Method and well pattern structure for mining oil deposit with nano magnetofluid displacement

Abstract

The invention discloses a method and a well pattern structure for mining an oil deposit with nano magnetofluid displacement. The method comprises the steps that an injection well, four edge wells and four corner wells form a square inverted nine-spot displacement well group; electromagnets are put into shafts of the edge wells and the corner wells; a nano magnetofluid dispersion solution is injected into the injection well; the electromagnets under the edge wells are started; a magnetic flux is adjusted; the electromagnets under the edge wells are closed; oil flow production is started; the electromagnets under the corner wells are started; a magnetic flux is adjusted; the electromagnets under the corner wells are closed; the oil flow production is started; the electromagnets under the edge wells are started; the magnetic flux is adjusted; and the edge wells and the corner wells alternately apply an electromagnetic field and alternately conduct the oil flow production for a certain period according to the sequence. The method for mining the oil deposit with the nano magnetofluid displacement changes an oil displacement direction and a speed of a nano magnetofluid in an oil layer by adopting the alternate magnetic field and an alternate production mode of the corner wells and the edge wells, so that crude oil between injection and production wells is used effectively, the sweep efficiency of an injection medium is improved, and a recovery ratio of the crude oil in the oil deposit is increased.

Description

technical field [0001] The invention relates to a mining method for thin oil and heavy oil reservoirs in the field of petroleum exploitation, in particular to a method for exploiting reservoirs by nanometer magnetic fluid displacement and its well pattern structure. Background technique [0002] According to the classification standard of crude oil viscosity, oil reservoirs worldwide can be divided into two categories, namely, thin oil reservoirs and heavy oil reservoirs. Among them, heavy oil reservoirs refer to the viscosity of degassed crude oil greater than 100 centimeters under reservoir conditions. Reservoirs above the mooring level, and the rest are thin oil reservoirs. [0003] Thin oil reservoirs are usually developed by water flooding. According to incomplete statistics, by the end of 2012, my country's thin oil reservoirs generally entered the period of high water cut and ultra-high water cut, and the comprehensive water cut generally reached more than 85%, but th...

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Problems solved by technology

[0003] Thin oil reservoirs are usually developed by water flooding. According to incomplete statistics, by the end of 2012, my country's thin oil reservoirs generally entered the period of high water cut and ultra-high water cut, and the comprehensive water cut generally reached more than 85%, but the average recovery degree was less than 40%, the water flooding high-permeability channel formed by water flooding for many years has limited effect on further improving water flooding recovery

[0004] Heavy oil reservoirs are usually developed by steam injection huff and puff or steam flooding. Steam huff and puff has the advantages of small periodic steam injection, long simultaneous production period, high periodic oil-steam ratio, and good economic benefits. However, during steam huff and puff development, due to the underground The viscosity of crude oil is high, and the steam injected into the oil layer is greatly resisted by the high-viscosity crude oil, making it difficult for the steam to enter the deep part of the oil layer to heat a wide range of oil layers. Production, steam huff and puff recovery is low, usually less than 20%

Steam flooding technology is usually used as a successor technology after steam huff and puff, but domestic and foreign steam flooding mine field tests show that due to serious steam channeling during steam injection, the effective production degree is low, the oil-steam ratio is low, and the economic benefits are poor

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