Foamable composition for killing wells

 

(57) Abstract:

Composition refers to the oil and gas industry, in particular foaming compositions, and can be used for plugging wells during repair work in conditions of abnormally low formation pressure. The technical result is increased stability and blocking properties of the foamable composition, while retaining the natural reservoir permeability after release, which reduces the time of development wells. Foamable composition for plugging wells contains, wt%: the mixture of surface-active substances, one component of which is condensed sulfite-alcohol bard kssb in the form of an aqueous solution of 25% concentration 17-19, another component distillation residues from the production of furfuryl alcohol Coffs harbour from 0.05 to 0.22, the foam stabilizer is a hydrocarbon liquid 12-15, solid phase - peat 3-7, the aqueous phase is an aqueous solution of calcium chloride density 1180-1200 kg/m3- the rest. 1 table, 4 Il.

The invention relates to the oil and gas industry, in particular foaming compositions, and can be used for plugging wells when renovations owner the following:

Known composition for killing wells, having the following formulation, by weight. %:

Lignin - 8,0-15,0

Alkali - 0,3-5,0

CMC - 0,2-0,6

SURFACTANT - 0,01-0,15

Oil - 1,0-5,0

The Ethylenediamine - 0,05-1,5

Water - the Rest

(see and. C. N1175951 from 30.01.84, class C 09 K 7/00, publ. in ABOUT N 32, 1985).

The disadvantage of this structure is the system instability, low blocking ability, a slight decrease of permeability strata after renovations.

The lack of stability (stability) of the system is determined by its component structure and proportion of the ingredients and does not provide the possibility of applying the liquid in the process of long-term repair work. Low blocking capability due to low rheological parameters, which does not allow to use the composition for plugging wells with abnormally low reservoir pressure and reservoir fractured type with a high permeability. Low values of plastic viscosity and dynamic shear stress give the composition the ability to penetrate deeply into the formation and even absorbed by the reservoir, and structural-mechanical properties of the resulting blokiruuschaya composition of its use for wells with productive reservoir of small capacity and low permeability. There is a slight decrease in the permeability of the productive layers after treatment with such a composition. The absence of thixotropy and low rheological parameters determine easy removal of the composition from the reservoir (and penetration), when the weak seal ability may not be an indicator of the effectiveness of the repair works.

The closest analogue is a foamable composition for killing wells, having the following composition, wt.%:

The foaming agent is a sulfonic acid or OP-10 - 1-3

Bentonite - 1-3

Polyacrylamide - 0,5-0,7

Condensed sulfite-alcohol bard kssb-4 - 5-8

Fresh water - the Rest

(USSR author's certificate N1208192, E 21 B 33/138, 30.01.1986).

The disadvantage of this foamable composition is the instability of the system, low blocking ability, lower permeability strata after repairs, and required considerable time to develop well.

Lack of blocking ability of the foam system due to its component structure, which allows to obtain three-phase foam, structural and mechanical properties of which do not provide the in the of more than 6 MPa is the rapid destruction of the foam due to the passage of midpiece fluid (syneresis), gas diffusion between bubbles and break the individual foam film, due to the weak forces of adhesion between the individual molecules in the adsorption layer. The syneresis is the result of insufficient stability (stability) of this part despite the presence of a solid phase (clay particles), which is due to the adhesion of solid particles to air bubbles contributes to the thickening and hardening of the surface of the film.

After release of the reservoir and well completion is a reduction of its natural permeability caused by deposition of the foam system its hard aggregate - clay at the destruction of the foam during the repair work. The precipitation of the solid phase and the clogging of the pore space of the formation of clay particles capable of interacting with the reservoir rock and saturating his fluids, necessitate the release layer at elevated depression with a view to fully restore its natural permeability.

In addition to the above reasons, the permeability of the productive formation may decrease as a result of repacking the individual particles of the breed when creating increased representitives as a result of additional operations to release, due to clogging of the first space formation of hard-to-solid phase.

The technical result that can be obtained by carrying out the present invention, is as follows:

- enhanced stability foaming composition, which provides the opportunity for long-term repairs in wells with various mining and geological conditions,

- increase the blocking properties of the composition, which allows the killing of wells with abnormally low formation pressure and and collectors of different permeability,

- preserves the natural reservoir permeability after release, which reduces the time of development wells.

