Exploitation method of thick oil type oil deposit

Abstract

The invention discloses an exploitation method of a thick oil type oil deposit, which comprises the following steps of: adding a chemical agent and hot fluid into an oil layer, enabling crude oil in the oil layer to be successfully seeped to an oil well and then enabling the crude oil to be raised to the ground from the inside of the oil well. The invention has the following advantages that: the invention can effectively solve the problem of phase precipitation of the asphaltene of the crude oil in the oil layer, can effectively exploit the thick oil type oil deposit, lowers the exploitation cost of the thick oil type oil deposit greatly, prolongs the production period of the oil well, increases the yield of the oil well, enhances the final recovery ratio of the oil deposit and has easy execution, high safety and reliability and obvious economic benefit.

Description

technical field [0001] The invention relates to a crude oil recovery method, in particular to a heavy oil type reservoir recovery method. Background technique [0002] At present, in crude oil production and exploitation, it is inevitable to exploit heavy oil reservoirs. As stated in "Oilfield Chemistry" page 175, line 13-14 of the 1st edition printed by Petroleum University Press in July 2000, "the thick oil is mainly due to the colloid and asphaltene content in the oil. High. The higher the colloid and asphaltene content in crude oil, the higher the viscosity of the oil”; and because the asphaltene in heavy oil can form an asphaltene phase that is insoluble in oil and water; if the heavy oil reservoir The original temperature or the temperature at the time of production seepage is less than or equal to the asphaltene phase precipitation temperature of the heavy oil contained in the reservoir, and the contained heavy oil will precipitate the asphaltene phase in the reservo...

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Problems solved by technology

The direct application of this method to heavy oil reservoirs has the following defects: first, it is severely restricted by the complexity of reservoir geological conditions, and it is difficult to inject steam; It is difficult to use a large amount of high-temperature and high-pressure steam in heavy oil reservoirs; third, the temperature of the entire heavy oil reservoir and the crude oil must be kept much higher than the asphaltene phase precipitation temperature of crude oil during the entire oil production process. There is a large amount of steam, and because of the huge heat capacity of the reservoir, the loss of heat dissipation is serious and inevitable, and it is difficult to guarantee the reservoir temperature; the fourth is that the steam method is complicated, and it is difficult to control the steam temperature, dryness and reservoir temperature field; fifth, the The method requires the higher the temperature of the steam, the better. The higher the steam temperature, the lower the corresponding cost. The steam below 200 °C is not only costly but also poor in effect, and the high temperature of the steam will cause serious thermal expansion and contraction of the wellbore of ordinary oil wells. , will cause great damage to the wellbore structure of ordinary oil wells. Production tests have proved that it is difficult to directly use high-temperature steam above 200°C in ordinary oil wells; Special softening will lead to a substantial increase in the cost of steam production; Seventh, the production of steam requires a large amount of energy, and a special thermal recovery well structure design must be adopted, which will double the construction costs of oil well drilling, well cementing, and well completion. As a result, the cost of oil production has risen sharply, and energy consumption has increased significantly

[0014] 1) If this method is used to only add the surfactant aqueous solution into the wellbore and not into the oil layer, this method can only solve the problem of the wellbore of the oil well, but cannot solve the problem of asphaltene phase precipitation of crude oil in the oil layer of the heavy oil reservoir, so it cannot be effective Solve the oil layer seepage problem caused by asphaltene phase precipitation;

[0015] 2) If the aqueous surfactant solution is added to the oil layer by this method, since the aqueous surfactant solution cannot effectively melt the asphaltene phase in the oil layer, this method cannot effectively solve the problem of the asphaltene phase precipitation of crude oil in the oil layer, so it cannot effectively solve Seepage problem in oil layer caused by asphaltene phase precipitation

[0018] 1) The maximum temperature of the water used in this method on the ground does not exceed 100°C. When entering the oil layer, the maximum water temperature is already lower than 100°C due to heat loss from the ground and the wellbore; because the porosity in the oil layer is difficult to exceed 30%, and the asphaltenes Phase melting is an endothermic process, which will further reduce the water temperature; relevant calculations show that it is difficult to ensure that the temperature of the oil layer is higher than the melting temperature of the asphaltene phase after the hot water enters the oil layer, and the asphaltene phase in the oil layer cannot be effectively melted.

[0019] 2) The water used in this method does not have the function of reducing the precipitation temperature of crude oil asphaltene phase. When its temperature in the oil reservoir is lower than the precipitation temperature of crude oil asphaltene phase, it cannot inhibit the growth of asphaltene phase and block the pore throat of the oil reservoir; on the contrary , if the temperature of the water entering the reservoir is lower than the asphaltene phase precipitation temperature of crude oil in the oil layer, the problem of asphaltene phase precipitation in crude oil will be further aggravated

[0024] If 80°C hot water enters the eastern oil layer, the temperature of the oil layer can be increased by up to 4°C, from 39.87°C to 44.87°C, which is 13.13°C lower than the asphaltene phase precipitation temperature, so the hot water cannot raise the oil layer temperature to Asphaltene phase melting temperature, even if the asphaltene phase melting and endothermic problem is not considered, the 80°C hot water cannot effectively melt the asphaltene phase in the oil layer, let alone effectively inhibit the asphaltene phase from continuing to grow and block the pore throat of the oil layer;

[0025] The production test in this block proves that the water injection method with surface wellhead water temperature of 90°C cannot effectively solve the problem of asphaltene phase precipitation of crude oil in the oil layer in the eastern reservoir of this block, and this method cannot be popularized and applied in the eastern reservoir of this block

[0026] In short, the comprehensive effect of the above methods in the exploitation of heavy oil reservoirs is not ideal