CN102061911B - Method for measuring wall thickness of downhole casing - Google Patents
Method for measuring wall thickness of downhole casing Download PDFInfo
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- CN102061911B CN102061911B CN 201010585175 CN201010585175A CN102061911B CN 102061911 B CN102061911 B CN 102061911B CN 201010585175 CN201010585175 CN 201010585175 CN 201010585175 A CN201010585175 A CN 201010585175A CN 102061911 B CN102061911 B CN 102061911B
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- wall thickness
- density
- value
- casing
- casing wall
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Abstract
The invention discloses a method for measuring the wall thickness of a downhole casing, comprising the following steps of: eliminating the influence of stratum density and cement sheath density on the calculated value of the wall thickness of the downhole casing according to a counting rate curve of a distance detector; and establishing a calculation formula of the wall thickness of the downhole casing to figure out the wall thickness of the downhole casing by utilizing a regression method. The calculation is carried out by adopting the counting rate of the distance detector and the influence of a stratum and a cement sheath on the counting rate of the distance detector when the stratum density and the cement sheath density are different is eliminated, thereby the calculation accuracy of the wall thickness of the downhole casing is improved.
Description
Technical field
The present invention relates to the measuring method of the sleeve pipe in a kind of oil field, relate in particular to a kind of method for measuring wall thickness of downhole casing, be applicable to the Damage Evaluation of down-hole casing.
Background technology
The measuring method of present gamma density casing wall thickness, only utilized nearly Detector count rate value to calculate, do not utilize the far detector counter data, and do not consider that the density difference of density of earth formations, cement sheath is on the impact of probe gamma photons counting rate yet, the difference that the casing wall thickness that calculates is larger with actual casing wall thickness existence has affected next step Construction Decision.The main cause that produces the problems referred to above is: 1. existing computational methods are only calculated with nearly Detector count rate value; 2. do not consider not scattering and the absorption of stratum to gamma photons simultaneously of density of earth formations; 3. do not consider cement sheath density not simultaneously, scattering and the absorption of cement sheath to gamma photons.
China Patent No. " 20,062,009,388 1.7 " discloses a kind of gamma density thickness logging tool graduation apparatus, the applying date is on October 28th, 2006, notice of authorization day is on October 17th, 2007, it is comprised of casing coupling, upper steel plate, inner sleeve outer sleeve, reinforcing bar, lower steel plate and G level cementing concrete, be provided with the different inner sleeve combination of the identical wall thickness of length in outer sleeve, fixed with G level cementing concrete between the inner-outer sleeve tube wall; Inside and outside sleeve pipe upper and lower is welded with respectively upper steel plate and lower steel plate, along the circumferential uniform root reinforcing bar that is welded with, upper and lower steel plate is held between the upper and lower steel plate in the outer sleeve outside, and the inner sleeve upper end is connected with casing coupling.In addition, Fang Zhou etc. has proposed " CALCULATION OF WALL THICKNESS OF EXPANDABLE CASING " in " drilling engineering " in May, 2006 " gas industry ".Aforesaid patented technology only detects for having or not with composition of cementing ring outside sleeve pipe, determines well cementation completion quality height with this." CALCULATION OF WALL THICKNESS OF EXPANDABLE CASING " described later is only suitable in the wall thickness of measuring expansion tube.
Summary of the invention
The object of the invention is to overcome the problems referred to above of the measuring method existence that has gamma density casing wall thickness now, a kind of method for measuring wall thickness of downhole casing is provided, the present invention adopts far and near Detector count rate to calculate, and eliminated due to density of earth formations and not stratum and the cement sheath impact on Detector count rate simultaneously of cement sheath density, improved the accuracy of computation of down-hole casing wall thickness.
For achieving the above object, the technical solution used in the present invention is as follows:
A kind of method for measuring wall thickness of downhole casing, it is characterized in that: according to the counting rate curve of far and near probe, eliminate density of earth formations and cement sheath density to the impact of casing wall thickness calculated value, utilize homing method, set up the casing wall thickness design formulas and calculate casing wall thickness.
The method for building up of described casing wall thickness design formulas is according to nearly Detector count rate TL, far detector counting rate PL, to utilize homing method to set up design formulas:
TH=TH
ST
?-?K*LN(TL/TL
ST
)+LN(PL/PL
ST
)+△TH
In following formula, TH is the calculated wall thickness value, TH
STBe the normal sleeve wall thickness value, K is calibration factor, and TL is nearly Detector count rate value, TL
STBe standard value well section average counter rate value, PL is the far detector counter data, PL
STBe standard value well section average counter rate value,
△ THThe correcting value when casing wall thickness calculates for density of earth formations and cement sheath density.
