RU2293100C1 - Grouting composition for isolation of lost-circulation zones and a method for preparation thereof - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to drilling boreholes for oil, gas, and water and is basically designed for use in zones with strong and extremely catastrophic losses of drilling fluids but can also be used in zones with normal loss. Grouting composition contains binding base, caustic magnesite, and tempering fluid comprising aqueous solution containing magnesium chloride and chemical additive controlling thickening and setting times, said aqueous solution being, in particular, bischofite solution having density 1.28 g/cc and said chemical additive being, in particular, double superphosphate, while said aqueous solution further contains, as fillers, clay powder and paper production waste (dehydrated sediment from treatment plants). Following proportions of components are used: 42.55-43.08% caustic magnesite, 8.62-10.64% clay powder, 2.34-2.84% paper production waste, 2.38-2.92% double superphosphate, and bischofite solution with density 1.28 g/cc - the rest. Preparation of grouting solution comprises(i) providing tempering fluid, namely aqueous solution containing magnesium chloride, to which above-mentioned chemical additive is added and (ii) tempering above-mentioned caustic magnetite with above-mentioned fillers added at weight ratio of tempering fluid to caustic magnetite with fillers at least 0.8.

EFFECT: enhanced reliability of isolation of lost-circulation zones in finely and macroporous, fractured, cavernous, and mixed rocks by providing high-elasticity, durable, and corrosion-resistant grouting stone exhibiting small expansion.

2 cl, 3 tbl

Description

The invention relates to drilling wells for oil, gas and water, and is intended for use, primarily in areas with strong and extremely catastrophic absorption of flushing fluid, and can also be used in areas with conventional absorption.

As an analogue, we take a composition containing (wt.%) Caustic magnesite 48.54-53.24, magnesium chloride 23.97-27.89, black monosulfite liquor 2.44-4.89, water - the rest (patent RU 2060360 C1).

A method of preparing a cement composition by analogy: first, an aqueous solution of magnesium chloride is prepared, monosulfite black liquor is added to the resulting solution, and caustic magnesite is mixed on this mixture, the resulting solution is thoroughly mixed.

The closest, in our opinion, to the claimed technical solution is a grouting composition containing (parts by weight) caustic magnesite 100, magnesium chloride 18.9-26.5, alkaline stock production of caprolactam SCHSPK 1.0-7.0, water 44.1-61.7 (patent RU 2065923 C1).

The method of preparation of the grouting composition according to the prototype: first, an aqueous solution is prepared by mixing magnesium chloride and SHCHSPK in tap water and caustic magnesite is closed on this solution.

However, the grouting compositions described above by analogy and prototype in the methods for their preparation, having waterproofing properties necessary for long-term isolation of aquifers, do not have sufficient properties to ensure reliable isolation of washout absorption zones in fine and coarse-grained, fractured, cavernous and mixed rocks with intense and catastrophic absorption of flushing fluid.

The aim of the present invention is to achieve a new technical result, namely: the development of cement composition and a method for its production, which will provide reliable isolation of the absorption zones of the washing fluid in fine and coarse-grained, fractured, cavernous and mixed rocks, having good ability to spread into zone cracks when spreading and the resulting cement stone will have a small increase in volume, will be highly elastic, durable, resistant to corrosion in contact with the layers liquids, gases, hydrogen sulfide.

The specified technical result is achieved by the proposed grouting composition for isolating the absorption zones of the washing liquid, containing a bonding base - caustic magnesite and a mixing liquid, including an aqueous solution containing magnesium chloride, and a chemical additive to control the thickening and setting time, while the new one is that it contains bischofite with a density of 1.28 g / cm ³ as the specified aqueous solution, superphosphate double SPFD as the specified chemical additive, and additionally fillers - clay powder and a by-product - waste from paper production SCOP, in the following ratio of components, wt.%:

Caustic Magnesite 42.55-43.08 Clay powder 8.62-10.64 SCOP 2.34-2.84 SPFD 2.38-2.92 Bischofite aqueous solution density of 1.28 g / cm ³ rest

The specified technical result is also achieved by the proposed method for the preparation of grouting composition for isolating the absorption zones of the washing fluid, including the preparation of a mixing fluid from an aqueous solution containing magnesium chloride, to which a chemical additive is added to control the thickening and setting time, mixing of the binding base obtained by the mixing fluid with caustic magnesite , while new is the fact that for the preparation of the claimed above grouting composition goth vyat bishofit said solution, in which the said chemical additive is added, mixing is carried out with caustic magnesite doabvkoy these fillers with respect to the mass of fluid mixing to the mass of solids - caustic magnesite with said excipients - not less than 0.8.

The components included in the proposed grouting composition in the stated ratio provide the following properties of the specified composition, namely: a bonding base - caustic magnesite - provides high penetration; fillers: clay powder gives the resulting cement stone high strength and fills small pores, channels and cavities; SCOP well isolates large-pore and fractured media; a chemical additive - double superphosphate - regulates the thickening and setting time of grouting composition, reduces the filtrate recovery, provides water resistance and salinity of grouting stone; an aqueous bischofite solution with a density of 1.28 g / cm ³ provides the necessary period of thickening and setting (hardening) of the cement composition.

