Disclosure of Invention
The invention aims to improve the plugging effect, avoid safety accidents and promote safe and efficient production of a mine, and provides a determination method for plugging depth of a waste petroleum well in a coal mining area, which is comprehensively considered, accurately analyzed, safe and efficient.
The purpose of the invention is realized as follows: a method for determining the plugging depth of a waste petroleum well in a coal mining area comprises the following steps:
step 1): theoretically calculating the damage depth of the bottom plate, collecting the damage data of the bottom plate of the mine working face, performing regression analysis calculation with the formula of the damage depth of the bottom plate in the regulation to obtain an improved empirical formula, and calculating the damage depth h of the bottom plate of each coal bed1;
Step 2): simulating the damage depth value of the bottom plate, and calculating the deformation damage depth h of the bottom plate affected by mining under the three conditions of an oil-free well, a naked eye well and a cased oil well according to the comparison of the stope stress and the plastic zone2Comparison by analysis h1And h2Taking the maximum value as a calculated value h of the damage depth of the bottom plate;
step 3): simulating the plugging length of the abandoned oil well to obtain the oil gas permeation height l after plugging the oil well without a metal sleeve and with the metal sleeve1Taking the maximum value as a calculated value l of the penetration height after plugging;
step 4): determining the plugging length of the abandoned oil well, and according to a formula: and L = k (L + h), and calculating to obtain the reasonable plugging length L of the abandoned oil well, wherein k is a safety coefficient.
In step 1), the improved empirical formula is h1=0.375l0 0.746Wherein l is0The length of the working face of the coal mine.
In the step 4), h is a calculated value of the damage depth of the bottom plate obtained in the step 2), and l is a calculated value of the penetration height after plugging obtained in the step 3).
In the step 4), k is 1.2-1.3.
The invention has the beneficial effects that: the invention provides a method for determining the plugging depth of a waste petroleum well in a coal mining areaNot only the penetration range of oil gas in surrounding rock and plugging concrete after plugging is considered, but also the damage depth of mining to the bottom plate is considered; when the damage depth of the bottom plate is theoretically calculated, regression analysis can be carried out on the rule formula and the collected damage data of the bottom plate of the mine working face to obtain an empirical formula, and the method is more scientific and reasonable; when the invention determines the calculated value h of the damage depth of the bottom plate, the theoretically calculated value h is calculated1And h obtained by simulation2Comparing, taking the maximum value, and taking the oil gas permeation height l obtained by simulation when determining the calculated value l of the permeation height after plugging1The maximum value is safe and efficient, safety accidents such as oil gas leakage can be avoided to the greatest extent, and the plugging effect is guaranteed; the method for determining the plugging depth of the waste petroleum well in the coal mining area has the advantages of comprehensive consideration, accurate analysis, safety and high efficiency.
Detailed Description
The invention will be further described with reference to abandoned oil wells in a double-horse coal mine and the accompanying drawings.
Examples
The method for determining the plugging depth of the waste oil well in the coal mining area as shown in the figures 1 to 4 comprises the following steps:
step 1): theoretically calculating the damage depth of the bottom plate, collecting the damage data of the bottom plate of the mine working face, performing regression analysis calculation with the formula of the damage depth of the bottom plate in the regulation to obtain an improved empirical formula, and calculating the damage depth h of the bottom plate of each coal bed1;
The regulation is 'the regulations for coal pillar setting and coal pressing mining of buildings, water bodies, railways and main roadways', wherein an empirical formula h is selected through effectiveness analysis in a formula given by the regulations0=0.303l0 0.80Wherein l is0The length of the working face of the coal mine.