The difference △ TH of described density of earth formations and standardization of casing value and casing wall thickness calculated value is the One-place 2-th Order relation, and the difference △ TH of cement slurry density and standardization of casing value and casing wall thickness calculated value is once relation of monobasic, utilizes homing method, obtains the expression formula of △ TH:
△ TH=(0.75 ρ
2
The stratum
+ 5.24 ρ
The stratum
-1.54 ρ
Cement paste
)-8
Wherein, TH
STBe the normal sleeve wall thickness value,
ρ The stratum Be density of earth formations,
ρ Cement paste Be cement slurry density.
Describedly utilize density of earth formations not simultaneously, the relation of the difference △ TH of density of earth formations and standardization of casing value and casing wall thickness calculated value, the pass that draws the difference △ TH of density of earth formations and standardization of casing value and casing wall thickness calculated value is the One-place 2-th Order relational expression.
Describedly utilize cement sheath density not simultaneously, the relation of the difference △ TH of cement sheath density and standardization of casing value and casing wall thickness calculated value, the pass that draws the difference △ TH of cement sheath density and standardization of casing value and casing wall thickness calculated value is relational expression of monobasic.
Employing the invention has the advantages that:
One, the present invention has utilized far and near explorer count rate curve to calculate, and has improved the accuracy of casing wall thickness calculated value.
Two, because density of earth formations is different, the stratum is also different to the ability of the scattering of gamma photons and absorption, far and near Detector count rate is also just different, the present invention has considered the impact of density of earth formations, eliminated because of the not impact of layer on Detector count rate over the ground simultaneously of density of earth formations, improved the accuracy of casing wall thickness calculated value.
Three, because cement sheath density has impact to far and near probe, the present invention has considered that the cement sheath of different cement sheath density is to gamma photons scattering and absorption, eliminated because of the not impact of cement sheath on Detector count rate simultaneously of cement sheath density, improved the accuracy of casing wall thickness calculated value, the present invention can accurately measure the down-hole casing wall thickness, and can realize under different interpretation platforms.
Description of drawings
Fig. 1 is the graph of a relation of the difference △ TH of density of earth formations and standardization of casing value and casing wall thickness calculated value
Fig. 2 is the graph of a relation of the difference △ TH of cement sheath density and standardization of casing value and casing wall thickness calculated value.
The specific embodiment
A kind of method for measuring wall thickness of downhole casing according to the counting rate curve of far and near probe, is eliminated density of earth formations and cement sheath density to the impact of casing wall thickness calculated value, utilizes homing method, sets up the casing wall thickness design formulas and calculates casing wall thickness.
Detailed process is as follows:
1. according to nearly Detector count rate (TL), far detector counting rate (PL), utilize homing method to set up and calculate the casing wall thickness method:
TH=TH
ST
?-?K*LN(TL/TL
ST
)+LN(PL/PL
ST
)+△TH
In following formula, TH is the calculated wall thickness value, TH
STBe the normal sleeve wall thickness value, K is calibration factor, and TL is nearly Detector count rate value, TL
STBe standard value well section average counter rate value, PL is the far detector counter data, PL
STBe standard value well section average counter rate value,
△ TH
The correcting value when casing wall thickness calculates for density of earth formations and cement sheath density.
2. utilize density of earth formations not simultaneously, the relation of the difference △ TH of density of earth formations and standardization of casing value and casing wall thickness calculated value, the pass that draws the difference △ TH of density of earth formations and standardization of casing value and casing wall thickness calculated value is the One-place 2-th Order relational expression.
3. utilize cement sheath density not simultaneously, the relation of the difference △ TH of cement sheath density and standardization of casing value and casing wall thickness calculated value, the pass that draws the difference △ TH of cement sheath density and standardization of casing value and casing wall thickness calculated value is relational expression of monobasic.
Difference △ TH by above density of earth formations and standardization of casing value and casing wall thickness calculated value is the One-place 2-th Order relation, cement slurry density and standardization of casing value and casing wall thickness calculated value poor
△ TH is once relation of monobasic, utilizes homing method, obtains the expression formula of △ TH:
△ TH=(0.75 ρ
2
The stratum
+ 5.24 ρ
The stratum
-1.54 ρ
Cement paste
)-8
In following formula, TH
STBe the normal sleeve wall thickness value,
ρ The stratum Be density of earth formations,
ρ Cement paste Be cement slurry density.
