CN110593835A - A method for in-situ upgrading and exploitation of shale oil by heating shale oil reservoirs with an electric field - Google Patents

Abstract

A method for in-situ modification exploitation of shale oil by heating a shale oil reservoir through an electric field is applied to the field of oil development. The method utilizes an electric field to heat a shale oil reservoir to in-situ produce shale oil. The method comprises the following steps: selecting a shale oil reservoir with large thickness, moderate organic matter maturity, high abundance and a type biased to crude oil; drilling a series of vertical wells or horizontal wells with proper well spacing aiming at the shale oil reservoir; thirdly, an insulating layer sleeve is additionally arranged between the metal sleeve in the shale oil reservoir and the metal sleeve in the non-shale oil reservoir, and a cable is lowered along the well mouth and connected with the metal sleeve in the shale oil reservoir; fourthly, the well mouth cables are connected with a power supply, and the metal sleeves of the anode and the cathode of the power supply in the shale oil reservoir are ensured to be adjacent; and fifthly, taking the shale oil reservoir as a resistance element, heating the shale oil reservoir by using an electric field, and breaking through the technical bottleneck of shale oil extraction to realize in-situ modification and extraction of shale oil.

Description

A method for in-situ upgrading and exploitation of shale oil by heating shale oil reservoirs with an electric field

technical field

The invention relates to the technical field of petroleum exploration and development, and relates to a method for in-situ upgrading and exploitation of shale oil by using an electric field to heat a shale oil reservoir.

Background technique

China has massive shale oil resources, but horizontal wells, staged fracturing and other technologies are not effective in exploiting shale oil, and breakthroughs in shale oil exploitation technologies are urgently needed. China's shale oil resources are mainly enriched in continental basins, and the application of horizontal wells and hydraulic fracturing technology to exploit shale oil is not ideal. Due to the high cost of drilling and fracturing horizontal wells for shale oil, and the production of shale oil wells is far from economically beneficial, the exploitation of shale oil in my country has basically stagnated in recent years. In the Yanchang Formation of the Ordos Basin, the Permian of the Junggar Basin, the Jurassic of the Sichuan Basin, the Shahejie Formation of the Bohai Bay Basin, the Cretaceous of the Songliao Basin, the Paleogene-Neogene of the Qaidam Basin, the Cretaceous of the Jiuxi Basin, and the Santang Lake Massive shale oil resources exist in mud shale formations such as the Permian in the Basin and the Jurassic in the Turpan-Hami Basin. If a breakthrough can be made in shale oil extraction technology and the economical and efficient extraction of shale oil can be achieved, it will be of great significance to alleviate the contradiction between my country's energy supply and demand, reduce the dependence on foreign oil and ensure national energy security.

Low-frequency electric field heating of shale oil reservoirs is expected to reduce viscosity, pressurize, increase permeability, increase volume, increase production, and reduce costs of shale oil. After large-scale implementation, it is very likely to break through the technical bottleneck of shale oil recovery. my country's shale oil reservoirs are low-porosity, low-permeability, organic-rich and highly plastic reservoirs. The production capacity obtained by relying on their own reservoir pressure decreases rapidly, and the control range of a single well is very limited. Horizontal wells, staged hydraulic fracturing and other technologies have been successful in North America, but they are obviously "unacclimated" in my country, and the cost of high-input drilling and fracturing seriously does not match the oil production. In view of the fact that shale oil reservoirs have a certain amount of highly mineralized formation water, if the shale oil reservoirs are directly used as resistance elements, the wellbore metal casing of the target layer is connected to the ground power supply equipment, and the shale oil reservoirs are heated by a low-frequency electric field. , to raise the reservoir temperature and approach or reach the critical temperature of water, 374.15°C. Then using low-frequency electric field to heat shale oil reservoirs can reduce the viscosity of shale oil, increase reservoir fluid pressure, form fractures to increase seepage capacity, and may promote a small amount of organic matter to generate hydrocarbons, increase shale oil well production and reduce shale oil production costs, namely The shale oil is exploited for viscosity reduction, pressurization, permeation enhancement, increment, production increase and cost reduction. In this way, the exploitation of shale oil does not require large-scale hydraulic fracturing, nor does it require special drilling to place heating pipes, etc., and the hydrocarbon gas produced can be used to generate electricity and continue to heat the reservoir. The approach is expected to result in significant cost reductions, water conservation and reduced environmental impact. Especially in the Ordos, Junggar, Qaidam, Santanghu and Tuha basins in the west, wind energy and solar energy can be fully utilized to reduce or eliminate the phenomenon of "abandoning wind and electricity" in wind and solar power generation. After the method is implemented on a large scale, it is expected to achieve a breakthrough in shale oil recovery.

