METHOD FOR EXTRACTING OIL AND GAS BY USING BOTTOM WATER RESOURCE OF OIL AND GAS RESERVOIR

Under the action of the movement of the formation crude oil and the production pressure difference, the upper part of the water layer of the oil and gas reservoir is continuously heated within a certain pressure range. The water continues to boil, and the bottom water vapor is used to inhibit and delay the intrusion of bottom water into the oil layer, and the combined driving force of bottom water vapor flooding, bottom hot water flooding formed by the uplift of the oil-water interface and reservoir thermal expansion elastic pressure flooding is used to recover oil and gas.

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Description
FIELD OF THE INVENTION

This method is applicable to the oil and gas exploitation of all oil and gas reservoirs containing edge and bottom water in the oil and gas industry.

BACKGROUND OF THE INVENTION

At present, the impact of edge and bottom water in oil and gas reservoirs on oil and gas development is expressed in two ways: one is, when edge and bottom water is pushed forward as a whole, oil and gas production is promoted; another kind of situation is, edge and bottom water is at the bottom water cone/ridge intrusion and edge water fingering intrude into the oil layer along the high-permeability layer, causing the oil layer to be flooded, the water cut of the production well increases, the oil production declines, the production is seriously affected, and even large-scale oil and gas wells have to be shut down.

In production, in order to prevent the intrusion of edge and bottom water, mostly adopt the method of avoiding edge and bottom water, that is, prevent the premature intrusion of edge and bottom water by avoiding the high-quality oil layer of a certain thickness or a certain distance, which causes certain amount of high-quality oil geological reserves cannot be used. When the shot avoidance is unsuccessful, mechanical or chemical methods are used to find and plug water in production. Most of these methods are short-lived, and some are simply ineffective. Even if the production wells are successfully found water and plugged, new water points are quickly re-appeared, and the end result is often the shutdown of large-scale production wells. Therefore, finding water plugging is complicated and difficult, and wastes a huge amount of resources.

On the other hand, in order to make up for the formation energy deficit, increase the driving energy of oil production, a common method is to utilize precious surface water resources to inject water/steam, and the early stage of steam injection in thermal recovery reservoirs is to increase temperature and reduce viscosity. Steam injection also has the effect of making up for the formation energy deficit and improving the driving energy of oil production. The result of this is that the cost of water/steam injection remains high, while the degree of recovery from the reservoir is limited. At present, the recovery degree of thin oil reservoirs is 60-70%, and the water content is as high as 98%. In heavy oil reservoirs, the average recovery factor is less than 20%, and the calibration recovery factor is less than 35%, and most of the oil and gas reserves are difficult to produce.

CN201480001286.3 proposes a kind of thermal recovery method that utilizes horizontal well to electrically heat oil reservoir edge and bottom water layer, namely provides thermal energy to the whole oil reservoir by heating the upper part of the oil reservoir edge and bottom water layer, and solves the problem of insufficiency of thermal energy injection in superficial heavy oil reservoirs in superficial-middle-deep and low thermal efficiency of steam in deep-ultra-deep reservoirs, not only achieve the purpose of heating and viscosity reduction of formation crude oil, but also form bottom water steam flooding, hot bottom water flooding and reservoir thermal expansion elastic pressure flooding in the production process, effectively make up for the formation energy deficit and improve the recovery degree of the reservoir.

Obviously, this method of utilizing natural formation water not only saves valuable surface water resources, but can effectively utilize the high-quality oil reservoirs in place for avoiding edge and bottom water, and because edge and bottom water and reservoir pore water are homologous, similar in nature, the intrusion of bottom water in the later stage does not significantly change the permeability of the reservoir. This is an in-situ concentrated thermal recovery method for oil reservoirs. The energy utilization efficiency of electric heating bottom water is higher and faster. It is a low-cost, energy-saving, high-efficiency; environmental protection, safe, convenient and fast thermal recovery method. However, like the conventional thermal recovery method, except for steam flooding in ordinary heavy oil reservoirs, this thermal recovery method only uses concentrated preheating thermal energy for oil recovery, that is, using the principle of heating and viscosity—reducing oil recovery, and lacks the power supply support for oil production in the production stage. Therefore, the improvement of the recovery factor is affected.

