CN112502680A - Method for judging fireflood combustion state - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 112
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 92
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 53
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 53
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000001301 oxygen Substances 0.000 claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 claims abstract description 48
- 230000003647 oxidation Effects 0.000 claims abstract description 43
- 238000006243 chemical reaction Methods 0.000 claims abstract description 29
- 238000001354 calcination Methods 0.000 claims abstract description 23
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- 230000000694 effects Effects 0.000 claims abstract description 22
- 239000003129 oil well Substances 0.000 claims abstract description 18
- 238000011160 research Methods 0.000 claims abstract description 12
- 238000010304 firing Methods 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims abstract description 3
- 239000007789 gas Substances 0.000 claims description 64
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 12
- 238000002347 injection Methods 0.000 claims description 11
- 239000007924 injection Substances 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 5
- 239000001569 carbon dioxide Substances 0.000 claims description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 5
- 239000003086 colorant Substances 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 238000005553 drilling Methods 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 2
- 238000011156 evaluation Methods 0.000 abstract description 7
- 238000012360 testing method Methods 0.000 abstract description 7
- 238000012544 monitoring process Methods 0.000 abstract description 6
- 238000004088 simulation Methods 0.000 abstract description 2
- 239000003921 oil Substances 0.000 description 39
- 239000010410 layer Substances 0.000 description 23
- 238000004458 analytical method Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 3
- 239000000295 fuel oil Substances 0.000 description 3
- 239000000700 radioactive tracer Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000012850 discrimination method Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- 239000003208 petroleum Substances 0.000 description 1
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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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/243—Combustion in situ
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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Abstract
The invention provides a method for judging a fire flooding combustion state, which comprises the following steps: determining the position of a firing line in a certain producing well direction in a target research area after the oil well takes effect according to a substance balance method of combustion reaction; determining a high-low temperature oxidation combustion state according to the oxygen conversion rate and/or the apparent H/C atomic ratio in the fireflooding process; and establishing a fire-driving core color code chart at different calcining temperatures and determining the fire-driving combustion temperature of the core after fire-driving according to the fire-driving core color code chart. The invention provides a method for comprehensively judging the fire flooding combustion state by multiple means by comprehensively applying an indoor physical simulation test and a field production dynamic monitoring result, and the method provided by the invention is suitable for determining the position of a fire wire, the high-temperature oxidation degree, the fire flooding temperature and the like in the fire flooding development process, thereby being capable of guiding the evaluation of the fire flooding development effect.
Description
Technical Field
The invention relates to a method for judging a fire flooding combustion state, and belongs to the technical field of petroleum development.
Background
Fire flooding is a thermal oil recovery method for generating heat in an oil layer, does not have heat loss along a shaft, and can be used as an effective replacing technology after steam huff and puff of a heavy oil reservoir. The fireflood, as one of the important methods for improving the recovery ratio of the thickened oil, has the advantages of high recovery ratio, low cost and wide application range. In the fireflood process, grasp gas injection well all directions live wire position and underground combustion state in real time, help knowing fireflood development effect, in time produce adjustment control, improve oil reservoir and use the degree, it is significant to oil field fireflood development.
At present, methods for determining the position of a live wire on site mainly include an infrared photograph, a micro seismic method, an interwell potential method, an unstable well testing method, a tracer monitoring method, a material balance method and the like, wherein the first 3 methods are easily interfered by a metal pipeline and a power facility, and are long in testing period, high in cost and not beneficial to large-scale application. The pressure drop well testing method needs to establish an ideal oil reservoir parameter model, the calculation process is complex, and the accuracy is greatly influenced by model parameters. The tracer in the tracer monitoring method is greatly influenced by temperature, and the error of the monitoring result is large. The material balance method is to derive a formula according to the material balance and energy conservation theorem of combustion reaction and calculate and obtain the position of the fire flooding front according to the formula.
Currently, the underground combustion state is mainly determined by CO in the tail gas2Content is carried out when CO in tail gas2When the content is more than 12%, the high-temperature oxidation combustion can be realized, but the discrimination method has single parameter and is greatly influenced by human and natural errors.
