploitation of tight reservoir.