The technical result is achieved in that the foamable composition for killing wells, consisting of a mixture of surfactants surfactants, one component of which is condensed sulfite-alcohol bard kssb, a foam stabilizer, solid and aqueous phase contains kssb in the form of an aqueous solution of 25% concentration, as another component of the mixture of surfactants - distillation residues from the production of furfuryl alcohol Coffs harbour, as a foam stabilizer - pleva 1180 - 1200 kg/m3in the following ratio, wt.%:

COFFS 0,05-0,22

Kssb aqueous solution of 25% concentration - 17-19

Hydrocarbon liquid - 12-15

Peat - 3-7

An aqueous solution of calcium chloride density 1180-1200 kg/m3- The rest,

Coffs harbour is used by THE 64-5312-03-69, they have the following composition, wt.%:

Furfuryl alcohol - 63,79

The furfural - to 2.06

Tetrahydrofurfuryl alcohol - 1,43

Sylvan - 0,58

Water - 0,14

Furan - 0,03

Diols Rest,

Kssb use THE 39-094-75, calcium chloride according to GOST 4460-77. As the hydrocarbon liquid used diesel or gas condensate, GOST 305-82.

Peat is an organic rock formed by the accumulation of plant residues affected by incomplete decomposition in swamp areas with difficult access of air and high humidity. The dry matter of peat consists of partially decomposed plant residues, decomposition products of plant tissues in the form of particles or aggregates of humus (humus), mineral substances. The content of organic component in the peat is 80-99% of dry substance, humic compounds in the organic component is in the range 16-86%.

Joint when adeusi complex technological properties, ensure the effectiveness of repairs. This is due to the following physical and chemical processes in multicomponent system proposed composition:

1. When interacting lignosulfonate kssb component COFFS furfuryl alcohol - formed ester according to the scheme (Fig.1).

2. Available in kssb phenol due to the activating effect of the hydroxyl group can be alkylated furfuryl alcohol Coffs harbour (Fig.2).

3. Furfuryl alcohol is present in the composition kssb formaldehyde can form acetals in accordance with the scheme of Fig.3.

4. The scheme of consolidation of the lignosulfonate molecules during their interaction with calcium chloride, is shown in Fig.4,a,b.

Macromolecule lignosulfonates are disordered branched spirals with different degree of compaction. Low molecular weight fractions can be linear. Distinct polydispersity, the presence of a charge, the high degree of dissociation indicate that precedence are strongly associated high hydrophilic palimony. Structure them in the form of aromatic chains with incorporated functional groups determines the dipole characteristic is deistvii lignosulfonate with calcium chloride, one of the components of the foamable composition, enlarging their molecules, due to the condensing effect of polyvalent cations (Ca2+). When this occurs, a new colloidal phase, which as a result of adsorption on the surface of the bubbles formed by the foaming system, together with obtained in accordance with the above reactions according to Fig. 1 - 3 Navy, increases the strength of the surface adsorption layer and increase the stability of the bubbles (foam stability).

Stabilization of foams is due to the presence of the adhesion forces between individual molecules in the adsorption layer, and the mobility of these molecules, which provides fast recovery of deformation arising from the possible leakage of liquid from a film of bubbles.

Stabilization of the foam also contributes to hardening of the adsorption layers of air bubbles formed globules of hydrocarbon liquids IT is the second dispersed phase (in the air) in the aqueous dispersion medium. When this surfactant-based lignosulfonate modified kssb in accordance with the reactions in Fig.1-4 adsorbed on the surface of a drop of IT, focusing gienia surrounding the air bubble surface layers of the adsorption film, preventing the leakage of liquid from the foam.

Obtain foam system with high stability leads to the uniform distribution of particles of peat role of the solid phase. Organic composition of peat predetermines the possibility of its physico-chemical interaction with forming foam system components, which dramatically increases the structural-mechanical properties of the foamable composition as a whole, its resistance to external impact. The stability of the foam structure increases with the strength of adhesion of solid peat particles to air bubbles.