For this reason, the present invention proposes a method for in-situ upgrading and exploiting shale oil by using an electric field to heat a shale oil reservoir. The method is easy to operate, and can be used in both the diameter section and the water well section, and does not need large-scale hydraulic fracturing of shale oil wells, which saves a lot of cost and water resources. If this method is used to exploit shale oil in oil and gas basins in Northwest China, it can also make full use of the electricity generated by wind and solar energy in Northwest China and avoid the phenomenon of "abandoning wind and electricity".

Contents of the invention

The object of the present invention is to provide a method for in-situ upgrading and exploitation of shale oil by heating shale oil reservoirs with an electric field, so as to realize the in-situ upgrading and exploitation of shale oil, and strive to break through the technical bottleneck of shale oil exploitation.

The technical solution adopted in the present invention is: a method for in-situ upgrading and exploitation of shale oil by using an electric field to heat a shale oil reservoir, which is characterized in that:

Step 1: Select shale oil reservoirs with large thickness, moderate organic matter maturity, high abundance, and oil-generating types;

Step 2: Drill a series of vertical wells or horizontal wells with a well spacing of 20-60m for the shale oil reservoir to ensure that the length of the well section of each well in the shale oil reservoir is equal and parallel;

Step 3: Add an insulation layer casing between the metal casing in the shale oil reservoir and the metal casing in the non-shale oil reservoir, lower the cable along the wellhead and connect the metal casing in the shale oil reservoir;

Step 4: Connect the power to these wellhead cables to ensure that the positive and negative metal casings connected to the power supply in the shale oil reservoir are adjacent;

Step 5: The shale oil reservoir is used as a resistance element, and the electric field is used to heat the shale oil reservoir to realize in-situ upgrading and exploitation of shale oil.

Beneficial effects of the present invention: the present invention uses an electric field to heat a shale oil reservoir for in-situ upgrading and exploitation of shale oil. The method is easy to operate, and can be used for diameter sections and well sections of water wells, and does not require shale Large-scale hydraulic fracturing of oil wells saves a lot of cost and water resources. If this method is used to exploit shale oil in oil and gas basins in Northwest China, it can also make full use of the electricity generated by wind and solar energy in Northwest China and avoid the phenomenon of "abandoning wind and electricity".

Description of drawings

Fig. 1 is a schematic flow chart of the method for in-situ upgrading and exploitation of shale oil by using an electric field to heat a shale oil reservoir according to the present invention.

Fig. 2 is a schematic diagram of a horizontal well arrangement scheme for in-situ upgrading and exploitation of shale oil by heating a shale oil reservoir with an electric field according to the present invention.

Detailed ways

Embodiment 1: As shown in Figure 1 and Figure 2, a method for in-situ upgrading and exploitation of shale oil by using an electric field to heat a shale oil reservoir comprises the following steps;

Step 1: In the Jiyang Depression of the Bohai Bay Basin, select shale oil reservoirs in the Shahejie Member of the Shahejie Formation that are relatively thick, with moderate organic matter maturity, high abundance, and oil-generating types;

Step 2: Drill two horizontal wells with a well spacing of 30m in the shale oil reservoir of the third member of the Shahejie Formation in the Jiyang Depression to ensure that the lengths of the two horizontal wells in the shale oil reservoir are equal and parallel;

Step 3: Add an insulating layer casing between the metal casing in the shale oil reservoir and the metal casing in the non-shale oil reservoir, lower the cable along the wellhead and connect the metal casing in the shale oil reservoir;

Step 4: Connect the power supply to the wellhead cables of these two horizontal wells, and ensure that the positive and negative metal casings connected to the power supply in the shale oil reservoir are adjacent;

Step 5: The shale oil reservoir is used as a resistance element, and the electric field is used to heat the shale oil reservoir to realize in-situ upgrading and exploitation of shale oil.

Claims (1)

1. A method for in-situ modification and exploitation of shale oil by heating a shale oil reservoir by an electric field is characterized by comprising the following steps:

step 1: selecting a shale oil reservoir with large thickness, moderate organic matter maturity, high abundance and a type biased to crude oil;

step 2: drilling a series of vertical wells or horizontal wells with the well spacing of 20-60m aiming at the shale oil reservoir, and ensuring that the well sections of each well in the shale oil reservoir are equal and parallel in length;

and step 3: a transitional insulating layer sleeve is added between the metal sleeve in the shale oil reservoir and the metal sleeve in the non-shale oil reservoir, and a cable is lowered along a well mouth and connected with the metal sleeve in the shale oil reservoir;

and 4, step 4: connecting a power supply to the well mouth cables to ensure that metal sleeves of the anode and the cathode of the power supply in the shale oil reservoir are adjacent;

and 5: the shale oil reservoir is used as a resistance element, and the shale oil reservoir is heated by an electric field, so that in-situ modification and exploitation of shale oil are realized.