Measured face floor water-induced zone depth of failure listed in the protocol of Table 1.1
Serial number
|
Working surface
|
Depth of cut/m
|
Inclination angle/°
|
Thickness per meter
|
Length of face/m
|
Depth of failure/m
|
Description of the invention
|
1
|
Handan royal phoenix mineral 1930
|
103~132
|
16~20
|
2.5
|
80
|
10
|
|
2
|
Handan royal phoenix mineral 1830
|
123
|
15
|
1.1
|
70
|
6~8
|
|
3
|
Handan royal phoenix mineral 1951
|
|
|
1.1
|
100
|
13.4
|
|
4
|
Peak-peak dike 2701
|
145
|
16
|
1.5
|
120
|
14
|
|
5
|
Peak-to-peak trimite 3707
|
130
|
15
|
1.4
|
135
|
>10
|
|
6
|
Peak four mine 4804, 4904
|
|
12
|
|
100+100
|
10.7
|
Coordinated mining
|
7
|
Feicheng Caozhuang ore 9203
|
132~164
|
18
|
|
95~105
|
9
|
|
8
|
Baizhuang mineral 7406 in Feicheng
|
225~249
|
|
1.9
|
60+140
|
7.2~8.4
|
|
9
|
Zibo double-hooke mine 1024, 1028
|
278~296
|
|
1.0
|
60+70
|
10.5
|
Oppositely pulled surfaces
|
10
|
Chengjiang bizie 22510
|
300
|
8
|
-
|
100
|
10
|
|
11
|
Hancheng equestrian 1100
|
230
|
10
|
2.3
|
120
|
13
|
|
12
|
Triple mine 128
|
230
|
26
|
3~4
|
180
|
20
|
Adopt two to stratify and reach 24m
|
13
|
From the chenchenchenchen stage 7802
|
234~284
|
4
|
3.0
|
160
|
16.4
|
|
14
|
Narrow from the schechensie ore 7607
|
310~330
|
4
|
5.4
|
60
|
9.7
|
|
15
|
From the chenchenchensie ore 7607 wide
|
310~330
|
4
|
5.4
|
100
|
11.7
|
|
16
|
Huainan Xinzhuanzi mine 4303
|
310
|
26
|
1.8
|
128
|
16.8
|
|
17
|
Well 38473
|
227
|
12
|
3.5
|
30
|
3.5
|
The failure depth of the fault zone is less than 7m
|
18
|
Well 38473, mine 4707 small
|
350~450
|
9
|
4
|
34
|
8
|
The thickness of the layer is 4m, and the failure depth is about 6m
|
19
|
Well 38473
|
400
|
9
|
4
|
45
|
6.5
|
Adopt a layer
|
20
|
Opening 28390of Zhao Zhuang Ore 1237
|
900
|
26
|
2
|
200
|
27
|
Coal seam containing 8m
|
21
|
Opening 28390of Zhao Zhuang Ore 2137
|
1000
|
26
|
2
|
200
|
38
|
8m coal and bottom fissure development
|
22
|
Wen Huafeng mine 41303
|
480~560
|
30
|
0.94
|
120
|
13
|
|
From the above empirical formula, it can be seen that the effect of the working face length on the damage depth of the baseplate is obvious, and from the damage depth values of the baseplate in table 1.1, the results calculated by the rule empirical formula are all larger than the measured values, and from table 1.1, the number of samples of the measured data is small, and the number of effective samples which can be used for regression analysis is small; therefore, the above formula is only a method for roughly estimating the depth of the damage zone of the baseplate, and the accuracy of the calculation result is limited; the intrinsic cause that the damage of the bottom plate is mainly the action result of the supporting pressure of the working face is analyzed, and the basic rule of the distribution characteristic of the supporting pressure of the working face is known, so that under the condition that other conditions are not changed, the distribution characteristic of the supporting pressure in the top bottom plate tends to be stable after the length of the working face exceeds a certain value; accordingly, the depth characteristic (maximum value) of the bottom plate fracture zone should be stable after the length of the working face exceeds a certain value, but the basic characteristic is not well reflected by the empirical formula of the regulation.
Further data on the failure of the floor of part of the mine face was collected and subjected to regression analysis together with the data in table 1.1 to give an improved empirical formula: h is1=0.375l0 0746Therefore, this equation is used for estimation.
Because the damage depth of the bottom plate in the improved empirical formula is only related to the length of the working face, the damage depths of the bottom plates of the double-horse coal mines are basically the same, the length of the working face of the double-horse coal mine is 265m, and the damage depth of the bottom plate of each coal bed is h1。
h1=0.375l0 0746=0.375*2650.746=24.08(m)
Step 2): simulating a bottom plate failure depth value by adopting a discrete element program UDEC, making three oil-free well models, an open hole model and a cased oil well model according to a mine, then processing a top plate by adopting a longwall coal mining method and a natural caving method to obtain a stope stress diagram and a shaping area distribution diagram under three conditions, and obtaining corresponding bottom plate deformation failure depth h2Comparison by analysis h1And h2Taking the maximum value as a calculated value h of the damage depth of the bottom plate;
as shown in fig. 1, when the working face is pushed to 60m, 180m and 300m and the production stopping line under the condition of no oil well, the stress of 0-10 m in front of the coal wall of the working face is gradually increased and has a peak value, the maximum value is about 50MPa, the stress of 10-28 m is gradually reduced to 30MPa, and the stress is gradually recovered to be close to the original rock stress value when the stress is about 80m in front of the coal wall; numerical simulation research shows that 0-26 m below a bottom plate of a working face is a bottom plate damage influence zone, namely the maximum damage depth of the bottom plate is 26m, the rock stratum of 26-44 m is less influenced by coal seam mining, and the rock stratum has a tendency close to the original rock stress downwards; as shown in fig. 2, when the working face is pushed to 60m, 180m, 300m and a mining stop line under the condition of an open hole, the vertical stress of 0-14 m in front of the coal wall of the working face is gradually increased and has a peak value, the maximum value is about 56MPa, the vertical stress of 14-33 m is gradually reduced to 33MPa, and the vertical stress is gradually restored to be close to the original rock stress value when the vertical stress is about 80m in front of the