Except thermal recovery oil reservoir, in unconventional oil and gas reservoir, tight oil and gas reservoir accounts for a large proportion, but its reserve quality is low; has the characteristics of poor reservoir permeability, low abundance and low pressure, and natural energy is insufficient, causing oil well to naturally yield is low. Therefore, hydraulic fracturing, advanced water injection and CO2 gas injection are mostly used in development. However, the cost of hydraulic fracturing is high, the fractures are easy to close, repeated operations are required, and the pressure on environmental protection is high: the water injection method usually affects the permeability of the reservoir due to the expansion of clay minerals in contact with water; and the CO2 gas injection method, there is a problem of carbon emission and environmental pollution, the carbon sequestration problem is not easy to solve.

It can be seen that, to improve the recovery factor of various types of oil and gas reservoirs, the fundamental condition is to control the bottom water cone/ridge advance and improve the driving ability of oil production.

SUMMARY OF THE INVENTION

The overall advancement of the edge and bottom water of an oil and gas reservoir is beneficial to oil and gas production, learning from the ancients' water control methods of dredging and utilizing rather than preventing and blocking, the thermal recovery method of CN201480001286.3 utilizing horizontal wells to electrically heat the edge and bottom water layers of the oil reservoir, and tight oil and gas reservoir fracturing, water injection and gas injection production experience, the purpose of this method is to seek a method for dredging and utilizing rather than preventing and blocking natural formation water resources to improve the production and recovery of oil and gas reservoirs.

The physical properties of water show that: under certain conditions of pressure, the temperature of water heated will rise. When the temperature reaches the boiling point, the water temperature will no longer rise, and if the water continues to be heated, the water will be continuously vaporized to form water vapor. During the whole heating process, the dissolved gas continuously overflows and the higher the temperature, the more dissolved gas overflows.

While heating under relatively airtight conditions, along with the continuous increase of water temperature, the more overflow of dissolved gas, the greater the pressure in the container increases continuously, and the higher the boiling point temperature of water is. The prediction curve of the relationship between water boiling point temperature and pressure under airtight conditions (FIG. 1) shows that the lower part of the curve is the region where dissolved gas is generated, liquid volume expands, and water temperature and pressure are continuously rising. When the water temperature and pressure reach a certain point on the curve, the water boiling point temperature and pressure change move along the predicted curve while the water continues to be heated. When the pressure value at any point on the curve is fixed, and the heating is continued under the pressure relief condition, a large amount of steam will be produced. The higher the temperature is, the greater the dryness of the steam.

A method for exploiting oil and gas by utilizing the bottom water resources of an oil and gas reservoir, characterized in that any oil and gas reservoir containing an edge and bottom water layer has original stratigraphic conditions A (Po, To), and a current development state B (Pi, Ti), according to the oil and gas reservoir geological characteristics, the original formation pressure and fracture pressure of the reservoir, and the prediction curve of the water boiling point temperature and pressure corresponding relationship, the upper part of the edge and bottom water layer of the oil and gas reservoir is continuously heated within a certain pressure range, and under the conditions of movable of the formation crude oil and the action of production pressure difference, the formation water directly enters the boiling state by means of pressure control and voltage stabilization and continuously generates bottom water vapor, which converts the bottom water resources of the oil and gas reservoir into the energy to push upward as a whole, generates a comprehensive oil and gas driving energy based on the area driving force mainly dominated by bottom water vapor flooding and hot bottom water flooding at the entire oil-water interface of the oil and gas reservoir and the reservoir thermal expansion elastic pressure throughout the entire oil and gas reservoir and oil and gas production process, and at the same time makes up for the formation energy deficit in the oil and gas reservoirs. The purpose of the method is to seek ways to divert, utilize rather than prevent and intercept natural formation water resources, and turn the harmful production side of edge and bottom water intrusion into a favorable production side, thereby further improving the level of producing reserve and recovery of various oil and gas reservoirs containing bottom water.

The oil recovery mechanism of this method includes, but is not limited to, the concentrated operation of the reservoir produces scale effect: the formation crude oil is heated up and reduced in viscosity; under the condition of complete vaporization of water, the steam volume of the same quality is about 17 times of the water volume, which is more easily diffused into the reservoir arbitrary micro space and makes up for the formation energy deficit and increases the production degree of the reservoir; the comprehensive oil recovery driving energy mainly based on bottom water steam flooding, hot bottom water flooding and reservoir thermal expansion elastic pressure flooding can improve the final recovery degree of the reservoir.

