Backfill for cementing wells with high gas ratio

FIELD: chemistry.

SUBSTANCE: invention relates to well construction, particularly backfill compositions used when cementing casing columns, mainly with high gas ratio. The backfill contains portland cement, oxyethylcellulose, a plasticiser, an antifoaming agent - modified organosilicon reagent POLYCEM DF, a modified vinyl acetate copolymer GASBLOCK and water. The backfill additionally contains an expansion agent - calcium oxide or calcium hydrosulphoaluminate and a setting accelerator - calcium chloride, the plasticiser is a substance the active ingredient of which is sulphonated melamine formaldehyde (CEMPLAST MF), or a product of condensation of naphthalene sulphonic acid and formaldehyde S-3, or polyether carboxylate (Melflux), with the following ratio of components, pts.wt: portland cement 95.0-99.9; modified vinyl acetate copolymer GASBLOCK 1.0-2.0; said expansion agent - up to 5.0; oxyethylcellulose 0.3-0.5; said plasticiser 0.6-0.8; calcium chloride - up to 2.0; said antifoaming agent 0.1-0.2; water 47-52. Total weight content of the dry mixture of cement and expansion agent is equal to 100 pts.wt, and total weight ratio of the modified vinyl acetate copolymer GASBLOCK and the expansion agent in the material is equal to 1:(2.5-5.0), respectively.

EFFECT: preventing migration of gas in the columned space after well cementing using the disclosed backfill.

4 cl, 2 tbl, 1 ex

 

The invention relates to the field of construction of wells, particularly, to cement compositions used in the cementing of casing in wells, mostly, with a large gas factor, for example, more than 100 m3/t at normal temperatures (up to 50°C).

Known grouting mortar containing cement, acetylcellulose, additive-based polymer resins - elementarray product, and water. Additionally, the solution containing the organosilicon product - ethylsilicate (RF patent No. 2149981, publ. 2000). We offer cement slurry can be used in conditions up to 100°C. the Use of plugging in the known solution of high viscosity grades of acetylcellulose (viscosity of 2%aqueous solution of which is not less than 6000 MPa·s) allows to reduce the filtering cement slurry. However, the flow rates are high, which limits the possibility of using cement slurries at normal temperatures (up to 50°C) due to the high hydraulic resistance when pumping.

In addition, used as accelerator ethylsilicate in the known solution, leads to uncontrolled shortening of the setting and hardening of cement slurry in an imprecise keeping his concentration.

The most is her near the present invention is a cement slurry, consisting of cement, acetylcellulose, polymer additives, re - dispersible latex powder manufactured under the brand of GASBLOK, plasticizer - sulfated melamineformaldehyde, the defoamer is a silicone composition on a substrate of silicon dioxide, and water (patent RF №2297437, publ. 2007)

The specified cement slurry has a high prevalence of adhesion, Flexural strength and compression, as well as reduced permeability.

The disadvantage of this known cement slurry is the lack of extensions formed of cement, which when cementing wells with a large gas factor can lead to the emergence of micro gaps and disturbance of the insulating properties of the cement sheath. In addition, due to the rapid development of static shear stress (SNA) in the known solution and the lack of sedimentation stability is not ensured to prevent the migration of gas to the annulus.

The technical result achieved by the invention, is to prevent the migration of gas to the annulus after cementing wells proposed backfill material, due to the slow development of static shear stress, ensure sedimentation stability and slowed down the second filter, the extremely low permeability of the backfill material and cement stone and his messagecast.

The specified technical result is achieved by the claimed backfill material for cementing wells with a large gas factor containing Portland cement, acetylcellulose, plasticizer, defoamer - modified crasneanscki the reagent POLICEM DF-modified copolymer of vinyl acetate GASBLOK and water, what's new is that it further comprises expanding additive is calcium oxide or hydrosulphuret calcium accelerator and hardening period - calcium chloride, as a plasticizer material contains a substance active active principle of which is sulfonated melamineformaldehyde, or the condensation product of naphthalenesulfonate and formaldehyde, or politicalmoneyline, in the following ratio, parts by weight:

Portland95,0 to 99.9
specified expanding additiveto 5.0
the modified copolymer
of the vinyl acetate GASBLOK1,0-2,0
exit cellulose 0,3-0,5
the specified plasticizer0,6-0,8
calcium chlorideto 2.0
the specified antifoam0,1-0,2
water47-52

while the total mass content of the dry mix of cement and extend the additive is 100 parts by weight, and the mass ratio of the modified copolymer of vinyl acetate GASBLOK and extend the additive material is 1:(2,5÷5,0), respectively.

As a plasticizer, an active beginning of which is sulfonated melamineformaldehyde, it contains the substance of CHEMPLAST Matt.