Therefore, the method is of great importance for evaluating the development effect of the fireflood by rapidly judging the position of the fire line and determining the underground combustion state, but no systematic and accurate comprehensive analysis and evaluation means exists at present. Therefore, providing a novel method for determining the combustion state of fireflooding has become an urgent technical problem to be solved in the art.
Disclosure of Invention
To solve the above-described drawbacks and disadvantages, an object of the present invention is to provide a method of determining a fireflood combustion state. The invention provides a method for comprehensively judging the fire flooding combustion state by multiple means by comprehensively applying an indoor physical simulation test and a field production dynamic monitoring result, and the method provided by the invention is suitable for determining the position of a fire wire, the high-temperature oxidation degree, the fire flooding temperature and the like in the fire flooding development process, thereby being capable of guiding the evaluation of the fire flooding development effect.
In order to achieve the above object, the present invention provides a method of judging a fireflood combustion state, wherein the method of judging the fireflood combustion state includes:
determining the position of a firing line in a certain producing well direction in a target research area after the oil well takes effect according to a substance balance method of combustion reaction;
determining a high-low temperature oxidation combustion state according to the oxygen conversion rate and/or the apparent H/C atomic ratio in the fireflooding process;
and establishing a fire-driving core color code chart at different calcining temperatures and determining the fire-driving combustion temperature of the core after fire-driving according to the fire-driving core color code chart.
As a specific embodiment of the above method of the present invention, the position of the firing line in a certain producing well direction in the target research area after the oil well is effective is determined according to the following formula 1) by the material balance method of the combustion reaction;
in formula 1), R is the position of a fire line, m;
Qis divided intoFor distributing gas, m, in each direction of the well3；
Y is the oxygen utilization rate in each oil well direction, and the decimal number;
alpha is the distribution angle of each oil well direction, °;
h is the thickness of an oil layer in each production well direction, m;
Asm is the air consumption per unit volume of oil layer burned3/m3；
Wherein, the oil layer thickness H in each production well direction and the oxygen utilization rate Y in each oil well direction in formula 1) are calculated according to the following formula 2) and formula 3), respectively:
in formula 2), hgThe effective thickness of the oil layer of the gas injection well is m;
h is the effective thickness of the oil layer of the production well, m;
rho is vertical combustion rate, decimal;
in formula 3), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%.
Wherein, the oxygen content and the nitrogen content in the tail gas are both volume percentage content, and are calculated by taking the total volume of the tail gas as a reference.
In the method for judging the fire flooding combustion state provided by the invention, the air consumption A of an oil layer per unit volume of combustionsCan be obtained by a physical model test.
In the method for judging the fireflood combustion state provided by the invention, the vertical combustion rate ρ can be obtained according to the field data condition, and in a more preferred embodiment of the invention, the vertical combustion rate ρ can be 0.7.
The method for determining the position of the fire line fully considers the thickness of an oil layer, the well pattern and well spacing, the air suction capacity, the gas production rate and the combustion rates of different oil reservoirs in all production well directions, and the calculation error of the method for determining the position of the fire line is about +/-5%.
As a specific embodiment of the above method of the present invention, the oxygen conversion rate in the fireflooding process is calculated according to the following formula 4), and then the high and low temperature oxidation combustion state is determined according to the calculated oxygen conversion rate;
in formula 4), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%.
Wherein, the oxygen content and the nitrogen content in the tail gas are both volume percentage content, and are calculated by taking the total volume of the tail gas as a reference.
As a specific embodiment of the above method of the present invention, wherein determining the high and low temperature oxidation combustion state based on the oxygen conversion rate comprises:
when the oxygen conversion rate is more than 50%, the fireflood process is determined to have reached the high temperature oxidation stage.
In the fireflood process, the tail gas component can most directly judge the combustion state of the reservoir, and the invention utilizes the fireflood tail gas component to calculate the oxygen conversion rate according to the formula 4), wherein the oxygen conversion rate can reflect O participating in high-temperature oxidation in the fireflood process2Formation of CO2And the degree of CO. The results of laboratory tests and field monitoring show that when the oxygen conversion rate Y' is greater than 50%, the fireflood can be considered to reach the high-temperature oxidation stage.