It can be seen from the curve of the corresponding relationship between water boiling point temperature and pressure that the pressure in the reservoir will continue to increase when the formation water is continuously heated under closed conditions. Therefore, except for tight oil and gas reservoirs, the pressure of general oil and gas reservoirs needs to be controlled below the fracture pressure of the reservoir during the heating process. Regulate the pressure level and keep the pressure stable by releasing the pressure of the production well or adjusting the heating method of the formation water, or both.

Different from the method of CN201480001286.3, the focus of this method is not to preheat the entire oil reservoir, but to keep the formation pressure stable and continuously heat the formation water under the condition that the formation crude oil can move, that is, under the effective condition of steam flooding, so that the formation water can continuously generate a large amount of steam, so as to actively realize bottom water steam flooding, hot bottom water flooding and reservoir thermal expansion elastic pressure flooding during the production process, suitable for including thermal recovery reservoirs development of any oil and gas reservoir with edge and bottom water resources (FIG. 2).

The CN201480001286.3 method is a necessary stage for the formation of bottom water vapor flooding for thermal recovery reservoirs in this method, that is, the stage of preheating the oil reservoir to realize the movement of the formation crude oil. After the preheating of the oil reservoir is completed, the formation under the condition of moving crude oil, the method needs to continue to stabilize the pressure, and then continue to heat the formation water to generate the required comprehensive driving energy for oil recovery. The core idea of the method of CN201480001286.3 is to centrally heat the oil reservoir, to heat up the crude oil to reduce the viscosity, and then to use the initial thermal energy formed in the preheating stage to carry out depressurization production.

The difference from the current steam flooding oil recovery method for ultra-heavy oil reservoirs is that the former oil reservoir is not fully preheated, and most of the crude oil in the formation is immovable. The production effect of steam huff and puff belongs to oil production while preheating, the formation crude oil is produced unevenly in the oil layer, the crude oil production degree is low; and the concept of flooding is not significant. This method continuously heats the formation water under the condition of pressure control and constant pressure under the condition of the movement of the formation crude oil, that is, after the method of CN201480001286.3, so as to generate the bottom water steam, and actively form the bottom water steam flooding, hot bottom water flooding and storage Layer elastic pressure drive.

This method develops and evolves on the basis of the CN201480001286.3 method, and is expanded and applied to the exploitation of all oil and gas reservoirs containing edge and bottom water, including CN201480001286.3 method and its heating process.

Different from CN201480001286.3 method to produce steam flooding and hot bottom water flooding mechanism, this method is to heat formation water in a certain pressure range, continuously heat formation water under a certain stable pressure condition, so that formation water generates a large amount of water steam, bottom water steam flooding can last for the whole production process. In the CN201480001286.3 method, bottom water vapor flooding occurs because the temperature at the bottom of the oil layer is higher than the vaporization temperature of formation water. Under the action of the production pressure difference, the high temperature bottom water invading the oil layer is vaporized to generate bottom water vapor flooding. When the temperature in the oil layer is less than or equal to the formation water vaporization temperature, the intrusion of bottom water can only form hot bottom water flooding. That is, after the centralized preheating, whether bottom steam flooding can be generated in the production stage depends on whether the temperature in the oil layer is higher than the vaporization temperature of water under the current pressure. If the conditions are not satisfied, bottom steam flooding will not occur.

Different from the CN201480001286.3 method, the horizontal well heating method can be, electric heating, and other energy-saving heat sources such as nuclear energy, solar energy, and wind energy can be used.

Consistent with the CN201480001286.3 method, the heat loss of the formation water in this method is within a controllable range. The principle includes: the heated formation water moves upward or obliquely upward under the action of thermodynamics (FIG. 3), and the moving formation water will recycle part of the thermal energy transferred downward: the gravity differentiation characteristics of cold and hot water make the hot water and cold water are distributed in upper and lower layers, which are not easy to mix, and the heat loss is only transferred downward in a small amount of contact heat transfer: the deployment of heating horizontal wells is optimized according to the characteristics of the oil and gas reservoir, and the horizontal wells are set in the edge and bottom water layers of the oil and gas reservoir. The upper part of the horizontal well is close to the oil-water interface, and the heated water is mainly the formation water above the horizontal well, not all of the formation water: the structure of the heated horizontal well can be designed for various energy-saving optimizations to promote the direction of heat energy transfer upward: widespread application of graphene material can reduce heat loss in wire parts: in-situ heating, without the heat loss of the wellbore and pipeline, heating the same volume of high-temperature formation water is more energy-saving than surface water: water has the function of heat storage, which can prolong the stable oil and gas production time and improve the input-output ratio: The heated high-temperature formation water can reduce the heat loss of the oil and gas reservoir, and the formation water that invades the oil layer will not cause cold damage and permeability damage to the reservoir: the reservoir temperature is controllable, with an average of 150˜260° C., which can avoid the cost of crude oil wellbore lifting and gathering and transportation heating.

