Exploitation method for wax precipitation oil reservoir

Abstract

The invention discloses an exploitation method for a wax precipitation oil reservoir. The method comprises the step of adding a chemical agent and thermal fluid into an oil layer to make crude oil in the oil layer smoothly seep into an oil well and then rise to the ground surface. The method has the advantages of effectively solving the problem of wax precipitation of the crude oil in the oil layer and exploiting the wax precipitation oil reservoir, greatly reducing the exploitation cost of the wax precipitation oil reservoir, prolonging the production period and increasing the yield of the oil well and enhancing the final recovery efficiency of the oil reservoir, along with easy implementation, safety and reliability and obvious economic benefit.

Description

technical field [0001] The invention relates to a crude oil recovery method, in particular to a wax analysis type oil recovery method. Background technique [0002] At present, in crude oil production and exploitation, it is inevitable to exploit wax-type oil reservoirs. This type of waxy oil reservoir or because the original temperature is less than or equal to the waxy temperature of the crude oil contained in the oil reservoir, the contained crude oil has produced or precipitated wax crystals under the original conditions of the reservoir; or although this type of waxy oil reservoir is originally The temperature is higher than the wax precipitation temperature of the crude oil contained in the reservoir, but when the contained crude oil seeps in the reservoir, the temperature of the crude oil will be lower than the wax precipitation temperature due to the vaporization and heat absorption of light hydrocarbons and natural gas. Wax crystals are produced or precipitated in ...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages when directly applied to wax-type oil reservoirs: first, it is severely restricted by the complexity of the geological conditions of the oil reservoirs, and it is difficult to inject steam; It is difficult to use a large amount of high-temperature and high-pressure steam in a waxy oil reservoir; third, the temperature of the entire waxy oil reservoir and the crude oil must be kept much higher than the waxy temperature of crude oil during the entire oil recovery process, so not only must a large amount of steam be consumed , and because the heat capacity of the reservoir is huge, the loss of heat dissipation is serious and unavoidable, it is difficult to guarantee the reservoir temperature; fourth, the steam method is complicated, and it is difficult to control the steam temperature, dryness and reservoir temperature field; fifth, 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 expensive but also less effective, and the high steam temperature will cause serious thermal expansion and contraction of the wellbore of ordinary oil wells, which will cause It will cause great damage to the wellbore structure of ordinary oil wells. The production test proves that it is difficult to directly use high-temperature steam above 200°C in ordinary oil wells; Sixth, in order to solve the problem of water scaling during steam production, it is necessary to specialize the water used to generate steam. softening, resulting in a substantial increase in the cost of steam production; Seventh, the generation 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, cementing, and well completion, resulting in The cost of oil production has risen sharply, and the energy consumption has increased significantly

The direct application of this method to wax-type oil reservoirs has the following defects: First, due to the severe constraints of the geological conditions of the reservoir, the survival rate and reproduction rate of microorganisms in wax-type oil reservoirs are low, resulting in the limited ability of microorganisms to consume wax molecules. The method has limited effect on crude oil with high wax content; second, microorganisms need a long breeding period to effectively reduce the wax content of crude oil in the reservoir and then reduce the wax precipitation temperature, so this method will lead to a significant reduction in the effective production time of the oil well

[0019] 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 highest water temperature is already lower than 100°C due to heat loss from the ground and the wellbore; since the porosity in the oil layer is difficult to exceed 30%, and the melting of wax It is a heat-absorbing 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 wax temperature after the hot water enters the oil layer, and cannot effectively melt the wax crystals in the oil layer

[0020] 2) The water used in this method does not have the function of reducing the wax precipitation temperature of crude oil. When its temperature in the oil reservoir is lower than the wax precipitation point of crude oil, it cannot inhibit the growth of wax crystals and block the pores of the oil reservoir; on the contrary, if the water temperature entering the reservoir Lower than the waxing temperature of crude oil in the oil layer, it will further aggravate the waxing problem of crude oil

[0025] If 80°C hot water enters the eastern oil layer, the temperature of the oil layer can be increased by 4°C at most, from 39.87°C to 44.87°C, which is still lower than its melting temperature of 10.13°C, so it is impossible for the hot water to raise the temperature of the oil layer to the melting point. Wax temperature, even without considering the heat absorption of melting wax, the 80°C hot water cannot effectively melt the wax crystals in the oil layer, let alone effectively inhibit the wax crystals from continuing to grow and block the pores of the oil layer;

[0026] If 80°C hot water enters the western oil layer, the temperature of the oil layer can be increased by 2°C at most, from 54°C to 56°C, which is still 4°C lower than its melting wax temperature, so it is impossible for the hot water to raise the temperature of the oil layer to the melting point. Wax temperature, even if the heat absorption of melting wax is not considered, the 80°C hot water cannot effectively melt the wax crystals in the oil layer, let alone effectively inhibit the wax crystals from continuing to grow and block the pores of the oil layer

[0027] The production test of this block proves that the water injection method with surface wellhead water temperature of 90°C cannot effectively solve the problem of wax precipitation of crude oil in the oil layer in this block, and this method cannot be popularized and applied in this block

[0028] In short, the comprehensive effects of the above methods are not ideal when developing wax-type oil reservoirs