As a specific embodiment of the above method of the present invention, wherein, the apparent H/C atomic ratio in the fireflooding process is calculated according to the following formula 5), and then the high and low temperature oxidation combustion state is determined according to the calculated apparent H/C atomic ratio;
in the formula 5), X is the H/C atomic ratio, decimal and dimensionless;
C(O2) Oxygen content,%, in the production well tail gas;
C(CO2) For the carbon dioxide content,%, in the production well tail gas;
c (CO) is the carbon monoxide content in the tail gas of the production well,%.
Wherein, the oxygen content, the carbon dioxide content and the carbon monoxide content in the tail gas are all volume percentage contents, and are calculated by taking the total volume of the tail gas as a reference.
As a specific embodiment of the above method of the present invention, wherein the determination of the high and low temperature oxidative combustion state based on the H/C atomic ratio comprises:
when the apparent H/C atomic ratio in the fireflooding process is less than 3, determining that the fireflooding process has a high-temperature oxidation reaction and is in a high-temperature oxidation combustion state;
and when the apparent H/C atomic ratio in the fireflooding process is more than or equal to 3 (such as 3-10), determining that the fireflooding process has a low-temperature oxidation reaction and is in a low-temperature oxidation combustion state.
The invention utilizes O in tail gas2、CO2And the percentage content of CO, calculating according to a formula 5) to obtain an apparent H/C atomic ratio, and when the apparent H/C atomic ratio is less than 3, determining that a high-temperature oxidation reaction occurs in the fireflood process and the fireflood process is in a high-temperature oxidation combustion state; when the H/C atomic ratio is 3 or more, it is considered that the fireflooding process is a low-temperature oxidation reaction and is in a low-temperature oxidation combustion state.
In the present invention, depending on the H/C atomic ratio (X), also called equivalent hydrogen to carbon atomic ratio, oxygen reacts with the organic fuel during fireflooding to produce CO2CO and H2The basic reaction products, such as O, approximately reflect the reaction of O, C and H during fireflooding and are therefore referred to as "apparent" or "equivalence ratio".
In the invention, when only oxygen conversion rate data or apparent H/C atomic ratio data exists on site, the high and low temperature oxidation combustion state can be determined by combining the oxygen conversion rate data or the apparent H/C atomic ratio data with site production data.
As a specific embodiment of the above method of the present invention, the establishing of the color scale charts of the pyrochlore cores at different calcination temperatures includes:
obtaining a real core of a reservoir in a target research area by coring, calcining the core at different temperatures for a period of time after oil washing, obtaining core colors at different temperatures after the calcined core is cooled, and establishing a fire-burning core color code chart at different calcining temperatures.
In one embodiment of the present invention, the calcination can be performed in a muffle furnace, the calcination temperature can be selected from 150 ℃, 250 ℃, 350 ℃, 450 ℃, 550 ℃, 650 ℃, 750 ℃, 850 ℃ and the like, and the calcination time can be 6 hours.
As a specific embodiment of the above method of the present invention, determining the fireflood combustion temperature of the core after fireflood according to the core color scale chart of the fireflood includes:
after the core after fireflooding obtained by the drilling coring or the borehole wall coring method is washed with oil, the color of the core is compared with a core color code plate, and the fireflood combustion temperature of the underground reservoir is determined according to the relationship between the core color and different calcination temperatures in the core color code plate.