For different oil and gas reservoirs, the specific implementation method can refer to FIG. 2 in particular:

    • {circle around (1)}{circle around (2)}{circle around (3)}{circle around (7)} suitable for ordinary oil and gas reservoirs with low temperature requirements, ordinary heavy oil and gas reservoirs with low temperature thermal recovery, and high pour point oil and gas reservoirs;
    • {circle around (4)}{circle around (8)}{circle around (10)} suitable for medium and high permeability reservoirs, heavy oil reservoirs and high pour point oil reservoirs that require high temperature thermal recovery;
    • {circle around (4)}{circle around (5)}{circle around (6)}{circle around (9)}{circle around (10)}{circle around (11)} suitable for tight oil and gas reservoirs requiring high pressure steam injection or hydraulic fracturing:
      Special note: For oil and gas reservoirs with high original formation pressure and good oil properties, the temperature requirements are low, and pressure relief production can be prioritized, that is, the reservoir pressure enters the state of B from A, and then, the formation water is heated by controlled pressure and constant pressure under low pressure until effective bottom water steam flooding and hot bottom water flooding are formed:
    • Section I: The reservoir pressure is between (Pi, Po), the formation energy is deficient, the oil and gas reservoir recovery degree is basically lower than the calibration recovery factor, but the power consumption is small;
    • Section II: The reservoir pressure is between (Po, Pb), the formation energy is supersaturated, and the temperature of the oil and gas reservoir is high, which helps to improve the recovery degree of the oil and gas reservoir, and the final recovery degree is much higher than the calibration recovery factor;
    • Stage III: Reservoir pressure≥Pb, reservoir rupture, high temperature and high pressure state is beneficial to low abundance oil and gas overflow, suitable for tight oil and gas reservoirs, and its recovery degree≥calibration recovery factor.

DESCRIPTION OF DRAWINGS

FIG. 1 water boiling point/water saturated steam temperature and pressure corresponding relationship prediction curve.

FIG. 2 Temperature and pressure change trajectory diagram during the heating process of formation water in oil and gas reservoirs

