CN108386170B - Underground energy consumption characterization method in oil reservoir development process - Google Patents
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- 238000002347 injection Methods 0.000 claims abstract description 57
- 239000007924 injection Substances 0.000 claims abstract description 57
- 238000004519 manufacturing process Methods 0.000 claims abstract description 47
- 239000012530 fluid Substances 0.000 claims abstract description 28
- 235000019198 oils Nutrition 0.000 claims description 65
- 235000019476 oil-water mixture Nutrition 0.000 claims description 13
- 238000004364 calculation method Methods 0.000 claims description 9
- 239000003129 oil well Substances 0.000 claims description 7
- 230000005484 gravity Effects 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 3
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- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
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Abstract
The invention belongs to the technical field of oil and gas development, and particularly relates to a method for representing underground energy consumption in an oil reservoir development process. The method comprises the following steps: step 1, acquiring parameters of an oil production well, and calculating to obtain the energy of fluid produced by the oil production well within a certain time; step 2, acquiring parameters of a water injection well, and calculating to obtain energy supplemented by injected water within a certain time; step 3, acquiring oil reservoir parameters, and calculating elastic energy stored or released by the oil reservoir after water injection by using an integral method; and 4, calculating the energy lost in the seepage process of the underground oil reservoir. The characterization method of the invention can definitely obtain the energy loss in the oil reservoir seepage process, accurately grasp the energy consumption of the underground oil reservoir system and the utilization condition of the energy, and guide the oil field to save energy and reduce consumption.
Description
Technical Field
The invention belongs to the technical field of oil and gas development, and particularly relates to a method for representing underground energy consumption in an oil reservoir development process.
Background
The oilfield flooding development refers to a process of supplementing stratum energy by artificial flooding in a flooding well, driving oil to the bottom of a production well through water, and lifting oil-water mixed liquid to the ground through an oil well lifting system. A large amount of energy is consumed in the water injection development process, and the cost directly influences the benefit of oil field development. The water injection development and production process mainly comprises a water injection well water injection process, an oil reservoir seepage process and an oil production well lifting process. At present, the detection and evaluation of energy consumption in the water injection development and production process only aim at the water well injection process and the oil production well lifting process, the theoretical basis and the characterization method are mature, relevant parameters are obtained through field test data, and calculation is carried out according to the method specified in relevant industry standards. For example, a node analysis method is used for determining nodes of energy consumption in the water well injection process, a characterization equation of the energy consumption of each node is deduced by using a fluid mechanics principle, and the overall energy consumption of the water injection process can be determined according to field measured parameters. The corresponding method is also used for the oil well shaft lifting process system. However, no clear characterization method exists at present for the energy consumption in the subsurface reservoir seepage process serving as the junction of the injection process of the water injection well and the lifting process of the oil well shaft.
In view of the above, the invention provides a method for representing underground energy consumption in an oil reservoir development process, which is used for calculating input, output, storage and loss energy in an underground oil reservoir seepage process in a water injection development production process according to test data, accurately grasping the energy consumption in the underground oil reservoir seepage process and guiding an oil field to save energy and reduce consumption.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a method for representing underground energy consumption in an oil reservoir development process.
The object of the invention can be achieved by the following technical measures:
a method for representing underground energy consumption in the process of oil reservoir development is characterized in that the evaluation standard is the ratio of the consumed energy to the input energy, and the method mainly comprises the following steps:
step 2, acquiring the height of the bottom of the oil production well relative to a reference surface, the density of an oil-water mixture at the bottom of the oil production well, the flow rate and the bottom flow pressure of water injected at the bottom of the water injection well, and the volume and the mass of the injected water in a certain time, and calculating to obtain the energy supplemented by the injected water in the certain time;
step 3, acquiring the pressure at the time t and the volume of the oil-water mixture at the position x in the oil reservoir, and calculating the elastic energy stored or released by the oil reservoir after water injection by using an integration method;
and 4, calculating the underground energy loss of the water-flooding oil reservoir.
