JP5374823B2 - Oil well cement composition and method for producing the same - Google Patents

Description

  The present invention relates to an oil well cement composition excellent in fluidity and strength that can be used for well drilling in oil fields and gas fields, and a method for producing the same.

  In the drilling of wells such as oil fields and gas fields, cement is used for the purpose of reinforcing casing pipes inserted into the wells, preventing corrosion, preventing the inflow of underground water into the wells, and the like. Since the cement used in this application is used under high temperature and high pressure, higher quality is required for slurry fluidity and strength development than general structural cement.

  Generally, in the drilling of oil wells and gas wells, a rotary drilling method is adopted, and drilling-cementing work by a bit is repeated. In this case, as the cementing condition, the temperature increases as the oil well becomes deeper, and the pressure also increases due to muddy water or cement slurry column pressure. Therefore, cement used in well drilling such as oil fields and gas fields is required to have workability and strength development under high temperature and high pressure.

  The American Petroleum Institute (hereinafter referred to as “API”) uses eight classes A to H as a cement composition used when drilling wells in oil fields, depending on the required performance, ordinary type (O), medium sulfate resistant type ( MSR) and three grades of high sulfate resistance type (HSR).

Among these, class G (high sulfate-resistant type (HSR)) is the most commonly used cement composition for oil well drilling, the amount of C ₃ S is 48 to 65% by mass, C ₃ A the amount is 3 mass% or _less, 2C 3 A _{+ C} 4 AF 24 wt% or less, the total alkali content of 0.75 wt% or less, the amount of MgO is 6.0 wt% or less, SO ₃ content of 3.0 wt% or less, The ignition loss is defined as 3.0% by mass or less, and the insoluble residue is defined as 0.75% by mass or less.

  However, even if the API standard is satisfied, depending on the excavation depth and well shape (size, etc.), further improvement in fluidity and compressive strength may be required.

Specification for Cements and Materials for Well Cementing API Specification 10A Twenty-third Edition, April 2002

  An object of the present invention is to provide an oil well cement composition that exhibits high fluidity and strength development under high temperature or high temperature / high pressure in an oil well cement composition used for well drilling in oil fields and gas fields, and a method for producing the same. Is to provide.

As a result of intensive studies to solve the above problems, the inventors of the present invention, in an oil well cement composition having a C ₃ S amount of 55 to 65% by mass and a C ₃ A amount of 2% by mass or less of the cement composition, The Blaine specific surface area is 2700-3700 cm ² / g, 45 μm sieve residue is 15% by mass or more, the amount of free calcium is 0.2-0.6% by mass, and the ratio of hemihydrate gypsum in gypsum is 20-80% by mass. As a result, it has been found that fluidity and strength development can be improved, and the present invention has been completed.

  Moreover, in order to stably produce this oil well cement composition, an open circuit type tube ball mill is used, and the amount of water spray is controlled within a range of 0 to 3% by mass and added to the cement composition. The inventors found that it is more effective to adjust the mill exit cement temperature to 70 to 120 ° C. and pulverize, and have completed the production method of the present invention.

  In addition, when it grind | pulverizes without using a grinding aid, a 45 micrometer sieve residue can be increased more efficiently and the cement composition of a more preferable quality can be obtained.

  According to the present invention, in the drilling of wells such as oil fields and gas fields, the oil well cement composition of the present invention is intended to reinforce casing pipes inserted into the wells, prevent corrosion, prevent inflow of underground water into the wells, etc. Can be used to improve workability and strength development even in wells at higher depths (high temperature and pressure), and even when retarding hardeners are added, the workable time can be controlled. There is an effect that it can be made easy.

  Hereinafter, preferred embodiments of the oil well cement composition according to the present invention will be described in detail.

The oil well cement composition of the present invention is a cement composition having a C ₃ S amount of 55 to 65% by mass and a C ₃ A amount of 2% by mass or less, and has a Blaine specific surface area of 2700 to 3700 cm ² / g and a 45 μm sieve residue. There 15 mass% or more, free calcium amount is 0.2 to 0.6 mass%, a SO ₃ amount 1.8 to 2.4 mass%, with hemihydrate gypsum ratio in the gypsum 20 to 80 wt% A cement composition. The basic mineral composition of the cement composition of the present invention increases the amount of C ₃ S excellent in strength development within the range of the API standard. From the point of compatibility, the amount of C ₃ A is lowered within the API standard.