As a specific embodiment of the above method of the present invention, the method specifically includes:
determining the position of a firing line in the direction of a certain production well in a target research area after the oil well takes effect according to the following formula 1) by a material balance method of combustion reaction;
in formula 1), R is the position of a fire line, m;
Qis divided intoFor distributing gas, m, in each direction of the well3；
Y is the oxygen utilization rate in each oil well direction, and the decimal number;
alpha is the distribution angle of each oil well direction, °;
h is the thickness of an oil layer in each production well direction, m;
Asm is the air consumption per unit volume of oil layer burned3/m3；
Wherein, the oil layer thickness H in each production well direction and the oxygen utilization rate Y in each oil well direction in formula 1) are calculated according to the following formula 2) and formula 3), respectively:
in formula 2), hgThe effective thickness of the oil layer of the gas injection well is m;
h is the effective thickness of the oil layer of the production well, m;
rho is vertical combustion rate, decimal;
in formula 3), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) As nitrogen in the exhaust gasGas content,%;
calculating the oxygen conversion rate in the fireflood process according to the following formula 4), and determining that the fireflood process has reached a high-temperature oxidation stage when the calculated oxygen conversion rate is greater than 50%;
in formula 4), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%;
calculating the apparent H/C atomic ratio in the fireflooding process according to the following formula 5), and determining that the fireflooding process has a high-temperature oxidation reaction and is in a high-temperature oxidation combustion state when the apparent H/C atomic ratio in the fireflooding process is less than 3;
when the apparent H/C atomic ratio in the fireflooding process is more than or equal to 3, determining that the fireflooding process has a low-temperature oxidation reaction and is in a low-temperature oxidation combustion state;
in the formula 5), X is the H/C atomic ratio, decimal and dimensionless;
C(O2) Oxygen content,%, in the production well tail gas;
C(CO2) For the carbon dioxide content,%, in the production well tail gas;
c (CO) is the content of carbon monoxide in the tail gas of the production well,%;
obtaining a real core of a reservoir in a target research area by coring, calcining the core at different temperatures for a period of time after washing oil, obtaining core colors at different temperatures after cooling the calcined core, and establishing a fire-burning core color code chart at different calcining temperatures;
after the core after fireflooding obtained by the drilling coring or the borehole wall coring method is washed with oil, the color of the core is compared with a core color code plate, and the fireflood combustion temperature of the underground reservoir is determined according to the relationship between the core color and different calcination temperatures in the core color code plate.
The method provided by the invention comprises the steps of firstly calculating to obtain the position of a fire wire by using a formula 1), a formula 2) and a formula 3), then calculating to obtain the conversion rate of the fireflood oxygen by using a formula 4), and then calculating to obtain the apparent H/C atomic ratio (X) by using a formula 5), wherein when the conversion rate of the fireflood oxygen is more than 50% and the apparent H/C atomic ratio is less than 3, the fireflood can be considered to realize high-temperature oxidation combustion and is in a high-temperature oxidation combustion state. On the basis of determining the high-temperature oxidation combustion, coring the stratum after the fireflood, comparing the oil-washed rock core with the core color code chart after the fireflood, and determining the fireflood combustion temperature, thereby realizing the comprehensive evaluation of the fireflood development effect.
As a specific embodiment of the above method of the present invention, the method further comprises:
and evaluating the reservoir fire flooding development effect according to the high and low temperature oxidation combustion state of each production well and the fire flooding combustion temperature of the core after fire flooding.
As a specific embodiment of the method described above, when the production well reaches a high-temperature oxidation combustion state and the fireflood combustion temperature of the core after fireflooding is 350 ℃ or higher, it is determined that the reservoir fireflood development effect is good, otherwise it is determined that the reservoir fireflood development effect is poor.
The method establishes the fire flooding combustion state evaluation standard by comprehensively applying four indexes such as a material balance method, an oxygen conversion rate, an apparent H/C atomic ratio, a fire core color code chart and the like, and further determines the method for judging the fire flooding combustion state.
The method provided by the invention utilizes the effective thickness of the perforation oil layer of the gas injection well and the oil production well and CO in tail gas2CO and N2And judging the characteristic position of the fire flooding front edge and the combustion temperature by the content, the color of the core after fire flooding and the like, determining the combustion state and evaluating the fire flooding development effect. Has the advantages of comprehensiveness, low cost, high accuracy and high speedThe method has the advantages of having important practical significance for the fire flooding development of the heavy oil reservoir.
Detailed Description
In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.
Example 1
In this embodiment, a method for determining a combustion state of a fireflood and a method for evaluating a development effect of the fireflood provided by the present invention are described in detail by taking 66 oil reservoirs of a du domestica in the liao river oil field as an example.
