Thermochemistry auxiliary reinforced steam flooding method

Abstract

The present invention relates to a thermochemistry assistant strengthening steam drive method for thermal recovery of horizontal well using oil-soluble compound viscosity reducer and carbon dioxide. The technique scheme is that: Drilling an horizontal well below the heavy oil reservoir layer, injecting periodically oil-soluble compound viscosity reducer, carbon dioxide liquid and steam in slug injection forms to horizontal well, after shutting in well and opening to blow, continuous oil extraction is operated by the inner lower pump in horizontal well. The present invention can reduce base oil viscosity of super heavy oil reservoir in lower or middle deep layers greatly, reduce steam injection pressure greatly, enhance steam hot wave and range, and enhance period exploitation effect. The scene experiment proves that the average period oil-steam ratio reaches to 0.75, average period oil production is 1800t, the room experiment proves that developing thermochemistry assistant strengthening steam drive in the late period of middle deep layer of super heavy oil reservoir, the final oil reservoir recovery can reach about 40%.

Description

1. Technical field: [0001] The invention relates to an oilfield exploitation technology, in particular to a thermochemically assisted enhanced steam flooding method utilizing an oil-soluble composite viscosity reducer and carbon dioxide to assist the thermal recovery development of a horizontal well. 2. Background technology: [0002] With the massive consumption of conventional oil and gas resources and the rising demand for oil, heavy oil resources have become the main potential for next-stage development due to their wide distribution, huge reserves, and low production rate of reserves. [0003] Domestic heavy oil resources are very rich, and the predicted proven reserves are 80×10 8 Ton. In the currently proven 20.6×10 8 Among the tons of heavy oil reserves, the undeveloped geological reserves are 7.01×10 8 Ton. Most of this reserve is due to: [0004] 1. The viscosity of crude oil is high, especially at 50°C, the viscosity of crude oil is greater than 10×10 4 mPa....

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Problems solved by technology

[0004] 1. The viscosity of crude oil is high, especially at 50°C, the viscosity of crude oil is greater than 10×10 4 mPa.s ultra-heavy oil reservoir, the steam injection process has high seepage resistance, high steam injection pressure, and poor steam injection quality. The existing thermal recovery technology cannot break through the production capacity barrier.

[0005] 2. Oil layers are deeply buried (greater than 1000m) and thin (less than 10m), resulting in increased wellbore and formation heat loss, low dryness of steam injection, small steam heat sweep range, and poor huff and puff effect

[0006] 3. The interlayer is thin and has strong edge and bottom water, which makes it easy for the steam injection process to escape from the pipe, and with the increase of the recovery degree, the edge and bottom water intrusion is serious, which greatly affects the production effect

For example, the patent No. CN101139923A is the carbon dioxide-assisted steam flooding method for developing heavy oil in deep layers. This type of method is mainly used for steam flooding oil production in the later stage of steam stimulation. The applicable reservoir conditions must have low crude oil viscosity, and conventional steam stimulation can achieve ideal results. , which is unrealizable for the medium-deep ultra-heavy oil reservoirs without productivity breakthrough under the current technology

[0009] It goes without saying that open-pit mining technology refers to oil reservoirs with shallow oil layers (generally less than 200m) that can be exploited open-pit. This type of technology is also not suitable for medium-deep ultra-heavy oil reservoirs

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