RU2728426C1 - Solution for construction of underwater passages of pipelines by horizontal directional drilling using shield using tunnel-and-bore complex in clay soils (embodiments) - Google Patents

Abstract

FIELD: soil or rock drilling.

SUBSTANCE: group of inventions relates to solutions used as washing liquids for construction of underwater passages of pipelines in clay soils by horizontal directional drilling using a shield using a tunnel-pumping complex. Solution contains encapsulating polymer ROSFLOK KVP (1–3 wt. %), sodium formate or acetate (3–10 wt. %), water (rest). In the second embodiment, the solution contains encapsulating polymer ROSFLOK KVP (1–3 wt. %), sodium formate or acetate (3–10 wt. %), vegetable oil (3–15 wt. %), water (rest).

EFFECT: enabling the well to be reinforced in the clay soils bedding zone, the drill cuttings carryover capacity is increased, the tunnelling facility complex passage speed is increased during the horizontal directional drilling by the underwater passages of the pipelines.

3 cl, 1 tbl

Description

The technical field to which the invention relates

The group of inventions relates to solutions used as flushing fluids for the construction of underwater pipelines in clayey soils by horizontal directional drilling with a shield using a tunnel boring complex.

State of the art

Traditionally, in the construction of underwater pipeline crossings in clay soils using a tunnel boring complex using the method of horizontal directional drilling with a shield (Direct pipe), water or water-based flushing fluids (solutions) are used as a hydraulic weight. The method of horizontal directional drilling (Direct pipe method) is a one-stage operation carried out by a tunnel boring complex, in which a remotely controlled tunneling machine with a hydraulic face load is attached to a siphon and installed on roller supports. The face is developed by a cutting-shearing tool - a plan-washer. The drilling process is accompanied by the supply through connecting lines to the bottomhole zone of the solution used for flushing and removing cuttings through the hydraulic transport system, as well as as a hydraulic weight of the bottom.

When passing through clayey soils, especially hard loams and clays, the speed of the tunnel boring complex is reduced by 2-3 times, compared with the passage of sections from non-cohesive soils. This is due to the fact that water (solution) intensively interacts with clay soil and increases its moisture and fluidity, which provokes clogging of the holes on the shield, the appearance of oil seals (adhesion of clay masses to the plan-washer), leads to a decrease in the ability to carry sludge along the hydraulic transport line. The result of such processes can be a loss of fluid circulation, sticking and jamming of the washer, which leads to the impossibility of further work.

To avoid these problems, various components are used to eliminate complications, clay inhibitors or stabilizers, lubricating additives for lubricating the tool and borehole walls to facilitate penetration, polymers that thicken the drilling fluid to maintain its required viscosity.

The state of the art knows "Alcoholic drilling mud" (RF patent for invention RU 2501828 C1, published: 12/20/2013, IPC: С09К 8/08), which refers to water-based drilling fluids and is used in drilling oil and gas wells, mainly when drilling unstable clay rocks. The drilling mud includes (wt%): PBMV clay powder (1.2), Saraksan biopolymer (0.2), potassium chloride (0.5-1.1), sodium acetate (2.5-3.1), anionic emulsion Rosflok PV (2.1), triethylene glycol (9.8), tall oil (11.3), bactericide "Remacid" (0.1), water - the rest. The known composition has insufficient stabilizing ability in relation to hard loams and clays, which does not effectively prevent the formation of stuffing box deposits on the washer.

The closest analogue to the claimed invention in terms of composition and technological essence is "Synthetic-based drilling mud" (RF patent for invention RU 2445336 C1, published: 03/20/2012, IPC: С09К 8/08), including an aqueous solution of polyhydric alcohol (for example, glycerol), biopolymer, dispersed phase in the form of dispersed chalk, anionic emulsion ROSFLOK PV, electrolyte salt - sodium formate or sodium acetate, bactericide. However, this drilling fluid does not allow to strengthen clayey soils in the well, to increase the carrying capacity of drill cuttings to prevent the formation of stuffing box deposits on the planer washer and to increase the speed of the tunnel boring complex. Especially the unsatisfactory efficiency of the known composition is manifested when drilling soils consisting of hard loams and clays with a yield index (I _L ) less than zero (according to GOST 25100-2011).