When the amount of C ₃ S is 55 to 65% by mass and the amount of C ₃ A is 2% by mass or less, strength development is good, so that a sufficient concrete compressive strength can be obtained and the thickening time is also excellent. . Further, when the specific surface area of the brane is 3700 cm ² / g or less, the problem that the viscosity of the slurry becomes high and the construction becomes difficult can be avoided, and when it is 2700 cm ² / g or more, the strength development does not decrease. Moreover, sufficient fluidity | liquidity and intensity | strength can be acquired as a 45 micrometer sieve residue is 15 mass% or more. In addition, when the amount of free calcium is 0.2 to 0.6% by mass, and the ratio of hemihydrate gypsum in the gypsum is 20 to 80% by mass, any of them does not cause a decrease in fluidity. be able to.

More preferably, the oil well cement composition of the present invention has a C ₃ S amount of 60 to 65% by mass, a C ₃ A amount of 1% by mass or less, a Blaine specific surface area of 3000 to 3700 cm ² / g, and a 45 μm sieve residue. 15-30 mass%, the amount of free calcium is 0.25-0.6 mass%, and the ratio of hemihydrate gypsum in gypsum is 40-80 mass%. The 45 μm sieve residue is more preferably 15 to 26% by mass.

Oil well cement compositions of the present invention, also, SO ₃ weight Ru 1.8 to 2.4% by mass. When the amount of SO ₃ is in this range, condensation and strength show appropriate values.

  Furthermore, in order to produce the oil well cement composition of the present invention, the cement clinker and gypsum are changed by using an open circuit type tube ball mill, and the amount of water spray is changed in the range of 0 to 3% by mass, so that the mill outlet cement temperature is increased. It is preferable to grind while controlling at 70 to 120 ° C, more preferably 90 to 115 ° C.

  More preferably, when the pulverization is performed without using the pulverization aid, the 45 μm sieve residue can be increased more efficiently.

  The oil well cement composition of the present invention includes silica powder such as meteorite powder and fly ash, slow hardener containing lignin sulfonate and oxycarboxylate, fast hardener containing calcium chloride and sodium chloride, bentonite Alternatively, a low specific gravity material such as diatomaceous earth or a high specific gravity material such as barite or hematite may be mixed or added.

  The oil well cement composition of the present invention can be produced as follows.

  First, cement clinker is a component in raw materials such as limestone, clay source materials (clay, coal ash, construction generated soil, sewage sludge, blast furnace slag, etc.), iron source materials (copper tangled, iron concentrate, etc.) and meteorites. It can be manufactured by controlling its use ratio according to the ratio and then adjusting the mineral composition of the Borg calculation.

In addition, the cement composition is adjusted by adjusting the amount of SO ₃ in the cement composition by introducing the cement clinker and gypsum produced as described above into a pulverizer and controlling the amount of gypsum added.

  The Blaine specific surface area of the cement composition is adjusted by controlling the total amount of cement clinker and gypsum to be charged (grinding amount). For example, to increase the Blaine specific surface area (to make the particle size finer), the grinding amount is decreased, and to reduce the Blaine specific surface area (to increase the particle size), the grinding amount is increased and adjusted.

  In order to increase the 45 μm sieve residue, in addition to crushing without using a grinding aid, use an open circuit tube ball mill that can easily control the outlet temperature, or a closed circuit tube that allows air flow control. Using a ball mill, the particle size distribution is adjusted by controlling the rotation speed, circulation rate, etc. of the separator.

  The pulverizer is characterized in that (1) the residence time during pulverization is short and aeration (slight weathering) hardly occurs, (2) the mill exit cement temperature hardly rises, and (3) the particle size distribution of the pulverized product is wide. It is preferable to use one having For example, the use of an open circuit type tube ball mill is preferable, but a closed circuit type tube ball mill can obtain the same performance by controlling the performance of the separator and the size of the mill.

  Furthermore, the ratio of the hemihydrate gypsum in the gypsum of the cement composition is adjusted to the amount of water (clinker watering amount) brought into the mill so that the cement temperature at the mill outlet is 70 to 120 ° C, more preferably 90 to 115 ° C. It can be controlled with. In addition, it is preferable that the amount of clinker watering is 3 mass% or less, and it is more preferable that it is 1.2 mass% or less. Furthermore, it is most preferable that the cement temperature be 60 ° C. or lower and stored in a silo immediately after milling using a cooling facility such as airflow cooling.

  Hereinafter, although an example explains composition and an effect of the present invention, the present invention is not limited to these examples.