The object of the invention can also be achieved by the following technical measures:
in the method for representing underground energy consumption in the oil reservoir development process, the fluid energy produced by the oil production well within a certain time in the step 1 comprises potential energy, pressure energy and kinetic energy, and the calculation formula is shown as the formula (I):
in the formula (I), Eo-the energy of the fluid produced by the production well over a certain time, J; rho1Density of oil-water mixture at bottom of oil well in kg/m3(ii) a g-acceleration of gravity, m/s2；z1-the height of the bottom of the production well relative to the reference surface, m; v1Volume of produced fluid at the bottom of the production well for a certain period of timeProduct of m3；p1-production well bottom flow pressure, Pa; v is1-flow velocity of the oil-water mixture at the bottom of the production well, m/s; m is1The mass of produced fluid in kg at the bottom of the production well for a certain time.
The energy supplemented by water injection in a certain time in the step 2 comprises potential energy, pressure energy and kinetic energy, namely a calculation formula is shown as a formula (II):
in the formula (II), Ei-energy of water injection replenishment over a certain time, J; rho2Density of injected water, kg/m3(ii) a g-acceleration of gravity, m/s2；z2-height of the bottom of the injection well relative to the datum level, m; v2Volume of water injected in the bottom of the injection well in a given time, m3；p2-bottom hole flow pressure, Pa, of the injection well; v is2-flow rate of water injected at the bottom of the injection well, m/s; m is2-the mass of water injected into the bottom of the injection well in kg over a period of time.
And 3, storing or releasing elastic energy of the oil reservoir after water injection, wherein the elastic energy is the energy stored or released due to the elastic deformation of the object, and the oil, the water and the rock matrix in the oil reservoir are all micro-compressible and deform under the action of external force so as to store or release the elastic energy. The volume deformation of oil, water and rock matrix in the oil reservoir can be finally reflected as the volume change of fluid in the oil reservoir; when the volumes of oil and water are contracted, the pressure of the oil reservoir is increased, and energy is stored; when the volume of oil and water expands, the pressure of the oil deposit is reduced, energy is released, the elastic energy stored or released by the oil deposit after water injection is calculated according to the change of the volume and the pressure of fluid in the oil deposit, and the calculation formula is shown as a formula (III):
in the formula (iii), the water injection well is used as the origin of coordinates, x is 0, the time for starting water injection is used as the time starting point, and t is 0; eeElastic energy stored or released by the reservoir after waterflooding, J; p is a radical ofx,t-pressure in the reservoir at time t, location x, Pa; vx,0Fluid volume at time 0, position x in the reservoir, m3；Vx,tFluid volume at time t, position x, m in the reservoir3。
Calculating the underground energy loss of the water-flooding oil reservoir in the step 4, taking the underground oil reservoir system as a unified whole according to the energy conservation principle, and then performing energy conservation on the whole system before and after development, namely within a certain time, subtracting the energy flowing out from the energy flowing in the system and the energy lost in the seepage process, wherein the energy change quantity before and after the system is equal to the energy change quantity, and the calculation formula is shown as a formula (IV):
formula (IV) HDecrease in the thickness of the steelSubsurface energy depletion of waterflood reservoirs.
The invention has the following characteristics:
according to the characterization and conversion of the hydrodynamic energy, the method for characterizing the underground energy consumption in the development process of the oil reservoir calculates and obtains the input energy (water injection supplemented energy), the output energy (oil well produced energy), the energy stored or released by the oil reservoir and the energy consumed in the seepage process of the underground oil reservoir, can accurately grasp the energy consumption and the utilization condition of the energy in the seepage process of the underground oil reservoir, and guides the energy conservation and consumption reduction of the oil field.