The 66 Du family oil layers in Liaohe oil field are embedded with the depth of 800-1200m, have the characteristics of long oil-containing well section, more oil layer layers, thin single-layer thickness and poor sand body continuity in the longitudinal direction, and belong to a typical deep-layer thick oil reservoir. The development method suitable for the deep-layer heavy oil reservoir similar to the 66 Du-Jia oil reservoirs is fire flooding exploitation, and in order to determine the fire flooding effect of each production well, the fire flooding front position, the oxidation state and the fire flooding temperature need to be judged urgently, and a fire flooding combustion state discrimination method is established.
The method comprises the following steps: live wire position calculation
The location of the fire line is calculated by taking a 039 well group as an example, and the 039 well group is put into multi-layer fireflood development in 2009. The gas injection well 039 had an effective fireflood thickness of 18.0m, and as long as 6 months of 2015, the well condition problem was rejected and the well group had cumulative gas injection of 1218.8 × 104m3. The effective thickness of the fireflood of the production well 040 is 14.8m, and the fireflood gas distribution and tail gas data of the production well 040 are shown in the following table 1.
TABLE 1
As can be seen from Table 1, well induction gas 130X 10 is accumulated in production well 0404m3Middle CO of well tail gas produced in 5 months 20152The average content was 18.6%, the average content of CO was 0.027%, and N was2Average content of 35.5%, O2The average content is 1.06%; the distribution angle is 28 degrees, and the air consumption per unit volume of 66 blocks of Du is 189m obtained by the physical model test3/m3. And calculating according to the parameters by using the formula 1) to the formula 3) to obtain the distance between the fire flooding front edge in the well direction of the production well 040 and the production well by 40.4 m.
Step two: oxygen conversion analysis
CO in tail gas of production well 040 well2The average content was 18.6%, the average content of CO was 0.027%, and N was2Average content of 35.5%, O2The average content was 1.06%. The oxygen conversion rate was calculated to be 89.2% using equation 4) based on the above parameters, from which it was confirmed that the well achieved high-temperature oxidative combustion.
Step three: analysis by visual H/C atomic ratio
CO in tail gas of production well 040 well2The average content was 18.6%, the average content of CO was 0.027%, and N was2Average content of 35.5%, O2The average content was 1.06%. The apparent H/C atomic ratio is calculated to be 0.33 by using the formula 5) according to the parameters, so that the well can be further determined to realize high-temperature oxidation combustion and be in a high-temperature oxidation combustion state.
Step four: fireflood combustion temperature analysis
Obtaining a real core of a reservoir in a target research area from a coring well 47039 in the target research area, washing the core with oil, then placing the washed core in a muffle furnace to be respectively calcined at 150 ℃, 250 ℃, 350 ℃, 450 ℃, 550 ℃, 650 ℃, 750 ℃ and 850 ℃ for 6 hours, obtaining core colors at different temperatures after the calcined core is cooled, and establishing a core color code chart of the fire-burning core at different calcination temperatures as shown in the following table 2;
TABLE 2
| Serial number | Core color | Calcination temperature (. degree.C.) |
| 1 | Green grey colour | Virgin core |
| 2 | Light grey | 150 |
| 3 | Light yellow gray | 250 |
| 4 | Yellow-gray | 350 |
| 5 | Light brown | 450 |
| 6 | Yellow brown | 550 |
| 7 | Yellow orange | 650 |
| 8 | Light orange | 750 |
| 9 | Bright orange color | 850 |
In the 6 th month of 2015, a fireflood gas injection well 039 well is scrapped due to well condition problems, a gas injection well K039 well is newly drilled at a position 38m away from the well, and the fireflood layer section of the Dujia platform oil layer of the K039 well is cored. The reservoir lithology of the Du 66 Du Jia platform oil reservoir is mainly gray brown sandstone containing gravels and unequal sandstone, and the core is green gray after oil washing. By observing the core and comparing with the color scale chart of the core of the fire-burned core at different calcining temperatures as shown in the table 2, the oil-washed K039 well with 943.5m-944.5m core is determined to be light brown-yellow brown, and the fire flooding temperature of the well section is presumed to be 450 ℃ and 550 ℃.
