Method for extracting thick oil

Abstract

The invention provides a heavy oil cold production method applied to the production of oilfield heavy oil reservoirs at normal temperature and pressure. The method is characterized by comprising: a. a step of preparing water-soluble viscosity reducer I; b. a step of preparing viscosity reducer II; c. a step of preparing viscosity reducer III; d. a step of squeezing the water-soluble viscosity reducer I into oil reservoirs; and e. a step of using an oil pumping unit or screw pump lifting equipment to lift produced well fluid and adding the pitshaft viscosity reducer II or the pitshaft viscosity reducer III from an annular space between an oil pipe and an casing pipe of an oil well according to the different viscosity of produced fluid crude oil. The method has the advantages that: a chemical method is adopted to reduce the viscosity of heavy oil in the oil reservoirs and well fluid inside pitshafts, so as to improve heavy oil production effect; and the method has the continuous production time of the oil wells far more than that of the production methods in the prior art, greatly reduces production operation cost, and is obviously superior to the prior heavy oil production technology.

Description

technical field [0001] The invention relates to an oil recovery method in an oil field, in particular to a heavy oil recovery method, in particular to a crude oil recovery method by reducing the viscosity of the crude oil. Applicable to surface crude oil at 50°C, the viscosity of crude oil is 100mPa·s~10000mPa·s; the density of crude oil at 20°C is greater than 0.92g / cm 3 The freezing point is -20°C to 50°C; the colloidal asphaltenes are greater than 25%; the sulfur content is greater than 0.2%; the wax content is greater than 1.0%, which is a problem in the exploitation of normal temperature and pressure heavy oil reservoirs. Background technique [0002] At present, the thermal extraction method is a traditional heavy oil extraction method in oilfields. Its technical core is to reduce the viscosity of crude oil and improve the flow performance of crude oil by heating the oil reservoir or wellbore, so as to achieve the purpose of increasing the production of oil wells. The...

AI Technical Summary

Problems solved by technology

According to the viscosity, freezing point, wax content, colloidal asphaltene content, oil layer thickness, effective porosity, and permeability of crude oil at 50°C of heavy oil, use 0.2% to 2.0% water-soluble viscosity reducer I: 50m 3 ~300m 3 After being squeezed into the oil layer, it solves the problem of formation crude oil flowing into the wellbore; during the wellbore lifting process, when the viscosity of the produced well fluid at 50°C is less than 5000mPa.s, the viscosity reducer II is used to reduce drag and viscosity. When the viscosity at 50°C is greater than 5000mPa.s, use viscosity reducer III, and use viscosity reducer III to reduce drag and viscosity

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