CN103806855B - The defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling - Google Patents

Abstract

The present invention relates to the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling, comprise the following steps: the rock core 1) drilling through a certain degree of depth of huge thick Salt layer, creep test is carried out to it, calculates the creep parameters A of this rock core, B and Q; 2) mineralogical composition test is carried out to rock core, measure the volume fraction V of NaCl _naCl; 3) choose other several degree of depth and repeat step 1) and 2), obtain creep parameters A, B and Q under huge thick Salt layer respective depth, and the volume fraction V of the NaCl of correspondence in rock salt _naCl; 4) according to the data that step 3) obtains, the volume fraction V of creep parameters A, B, Q and NaCl is set up _naClbetween dependency relation; 5) the NaCl volume fraction V under utilizing log data to calculate the huge thick Salt layer consecutive variations degree of depth _naCl; 6) A, B, Q and the V of foundation is utilized _naCldependency relation, calculate creep parameters A, B and Q under the huge thick rock salt continually varying degree of depth; 7) determine that the full well section in huge thick rock salt stratum is for controlling the drilling fluid density of hole shrinkage speed, and draw drilling fluid density plate.

Description

The defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling

Technical field

The present invention relates to the defining method of drilling fluid density in a kind of field of oil development, be specifically related to the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling.

Background technology

Along with the continuous exploitation of Shallow Oil-Gas resource, Shallow Oil-Gas resource is close to exhausted, and in order to meet growing energy demand, Deep Oil And Gas Exploration resource and bad ground petroleum resources more and more cause the concern of people.Rock salt stratum is the fine cap rock of Hydrocarbon Formation Reservoirs, usually contain a large amount of petroleum resourceses under rock salt stratum, in the Middle East, the Central Asia, the Gulf of Mexico, China the Sichuan Basin, Tarim Oilfield, Zhongyuan Oil Field, Jianghan Oil-field etc. area all found a large amount of petroleum resourceses at subsalt layer.But saline bed is a kind of stratum with extremely strong creeping property, and especially in the high temperature and high pressure environment of down-hole, rheological characteristic is strong.After well is bored and opened, rock salt well can along with the continuous undergauge of time, if drilling fluid density is selected improper, well bore open a period of time after may there is hole shrinkage, cave in, bit freezing, the complex accident such as leakage of thin layer.Well creep unique artificial controllable factor in salt constituent stratum is drilling fluid density, therefore, determines that rational drilling fluid density is of crucial importance in the exploitation of petroleum resources.By determining that rational drilling fluid density can realize controlling to ensure safety to the well creep of salt constituent stratum creeping into.

Determine that the prerequisite of rational drilling fluid density is the creep parameters obtaining rock salt stratum, traditional method when determining rational drilling fluid using the creep rate on whole rock salt stratum as a constant, but encounter a lot of huge thick rock salt stratum in actual well drilled, the Gulf of Mexico as the U.S. has the thick rock salt stratum of a few km as oil gas cap rock, huge thick rock salt stratum due to the degree of depth difference larger, the mineral constituent of different layers position rock salt, stress state and Temperature-pressure Conditions are widely different, and creep parameters also has very large difference.Therefore, when huge thick rock salt strata drilling, traditional method is also inapplicable.On the other hand, carry out creep test can obtain creep parameters although drill through rock core to rock salt stratum, wanting to realize drilling through rock core continuously when in the face of huge thick rock salt stratum is that prior art cannot realize.

Summary of the invention

For the problems referred to above, the object of this invention is to provide a kind of defining method with the liquid-tight degree of huge thick rock salt strata drilling of engineering practicability.

For achieving the above object, the present invention is by the following technical solutions: the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling, comprises the following steps:

1) rock core drilling through a certain degree of depth of huge thick Salt layer is some, carries out creep test to institute's coring, and calculates creep parameters A, B and Q of this rock core; Wherein A, B are Mineral rheology parameter; Q is the activation energy of rock salt;

2) mineralogical composition test is carried out to the rock core got by drilling, measure the volume fraction V of NaCl in rock salt _naCl;

3) choose other several degree of depth of huge thick Salt layer and repeat step 1) and 2), obtain creep parameters A, B and Q under huge thick Salt layer respective depth, and the volume fraction V of the NaCl of correspondence in rock salt _naCl;

4) according to the data that step 3) obtains, approximating method is adopted to set up the volume fraction V of creep parameters A, B, Q and NaCl _naClbetween dependency relation;

5) stratum density ρ, rock salt degree of porosity φ under the huge thick Salt layer consecutive variations degree of depth is obtained by log data, and the volume fraction V of clay mineral in rock salt _cl, calculate the NaCl volume fraction V under the huge thick Salt layer consecutive variations degree of depth by following formula _naCl:

$\mathrm{\φ}\×{\mathrm{\ρ}}_{\mathrm{fluid}}+{\mathrm{\ρ}}_{\mathrm{NaCl}}\×{V_{\mathrm{NaCl}}+V}_{{\mathrm{CaSO}}_4}\×{\mathrm{\ρ}}_{{\mathrm{CaSO}}_4}+V_{\mathrm{cl}}\×{\mathrm{\ρ}}_{\mathrm{cl}}=\mathrm{\ρ}$

$\mathrm{\φ}+V_{\mathrm{NaCl}}+V_{{\mathrm{CaSO}}_4}+V_{\mathrm{cl}}=1$

In formula: φ is rock salt degree of porosity; ρ _fluidfor pore-fluid density; ρ _naClfor NaCl density; V _naClfor the volume fraction of NaCl in rock salt; for CaSO ₄density; for CaSO ₄volume fraction in rock salt; V _clfor the volume fraction of clay mineral in rock salt; ρ _clfor clay mineral density; ρ is rock salt density; The wherein density p of each component _fluid, ρ _naCl, , ρ _clbe given value;

6) A utilizing step 4) to set up, B, Q and V _naCldependency relation, calculate creep parameters A, B and Q under the huge thick rock salt continually varying degree of depth;

7) determine that the full well section in huge thick rock salt stratum is for controlling the drilling fluid density of hole shrinkage speed by following formula, and draw drilling fluid density plate:

${\mathrm{\ρ}}_l=100\{{\mathrm{\σ}}_h-\underset{r_w}{\overset{\∞}{\∫}}\frac{2}{\sqrt{3}}\×\frac{1}{B\left(h\right)r}\×1n[\frac{D\left(h\right)r_w^{2}n(2-n)}{2}{\left(\frac{r_w}{r}\right)}^2+\sqrt{{\left(\frac{D\left(h\right)r_w^{2}n(2-n)}{2}\right)}^2{\left(\frac{r_w}{r}\right)}^4}+1\left]\frac{\mathrm{dr}}{H}\right\}$

In formula: D (h) is Mineral rheology parameter; σ _hfor level minimally stress; r _wfor well radius; R is the distance of stratum apart from borehole axis; H is well depth; N is experience undergauge speed.

In described step 7), the computational methods of hole shrinkage speed n are:

$n=\frac{\mathrm{\ΔS}}{t\·S}$

In formula: Δ S is the variable quantity of well area after creep; T is creep time; S is former well area; And:

$\mathrm{\ΔS}=\mathrm{\π}(R_0^2-R_1^2)$

$S=\mathrm{\π}{R}_0^2$

In described step 7), the computational methods of D (h) are:

$D\left(h\right)=\frac{2}{\sqrt{3}A\left(h\right){r_w}^2}\exp \left(\frac{Q\left(h\right)}{\mathrm{RT}}\right)$

In formula: h is depth of stratum; R is gas molar constant, i.e. R=1.987cal/molK; T is thermodynamic temperature.

In described step 1), creep test adopts creep of rock testing machine to carry out.

Described step 2) Mineral Component test adopts X diffractometer to carry out.

The present invention is owing to taking above technical scheme, it has the following advantages: the present invention is the new method proposed based on on-the-spot physical condition on the basis that rock salt stratum dynamics parameter laboratory test is measured and on-the-spot log data combines, the method engineering practicability is strong, this can reflect the data of down-hole formation characteristic to take full advantage of log data, through on-site actual situations inspection, there is good effect.The present invention is applicable to the prediction of huge thick rock salt stratum safe drilling fluid density.

Accompanying drawing explanation

Fig. 1 is flow chart of the present invention;

Fig. 2 is creep test curve and the matched curve under Heard pattern;

Fig. 3 is that huge thick rock salt stratum is for controlling the drilling fluid density plate of hole shrinkage speed.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described in detail.

The defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling of the present invention, comprises the following steps (as shown in Figure 1):

1) rock core drilling through a certain degree of depth of huge thick Salt layer is some, carries out creep test to institute's coring, and calculates creep parameters A, B and Q of this rock core; Wherein A, B are Mineral rheology parameter; Q is the activation energy of rock salt; A, B and Q are all the functions changed with formation depth.Detailed process is as follows:

Under the Temperature-pressure Conditions of down-hole, the creep of rock salt belongs to the category of dislocation movement by slip, and under the Heard pattern in creep test and down-hole Temperature-pressure Conditions, the creep of rock salt is the most identical.Under Heard pattern, it has been generally acknowledged that the Creep of Salt under higher stress and lower temperature (being less than 250 DEG C) is that lattice mismatch slippage is preponderated, Creep of Salt equation so now can be described as:

$\stackrel{\·}{\mathrm{\ϵ}}=\mathrm{Aexp}(-Q/\mathrm{RT})\mathrm{sh}\left(\mathrm{B\σ}\right)$

In formula: for creep rate; R is gas molar constant, R=1.987cal/molK; σ is stress difference; T is thermodynamic temperature.