(1) Trial manufacture of cement The cement composition was prepared by crushing cement clinker and gypsum fired using an actual machine NSP kiln using an actual machine crusher (open circuit tube ball mill or closed circuit tube ball mill). The 21 types of cement described in 1-1 and 1-2 were trial manufactured. The gypsum used was Thai natural gypsum.

The outline of the crusher is as shown in FIGS.
The open circuit type tube ball mill shown in FIG. 1 is not attached with a separator, and all the clinker and gypsum introduced are discharged out of the system as manufactured products. On the other hand, the closed circuit type tube ball mill shown in FIG. 2 is provided with a separator, and the coarse particle portion classified by the separator is returned to the mill again, and only the fine particle portion is discharged as a product. In the closed circuit system, the coarse grain portion is returned to the mill and circulated in the pulverizer, so that the residence time of the cement composition in the mill becomes longer than that in the open circuit system.

In Examples 1 to 10, a cement clinker calcined using an actual NSP kiln was used, the Blaine specific surface area was 2700 to 3700 cm ² / g, the 45 μm sieve residue was 15% by mass or more, free calcium (hereinafter “f.CaO”). ”) Is a cement pulverized so that the amount is 0.2 to 0.6% by mass and the proportion of hemihydrate gypsum in the gypsum is 20 to 80% by mass. In these examples, an open circuit type tube ball mill was used, and each characteristic value was adjusted mainly as shown below. That is, the Blaine specific surface area and the 45 μm sieve residue are the amount of grinding, f. For CaO, the amount of water sprayed, the burning temperature of the combustion gas of the NSP kiln, and the residence time of the clinker in the kiln, and the ratio of hemihydrate gypsum were controlled by the mill outlet temperature. In addition, when storing in a silo, the cement temperature was set to 60 ° C. or less immediately after milling to reduce the dehydration of dihydrate gypsum in the silo as much as possible.

  Although Comparative Examples 1-4 used the open circuit type tube ball mill, compared with Examples 1-10, either of the control conditions of each characteristic value differs from an Example. As a result, Comparative Examples 1 and 2 show f. A cement in which the amount of CaO was increased to 0.66% by mass, or the proportion of hemihydrate gypsum was increased to 92% by mass, and Comparative Examples 3 and 4 were f. This is a cement in which the CaO amount is increased to 0.64 to 0.68% by mass and the hemihydrate gypsum ratio is increased to 85 to 100% by mass.

  Comparative Examples 5 to 8 are cements in which the 45 μm sieve residue is reduced to 6.9 to 10.1% by mass as a result of using a closed circuit tube ball mill that classifies and regrinds cement after grinding.

  Comparative Examples 9 and 10 are cements using a closed-circuit tube ball mill and the hemihydrate gypsum ratio being increased to 90 to 100% by mass at a high mill exit temperature.

  Comparative Example 11 uses a closed circuit tube ball mill and f. This is a cement in which the CaO amount is increased to 0.69% by mass, and the 45 μm sieve residue is reduced to 14.7% by mass.

(2) Characterization of cement
<2-1> Mineral Composition and Minor Component Content The mineral composition of the cement was determined according to JIS R 5202: 1999 “Chemical analysis method of Portland cement”, CaO, SiO ₂ , Al ₂ O ₃ , Fe ₂ O. ₃ and the amount of SO ₃ were calculated by the following formula.

C ₃ S amount (% by mass) = (4.07 × CaO) − (7.60 × SiO ₂ ) − (6.72 × Al ₂ O ₃ ) − (1.43 × Fe ₂ O ₃ ) -2. 85 x SO ₃
C ₂ S amount (% by mass) = (2.87 × SiO ₂ ) − (0.754 × C ₃ S)
C ₃ A amount (% by mass) = (2.65 × Al ₂ O ₃ ) − (1.69 × Fe ₂ O ₃ )
C ₄ AF amount (mass%) = 3.04 × Fe ₂ O ₃

The amount of MgO, SO ₃ , Na ₂ O and K ₂ O in the cement was determined in accordance with JIS R 5202: 1999 “Chemical analysis method for Portland cement”. The total amount of alkali _(R 2 O) was calculated as the terms of Na ₂ O amount from the following equation.

R ₂ O = Na ₂ O + 0.658 × K ₂ O

<2-2> Free calcium content (f.CaO content)
F. In Portland cement. The amount of CaO was quantified according to JCAS I-01: 1981 “Analytical method of free calcium”.