When jacking into the formation of the inventive foamable composition of its blocking properties are implemented through education in the pores and channels of the formation of a mesh structure of the fibers and separate particles of peat, cells which are filled with foam. Peat particles having sufficient strength and elasticity, are held on an uneven surface of the rock due to the fibrous formations and the ability to cling to the rough edges and ledges of rocks as it moves into the reservoir. The resulting net frame has the property of "check valve": withstands high shifts is released from the reservoir with a slight depression (only 0.1-0.5 MPa), what contributes to the preservation of the natural permeability of the formation.

Thus, the increase of the blocking action of the composition caused by a combination of properties actually foam having a high resistance, and peat filler, improving system stability and forming a strong reinforcing frame. However, due to the fibrous structure of peat foamable composition differs from the known fact that not penetrate into the formation to a greater depth even with its high permeability. This greatly facilitates the removal of the composition from the reservoir during the release in the process of completing repairs and is one of the main conditions for the restoration of its filtration properties.

The use of still residue of the production of furfuryl alcohol was not detected on the available sources.

Know the use of furfural (reagent included in the still bottoms) in the processing method of cement slurries for cementing to improve the mechanical strength and increase the deceleration time setting (see and. C. N 323543, E 21 B 33/138, publ. in ABOUT N 1, 1971), in compositions for cementing to improve the stability of the composition of the formulations to increase adhesion to wet surfaces and not hardening the sealant mastics and increase the strength of the adhesive joint (see A. with. N 724546, C 09 3/12 I, publ. in ABOUT N 12, 1980).

Know the use of furfuryl alcohol (reagent included in the still bottoms) in cement mortar with the purpose of increasing the strength of cement stone in the early stages of hardening as antifoam (see and.with. N 675169, E 21 B 33/138, publ. in ABOUT N 27, 1979), with the aim of obtaining cement slurry at low fluid loss and increased strength as antifoam (see and.with. N 684129, E 21 B 33/138, publ. in ABOUT N 33, 1979), in the adhesive compositions in a mixture with organic reagents for the purpose of enhancing the bonding strength and the acceleration of the contact setting (see and.with. N 642348, C 09 3/14, publ. in ABOUT N2, 1979).

It is known the use of hydrocarbon fluids (oil, vaseline oil, spun oils, cyclohexane) in the foaming solution for limiting water inflow into the well to increase the stabilizing ability (see and.with. N933962, E 21 B 43/32) in the foaming composition for well development with the aim of increasing the stability of the foam in the mixture with the PRS or the RRT (see and.with. N 1398510, E 21 B 43/25).

Know the use of peat as a reagent for the mud to ensure the reduction in the rate of water loss of the drilling fluid in the conditions of mineral aggression when obrazom, the use in Coffs harbour in a mixture with a hydrocarbon liquid and peat in the solution of calcium chloride was not detected in the available sources.

The inventive composition involves an inventive step.

In more detail the essence of the invention is described in the following examples.

Example 1

To 159 ml of 25% solution kssb ( = 1070 kg/m3), which amounts to 17 wt. percent, poured and 0.46 ml Coffs harbour ( = 1090 kg/m3), which is 0.05 wt.%, 143 ml of diesel fuel ( = 840 kg/m3), which amounts to 12 wt.%, and 576 ml of an aqueous solution of calcium chloride ( = 1180 kg/m3). In the mixture of fluids injected 30 g (3 wt.%) air-dried peat and the composition is thoroughly mixed.

The resulting composition is injected into the core at the maximum withstand foam system pressure drop and leave for 24 hours Then determine the blocking properties of the pressure breakthrough foam screen and backwashing of the core determine the pressure release.

Foamable composition has the following properties: resistance - 84600/cm3the pressure breakthrough foam screen (blocking property) - 23 MPa, pressure release - 0,10 MPa, a coefficient of restitution of the core permeability - 0,96.

3); COFFS 2,02 ml/0.22 wt.% ( = 1090 kg/m3); the condensate 208 ml/15 wt.% ( = 720 kg/m3); calcium chloride - 490 ml/58,78 wt.% ( = 1200 kg/m3); peat - 70 g/7 wt.%.

Next, perform all operations as described in example No. 1.