After the rock core getting a certain degree of depth by drilling, strain-time graph (as shown in Figure 2) can be obtained by creep test, creep parameters A, B and Q can be obtained by the curve under Heard pattern.

Above-mentioned creep test can adopt creep of rock testing machine to carry out.

2) mineralogical composition test is carried out to the rock core got by drilling, measure the volume fraction V of NaCl in rock salt _naCl.

Above-mentioned mineralogical composition test can adopt X diffractometer to carry out.

3) choose other several degree of depth of huge thick Salt layer, repeat step 1) and 2), obtain creep parameters A, B and Q under several degree of depth of huge thick Salt layer, and the volume fraction V of the NaCl of correspondence in rock salt _naCl.

4) according to the data that step 3) obtains, approximating method is adopted to set up the volume fraction V of creep parameters A, B, Q and NaCl _naClbetween dependency relation.

5) stratum density ρ, rock salt degree of porosity φ under the huge thick Salt layer consecutive variations degree of depth is obtained by log data, and the volume fraction V of clay mineral in rock salt _cl, calculate the NaCl volume fraction V under the huge thick Salt layer consecutive variations degree of depth further _naCl.Detailed process is as follows:

Mineralogical composition in rock salt generally comprises NaCl, CaSO ₄, clay mineral (shale) and pore-fluid, meet following equation between various mineral content:

$\mathrm{\φ}\×{\mathrm{\ρ}}_{\mathrm{fluid}}+{\mathrm{\ρ}}_{\mathrm{NaCl}}\×{V_{\mathrm{NaCl}}+V}_{{\mathrm{CaSO}}_4}\×{\mathrm{\ρ}}_{{\mathrm{CaSO}}_4}+V_{\mathrm{cl}}\×{\mathrm{\ρ}}_{\mathrm{cl}}=\mathrm{\ρ}$

$\mathrm{\φ}+V_{\mathrm{NaCl}}+V_{{\mathrm{CaSO}}_4}+V_{\mathrm{cl}}=1$

In formula: φ is rock salt degree of porosity; ρ _fluidfor pore-fluid density; ρ _naClfor NaCl density; V _naClfor the volume fraction of NaCl in rock salt; for CaSO ₄density; for CaSO ₄volume fraction in rock salt; V _clfor the volume fraction of clay mineral in rock salt; ρ _clfor clay mineral density; ρ is rock salt density.

The density p of each component in above-mentioned two equations _fluid, ρ _naCl, , ρ _clbe given value.Stratum density ρ, rock salt degree of porosity φ, and the volume fraction V of clay mineral in rock salt _clall can be drawn by log data, therefore, the volume fraction V of NaCl in rock salt can be tried to achieve by above-mentioned two equations _naCl.

6) A utilizing step 4) to set up, B, Q and V _naCldependency relation, calculate creep parameters A, B and Q under the huge thick rock salt continually varying degree of depth.

7) determine that the full well section in huge thick rock salt stratum is for controlling the drilling fluid density of hole shrinkage speed, and draw drilling fluid density plate (as shown in Figure 3), detailed process is as follows:

For controlling the drilling fluid density ρ of rock salt stratum hole shrinkage speed _lcomputational methods be:

${\mathrm{\ρ}}_l=100\{{\mathrm{\σ}}_h-\underset{r_w}{\overset{\∞}{\∫}}\frac{2}{\sqrt{3}}\×\frac{1}{B\left(h\right)r}\×1n[\frac{D\left(h\right)r_w^{2}n(2-n)}{2}{\left(\frac{r_w}{r}\right)}^2+\sqrt{{\left(\frac{D\left(h\right)r_w^{2}n(2-n)}{2}\right)}^2{\left(\frac{r_w}{r}\right)}^4}+1\left]\frac{\mathrm{dr}}{H}\right\}$

In formula: D (h) is Mineral rheology parameter; σ _hfor level minimally stress; r _wfor well radius; R is the distance of stratum apart from borehole axis; H is well depth; N is experience undergauge speed.

Wherein, hole shrinkage speed n is defined as:

$n=\frac{\mathrm{\ΔS}}{t\·S}$

In formula: △ S is the variable quantity of well area after creep; T is creep time; S is former well area, and:

$\mathrm{\ΔS}=\mathrm{\π}(R_0^2-R_1^2)$

$S=\mathrm{\π}{R}_0^2$

In addition, the computational methods of D (h) are:

$D\left(h\right)=\frac{2}{\sqrt{3}A\left(h\right){r_w}^2}\exp \left(\frac{Q\left(h\right)}{\mathrm{RT}}\right)$

In formula: h is depth of stratum.