As a plasticizer, an active beginning which is the condensation product of naphthalenesulfonate and formaldehyde, it contains a substance With a 3.

As a plasticizer, an active beginning which are politicalmoneyline, it contains a substance Melflux.

The achievement of the technical result is achieved through a synergistic effect when a particular selection of components (qualitative and quantitative) in the inventive cement material.

Thanks to the introduction of cement mater what al the specified extender additives and simultaneously polymer additives - modified copolymer of vinyl acetate GASBLOK, at certain stated their ratio, porosity is reduced cement, reducing water loss, filtration rate, relative permeability and an increase in the adhesion performance by increasing the volume of backfill material due to expanding additives and reduce the permeability of the backfill material due to the small size of the modified copolymer of vinyl acetate GASBLOK and lower its density, in comparison with particles of cement that will allow downhole conditions to prevent gas migration.

But due to a synergistic effect in conjunction with other components of the proposed backfill material will have a delayed filter that will allow in field cementing to avoid breakthrough of gas hardening grouting material after installation the space surrounding the well.

As the expanding additive is proposed to enter into the proposed material inorganic compounds - modified calcium oxide RU-1 or hydrosulphuret calcium RU, related in composition to the mineral, which is part of Portland cement, which are modified calcium sulphate and aluminum.

The introduction of the proposed backfill material is ashiraya additives specified in the proposed correlation makes it possible to obtain an extension of grouting material at an early stage of hardening and the formation of cement stone, to avoid self-destruction of its structure (cracking, loss of strength).

It is important that the enlargement process was completed in early hardening of cement stone, as long hardening process is accompanied by the destruction of cement stone. But for the time factor in the process of expanding, not less important is the volume expansion, which is expressed as a linear expansion of cement stone. Because the purpose of the enlargement process is the formation of more dense contact cement stone with bearing surfaces, the linear expansion of cement stone should not exceed 1.0%. Larger volume expansion in cement stone may cause loss of strength.

The presence of the accelerator of terms - of calcium chloride, can provide an acceptable period of setting and hardening of cement material, and at the same time, apparently, has a chemical effect on the expanding additive with the formation of complex compounds, providing uniform expansion of the material on the stage set, its strength, and without destruction of the structure formed of stone, and a modified copolymer vinylacetat GASBLOK. It also shortens the time of setting up required for a particular borehole limits on this to obtain a uniform expansion of the cement stone, not having a negative impact on its strength properties.

The use of the proposed backfill material softener one of these three types allows you to modify the structure of the cement slurry, sealing it, which contributes in turn to increase the strength of cement (cement stone. In addition, in conjunction with other components this leads to slow development of static shear stress that in field conditions will ensure the transfer pressure hardening of cement material and the inability of the breakthrough gas fluids in a long time.

The introduction of the proposed backfill material antifoam brand POLICEM DF reduces the foaming, early and reliable stabilization of the density of the backfill material, which must be calculated using a computer simulation program cementation process to prevent flow of gas during the injection and holding pressure in critical areas in the required interval between the pore pressure and the pressure of the fracturing during cementing, and immediately after it. Any error in density admitted mixing grouting material on the surface, can lead to uncontrolled changes of the most important indicators of who she is: rheology and setting time.

To obtain the claimed grouting material in the laboratory, we used the following substances:

- cement Portland cement PCT IG-SS-1 (GOST 1581-96).

- acetylcellulose brand HYDROCHEM mark N. and TU-009-40912231-2003;

a plasticizer, an active component of which is sulfonated melamineformaldehyde CHEMPLAST MT, with a pH of 1%aqueous solution of 8.5 to 10.5; on THE other 2223-011-40912231-2003;

a plasticizer, an active component of which is the condensation product of naphthalenesulfonate and formaldehyde, p-3 on THE other 6-360204229-625-90.

a plasticizer, an active component of which are politicalmoneyline Melflux - water-reducing additive according to the degree of plasticization by GOST 24211-91 belongs to the group of superplasticizers, manufacturer: Degussa meetings with pre Polymers (SKW Trostberg, Germany); powder product obtained by the method of spray drying on the basis of the modified politicalmoneyline. Technical data: form - yellowish powder; bulk density of 400-600 g/l; loss when heated - max 2.0 wt.%; a 20% solution at 20°C has a pH of 6.5 to 8.5. Features:

high - performance disperser;

- reduces shrinkage;

- effective in a wide range of temperatures;

the accelerator of terms - calcium chloride;

the antifoam brand POLICEM DF modified crasneanscki Reagan is beyond 2228-010-40912231-2003;

- expanding additive - amorphous calcium oxide grades PN-1, on THE other 2123-020-53501222-2001;

- expanding additive hydrosulphuret calcium brands RU TU 2157-034-40912231-2005;

- modified copolymer of vinyl acetate GASBLOK on THE 2458-055-40912231-2009.