<2-3> Ratio of dihydrate and half-water gypsum in gypsum The percentage of half-water gypsum was determined by the following method.
First, the amount of hemihydrate gypsum and the amount of dihydrate gypsum were quantified by differential thermogravimetric analysis (TG-DTA). Specifically, using a differential thermothermal gravimetric analyzer TG-DTA6200 (manufactured by Seiko Instruments Inc.), about 30 mg of the sample is put into a cell (made of aluminum) having a hole of 20 μm in diameter and having a capacity of 30 μL. The temperature was raised from room temperature to 300 ° C. at a rate of 5 ° C./min. As shown in FIG. 3, first, from the curve (DTG in FIG. 1) obtained by differentiating the weight loss curve (TG in FIG. 3), the DTG peak A rising temperature (about 125 ° C.), DTG accompanying dehydration of hemihydrate gypsum The rise temperature of peak B (about 155 ° C.) and the end point of peak B (about 195 ° C.) were determined. Next, the weight loss around 125 to 155 ° C. due to dehydration of dihydrate gypsum (a mass%) and the weight loss near 155 to 195 ° C. due to dehydration of hemihydrate gypsum (b mass%) are obtained, and the formula (1) And the amount of dihydrate gypsum (mass%) and the amount of hemihydrate gypsum (mass%) in the gypsum of the cement were calculated using the equation (2). From these, the ratio (mass%) of hemihydrate gypsum was computed using Formula (3). An aluminum plate was used as a reference.

Dihydrate gypsum amount (mass%) = weight loss a (mass%) × 172 (molecular weight of dihydrate gypsum) ÷ (1.5 × 18 (molecular weight of H ₂ O)) (1)
Hemihydrate gypsum amount (mass%) = (weight loss b (mass%) − weight loss a (mass%) ÷ 3) × 145 (molecular weight of hemihydrate gypsum) ÷ (0.5 × 18 (molecular weight of H ₂ O)) (2)
Hemihydrate gypsum ratio (mass%) = hemihydrate gypsum amount ÷ (semihydrate gypsum amount + dihydrate gypsum amount) x 100 (3)

<2-4> Blaine specific surface area and 45 μm sieve residue The Blaine specific surface area and 45 μm sieve residue of Portland cement were measured according to JIS R 5201: 1997 “Cement physical test method”.

(3) Evaluation of physical properties of cement
<3-1> Slurry Preparation Cement slurry was prepared using API Spec. 10A: Compliant with 2002 (Class G (Type HSR) test method). Tap water (27 ° C.) and cement were mixed so that the water-cement ratio was 44% by mass, and API Spec. The slurry was put into a mixer suitable for 10A and kneaded for 15 seconds at a rotational speed of 4000 rpm of the rotor blades, and then 35 seconds at 12000 rpm to obtain a test slurry.

<3-2> Free Water, Compressive Strength, Consistency, Initial Viscosity and Thickening Time Test Free water, compressive strength, initial viscosity and thickening time, and consistency test are the same as API Spec. . 10A: 2002 class G (type HSR) test method).

  For free water, the slurry prepared in <3-1> was placed in a Halliburton Consistometer described in API standard, stirred at 27 ° C. for 20 minutes, and then 760 g of slurry was placed in a 500 ml Erlenmeyer flask and surface water (floating) Water) was collected with a spoid and weighed. Free water was expressed in mass%.

  Consistency was measured by placing the slurry prepared in <3-1> into a Halliburton Consistometer described in the API standard, and reading the consistency meter (BC) during stirring after 0, 5, and 20 minutes.

  Thickening time is to put the slurry prepared in <3-1> into API high temperature and high pressure thickening time tester, temperature and pressure history is schedule 5 as described in the above standard, measure slurry consistency, The time for 100 BC was taken as the thickening time. In this test, the initial maximum viscosity of the consistency in the first 15 to 30 minutes was defined as the initial viscosity.

<3-3> Fluidity (VG meter)
The fluidity (VG meter) test was performed according to Determination of Rheological Properties of API RP 10B: 12th Edition (1997). The slurry prepared in <3-1> is placed in a Halliburton Consistometer, stirred at 27 ° C. for 20 minutes, and then 600, 300, 200, 100 rpm using a VG meter (coaxial cylindrical rotational viscometer). Recorded meter reading at

(4) Evaluation results Table 2 shows the physical property evaluation results of the cement.