Drawings
FIG. 1 is a flowchart illustrating a method for characterizing underground energy consumption during reservoir development according to an embodiment of the present invention;
FIG. 2 is a graph of energy of fluid produced by a producing well, cumulative energy produced, versus time in an embodiment of the present invention;
FIG. 3 is a diagram showing the relationship between the energy of water injection replenishment and the accumulated replenishment and the time according to the embodiment of the present invention;
FIG. 4 is a graph of stored energy of a reservoir, cumulative stored energy, and time in accordance with an embodiment of the present invention.
Detailed Description
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Examples
A one-dimensional model of one injection and one production is established by using a numerical simulation means, wherein the one-dimensional model only comprises one water injection well and one oil production well, and comprises 11 grids, the size of each grid is 30m multiplied by 10m multiplied by 5m, the porosity is 0.28, and the permeability is 1800 multiplied by 10-3um2The stratum viscosity is 24 mPa.s, the initial oil saturation is 0.7, the liquid extraction speed is 15%, and relevant oil reservoir parameters are measured and counted to explain the underground energy consumption characterization method in the oil reservoir development process; the method for representing the underground energy consumption of the oil reservoir by water injection exploitation comprises the following steps: the steps are shown in figure 1:
in the formula (I), Eo-the energy of the fluid produced by the production well over a certain time, J; rho1Density of oil-water mixture at bottom of oil well in kg/m3(ii) a g-acceleration of gravity, m/s2；z1-the height of the bottom of the production well relative to the reference surface, m; v1Volume of produced fluid m in a certain time at the bottom of the production well3；p1-production well bottom flow pressure, Pa; v is1-flow velocity of the oil-water mixture at the bottom of the production well, m/s; m is1The mass of produced fluid in kg at the bottom of the production well for a certain time. Calculated for 90 daysThe cumulative output energy is 788833471J, i.e. 219.12 Kw.h, wherein the specific output energy value of 1-86 days is shown in figure 2.
103, calculating the energy supplemented by the water injection well, and acquiring the height of the bottom of the oil production well relative to a reference surface, wherein the reference surface is taken at the well depth of the oil production well (same as the well depth of the water injection well), namely the height is 0, and the density of the injected water is 1000Kg/m3) The flow rate of injected water at the bottom of the water injection well is 0.8m/s, the bottom flowing pressure is 23.1MPa, and the volume of injected water (0.5 m) in 90 days3D, total 45m3) And the mass (45000Kg), the energy supplemented by injected water in 90 days and the energy supplemented by accumulation are calculated by applying a formula (II), wherein the specific input energy in 1-86 days is shown in figure 3;
in the formula (II), Ei-energy of water injection replenishment over a certain time, J; rho2Density of injected water, kg/m3(ii) a g-acceleration of gravity, m/s2；z2-height of the bottom of the injection well relative to the datum level, m; v2Volume of water injected in the bottom of the injection well in a given time, m3；p2-bottom hole flow pressure, Pa, of the injection well; v is2-flow rate of water injected at the bottom of the injection well, m/s; m is2-the mass of water injected into the bottom of the injection well in kg over a period of time. The accumulated energy input in 90 days is calculated, namely the energy supplemented by the water injection well is 1038061478J, namely 288.35 Kw.h.
In step 105 of FIG. 1, after 90 days of steady waterflooding, the average pressure of the reservoir did not change much, still 19.8 MPa. Reservoir fluid volume reduction of 2.5m3Elastic energy is stored. The accumulated stored elastic energy was calculated to be 50449925j, i.e., 14.01 Kw.h, using equation (III). Acquiring the pressure and the volume of an oil-water mixture at a position with time t and a position x in an oil reservoir, and calculating the elastic energy stored or released by the oil reservoir after water injection by using an integral method, wherein the specific energy storage value in 1-86 days is shown in figure 4;
in the formula (iii), the water injection well is used as the origin of coordinates, x is 0, the time for starting water injection is used as the time starting point, and t is 0; eeElastic energy stored or released by the reservoir after waterflooding, J; p is a radical ofx,t-pressure in the reservoir at time t, location x, Pa; vx,0Fluid volume at time 0, position x in the reservoir, m3；Vx,tFluid volume at time t, position x, m in the reservoir3。
Calculating the subsurface energy loss of the waterflood reservoir in step 107 in fig. 1;
the calculation formula is shown as formula (IV):
formula (IV) HDecrease in the thickness of the steelSubsurface energy depletion of waterflood reservoirs.