According to the drilling fluid density plate that said method obtains, according to the Creep of Salt situation of full well section, rational drilling fluid density can be determined.

The present invention is only described with above-described embodiment, and the structure of each parts, setting position and connecting all can change to some extent.On the basis of technical solution of the present invention, all improvement of carrying out individual part according to the principle of the invention or equivalents, all should not get rid of outside protection scope of the present invention.

Claims (5)

1. a defining method for the liquid-tight degree of huge thick rock salt strata drilling, comprises the following steps:

1) rock core drilling through a certain degree of depth of huge thick Salt layer is some, carries out creep test to institute's coring, and calculates creep parameters A, B and Q of this rock core; Wherein A, B are Mineral rheology parameter; Q is the activation energy of rock salt;

2) mineralogical composition test is carried out to the rock core got by drilling, measure the volume fraction V of NaCl in rock salt _naCl;

3) choose other several degree of depth of huge thick Salt layer and repeat step 1) and 2), obtain creep parameters A, B and Q under huge thick Salt layer respective depth, and the volume fraction V of the NaCl of correspondence in rock salt _naCl;

4) according to step 3) data that obtain, adopt approximating method to set up creep parameters A, B, Q and the NaCl volume fraction V in rock salt _naClbetween dependency relation;

5) stratum density ρ, the rock salt degree of porosity φ under the huge thick Salt layer consecutive variations degree of depth is obtained by log data, and the volume fraction V of clay mineral in rock salt _cl, calculate the volume fraction V of NaCl in rock salt under the huge thick Salt layer consecutive variations degree of depth by following formula _naCl:

$\mathrm{\φ}\×{\mathrm{\ρ}}_{fluid}+{\mathrm{\ρ}}_{NaCl}\×V_{NaCl}+V_{{\mathrm{CaSO}}_4}\×{\mathrm{\ρ}}_{{\mathrm{CaSO}}_4}+V_{cl}\×{\mathrm{\ρ}}_{cl}=\mathrm{\ρ}$

$\mathrm{\φ}+V_{NaCl}+V_{{\mathrm{CaSO}}_4}+V_{cl}=1$

In formula: φ is rock salt degree of porosity; ρ _fluidfor pore-fluid density; ρ _naClfor NaCl density; V _naClfor the volume fraction of NaCl in rock salt; for CaSO ₄density; for CaSO ₄volume fraction in rock salt; V _clfor the volume fraction of clay mineral in rock salt; ρ _clfor clay mineral density; ρ is stratum density; The wherein density p of each component _fluid, ρ _naCl, ρ _clbe given value;

6) utilize step 4) A that sets up, B, Q and V _naCldependency relation, calculate creep parameters A, B and Q under the huge thick rock salt continually varying degree of depth;

7) determine that the full well section in huge thick rock salt stratum is for controlling the drilling fluid density ρ of hole shrinkage speed by following formula _l, and draw drilling fluid density ρ _lplate:

${\mathrm{\ρ}}_l=100\{{\mathrm{\σ}}_h-\underset{r_w}{\overset{\mathrm{\∞}}{\∫}}\frac{2}{\sqrt{3}}\×\frac{1}{B\left(h\right)r}\×\ln \[\frac{D\left(h\right)r_w^{2}n(2-n)}{2}{\left(\frac{r_w}{r}\right)}^2+\sqrt{{\left(\frac{D\left(h\right)r_w^{2}n(2-n)}{2}\right)}^2{\left(\frac{r_w}{r}\right)}^4}+1\]\frac{dr}{H}\}$

In formula: D (h) is Mineral rheology parameter; σ _hfor level minimally stress; r _wfor well radius; R is the distance of stratum apart from borehole axis; H is well depth; N is hole shrinkage speed; H is depth of stratum; B (h) represents the functional relation that creep parameters B changes with depth of stratum h.

2. the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling as claimed in claim 1, is characterized in that, described step 7) in the computational methods of D (h) be:

$D\left(h\right)=\frac{2}{\sqrt{3}A\left(h\right){r_w}^2}\exp \left(\frac{Q\left(h\right)}{RT}\right)$

In formula: h is depth of stratum; R is gas molar constant, i.e. R=1.987cal/molK; T is thermodynamic temperature; Q (h) represents the functional relation that creep parameters Q changes with depth of stratum h; A (h) represents the functional relation that creep parameters A changes with depth of stratum h.

3. the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling as claimed in claim 1 or 2, is characterized in that, described step 1) in creep test adopt creep of rock testing machine to carry out.

4. the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling as claimed in claim 1 or 2, is characterized in that, described step 2) Mineral Component test adopts X diffractometer to carry out.

5. the defining method of the liquid-tight degree of a kind of huge thick rock salt strata drilling as claimed in claim 3, is characterized in that, described step 2) Mineral Component test adopts X diffractometer to carry out.