阅读说明：本技术 一种含高杂质盐岩及泥岩夹层的盐岩地层的气垫式采卤方法 (Air cushion type bittern collecting method for salt rock stratum containing high-impurity salt rock and mudstone interlayer ) 是由 王路 蔡旭 舒树强 李海勇 张立平 宋子军 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种含高杂质盐岩及泥岩夹层的盐岩地层的气垫式采卤方法,包括1)建立溶腔；2)通过造腔外管和卤水中心管之间的注气通道注入高压气体,在腔体顶部形成气垫；3)侧溶待腔体横向尺寸达标后,使气液界面保持在盐岩顶板上方；4)上溶一段时间待溶蚀不充分时,上调注入清水的排量；5)上溶遇到泥岩夹层时,使气液界面下降在泥岩夹层下方形成气垫,待泥岩夹层下方腔体横向尺寸达标,提升气液界面,使卤水与泥岩夹层充分接触,以促进卤水往泥岩夹层渗透、软化和垮塌泥岩夹层；6)泥岩夹层完全垮塌后,使得腔体主要发生上溶；按3-6循环,本发明解决了高杂质盐岩地层的溶蚀、夹层垮塌控制及腔体形态控制的问题。(The invention discloses an air cushion type bittern collecting method for a salt rock stratum containing high-impurity salt rock and mudstone interlayer, which comprises the steps of 1) establishing a dissolving cavity; 2) injecting high-pressure gas through a gas injection channel between the cavity-making outer tube and the brine central tube to form an air cushion at the top of the cavity; 3) after the transverse dimension of the cavity reaches the standard, keeping a gas-liquid interface above the salt rock top plate; 4) when the upper solution is dissolved for a period of time and the corrosion is insufficient, the discharge capacity of the injected clean water is adjusted up; 5) when the upward dissolution meets a mudstone interlayer, the gas-liquid interface is lowered below the mudstone interlayer to form an air cushion, and when the transverse dimension of the cavity below the mudstone interlayer reaches the standard, the gas-liquid interface is lifted, so that the brine is fully contacted with the mudstone interlayer, and the permeation, softening and collapse of the brine to the mudstone interlayer are promoted; 6) after the mudstone interlayer is completely collapsed, the cavity is mainly dissolved; according to 3-6 cycles, the invention solves the problems of corrosion of high-impurity salt rock stratum, interlayer collapse control and cavity shape control.)

1. The air cushion type bittern collecting method is characterized in that an air cushion type bittern collecting device is adopted, the air cushion type bittern collecting device comprises a three-layer sleeve, the three-layer sleeve is respectively a clean water central pipe, a bittern central pipe and a cavity building outer pipe which are sequentially sleeved from inside to outside, clean water is injected into the clean water central pipe from the previous cavity, the bittern central pipe is used for collecting bittern from the cavity, the cavity building outer pipe is used for injecting gas into the cavity, a bittern collecting channel is formed between the bittern central pipe and the clean water central pipe, and a gas injection channel is formed between the cavity building outer pipe and the bittern central pipe; the bittern collecting method comprises the following steps:

step 1) an initial procedure, namely establishing a dissolving cavity;

step 2) injecting high-pressure gas through a gas injection channel between the cavity-making outer pipe and the brine central pipe, forming a layer of gas cushion on the top of the cavity for preventing brine from contacting the salt rock top plate, and forming a gas-liquid interface between the gas cushion and the brine so that the interior of the cavity can only be laterally dissolved;

step 3), after the lateral size of the cavity reaches the standard after the lateral dissolution is carried out for a period of time, adjusting the pressure and the injection amount of high-pressure gas to enable a gas-liquid interface to rise and be kept above the salt rock top plate, and enabling brine to be in contact with the surface of the salt rock top plate and to be dissolved upwards;

step 4), when the solution is dissolved for a period of time and the solution is not sufficiently corroded, the discharge capacity of the injected clear water is adjusted upwards;

step 5), when the upward dissolution meets a mudstone interlayer, the gas-liquid interface is lowered below the mudstone interlayer to form an air cushion, so that salt rock below the mudstone interlayer is fully dissolved, and when the transverse dimension of a cavity below the mudstone interlayer reaches the standard, the gas-liquid interface is lifted to be kept between the upper surface and the lower surface of the mudstone interlayer, so that brine is fully contacted with the mudstone interlayer, and the permeation, softening and collapse of the brine to the mudstone interlayer are promoted;

step 6), after the mudstone interlayer completely collapses, keeping a gas-liquid interface above the salt rock top plate to ensure that the cavity is mainly dissolved; after the transverse dimension of the cavity reaches the standard, a gas-liquid interface is lowered below a rock stratum top plate to form an air cushion, so that the rock stratum between the salt rock top plate and brine is subjected to side dissolution; and circulating according to the steps 3-6.

2. The brine mining method of claim 1, wherein the salt rock is a high impurity salt rock having an impurity content of: 20-40%.

3. The brine extraction method according to claim 1, wherein the transverse dimension of the cavity in steps 3), 5) and 6) is up to standard by calculation according to the brine extraction amount and the brine concentration.