    • A: The original formation conditions of the oil and gas reservoir (Po, To), the original formation pressure Po, MPa; To: The original formation temperature, ° C.;
    • B: Current formation conditions of oil and gas reservoirs (Pi, Ti), current formation pressure Pi, MPa; Ti: current formation temperature, ° C.;
    • Pb: oil and gas reservoir fracture pressure, MPa;
    • Section I: The reservoir pressure is between (Pi, Po), the formation energy is deficient, and the oil and gas reservoir recovery degree is less than or equal to the calibration recovery factor;
    • Section II: The reservoir pressure is between (Po, Pb), the formation energy is supersaturated, and the oil and gas reservoir recovery degree≥the calibration recovery factor;
    • Stage III: Reservoir pressure≥Pb, reservoir rupture, tight oil and gas reservoir recovery degree≥calibration recovery factor;
    • {circle around (1)} continuously heating the formation water to the boiling point temperature of the water under the condition of pressure relief and pressure stabilization in open oil and gas reservoirs, and then continuously heating under the stable pressure to form an effective bottom water steam flooding;
    • {circle around (2)} heating the formation water to the boiling point temperature under the condition of open oil and gas reservoir pressure control, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
    • {circle around (3)} heating the formation water under the condition of pressure control in open oil and gas reservoirs, when the pressure is slightly higher than the original formation pressure, then keep the pressure and continuously heating until effective bottom water steam flooding is formed;
    • {circle around (3)} continuously heating the formation water under the condition of pressure control in open oil and gas reservoirs, when the pressure is close to the fracture pressure of the reservoir, then stabilizing the pressure and heating until an effective bottom water steam flooding is formed;
    • {circle around (5)} continuously heating the formation water under the condition of pressure control in open oil and gas reservoirs to the boiling point temperature of water, and the pressure slightly higher than the fracture pressure of the reservoir, and then continuously heating under constant pressure to form an effective bottom water vapor flooding;
    • {circle around (6)} continuously heating the formation water under the condition of pressure control in the open oil and gas reservoir, when the pressure is slightly higher than the fracture pressure of the reservoir, and then stabilizing and continuously heating until an effective bottom water steam flooding is formed;
    • {circle around (7)} continuously heating the formation water to the boiling point temperature of the water under pressure relief and pressure stabilization conditions in closed oil and gas reservoirs, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
    • {circle around (8)} continuously heating the formation water to the boiling point temperature of the water under the condition of pressure control in closed oil and gas reservoirs, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
    • {circle around (9)} continuously heating the formation water under the condition of pressure control in closed oil and gas reservoirs, when the pressure is slightly higher than the fracture pressure of the reservoir, then stabilizing the pressure and continuously heating continues until an effective bottom water steam flooding is formed;
    • {circle around (10)} continuously heating the formation water under pressure control conditions in closed oil and gas reservoirs, when the pressure is close to the fracture pressure of the reservoir, stabilizing the pressure and continuously heating until effective bottom water steam flooding is formed;
    • {circle around (11)} continuously heating the formation water under pressure control conditions in closed oil and gas reservoirs, when the pressure is slightly higher than the fracture pressure of the reservoir, stabilizing the pressure and continuously heating until an effective bottom water steam flooding is formed.

FIG. 3 shows the movement direction of the water spot below the heating well—the energy saving principle diagram when the formation water is heated.

FIG. 4 shows the numerical model production result diagram of a thermal recovery reservoir applying “A Method for Exploiting Oil and Gas by Utilizing Bottom Water Resources of Oil and Gas Reservoirs”.

 BENEFICIAL DEVELOPMENT EFFECT

Utilizes natural oil and gas reservoir edge and bottom water resources to exploit oil and gas, heats the upper part of the edge and bottom water layer of oil and gas reservoir by controlled pressure method, under the action of crude oil movable condition and production pressure difference, forms effective bottom water vapor flooding, hot bottom water flooding and reservoir thermal expansion elastic pressure flooding, promote the overall upward movement of edge and bottom water energy, divert the harmful side to production of edge and bottom water to the one beneficial to production, and at the same time can fully make up for the formation energy deficit and improve the level of producing reserve and recovery of various oil and gas reservoirs containing bottom water.

The method is the upgrading, improvement and expansion application of CN201480001286.3 in-situ thermal recovery method, which is an effective method for actively utilizing the edge and bottom water energy of oil and gas reservoirs to improve the driving energy of oil recovery, and can utilize bottom water vapor and reservoir expansion to fully compensate for the formation energy deficit of various oil and gas reservoirs, and inject enough heat to heat up the crude oil in heavy oil reservoirs to reduce viscosity and improve the wax precipitation of crude oil in high pour point oil reservoirs, and improve the permeability of tight oil and gas reservoirs by high-pressure steam injection and reservoir overpressure fracturing methods, and increase the driving energy required for oil and gas production by three driving energies, which can effectively improve the production degree and final production degree of oil and gas reservoirs.

This method no longer needs to inject precious surface water resources, no longer needs to find water, water blocking repeated operations, can effectively utilize the high-quality oil-in-place reserves that avoid edge and bottom water, do not need to do sewage treatment, do not need to worry about tightness, do not need to worry about environmental pollution in the problem of crack closure in oil and gas formations. This method utilizes natural formation water resources, uses local materials, and makes the best use of the situation. It is a low-cost, energy-saving, efficient, environmentally friendly, safe, convenient and fast thermal oil and gas recovery method.

Meanwhile, after adopting this method, original water injection or steam injection well can be converted into production well, save production well drilling cost, improve oil reservoir productivity: Oil and gas reservoir temperature is controllable, and high temperature production of crude oil can save wellbore oil and gas lift. The cost of heating and gathering and transportation: enough heat can be injected at one time through the formation water to heat up the crude oil in heavy oil reservoirs and reduce the viscosity, improve the paraffin formation of crude oil in high pour point oil reservoirs, exert the scale effect of concentrated thermal recovery, and save time and cost.