Claims (1)
1. method for measuring wall thickness of downhole casing, it is characterized in that: according to the counting rate curve of far and near probe, eliminate density of earth formations and cement sheath density to the impact of casing wall thickness calculated value, utilize homing method, set up the casing wall thickness design formulas and calculate casing wall thickness;
The method for building up of described casing wall thickness design formulas is according to nearly Detector count rate TL, far detector counting rate PL, to utilize homing method to set up design formulas:
TH=TH
ST
?-?K*LN(TL/TL
ST
)+LN(PL/PL
ST
)+△TH
In following formula, TH is the casing wall thickness calculated value, TH
STBe the normal sleeve wall thickness value, K is calibration factor, and TL is nearly Detector count rate, TL
STBe nearly probe standard value well section average counter rate value, PL is the far detector counting rate, PL
STBe far detector standard value well section average counter rate value,
△ THThe correcting value when casing wall thickness calculates for density of earth formations and cement sheath density;
Utilize density of earth formations not simultaneously, the relation of the difference of density of earth formations and normal sleeve wall thickness value and casing wall thickness calculated value, the pass that draws the difference of density of earth formations and normal sleeve wall thickness value and casing wall thickness calculated value is the One-place 2-th Order relational expression;
Utilize cement sheath density not simultaneously, the relation of the difference of cement sheath density and normal sleeve wall thickness value and casing wall thickness calculated value, the pass that draws the difference of cement sheath density and normal sleeve wall thickness value and casing wall thickness calculated value is relational expression of monobasic;
Difference by above density of earth formations and normal sleeve wall thickness value and casing wall thickness calculated value is the One-place 2-th Order relation, and the difference of cement sheath density and normal sleeve wall thickness value and casing wall thickness calculated value is once relation of monobasic, utilizes homing method, obtains the expression formula of △ TH:
Wherein,
ρ The stratum Be density of earth formations,
ρ Cement paste Be cement sheath density.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010585175 CN102061911B (en) | 2010-12-13 | 2010-12-13 | Method for measuring wall thickness of downhole casing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010585175 CN102061911B (en) | 2010-12-13 | 2010-12-13 | Method for measuring wall thickness of downhole casing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102061911A CN102061911A (en) | 2011-05-18 |
| CN102061911B true CN102061911B (en) | 2013-06-26 |
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ID=43997383
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|---|---|---|---|
| CN 201010585175 Expired - Fee Related CN102061911B (en) | 2010-12-13 | 2010-12-13 | Method for measuring wall thickness of downhole casing |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106761667B (en) * | 2016-11-09 | 2019-12-17 | 中国石油大学(北京) | Method and device for four-probe scattering gamma logging and linear data inversion |
| CN106761666B (en) * | 2016-11-09 | 2019-12-17 | 中国石油大学(北京) | Method and device for four-probe scattering gamma logging and nonlinear data inversion |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4715442A (en) * | 1984-04-11 | 1987-12-29 | Pa Incorporated | Apparatus for servicing tubular strings in subterranean wells |
| CN2737943Y (en) * | 2004-10-26 | 2005-11-02 | 西安市首创科技工程有限公司 | Detector for low-energy gamma source fluid density well logging instrument |
| CN200961479Y (en) * | 2006-10-28 | 2007-10-17 | 辽河石油勘探局 | Gamma logging device graduation device for density and thickness |
| CN201071713Y (en) * | 2007-08-16 | 2008-06-11 | 西安威盛电子仪器有限公司 | Down-hole vertical poly-magnetic probe |
| CN201144688Y (en) * | 2007-10-26 | 2008-11-05 | 辽河石油勘探局 | Aggregate unit of multi-arm caliper and electromagnetic flaw detector |
| CN101737039A (en) * | 2009-12-31 | 2010-06-16 | 西安思坦仪器股份有限公司 | Multi-functional underground electromagnetic crack detector |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU1789662C (en) * | 1990-02-28 | 1993-01-23 | Западно-Сибирский Научно-Исследовательский И Проектно-Конструкторский Институт Технологии Глубокого И Разведочного Бурения | Method for placing cement bridging plugs in wells with lost circulation |
-
2010
- 2010-12-13 CN CN 201010585175 patent/CN102061911B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4715442A (en) * | 1984-04-11 | 1987-12-29 | Pa Incorporated | Apparatus for servicing tubular strings in subterranean wells |
| CN2737943Y (en) * | 2004-10-26 | 2005-11-02 | 西安市首创科技工程有限公司 | Detector for low-energy gamma source fluid density well logging instrument |
| CN200961479Y (en) * | 2006-10-28 | 2007-10-17 | 辽河石油勘探局 | Gamma logging device graduation device for density and thickness |
| CN201071713Y (en) * | 2007-08-16 | 2008-06-11 | 西安威盛电子仪器有限公司 | Down-hole vertical poly-magnetic probe |
| CN201144688Y (en) * | 2007-10-26 | 2008-11-05 | 辽河石油勘探局 | Aggregate unit of multi-arm caliper and electromagnetic flaw detector |
| CN101737039A (en) * | 2009-12-31 | 2010-06-16 | 西安思坦仪器股份有限公司 | Multi-functional underground electromagnetic crack detector |
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|---|---|
| CN102061911A (en) | 2011-05-18 |
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Granted publication date: 20130626 Termination date: 20171213 |