Oil production technological method for multi-stage plug injection of oil-soluble viscosity reducer and liquid CO2 in deep super-heavy oil

Abstract

The invention discloses an oil production technological method for multi-stage plug injection of oil-soluble viscosity reducer and liquid CO2 in deep super-heavy oil. The oil-soluble viscosity reducer and the liquid CO2 are injected in a four-stage plug injection mode. The injection intensity of the oil-soluble viscosity reducer ranges from 2 t / m to 3 t / m, the injection intensity of the liquid CO2 ranges from 15 t / m to 20 t / m, and the injection ratio of the oil-soluble viscosity reducer to the liquid CO2 ranges from 1:6 to 1:12. The injection speed of the oil-soluble viscosity reducer ranges from 8 m3 / h to 12 m3 / h, and the injection speed of the liquid CO2 ranges from 10 t / h to 15 t / h. In the first stage, the oil-soluble viscosity reducer taking up 40% of the total injection quantity of the oil-soluble viscosity reducer is plug-injected at the injection speed ranging from 8 m3 / h to 12 m3 / h; in the second stage, the liquid CO2 taking up 33% of the total injection quantity of the liquid CO2 is plug-injected at the injection speed ranging from 10 t / h to 15 t / h, and 20% of the oil-soluble viscosity reducer is injected at the injection speed ranging from 8 m3 / h to 12 m3 / h; in the third stage, 33% of the liquid CO2 is injected at the injection speed ranging from 10 t / h to 15 t / h, and 20% of the oil-soluble viscosity reducer is injected at the injection speed ranging from 8 m3 / h to 12 m3 / h; in the fourth stage, 33% of the liquid CO2 is injected at the injection speed ranging from 10 t / h to 15 t / h, 20% of the oil-soluble viscosity reducer is injected at the injection speed ranging from 8 m3 / h to 12 m3 / h, conventional injection is adopted, a high-temperature anti-swelling agent solution is used for substitution, and shut-in and soaking are conducted for 10-15 days before a well is opened for production.

Description

Technical field [0001] The present invention involves deep low -lying ultra -thick oil -cold mining technology in the field of oil mining. Specifically, it is a deep ultra -thick oil multi -stage plugging oil solubility lowering adhesive and liquid CO 2 Oil collection process method. Background technique [0002] More than one -third of my country's crude oil reserves belong to thick oil collection. Due to the material nature of thick oil (high underground viscosity, poor liquidity, high glue and asphalt content) technology.The Island Oilfield Chuxit and the ultra -thick oil collection mainly include the three sections of the East East, Saudi Section and Sanhe Village, with a reserves of 2800 ~ 4500 × 10 4 t.Among them, the three sections of the east are deep, medium and high-thick oil-extraordinary oil; sand three-sand sections are ultra-deep low-hole low-lyon and thick oil-ultra-thick oil, geological reserves of 2500 ~ 4000 × 10 4 t, the hidden depth of the pungent is 200...

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Problems solved by technology

[0003] Heavy oil steam injection huff and puff On the one hand, from the perspective of reservoir conditions, the buried depth of the reservoir is less than 1800m, and the permeability is greater than 300×10 -3 μm 2 (for ultra-heavy oil, the permeability is required to be increased), and the porosity is generally required to be greater than 28%. On the other hand, from the perspective of ground equipment, the current injection critical pressure of ground steam injection boilers is 26MPa, the formation pressure is generally required to be lower than 20MPa. As the depth of the reservoir increases, the formation pressure increases and the dryness of the steam at the bottom becomes lower. According to the prediction of steam injection pressure, when the oil layer (permeability is not less than 800×10 ~ 3 μm 2 ) If there is no water sensitivity in the near-wellbore area or the permeability remains 80% of the original, the pressure can be guaranteed to be lower than 22MPa 5 days before steam injection, when the permeability is only the original At 50% or even 20%, the supercritical boiler (26MPa) cannot meet the steam injection requirements

The super-heavy oil reservoirs in the Sha 3-Sha 4 Member in Kenxi are deeply buried, with high formation pressure, low porosity, strong water sensitivity in the formation, poor steam injection quality, and cannot achieve the effect of steam injection huff and puff thermal recovery

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