Case Analysis

Utilize this method, carry out numerical simulation to a super heavy oil reservoir containing bottom water, reservoir geological condition:

    • Depth: 1000 m, K: 1500 um2, ϕ: 0.30, T: 42° C., P: 9.5 MPa, So:65%, μ; 7272 mPa·m/s.

Simulation process: first concentrated preheating the oil reservoir, heating well spacing 30˜40 m, when the reservoir temperature reaches the crude oil movable condition, exceeds the crude oil viscosity-temperature inflection point temperature, pressure relief production is performed, and then, the formation water is continuously heated under constant pressure, and the bottom water is continuously boiled for production. When the water content reaches 98%, the production stops.

The numerical simulation results show that the preheating time of the oil reservoir is 2.5 to 5 years, and the bottom water vapor flooding is formed under the high pressure or low pressure stable condition. The recovery degree of the reservoir can reach at least 70˜80%, the energy consumption is between 66.6˜94×105 kJ/t. The cost of electricity per ton calculated by the optimal digital model is 950˜1057 Υ-/ton, equivalent to 21˜24 USD/Bucket (FIG. 4).

Considering the impact of the electric heater energy-saving design on the cost, the actual application cost of the electricity bill of this scheme can be saved at least ⅓, that is, the electricity bill cost can be reduced to 634˜705 Υ-/t, 14˜16 $/b.

Claims

1. A method for exploiting oil and gas by utilizing bottom water resources of oil and gas reservoirs, wherein the oil and gas reservoir containing an edge-bottom water layer and having an original stratigraphic condition A (Po, To) and current development state B (Pi, Ti), comprising:

continuously heating the upper part of the edge-bottom water layer in reservoir within a certain pressure range according to the reservoir geological characteristics, original reservoir formation pressure, fracture pressure, prediction curve of the temperature and pressure of the water boiling point;
getting the formation water directly into the boiling state and continuously generating the vapor by controlling and stabilizing the pressure under the condition of movable formation crude oil and difference of production pressure;
converting the bottom water of the oil and gas reservoir to an overall upward pushing power;
producing the comprehensive oil and gas production driving energy primarily by the area driving force mainly in bottom water steam flooding and hot bottom water flooding, and reservoir thermal expansion elastic pressure throughout the reservoir and production process, at the same time compensating the energy deficit in the reservoir simultaneously; and
dredging, utilizing rather than preventing and blocking natural formation water resources, and changing the harmful side of edge and bottom water intrusion into oil layer into the beneficial side to production, so as to improve the level of producing reserve and recovery of various oil and gas reservoirs containing bottom water.

2. The method according to claim 1, wherein, the principle of energy saving and efficiency enhancement, including, comprising:

recycling part of the heat energy transferred downward depending on the formation water under the action of thermal dynamics;
continuously heating formation water under certain stable pressure for the reason that the temperature of the water does not rise any more when the water gets into boiling state, the continuously heating energy is mainly used for the vaporization of the water;
extending the stable oil and gas production time and improving the input-output ratio by using the heat storage function of heated water;
reducing heat loss, cold damage and permeability damage in oil and gas reservoir relying on the heated formation water intruding into the reservoir;
heating formation water instead of surface water to reduce heat loss in well bore and pipeline;
optimizing the layout of heating horizontal well according to the characteristics of oil and gas reservoirs which located at the upper part of the edge-bottom water layer near the water-oil contact;
using graphene materials to reduce the heat loss of wire;
improving the problem of fracture closure and environmental protection in tight reservoirs by overpressure fracturing;
reducing the operation cost caused by cold formation water intrusion in surface water injection oil and gas recovery by means of bottom water steam flooding and bottom hot water flooding;
providing driving energy for oil and gas production in the production stage and compensating for the formation energy deficit to improve the level of producing reserves and recovery and the oil and gas input-output ratio;
controlling reservoir temperature and recovering oil at high temperature to reduce wellbore oil extraction cost and pipeline gathering and transportation cost;
converting water or steam injection wells into production wells to save the drilling cost of production wells and improve the level of production;
Utilizing natural bottom water resource of oil and gas reservoir to save surface water resource and reduce the cost of environmental protection;
injecting heat energy and production kinetic energy required at a time through formation water to save costs of operation and time wherein centralized thermal recovery plays roles to the scale effect.