The proposed grouting composition for isolating washout absorption zones obtained according to the proposed method was tested in the field while drilling wells at the Ozerny oil field, where intense washout absorptions are found in Upper Carboniferous sediments and in the Sakmaroassel layer. This tier contains hydrogen sulfide in produced water. The elimination of absorption zones is also complicated by the fact that the wells at the Ozernoye field are characterized by large spacing up to 1,500 m, while the wellbores run at angles of 45 to 65 degrees. However, the proposed grouting composition prepared by the present method eliminated the absorption in one treatment, which excluded the possibility of killing the second trunks.

Table 1 shows the actual data on the time spent on the elimination of the zones of absorption of drilling fluid during drilling in 2003 at the Ozernoye field, on the basis of which it can be concluded that the use of the inventive grouting composition prepared according to the proposed method effectively eliminates the absorption zones during drilling of wells in formations with an injection coefficient of at least 4. The average time for elimination of washout absorption zones was about 40 hours. The proposed grouting composition can also be used to eliminate the zones of absorption of flushing fluid in the formations with an injectivity of less than 4.

Moreover, the use of the proposed grouting composition in the field showed that it is convenient to use, because it is compatible with the drilling fluid, because as a result of their mixing, the rheological and structural-mechanical parameters of the drilling fluid change insignificantly, and the resulting cement stone has a slight positive deformation and is corrosion resistant to formation waters and hydrogen sulfide.

The selection of the components of the proposed grouting composition for isolating the absorption zones of the washing fluid and establishing their quantitative ratio to ensure the specified technical result was carried out by laboratory research.

Caustic magnesite (caustic magnesite powder - PMC) of batch 408 was selected as the basis for the preparation of grouting composition in laboratory conditions. It is known that different batches of PMC have different properties and in the laboratory it is possible to choose a batch of PMC for any absorption zone.

Example. To obtain 100 g of the proposed grouting composition, a mixing fluid was first prepared, for which 42.33 g of an aqueous bischofite solution with a density of 1.28 g / cm ³ were taken and SPPD was added into it in an amount of 2.92 g. A mixture of solids from 43 was separately prepared. 08 g of PMK-408 binding base and from fillers: 10.64 g of clay powder and 2.84 g of SCOP. Then, with stirring, the resulting mixture of solids was mixed with a mixing liquid based on the ratio of the mass of the mixing liquid to the mass of solids as 0.8 and the proposed grouting composition was obtained with the following content of components, wt.%: PMK 43.08; clay powder 10.64; SCOP 2.84; SPFD 2.92 and an aqueous solution of bischofite with a density of 1.28 g / cm ³ 42.33.

Grouting compositions with other ratios of components were prepared in a similar way.

In the course of laboratory studies, the following properties of the proposed grouting composition based on PMK-408 were determined: spreadability, density of the grouting composition, thickening and setting time, strength of the resulting grouting stone, and also the parameters of the grouting composition were adjusted, taking into account the following:

- with increasing or decreasing temperature of the mixing fluid, the thickening and setting time changes (with increasing temperature, the thickening time decreases; with decreasing temperature, the thickening time increases);

- the chemical additive SPFD (double superphosphate) regulates the thickening and setting time of the grouting composition to technologically necessary values, reduces the filtrate recovery, provides water resistance and salt resistance of the resulting grouting stone;

- an increase or decrease in the amount of filler of bentonite clay powder is regulated by the thickening time, the strength of the cement stone;

- when using additives of palygorskite clay powders, it is possible to sharply increase the viscosity of the grouting composition, which makes it possible to use it to eliminate the catastrophic absorption zones of washing liquid at a shallow depth.

The results of laboratory studies are shown in tables 2 and 3: table 2 shows data on the component content of the investigated proposed cement compositions; table 3 - data on the properties of grouting compositions.

The use of the inventive grouting composition to isolate the zones of absorption of flushing fluid when drilling wells at the Ozernoye field and laboratory studies have shown that this composition has the ability to spread well into the channels of the absorption zones when spreading, thicken and turn into an almost impermeable solid (cement stone), which has good adhesion to rocks, has a small increase in volume, durability, corrosion resistance in contact with formation fluids gases, hydrogen sulfide, and not destroyed when interacting with the reservoir fluid.

Claims (2)

1. The grouting composition for isolating the absorption zones of the washing liquid, containing a bonding base - caustic magnesite and a mixing liquid, including an aqueous solution containing magnesium chloride, and a chemical additive for regulating the thickening and setting time, characterized in that it contains as the specified aqueous solution solution bishofit density of 1.28 g / cm ^3, as said chemical additive SPFD double superphosphate, and further excipients - gel powder and by-product - waste production boom SCOP and the following component ratio, wt.%: Caustic Magnesite 42.55-43.08 Clay powder 8.62-10.64 SCOP 2.34-2.84 SPFD 2.38-2.92 Bischofite aqueous solution density of 1.28 g / cm ³ Rest 2. A method of preparing a grouting composition for isolating the absorption zones of washing liquid, including preparing a mixing liquid from an aqueous solution containing magnesium chloride, to which a chemical additive is added to control the thickening and setting time, mixing the obtained base liquid with a binding base - caustic magnesite, characterized in that for the preparation of the composition according to claim 1, the specified bischofite solution is prepared, to which the specified chemical additive is added, mixing static magnesite with the addition of these fillers when the ratio of the mass of the mixing fluid to the mass of solids - caustic magnesite with the specified fillers is not less than 0.8.