Foamable composition has the following properties: resistance - 129600/cm3the pressure breakthrough foam screen - 42 MPa, pressure release - 0,50 MPa, a coefficient of restitution of the core permeability to 0.92.

Example 3

Prepare a foamable composition containing the following components: kssb - 168 ml/18 wt. % 25% R-RA ( = 1070 kg/m3); COFFS 1,19 ml/0.13 wt.% ( = 1090 kg/m3); diesel fuel - 155 ml/13 wt.% ( = 840 kg/m3); calcium chloride - 537 ml/63,87 wt.% ( = 1190 kg/m3); peat - 50 g/5 wt.%.

Next, perform all operations as described in example No. 1.

Foamable composition has the following properties: resistance - 103680/cm3the pressure breakthrough foam screen - 38 MPa, pressure release - 0,30 MPa, a coefficient of restitution of the core permeability - 0,94.

Example 4

Prepare a foamable composition containing the following components: kssb - 150 ml/16 wt. % 25% R-RA ( = 1070 kg/m3); COFFS 1,28 ml of 0.04 wt.% ( = 1090 kg/m

Next, perform all operations as described in example No. 1.

Foamable composition has the following properties: resistance - 71600/cm3the pressure of breaking the foam screen 10 MPa, pressure release - 0.07 MPa, a coefficient of restitution of the core permeability - 0,96.

Example 5

Prepare a foamable composition containing the following components: kssb - 187 ml/20 wt. % 25% R-RA ( = 1070 kg/m3); COFFS 2,11 ml/0.23 wt.% ( = 1090 kg/m3); the condensate 222 ml/16 wt.%, ( = 720 kg/m3); calcium chloride - 469 ml/55,77 wt.% ( = 1190 kg/m3); peat - 80 g/8 wt.%.

Next, perform all operations as described in example No. 1.

Foamable composition has the following properties: resistance - 130800/cm3the pressure breakthrough foam screen - 37 MPa, pressure release - 0,10 MPa, a coefficient of restitution of the core permeability - 0,90.

The compositions and results are given in the table.

Content kssb in the composition of less than 17 wt.%, COFFS less than 0.05 wt.%, while the hydrocarbon liquid of less than 12 wt.% does not ensure the formation of the foam system with increased stability due to the reduction of structural-mechanical properties of the foam.

Sod is impractical because a significant increase in technological properties of the composition does not occur.

The content of the peat in the composition is less than 3 wt.% reduces resistance and blocking effect of the foam system, and more than 7 wt.% reduces the coefficient of restitution of the core permeability.

The use of an aqueous solution of calcium chloride density less than 1180 kg/m3reduces the stability of the composition and its blocking properties as a result of insufficient amount of calcium chloride to fully interact with the lignosulfonate kssb, and the use of calcium chloride density above 1200 kg/m3it is impractical because of improvement of technological properties of the composition does not occur.

Compared with the prototype of the inventive foamable composition has increased 6.5-8.0 times the resistance to 4-7 times the pressure breakthrough foam screen, the pressure release decreases 7-35 times, and the restitution coefficient of permeability increases by 25-28%.

The practical implementation of composition and technology of killing the well based on the use of standard pump and compressor equipment. To obtain this composition in field conditions is recommended to use the unit you need a kitchen the gas ejector.

Foamable composition for killing wells, consisting of a mixture of surface-active substances (surfactants), one component of which is condensed sulfite-alcohol bard kssb, a foam stabilizer, solid and aqueous phase, characterized in that it contains kssb in the form of an aqueous solution of 25% concentration, as another component of the mixture of surfactants - distillation residues from the production of furfuryl alcohol (Coffs harbour), as a foam stabilizer is a hydrocarbon liquid, as a solid phase - peat, as the aqueous phase is an aqueous solution of calcium chloride density 1180 - 1200 kg/m3in the following ratio, wt.%:

COFFS 0,05 - 0,22

Kssb aqueous solution of 25% concentration of 17 - 19

Hydrocarbon liquid - 12 - 15

Peat - 3 - 7

An aqueous solution of calcium chloride density 1180 - 1200 kg/m3- The rest

 

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9 ex

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3 ex

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