The energy consumed in the seepage process is calculated and calculated by applying the formula (IV) to be 198778082j, namely 55.22 Kw.h.
Claims (4)
1. A method for representing underground energy consumption in an oil reservoir development process is characterized by comprising the following steps:
step 1, acquiring the height of a well bottom of a production well relative to a reference surface, the density, the flow rate and the well bottom flowing pressure of an oil-water mixture at the well bottom of the production well, and the volume and the mass of produced liquid in a certain time, and calculating to obtain the fluid energy produced by the production well in a certain time;
step 2, acquiring the height of the bottom of the water injection well relative to a reference surface, the density of injected water, the flow rate and bottom flow pressure of the injected water at the bottom of the water injection well, and the volume and mass of the injected water in a certain time, and calculating to obtain the energy supplemented by the injected water in the certain time;
step 3, acquiring the pressure and the volume of the oil-water mixture at different time and different positions in the oil reservoir, and calculating the elastic energy stored or released by the oil reservoir after water injection by using an integration method;
step 4, calculating the underground energy loss of the water-flooding oil reservoir;
the calculation formula of the fluid energy produced by the oil production well within a certain time in the step 1 is shown as the formula (I):
in the formula (I), Eo-the energy of the fluid produced by the production well over a certain time, J; rho1Density of oil-water mixture at bottom of oil well in kg/m3(ii) a g-acceleration of gravity, m/s2；z1-the height of the bottom of the production well relative to the reference surface, m; v1Volume of produced fluid m in a certain time at the bottom of the production well3；p1-production well bottom flow pressure, Pa; v is1-flow velocity of the oil-water mixture at the bottom of the production well, m/s; m is1The mass of produced fluid in kg at the bottom of the production well for a certain time.
2. The method for characterizing underground energy consumption in the oil reservoir development process according to claim 1, wherein the energy supplemented by water injection in a certain time period in the step 2 is calculated according to a formula (II):
in the formula (II), Ei-energy of water injection replenishment over a certain time, J; rho2Density of injected water, kg/m3(ii) a g-acceleration of gravity, m/s2；z2-height of the bottom of the injection well relative to the datum level, m; v2Volume of water injected in the bottom of the injection well in a given time, m3；p2-bottom hole flow pressure, Pa, of the injection well; v is2-flow rate of water injected at the bottom of the injection well, m/s; m is2-the mass of water injected into the bottom of the injection well in kg over a period of time.
3. The method for characterizing underground energy consumption in the oil reservoir development process according to claim 1, wherein the calculation formula of the elastic energy stored or released by the oil reservoir after water injection in the step 3 is shown as a formula (III):
in the formula (iii), the water injection well is used as the origin of coordinates, x is 0, the time for starting water injection is used as the time starting point, and t is 0; eeElastic energy stored or released by the reservoir after waterflooding, J; p is a radical ofx,t-pressure in the reservoir at time t, location x, Pa; vx,0Fluid volume at time 0, position x in the reservoir, m3；Vx,tFluid volume at time t, position x, m in the reservoir3。
4. The method for characterizing underground energy consumption in the oil reservoir development process according to claim 1, wherein the underground energy consumption of the water-flooding oil reservoir is calculated in the step 4, and the calculation formula is shown as a formula (IV):
formula (IV) HDecrease in the thickness of the steelSubsurface energy depletion of waterflood reservoirs.
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