- water technical.

Enablement of the claimed invention is confirmed by the following example.

Example: To obtain the proposed backfill material in the laboratory took 520 g of water technical, 950 g of Portland cement; 50 g extends supplements of calcium oxide; 20 g of calcium chloride; 4 g acetylcellulose HYDROCHEM N; 6 g of plasticizer CHEMPLAST MT, 2 g of the antifoam POLICEM DF and 20 g of the modified copolymer of vinyl acetate GASBLOK. The result was obtained backfill material with the following content components, mass: Portland 95,0; expanding additive is calcium oxide RU-1 to 5.0; the modified copolymer of vinyl acetate brand GASBLOK - 2,0; calcium chloride 2,0; acetylcellulose brand HYDROCHEM N - 0,4; plasticizer - sulfated melamineformaldehyde CHEMPLAST MT - 0,6; antifoam brand POLICEM DF - 0,2; water 52,0.

Backfill materials with other content components was prepared in the same way.

In laboratory tests was determined by well known methods, the following properties of the backfill material:

the density improvement is ü, g/cm3

- filtrated for 30 min at Δ=0.7 MPa, ml

the water segregation, ml

- the strength of cement stone bending/compression 2 days. storage, MPa, and determined the following properties of cement stone:

the time of thickening up to 30 In, h min

- the permeability of the cement stone, MD

- force push the cement out of the metal sleeve, MPa

In addition, according to the methodology described in the report of the moon and Wang (SPE Paper #55650) /1/ were made to define a static shear stress (SNA) static Static Shear Stress Chandler Engineering Model 5265 (SGSA). The test result was determined by the time of the formation of static shear stress 1200 1b/100 ft / min

The next step was tested for breakthrough capabilities of gas through hardening cement mortar. With this purpose designed test fluid migration (FMA), developed a method of reducing scale, with thermobaric conditions well described Beirute and Cheung (SPE 19522) /2/. The test fluid migration was performed using the Analyzer Fluid Migration Chandler Engineering Model 7150 (FMA) is a laboratory device for testing formulations of grouting materials for use in the management of the tributaries of fluids after cementing. The apparatus simulates the conditions of the well (temperature, hydrostatic pressure, the layers of the e pressure, and the pressure gradient causing flow of fluid through the post grouting composition).

Data on the composition of the investigated cement materials are shown in table 1, and data about their properties in table 2.

The data given in tables 1 and 2 show that the proposed component structure allows to obtain backfill materials, characterized by the following advantages over the known:

high sedimentation stability, water segregation - 0);

- the slow development of static shear stress (145-257 min);

- low volume filtration at reduced speed (16-32 ml);

- improved adhesive performance, the force of the ejection samples (1,32-1,64 MPa);

- low permeability cement (0,41-0,54 MD).

The choice of quantitative limits components attributable to the following: when the ratio of the components is less and more of the indicated concentrations (table 2, item 6) deteriorate technological properties of backfill materials (filtration and the formation SNA), which leads to the impossibility of ensuring prevent breakthrough of gas through hardening of the grouting material and formed from it the cement stone.

Thanks to these properties, the proposed backfill materials will help in field conditions to prevent breakthrough of gas at cementeria the AI casing strings in wells with large gas factor.

LIST of USED SOURCES

1. Acoustic method for determining the static shear stress of cement. Jeff Moon, P.E., Steven Wang, SPE 55650.

2. Beirute, R. and Cheung, P.R. "A Scale-Down Laboratory Test Procedure for Tailoring to Specific Well Conditions, the Selection of Cement Recipes to Control Formation Fluids Migration After Cementing," SPE 19522, 64thSPE Annual Technical Conference, San Antonio, Texas, October 8-11, 1989.

Table 1
Data on the composition of the proposed and known plugging materials
No.Components, wt.%
PortlandExtension
statistical
a common additive
Accelerator terms of shutiva
of CaCl2
Axiety celluloseThe plasticizerPenaga
Khabibullina POLY
CEM DF
A modified copolymer of vinyl acetate GASBLOKWater
The proposed backfill material
19730,50,5 0,80,11,047
29552,00,30,60,12,052
39642,00,50,70,21,549
49642,00,40,60,22,052
59641,50,40,60,11,551
610062,0 0,80,22,047
Known backfill material
7100--0,30,30,2444
8100--0,20,50,2244
Note:
1. As the plasticizer used in experiments 1, 3 - C-3; experience 4 - Melflux; in others, CHEMPLAST Matt.
2. As filtrate agent in experiments 2, 4, 6 - used acetylcellulose HYDROCHEM stamps; in other - HYDROCHEM brand N.
3. As expanding additives in experiments 1, 3, 5 used hydrosulphuret calcium RU; in experiments 2, 4, used the calcium oxide of RU-1.