Step five: fireflood effect evaluation analysis
In the first step, by using a material balance equation, calculating and obtaining the position of the fire flooding front edge in the 040 well direction, which is 40.4m away from the gas injection well, through parameters such as the thickness of an oil layer of the production well 040 well, tail gas components, unit volume air consumption and the like;
in the second step, CO in the tail gas component of the production well 040 is added2、CO、O2And N2Substituting the content data into a formula 4), and calculating to obtain that the oxygen conversion rate Y' of the well is 89.2 percent, which indicates that the well realizes high-temperature oxidation combustion;
in the third step, the CO in the tail gas component of the production well 040 is added2CO and O2The content is carried into a formula 5), the well apparent H/C atomic ratio is calculated to be 0.33, and the well is further shown to realize high-temperature oxidation combustion and is in a high-temperature oxidation combustion state;
in the fourth step, the oil washing of the core at 943.5m-944.5m is light brown-yellow brown, and the fireflood temperature of the well section is presumed to be 450-;
in the fifth step, the well determined in the second step and the third step realizes high-temperature oxidation combustion by utilizing the position of the fire flooding front edge of the 039 well group determined in the first step, the fire flooding temperature of the well determined in the fourth step can reach about 550 ℃, the reservoir fire flooding development effect is evaluated, and the evaluation result shows that the 040 well reservoir fire flooding development effect is better.
The above description is only exemplary of the invention and should not be taken as limiting the scope of the invention, so that the invention is intended to cover all modifications and equivalents of the embodiments described herein. In addition, the technical features and the technical inventions of the present invention, the technical features and the technical inventions, and the technical inventions can be freely combined and used.
Claims (12)
1. A method for judging a fireflood combustion state is characterized by comprising the following steps:
determining the position of a firing line in a certain producing well direction in a target research area after the oil well takes effect according to a substance balance method of combustion reaction;
determining a high-low temperature oxidation combustion state according to the oxygen conversion rate and/or the apparent H/C atomic ratio in the fireflooding process;
and establishing a fire-driving core color code chart at different calcining temperatures and determining the fire-driving combustion temperature of the core after fire-driving according to the fire-driving core color code chart.
2. The method of claim 1, wherein the location of the firing line in a direction of a production well in the target area of interest after the well has been activated is determined according to the following equation 1) based on the material balance of the combustion reaction;
in formula 1), R is the position of a fire line, m;
Qis divided intoFor distributing gas, m, in each direction of the well3；
Y is the oxygen utilization rate in each oil well direction, and the decimal number;
alpha is the distribution angle of each oil well direction, °;
h is the thickness of an oil layer in each production well direction, m;
Asm is the air consumption per unit volume of oil layer burned3/m3；
Wherein, the oil layer thickness H in each production well direction and the oxygen utilization rate Y in each oil well direction in formula 1) are calculated according to the following formula 2) and formula 3), respectively:
in formula 2), hgThe effective thickness of the oil layer of the gas injection well is m;
h is the effective thickness of the oil layer of the production well, m;
rho is vertical combustion rate, decimal;
in formula 3), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%.
3. The method according to claim 1, wherein the oxygen conversion rate in the fireflooding process is calculated according to the following formula 4), and then the high and low temperature oxidation combustion state is determined according to the calculated oxygen conversion rate;
in formula 4), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%.
4. The method of claim 1, wherein determining the high and low temperature oxidative combustion state based on the oxygen conversion comprises:
when the oxygen conversion rate is more than 50%, the fireflood process is determined to have reached the high temperature oxidation stage.
5. The method of claim 3, wherein determining the high and low temperature oxidative combustion state based on the oxygen conversion comprises:
when the oxygen conversion rate is more than 50%, the fireflood process is determined to have reached the high temperature oxidation stage.
6. The method according to claim 1, characterized in that, the apparent H/C atomic ratio in the fireflooding process is calculated according to the following formula 5), and then the high and low temperature oxidation combustion state is determined according to the calculated apparent H/C atomic ratio;
in the formula 5), X is the H/C atomic ratio, decimal and dimensionless;
C(O2) Oxygen content,%, in the production well tail gas;
C(CO2) For the carbon dioxide content,%, in the production well tail gas;
c (CO) is the carbon monoxide content in the tail gas of the production well,%.