  Free water is used to evaluate the separability of materials in cement slurry poured during well drilling. A large amount of this indicates that the material is easily separated, and there is a concern about adverse effects on construction. It has been empirically confirmed that free water can be used without problems if it is 4.3% or less.

  The initial viscosity, consistency, and fluidity (VG meter) are indicators that represent the fluidity of the slurry. If any of the values is large, the fluidity is poor, and the construction is adversely affected during cementing. Empirically, it has been confirmed that if these indicators satisfy the target values listed in Table 2, they can be used without problems in construction.

  Thickening time relates to the setting time of cement slurry in a well under high temperature and pressure. From the viewpoint of cementing work, if the slurry viscosity (consistency) exceeds 100 BC, the work cannot be performed. Therefore, the thickening time is preferably 90 to 120 minutes in consideration of the work time. The cements in Table 1 were prepared by changing the specific surface area of the brane so that the thickening time was 90 to 120 minutes.

The compressive strength must be strong enough to continue the next excavation operation within 8 hours of hardening waiting in terms of excavation operation. In 38 ° C. in API standard 2.1 N / mm ² or more, but is defined as at 60 ℃ 10.3N / mm ² or more, actually desirable to have high compressive strength than this, in Table 2 It is important to satisfy the target value shown.

  In Table 2, “○” is shown for those satisfying the target values for each physical property, and “X” is shown for those not satisfying.

As can be seen from Table 2, Examples 1 to 10 are very good in any physical properties, and are excellent in fluidity and strength development. This is because the specific surface area of Blaine is in an appropriate range (2700-3700 cm ² / g), and the residue of 45 μm sieve is contained by 15% by mass or more. Strength development improves, f. This is because the CaO amount is 0.2 to 0.6% by mass and the hemihydrate gypsum ratio is 20 to 80% by mass, so that the stiffness phenomenon does not occur and the fluidity is improved.

  On the other hand, in Comparative Examples 1 to 4, as can be seen from the fluidity (VG meter) in Table 2, the ratio of hemihydrate gypsum exceeds 80%, f. Since the amount of CaO exceeds 0.6% by mass, stiffness occurs and fluidity decreases. In particular, the proportion of hemihydrate gypsum is 100% by mass and f. It can be seen that Comparative Example 4 having a large CaO content of 0.68% by mass exceeds the target value even at the initial viscosity and has poor fluidity.

  Moreover, since the comparative examples 5-11 have few 45 micrometer sieve residue, and sufficient filling property is not acquired, especially 38 degreeC compressive strength is low. Further, as in Comparative Example 10, the ratio of hemihydrate gypsum exceeds 80% by mass, f. When the CaO amount exceeds 0.6 mass%, the fluidity (VG meter) tends to be inferior.

  Further, as can be seen from the results in Table 2, the production method is easier to produce the cement composition of the present invention when using an open circuit type tube ball mill. The reason is that because of the open circuit type, the particle size is continuous and the particle size distribution is widened, the residence time in the mill of the cement is short, and the mill outlet cement temperature is difficult to rise, so the ratio of hemihydrate gypsum is low, aeration ( It is difficult to receive fine weathering) and has excellent strength development.

  In addition, the cement composition of this invention is API Spec. 10A: Can be used as a class H defined in 2002.

It is the schematic of an open circuit type tube ball mill. It is the schematic of a closed circuit type tube ball mill. It is a figure which shows the example which measured the amount of hemihydrate gypsum in a cement composition using differential thermogravimetric analysis (TG-DTA).

Claims (2)

In an oil well cement composition having a C ₃ S amount of 55 to 65% by mass and a C ₃ A amount of 2% by mass or less, the Blaine specific surface area is 2700 to 3700 cm ² / g, and the 45 μm sieve residue is 15.0% by mass or more, The amount of free calcium is 0.2 to 0.6% by mass, the amount of SO ₃ is 1.8 to 2.4% by mass, and the proportion of hemihydrate gypsum in the gypsum is 20 to 80% by mass. Oil well cement composition. Limestone, Keiseki, using clay source material and iron source material, depending on the component ratio in the raw material, and controls the use ratio of the raw material, the mineral composition of Borg formula Calculation C _{3 S} content is 55 to 65 mass % And a C ₃ A amount adjusted to 2% by mass or less, a cement composition containing cement clinker and gypsum was added with water to the cement composition using an open circuit tube ball mill. and watering mass% or less, or without water spray and ground to control the mill outlet cement temperature of open circuit type tube ball mill 70 to 120 ° C., prepared according to claim 1 Symbol placement of oil well cement composition Method.

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