Table 2
Data on the properties of cement materials, shut on offer and known backfill materials
A number of experiences from table 1Properties of cement slurryProperties of cement stone
Density, g/cm3,Filtrated for 30 min at Δ=0.7 MPa, mlThe water segregation, mlThe time of the formation of static shear stress 1200 1b/100 ft, minThe presence of gas flowTime zagustevat
of up to 30 Aircraft, h-min
The tensile strength in bending/compression, MPaThe permeability of the cement stone, MDForce eject samples, MPa
For the proposed backfill material
11,90260257no4-40 3,6/9,80,461,32
2to 1.86220154no3-403,9/11,20,541,61
31,87280233no4-154,1/13,40,471,53
41,87160168no4-354,0/13,10,491,47
51,89200245no4-303,7/12,10,4461,90320135no3-304,2/12,80,411,64
For known grouting material
71,93562,0964-204,48/13,250,610,09
81,93424,0724-004,67/13,250,510,13

1. Backfill material for cementing wells with a large gas factor containing Portland cement, acetylcellulose, plasticizer, defoamer - modified crasneanscki the reagent POLICEM DF-modified copolymer of vinyl acetate GASB is OK and water, characterized in that it further comprises expanding additive is calcium oxide or hydrosulphuret calcium accelerator and hardening period - calcium chloride, as a plasticizer material contains a substance active active principle of which is sulfonated melamineformaldehyde, or the condensation product of naphthalenesulfonate and formaldehyde, or politicalmoneyline, in the following ratio of components, parts by weight:

Portland95,0 to 99.9
specified expanding additiveto 5.0
the modified copolymer
of the vinyl acetate GASBLOK1,0-2,0
acetylcellulose0,3-0,5
the specified plasticizer0,6-0,8
calcium chlorideto 2.0
the specified antifoam0,1-0,2
water47-52,

while the total mass content of the dry mix of cement and races is irawma Supplement is 100 parts by weight, and the mass ratio of the modified copolymer of vinyl acetate GASBLOK and extend the additive material is 1:(2,5÷5,0), respectively.

2. The grouting material according to claim 1, characterized in that as a plasticizer, an active beginning of which is sulfonated melamineformaldehyde, it contains the substance of CHEMPLAST Matt.

3. The grouting material according to claim 1, characterized in that as a plasticizer, an active beginning which is the condensation product of naphthalenesulfonate and formaldehyde, it contains a substance With a 3.

4. The grouting material according to claim 1, characterized in that as a plasticizer, an active beginning which are politicalmoneyline, it contains a substance Melflux.



 

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FIELD: chemistry.

SUBSTANCE: liquid composition contains the following: suspension on oil basis, which includes base oil, organophilic clay, polar activating agent, wetting agent, and composition improving the operability in winter conditions, which contains one or many composite monoesters of polyols and/or composite diesters of polyols. Composition is meant for hydraulic fracturing of underground formation, removal of combined wafer from productive underground formation. Hydraulic fracturing method of underground formation involves pumping to the formation under the pressure which is enough for fracturing, liquid for fracturing, which contains propping agent and suspension on oil base, which includes base oil, organophilic clay, polar activating agent, wetting agent and the above composition, or according to the other version - fracturing liquid containing the above suspension, and pumping to the formation subjected to fracturing under pressure which is enough for protection of cracks against joining of carrying liquid with propping agent. Production method involves circulation and/or pumping to production well of the liquid including the above suspension.

EFFECT: improving operability in winter conditions.

25 cl, 18 tbl, 3 ex, 4 dwg

FIELD: production and exploratory well drilling, particularly foaming drilling fluids used during penetration through incompetent rock intervals and during primary productive oil and gas deposit opening in the case of abnormally low formation pressure.

SUBSTANCE: foam composition comprises surfactant, foam stabilizer, water, water hardness control additive and lubricant. The water hardness control additive is sodium silicate. The lubricant is VNIINP-117 emulsion. The foam stabilizer is polyacrylamide, the surfactant is sulphonole. All above components are taken in the following amounts (% by weight): sulphonole - 0.8-1.5, sodium silicate - 0.2-0.5, polyacrylamide - 0.1-0.5, VNIINP-117 - 0.5-2, remainder is water.

EFFECT: reduced power inputs for well drilling, as well as reduced coefficient of friction between drilling tool and well wall.

1 tbl

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