coal wall; numerical simulation research shows that 0-32 m below a bottom plate of a working face is a bottom plate damage influence zone, namely the maximum damage depth of the bottom plate is 32m, rock strata of 32-50 m are less influenced by coal seam mining, and then the rock strata downwards have a tendency close to the original rock stress; as shown in fig. 3, when the working face is pushed to 60m, 180m, 300m and the production stopping line under the condition of a cased oil well, the vertical stress of 0-7 m in front of the coal wall of the working face is gradually increased and has a peak value, the maximum value is about 44MPa, the vertical stress of 7-19 m is gradually reduced to 22MPa, and the vertical stress is gradually restored to be close to the original rock stress value when the vertical stress is about 80m in front of the coal wall; numerical simulation research shows that 0-19 m below a bottom plate of a working face is a bottom plate damage influence zone, namely the maximum damage depth of the bottom plate is 19m, rock strata of 19-36 m are less influenced by coal seam mining, and then the rock strata downwards have a tendency close to the original rock stress; as shown in fig. 4-6, when the working face is pushed to 60m, 180m, 300m and the mining line under three conditions of no oil well, open hole and casing oil well, the top plate of the goaf is subjected to flexural deformation along with the continuous pushing of the working face, the bottom plate generates certain pressure relief expansion when the direct roof is not subjected to collapse damage, the basic roof is subjected to slight flexural deformation after the direct roof collapses, the bottom plate is bulged after the direct roof collapses, the bottom bulge amount is rapidly increased along with the pushing of the working face before and after the direct roof is subjected to initial collapse after the goaf fully discharges the top plate rock stratum, the increasing speed is smaller and smaller, the increasing speed of the bottom bulge amount is close to zero after the basic roof is subjected to initial fracture, and the deformation form is gradually changed from expansion to compression; with the continuous propulsion of the working face, the collapse of the top plate rock stratum gradually tends to be stable, and the bottom bulging amount tends to a certain value.
According to the comparison of stope stress and plastic zone under three conditions, the deformation and damage depth h of the bottom plate affected by mining under the oil-free well condition is obtained through analysis2=26 (m), with open hole h2=32 (m), h under cased well conditions2=19 (m), and the floor damage depth h is obtained by theoretical calculation in step 1)1And =24.08 (m), comparing and taking the maximum value, and finally determining the calculated floor damage depth h =32 (m).
Step 3): simulating the plugging length of the abandoned oil well by adopting an ANSYS finite element program, establishing an oil well model without a metal sleeve and with the metal sleeve according to the double-horse coal mine, and performing plugging simulation to obtain a gas permeation flow diagram, wherein the gas permeation height l of the plugged oil well without the metal sleeve and with the metal sleeve is obtained by analysis1Taking the maximum value as a calculated value l of the penetration height after plugging;
as shown in FIG. 7, the gas of the uncased oil well mainly exists at the bottom 290m, and the height of the oil-gas penetration mixed plugging concrete is about 40m because the bottom 250m is not plugged; as shown in FIG. 8, the gas of the cased well is mainly present at the bottom 277m, the height of the oil-gas penetration mixed plugging concrete is about 27m because the bottom 250m is not plugged, and the oil-gas penetration height l after plugging of the uncased well is compared1=40 (m) and oil and gas penetration height l of cased well1And taking the maximum value of the =27 (m), and determining the calculated penetration height after plugging, i =40 (m).
Step 4): determining the plugging length of the abandoned oil well, and according to a formula: and L = k (L + h), calculating to obtain the reasonable plugging length L of the abandoned oil well, wherein k is a safety factor, k =1.3 in consideration of safety factors, and substituting h =32 (m) and L =40 (m) into the formula to obtain the reasonable plugging length of the abandoned oil well.
L=k(l+h)=1.3*(32+40)=93.6(m)
In the embodiment, the plugging length of the abandoned oil well is finally determined to be 100m in consideration of safety factors.
The method for determining the plugging depth of the waste petroleum well in the coal mining area not only considers the penetration range of oil gas in surrounding rock and plugging concrete after plugging, but also takes the damage depth of mining to a bottom plate into consideration; when the damage depth of the bottom plate is theoretically calculated, regression analysis can be carried out on the rule formula and the collected damage data of the bottom plate of the mine working face to obtain an empirical formula, and the method is more scientific and reasonable; the invention is inWhen determining the calculated value h of the damage depth of the bottom plate, calculating the theoretical value h1And h obtained by simulation2Comparing, taking the maximum value, and taking the oil gas permeation height l obtained by simulation when determining the calculated value l of the permeation height after plugging1The maximum value is safe and efficient, safety accidents such as oil gas leakage can be avoided to the greatest extent, and the plugging effect is guaranteed; the method for determining the plugging depth of the waste petroleum well in the coal mining area has the advantages of comprehensive consideration, accurate analysis, safety and high efficiency.