3. The method according to claim 1, wherein, the oil recovery mechanism of this method, comprising:

Carrying out concentrated operation in the process of heating and production which brings forth scale effect;
Reducing crude oil viscosity by preheating and bottom water steam flooding and hot bottom water flooding;
vaporizing the bottom water to compensate the formation energy deficit and further to increase the producing degree of the reservoir according to the phenomenon that the volume of steam with the same mass is about 17 times that of water, which is easier to diffuse into any micro-space of the reservoir;
utilizing the comprehensive oil recovery driving energy based on bottom water steam flooding, bottom hot water flooding and reservoir thermal expansion elastic pressure driving, to improve the final recovery degree of the reservoir.

4. The method according to claim 1, wherein, the mechanism of driving force of oil and gas production, comprising:

forming oil and gas area displacement with bottom water vapor by means of stabilizing pressure and continuously heating as the water vapor is easy to spontaneously form an upward thermal driving force along the entire oil-water contact, and the water vapor is easier to diffuse than water;
under the action of bottom water steam driving and production pressure difference, utilizing bottom water advances integrally to form hot bottom water driving with oil-water contact interface rising;
continuously heating the formation water and promoting the thermal expansion of reservoir particles, fluid, the overflow of dissolved gas and water vapor to form reservoir thermal expansion elastic pressure driving throughout the reservoir and production process;
increasing reservoir permeability by means of heating the bottom water layer of oil and gas reservoirs resulting in the heterogeneous distribution of temperature and pressure, when the pressure exceeds the reservoir fracturing pressure, the oil and gas reservoirs will produce microfractures;
continuously heating the formation water to keep the bottom water vapor continuously generating and driving upward, then to keep the reservoir microfracture opening.

5. The method according to claim 1, comprising applying the method to various oil and gas reservoirs containing edge and bottom water layers, tight oil and gas reservoirs, heavy oil and high pour point oil and gas reservoirs that need to be developed by thermal recovery, and ordinary oil and gas reservoirs that need to be developed by water injection.

6. The method according to claim 1, comprising controlling the pressure of general oil and gas reservoirs except for tight oil and gas reservoirs to be under the fracture pressure of the reservoir during the heating process, wherein, the pressure controlling method:

producing to depressurize,
adjusting the heating pattern of formation water, or
a combination of the two methods.

7. The method according to claim 1, wherein, within a certain pressure range, the formation water is boiled and the bottom water vapor is continuously generated by means of the pressure control and stabilization, the pressure of oil and gas reservoir is fixed while the formation water is continuously heated at relatively low pressure, and the bottom water steam flooding and hot bottom water flooding are formed under the production pressure difference.

8. The method according to claim 1, comprising, for thermal recovery of the oil and gas reservoir, preheating the bottom water to get the crude oil in the formation movable, and then heating the formation water under pressure control and stabilization to keep the formation water boiled, and under the action of the production pressure difference, using the comprehensive exploitation of oil and gas driving energy to carry out oil and gas extraction.

9. The method according to claim 1, comprising generating the steam needed in the bottom water steam flooding by means of getting the bottom water boiled and vaporizing the bottom water invading into the oil layer where the temperature is higher than the boiling temperature corresponding to pressure.

10. The method according to claim 1, comprising increasing the level of producing and recovery of the reservoir, including the increase in the process of concentrated thermal recovery, and the increase of the residual oil due to the continuous provision of driving energy in the oil production stage.

11. The method according to claim 1, comprising improving permeability of the tight oil and gas reservoirs by continuously heating the formation water and pressure control and voltage stabilization, as well as the action of the production pressure difference until the reservoir ruptures, and then utilizing the bottom water vapor flooding method, or, under the condition of lower and close to the reservoir rupture pressure, directly to avoid the closure of the reservoir fractures.

12. The method according to claim 1, comprising heating the formation water of non-thermal recovery medium and high permeability ordinary oil and gas reservoirs under low pressure and pressure stabilization conditions to make it continue to boil, and then keeping the pressure slightly higher than the original formation pressure by means of pressure control and pressure stabilization, and carrying out oil and gas extraction by comprehensive oil recovery driving energy.