The essence of the invention

The objective of the claimed group of inventions is to obtain a composition of a solution used as a flushing fluid for the construction of underwater pipeline crossings by a tunnel boring complex using the method of horizontal directional drilling with a shield (Direct pipe) in clay soils, including soils consisting of hard loams and clays.

The technical result of the claimed group of inventions is to provide the possibility of strengthening the well in the zone of occurrence of clayey soils, increasing the ability to carry out drill cuttings, increasing the speed of passage of the tunnel boring complex during horizontal directional drilling with the shield of underwater pipelines.

The claimed technical result is achieved due to the fact that the composition of the solution for the construction of underwater passages in clayey soils includes water, an encapsulating polymer, sodium formate or sodium acetate with the following ratio of components, wt. %:

- ROSFLOKKVP 1-3; - sodium formate or acetate 3-10; - water rest.

In addition, the specified technical result is also achieved due to the fact that the composition of the solution for the construction of underwater pipelines in clayey soils includes water, an encapsulating polymer, sodium formate or sodium acetate, vegetable oil with the following ratio of components, wt. %:

- ROSFLOKKVP 1-3; - sodium formate or acetate 3-10; - vegetable oil 3-15; - water rest.

Sunflower or rapeseed oil is used as vegetable oil.

The second variant of the solution is most effective when drilling soils consisting of hard loams and clays with a fluidity index (I _L ) less than zero (according to GOST 25100-2011).

The following compounds are used in the claimed solution options:

- ROSFLOK KVP (in accordance with TU 2458-002-22361394-2001) - high molecular weight hydrolysis polyacrylamide, which is an anionic emulsion soluble in water. Forms gel-like structures, thereby preventing the penetration of the aqueous phase of the clay into its composition;

- sodium formate (in accordance with TU 2432-008-50685486-2004) or sodium acetate (in accordance with TU 2432-043-07510508-2003), which act as a swelling inhibitor and stabilizer of the state of shale;

- vegetable oil (in accordance with TU 9141-334-37676459-2015), which acts as an enhancer of the action of salts of monocarboxylic acids (sodium formate and acetate), as well as a lubricant additive and has antifriction properties.

The effectiveness of the proposed solution is due to the following. A feature of the existence of polyacrylamides in an aqueous medium is that the structure of their solution at high shear gradients, for example, after passing through the jet nozzles, is subject to intense destruction. Therefore, the solution based on the ROSFLOK KVP encapsulating polymer loses its performance properties. This phenomenon is also called "aging" or "degradation". It is due to the fact that the hydrogen bonds formed between the water shells of the dissolved polyacrylamide molecules are destroyed, and the water bound by them closes the hydrogen bonds between individual water molecules in this structure. The structure of the solution is given a discrete character, i.e. it begins to represent a dispersion medium and individual hydrated polymer molecules. This is due to the fact that the induction period for the formation of hydrogen bonds increases, thereby imparting hydrophobicity to the structure of water bound by polyacrylamides.

However, the presence of sodium formate or sodium acetate in the solution prevents this phenomenon. This is due to the fact that these compounds at a concentration of 3-10 wt. % behave in solution like typical electrolytes. Because of this, they polarize the hydrogen bonds created between polyacrylamide molecules dissolved in water. An increase in the polarization of hydrogen bonds significantly reduces the induction period for the formation of hydrogen bonds. This contributes to imparting greater flexibility to hydrogen bonds, and increasing their ability to quickly recover after the destruction that has occurred, thereby contributing to the preservation of the operational properties of aqueous solutions of polyacrylamides.

ион ацетата -

), то они способны наполнять пространственные гидратные структуры, созданные на основе водородных связей. Так как при связывании воды глиной формируются пространственные структуры, то ионы формиата или ацетата способны заполнять внутреннее пространство подобных структур с формированием краун-эфиров, которые относятся к соединениям включения.However, due to the fact that these compounds are formed by large-size ions (formate ion -

acetate ion -

), then they are capable of filling spatial hydration structures created on the basis of hydrogen bonds. Since when water is bound by clay, spatial structures are formed, formate or acetate ions are able to fill the internal space of such structures with the formation of crown ethers, which are inclusion compounds.