7. The method according to claim 1 or 6, wherein determining the high and low temperature oxidative combustion state according to the H/C atomic ratio comprises:
when the apparent H/C atomic ratio in the fireflooding process is less than 3, determining that the fireflooding process has a high-temperature oxidation reaction and is in a high-temperature oxidation combustion state;
and when the apparent H/C atomic ratio in the fireflooding process is more than or equal to 3, determining that the fireflooding process has a low-temperature oxidation reaction and is in a low-temperature oxidation combustion state.
8. The method as claimed in claim 1, wherein the establishing of the color scale charts of the fired cores at different calcination temperatures comprises:
obtaining a real core of a reservoir in a target research area by coring, calcining the core at different temperatures for a period of time after oil washing, obtaining core colors at different temperatures after the calcined core is cooled, and establishing a fire-burning core color code chart at different calcining temperatures.
9. The method as claimed in claim 1 or 8, wherein determining the fireflood combustion temperature of the core after fireflood from the core color scale chart comprises:
after the core after fireflooding obtained by the drilling coring or the borehole wall coring method is washed with oil, the color of the core is compared with a core color code plate, and the fireflood combustion temperature of the underground reservoir is determined according to the relationship between the core color and different calcination temperatures in the core color code plate.
10. The method according to claim 1, characterized in that it comprises:
determining the position of a firing line in the direction of a certain production well in a target research area after the oil well takes effect according to the following formula 1) by a material balance method of combustion reaction;
in formula 1), R is the position of a fire line, m;
Qis divided intoFor distributing gas, m, in each direction of the well3；
Y is the oxygen utilization rate in each oil well direction, and the decimal number;
alpha is the distribution angle of each oil well direction, °;
h is the thickness of an oil layer in each production well direction, m;
Asm is the air consumption per unit volume of oil layer burned3/m3；
Wherein, the oil layer thickness H in each production well direction and the oxygen utilization rate Y in each oil well direction in formula 1) are calculated according to the following formula 2) and formula 3), respectively:
in formula 2), hgThe effective thickness of the oil layer of the gas injection well is m;
h is the effective thickness of the oil layer of the production well, m;
rho is vertical combustion rate, decimal;
in formula 3), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%;
calculating the oxygen conversion rate in the fireflood process according to the following formula 4), and determining that the fireflood process has reached a high-temperature oxidation stage when the calculated oxygen conversion rate is greater than 50%;
in formula 4), c (O)2) Is the oxygen content in the tail gas,%;
c(N2) Is the nitrogen content in the tail gas,%;
calculating the apparent H/C atomic ratio in the fireflooding process according to the following formula 5), and determining that the fireflooding process has a high-temperature oxidation reaction and is in a high-temperature oxidation combustion state when the apparent H/C atomic ratio in the fireflooding process is less than 3;
when the apparent H/C atomic ratio in the fireflooding process is more than or equal to 3, determining that the fireflooding process has a low-temperature oxidation reaction and is in a low-temperature oxidation combustion state;
in the formula 5), X is the H/C atomic ratio, decimal and dimensionless;
C(O2) Oxygen content,%, in the production well tail gas;
C(CO2) For the content of carbon dioxide in the tail gas of the production wellAmount,%;
c (CO) is the content of carbon monoxide in the tail gas of the production well,%;
obtaining a real core of a reservoir in a target research area by coring, calcining the core at different temperatures for a period of time after washing oil, obtaining core colors at different temperatures after cooling the calcined core, and establishing a fire-burning core color code chart at different calcining temperatures;
after the core after fireflooding obtained by the drilling coring or the borehole wall coring method is washed with oil, the color of the core is compared with a core color code plate, and the fireflood combustion temperature of the underground reservoir is determined according to the relationship between the core color and different calcination temperatures in the core color code plate.
11. The method according to any one of claims 1-10, further comprising:
and evaluating the reservoir fire flooding development effect according to the high and low temperature oxidation combustion state of each production well and the fire flooding combustion temperature of the core after fire flooding.
12. The method as claimed in claim 11, wherein when the production well reaches a high-temperature oxidation combustion state and the fireflood combustion temperature of the core after fireflooding is more than 350 ℃, the reservoir fireflood development effect is judged to be good, otherwise the reservoir fireflood development effect is judged to be poor.
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