13. The method according to claim 1, wherein the methods of heating the edge and bottom water of oil and gas reservoirs according to the geological characteristics of different oil and gas reservoirs, comprising

{circle around (1)} continuously heating the formation water to the boiling point temperature of the water under the condition of pressure relief and pressure stabilization in open oil and gas reservoirs, and then continuously heating under the stable pressure to form an effective bottom water steam flooding;
{circle around (2)} heating the formation water to the boiling point temperature under the condition of open oil and gas reservoir pressure control, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
{circle around (3)} heating the formation water under the condition of pressure control in open oil and gas reservoirs, when the pressure is slightly higher than the original formation pressure, then keep the pressure and continuously heating until effective bottom water steam flooding is formed;
{circle around (4)} continuously heating the formation water under the condition of pressure control in open oil and gas reservoirs, when the pressure is close to the fracture pressure of the reservoir, then stabilizing the pressure and heating until an effective bottom water steam flooding is formed;
{circle around (5)} continuously heating the formation water under the condition of pressure control in open oil and gas reservoirs to the boiling point temperature of water, and the pressure slightly higher than the fracture pressure of the reservoir, and then continuously heating under constant pressure to form an effective bottom water vapor flooding;
{circle around (6)} continuously heating the formation water under the condition of pressure control in the open oil and gas reservoir, when the pressure is slightly higher than the fracture pressure of the reservoir, and then stabilizing and continuously heating until an effective bottom water steam flooding is formed;
{circle around (7)} continuously heating the formation water to the boiling point temperature of the water under pressure relief and pressure stabilization conditions in closed oil and gas reservoirs, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
{circle around (8)} continuously heating the formation water to the boiling point temperature of the water under the condition of pressure control in closed oil and gas reservoirs, and then continuously heating under constant pressure until an effective bottom water vapor flooding is formed;
{circle around (9)} continuously heating the formation water under the condition of pressure control in closed oil and gas reservoirs, when the pressure is slightly higher than the fracture pressure of the reservoir, then stabilizing the pressure and continuously heating continues until an effective bottom water steam flooding is formed;
{circle around (10)} continuously heating the formation water under pressure control conditions in closed oil and gas reservoirs, when the pressure is close to the fracture pressure of the reservoir, stabilizing the pressure and continuously heating until effective bottom water steam flooding is formed;
{circle around (11)} continuously heating the formation water under pressure control conditions in closed oil and gas reservoirs, when the pressure is slightly higher than the fracture pressure of the reservoir, stabilizing the pressure and continuously heating until an effective bottom water steam flooding is formed.

14. The method according to claim 1, wherein the principle of heating the edge and bottom water layers of oil and gas reservoirs, comprising

keeping the dynamic pressure of the reservoir greater than or equal to Po;
for thermal recovery reservoirs, getting the formation crude oil movable before bottom water steam-flooding;
During the period;
Stage I, the reservoir pressure is between (Pi, Po), the power consumption is small, but the formation energy is deficient. It is suitable for ordinary oil and gas reservoirs with good oil properties and medium and high permeability that do not require high temperature, and ordinary heavy oil reservoirs and high pour point oil reservoirs with low temperature thermal recovery;
Section II, the reservoir pressure is between (Po, Pb), the formation energy is supersaturated, and the temperature of the oil and gas reservoir is high. It is suitable for medium and high permeability reservoirs, requiring high temperature thermal recovery of heavy oil and gas reservoirs and high pour point oil and gas reservoirs;
In stage III, the reservoir pressure is greater than or equal to the fracture pressure Pb of the reservoir, and the high temperature and high pressure state is beneficial to the overflow of low abundance oil and gas, and is suitable for tight oil and gas reservoirs requiring high pressure steam injection or hydraulic fracturing.

15. The method according to claim 1, comprising heating side and bottom water layer including,

various electric heating and nuclear heating;
heating wells for heating edge and bottom water layers can be various types of horizontal wells;
the heaters placed in the horizontal wells can be of various energy-efficient models of heating equipment.
Patent History
Publication number: 20240218771
Type: Application
Filed: Nov 27, 2020
Publication Date: Jul 4, 2024
Applicant: BEIJING HONGLANHEI ENERGY TECHNOLOGY CO., LTD (Beijing)
Inventor: Wenying Yu (Beijing)
Application Number: 17/800,057
Classifications
International Classification: E21B 43/24 (20060101); E21B 43/26 (20060101);