Steam-carbon dioxide assisted gravity oil drainage oil production method

Abstract

The invention provides a steam-carbon dioxide assisted gravity oil drainage oil production method, which comprises the following steps of: 1, preheating two horizontal wells in parallel distribution; 2, injecting steam into the upper part horizontal well, and maintaining the original formation pressure in the lower part horizontal well for production; 3, simultaneously injecting the steam and carbon dioxide into an oil layer through the upper part horizontal well, and maintaining the original formation pressure in the lower part horizontal well for production; and 4, stopping the carbon dioxide injection, continuously injecting the steam into the upper part horizontal well, and continuously performing production in the lower part horizontal well. The steam-carbon dioxide assisted gravity oil drainage oil production method has the advantage that through a steam assisted gravity oil discharge technology for reducing the crude oil viscosity, reducing the shaft heat loss and improving the steam enthalpy through adding the carbon dioxide, the recovery ratio of a super-heavy oil reservoir can be improved.

Description

technical field [0001] The invention relates to the technical field of oil recovery in oilfields, in particular to a method for improving the recovery rate of extra-super heavy oil reservoirs by utilizing steam-carbon dioxide assisted gravity drainage. Background technique [0002] Shengli Oilfield currently has proven heavy oil geological reserves of 6.4×10 8 t, of which the proven heavy oil in place in the eastern oil region is 5.89×10 8 t, currently used 4.69×10 8 t; Chunfeng and Chunhui oilfields were successively discovered in the western oil region, with proven geological reserves of 5128×10 4 t, currently used 2471×10 4 t. [0003] In 2011, the Chunhui Oilfield in Shengli Western Oilfield reported 53.33 million tons of controlled and predicted reserves, but it was basically impossible to use the existing technology, mainly due to: [0004] 1. The viscosity of crude oil is extremely high, and the viscosity of degassed crude oil at formation temperature (23°C) is c...

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Problems solved by technology

Due to the large seepage resistance of steam injection and the small heating radius, the conventional steam huff and puff cannot break through the production capacity

[0005] 2. The thickness of the oil layer is not large (10-25m), which is at the lower limit of the conventional steam-assisted gravity drainage technology (15m). Steam injection leads to a large heat loss in the top and bottom cap layers, and the formed steam chamber is small in volume, which affects the development effect

The conditions of heavy oil reservoirs in Chunhui Oilfield in China are quite different from those in foreign countries. One of the main differences is the high viscosity of crude oil in the formation, which is close to 2000×10 4 mPa·s, which is much larger than similar foreign oil reservoirs, resulting in large steam injection seepage resistance and small heating radius, it is still difficult to effectively develop oil reservoirs with such a high viscosity by conventional SAGD development technology

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