Such a control over the behavior of water bound by the clay allows at the same time to reduce the rate of water entering the clay, to reduce the amount of its swelling and the rate of this process. The formation of hydrate compounds of inclusions will slow down and even completely stop the wetting of clays due to the lack of access channels for water monomers through the aqueous structure of the clay. Those. Combinations of protective reagents in the form of a polymer (ROSFLOK KVP) together with sodium formate or sodium acetate create hydrated inclusion compounds in the aqueous structure of clay. Therefore, the surface of clay rocks, in the presence of an optimal compromise between dispersion and chemical bonds in its water structure, can become hydrophobic and form a hydrated structure in the volume of clay, which unites it into a single, durable whole.

However, this effect of polyacrylamides and sodium formate or acetate will be characteristic only for plastic clays. This is due to the fact that hard clays absorb water more intensively than plastic clays. The first stage in the interaction of water with clay is the absorption of water by the clay and its swelling, the second stage is the dispersion of the hydrated clay particles. For clayey sediments containing clays with a positive fluidity index, both of these stages are significantly extended in time. For clayey sediments containing clays with negative values of the flow index, these stages, in fact, occur simultaneously due to the volumetric destruction of clayey soil. Therefore, it is necessary to use an additional stabilizer capable of stabilizing hard clays, especially those with a high plasticity.

Many organic non-electrolytes can play a similar role as an additional stabilizer. However, the peculiarities of the implementation of the method of horizontal directional drilling (method of Direct pipe) require the use of environmentally friendly joints that can be destroyed under the influence of the environment. These include natural vegetable oils (sunflower, rapeseed).

Restrictions on the content of the introduced reagents are due to the fact that when the ROSFLOK KVP polymer content is more than 3 wt. % solution turns into a structured gel, which is unsuitable for pumping and passing through the hydromonitor nozzles, and when the ROSFLOK KVP polymer content is less than 0.5 wt. % solution becomes a liquid, unable to keep the emulsion with vegetable oil in a stable state.

The study of the stability of clay samples was carried out according to the following method. On the basis of subbentonite (Almetyevsk clay powder), by mixing it with water and sand, samples of sandy loam, loam and clay were formed with different indicators of fluidity. From the mixtures obtained, tablets with a diameter of 1 cm and a height of 1 cm were pressed. To equalize the humidity, the samples were kept in a desiccator for 1 week. The prepared samples were placed in various test environments, where they were kept for a period of time that ensured their stable existence. The time of stable existence was determined visually by the absence of chips, cracks, shattering of samples, as well as their swelling. The optimal time of stable existence of clay samples was determined on the basis of the maximum possible time required for the delivery of drilled cuttings to the day surface - 2-3 hours.

The test solutions (flushing liquids) were obtained by mechanical mixing of the components within the stated limits of the content of the components.

The results of the experiments, shown in the table, made it possible to establish the optimal formulation of the solution.

The table shows the rheological parameters of solutions and the state of samples of clay soils. The compositions of the solutions are shown in the attached table. The composition of the solutions is indicated in wt. %, which corresponds to the amount of reagents in grams required to prepare 100 g of a solution.

The main limitations for the proposed composition of the solution were the conditions for the stable existence of the liquid itself. At excessive concentrations of the encapsulating polymer ROSFLOK KVP in the volume of the solution, a low pumpable gel was formed, and at low concentrations of the specified polymer, when creating an emulsion with vegetable oil, the resulting flushing liquid was unstable. First of all, this is due to the fact that the resulting emulsion has a stabilization protection of the structural and mechanical type.

Thus, it was found that the compositions of the solutions given in paragraphs 1-6 and 11-16 of the table, for which the time of stable existence of the sample was 24 hours or more, provide the possibility of strengthening the well in the zone of occurrence of clayey soils, increase the ability to carry out drill cuttings, in As a result, the speed of passage of the tunnel boring complex increases during horizontal directional drilling with the shield of underwater pipelines.

Claims (5)

1. A solution for the construction of underwater pipelines in clayey soils, including water, encapsulating polymer, sodium formate or sodium acetate in the following ratio of components, wt. %: ROSFLOCK KVP 1-3 sodium formate or acetate 3-10 water rest 2. A solution for the construction of underwater pipelines in clayey soils, including water, encapsulating polymer, sodium formate or sodium acetate, vegetable oil in the following ratio of components, wt. %: ROSFLOCK KVP 1-3 sodium formate or acetate 3-10 vegetable oil 3-15 water rest 3. A solution according to claim 2, characterized in that sunflower or rapeseed oil is used as the vegetable oil.