Perforation fracturing method for longitudinal residual oil dig-down of old well of single-sand body oil reservoir

Abstract

The invention discloses a perforation fracturing method for longitudinal residual oil dig-down of an old well of a single-sand body oil reservoir, which comprises the following steps: perforating a longitudinal oil layer section by utilizing a fixed surface perforation technology, then putting a separate layer fracturing drilling tool, and adopting fracturing working fluid composed of 0.3% of cross-linking liquid, 0.6%-0.8% of degradable fiber, a rigid temporary plugging agent (2mm, 3mm and 4mm) with multiple particle size differences and a 20 / 40-mesh low-density selective wetting proppant (1.5g / cm<3>); fracturing is conducted on the perforation section, injecting fracturing fluid composed of fibers and a multi-particle-size rigid temporary plugging agent, local rapid pressure rise is formed in the near-wellbore zone, the crack net pressure is increased, natural micro cracks are opened, the transformation size is increased, and the purpose of fully using longitudinal remaining oil is achieved; at the later stage of sand adding, a selective wetting agent is added to form a package in a near-wellbore zone, and the water content of an oil well is prevented from rising by utilizing thecharacteristics of oil permeability and water resistance. The technological process is high in operability, low in cost and remarkable in oil field development benefit. The problems that water is prone to being seen in conventional perforation fracturing cracks, longitudinal transformation is not sufficient, and remaining oil is difficult to use effectively are solved.

Description

technical field [0001] The invention relates to the technical field of oil reservoir production stimulation measures for oil and gas field development engineering, and in particular to a perforation and fracturing method for tapping the remaining oil potential of old wells in single sand body reservoirs. Background technique [0002] Some ultra-permeable oil reservoirs in Changqing Oilfield contain more than 60% of the oilfield’s reserves, and the reservoirs are relatively integrated. The initial perforation is mainly in the high-permeability section in the middle and upper parts of the oil layer, with an average vertical perforation degree of 33%. The initial stimulation measures are conventional pressure. After nearly 20 years of exploitation, the controlled crude oil around the main fractures has been basically exhausted. Affected by the vertical heterogeneity of the reservoir, a large amount of remaining oil in the low-permeability section cannot be displaced to the main ...

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Problems solved by technology

Therefore, how to effectively produce the remaining oil in the low-permeability section becomes the key to solve the problem of this type of reservoir. The current conventional refracturing can only restore the conductivity of old fractures, and the stimulation effect is not obvious; Evenly arranged, the fractures can only expand in the direction perpendicular to the minimum principal stress of the reservoir, and the fracture direction cannot be controlled. The fracture direction does not expand radially along the wellbore, so it is easy to cause cross communication with old fractures, affecting the fracturing effect and Drain area

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