4. The brine mining method according to claim 1, wherein the decrease of the brine concentration collected in the step 4) indicates insufficient corrosion, and the increase of the injected clean water is 20-50% higher than the injection amount, which is determined by combining the change of the brine concentration produced on site.

5. The brine recovery method of claim 1, wherein the brine of step 5) is stopped when it is sufficiently contacted with the mudstone interlayer, while increasing the gas pressure and brine pressure, but maintaining the gas-liquid interface above the bottom surface of the mudstone interlayer.

Technical Field

The invention relates to a bittern collecting method, in particular to an air cushion type bittern collecting method.

Background

China is a big country for well and mineral salt exploitation, the annual exploitation amount of well and mineral salt reaches 5000 ten thousand tons, which is close to 60 percent of the salt yield of China, and a large amount of industrial raw material-NaCl can be obtained through well and mineral salt exploitation. Meanwhile, a huge solution cavity can be formed underground through well and mineral salt exploitation, and the cavity is considered as an ideal space for oil and gas storage by domestic and foreign public. The dependence of petroleum and natural gas in China on the outside is as high as 70 percent and 45 percent, and a complete strategic oil gas storage system is established, which is an important ring for ensuring the national energy safety. Particularly, the promotion of the trade war in China and America and the devil of new crown epidemic situations remind people to build the urgency of an energy storage system of the people. Therefore, the cavity formed after brine extraction of the salt rock stratum in the eastern region of China is used as an oil-gas storage space, and the method is an important way for realizing dual purposes of underground space utilization and energy storage of the mine.

However, except for the gold altar salt mine, the salt mine in the middle east area has the characteristics of high impurity content (20-40%), multiple mudstone interlayers and the like. The surface of the brine-collecting and cavity-making surface of the stratum is provided with a plurality of challenges such as difficult control of salt layer corrosion, low cavity forming rate and the like. The existing oil cushion method brine extracting/cavity making process is suitable for a pure salt layer and a stratum with few interlayers, but also faces the problem that brine extracted contains emulsified oil, so that the problem that the whole economic benefit of brine extracting/cavity making is influenced because refined brine cannot be obtained (the value is high) is solved. If the high-impurity salt rock stratum adopts an oil cushion method to extract brine/make cavities, the surface of the high-impurity salt rock is uneven (impurity blocks are difficult to dissolve) after the high-impurity salt rock is corroded, and for a common oil cushion (common diesel oil) with the thickness of only 2mm, the diesel oil inevitably enters a depression on the surface of the salt rock first, so that the salt rock is weakened or loses efficacy in dissolution control. If the thickness of the oil pad is increased, the cost is increased, the content of the produced brine is further increased, the brine cannot be sold, and the treatment cost for treating the brine containing oil pollution is increased.

Many salt mines in China all contain salt layers and interlayers with high impurities, such as Huaian salt mines, flat-topped mountain salt mines, Fengxian salt mines, Yiyun salt mines and the like. The existing oil pad method brine mining/cavity making process has extremely limited applicability when facing such high-impurity salt rock stratum and interlayer, and also has the problems that salt mine enterprises cannot obtain refined brine to influence economic benefit and the like; the excessive oil pad not only increases the cost, but also faces the problem of disposal of the brine containing oil pollution and the problem of potential environmental pollution. The method promotes the innovation of a novel brine-mining/cavity-building process technology, and provides new guidance and thinking for brine-mining/cavity-building of a high-impurity rock salt and interlayer rock salt stratum in China.

Disclosure of Invention

The invention aims to provide an air cushion type bittern collecting method for a salt rock stratum containing high-impurity salt rock and mudstone interlayer, which aims to solve the problems of corrosion, interlayer collapse control and cavity shape control of the high-impurity salt rock stratum and solve the problem of how to obtain high-value refined bittern during bittern collecting and cavity building of salt mines.

The purpose of the invention is realized as follows: the air cushion type bittern collecting method is characterized in that an air cushion type bittern collecting device is adopted, the air cushion type bittern collecting device comprises a three-layer sleeve, the three-layer sleeve is respectively a clean water central pipe, a bittern central pipe and a cavity building outer pipe which are sequentially sleeved from inside to outside, clean water is injected into the clean water central pipe from the previous cavity, the bittern central pipe is used for collecting bittern from the cavity, the cavity building outer pipe is used for injecting gas into the cavity, a bittern collecting channel is formed between the bittern central pipe and the clean water central pipe, and a gas injection channel is formed between the cavity building outer pipe and the bittern central pipe; the bittern collecting method comprises the following steps:

step 1) an initial procedure, namely establishing a dissolving cavity;

step 2) injecting high-pressure gas through a gas injection channel between the cavity-making outer pipe and the brine central pipe, forming a layer of gas cushion on the top of the cavity for preventing brine from contacting the salt rock top plate, and forming a gas-liquid interface between the gas cushion and the brine so that the interior of the cavity can only be laterally dissolved;

step 3), after the lateral size of the cavity reaches the standard after the lateral dissolution is carried out for a period of time, adjusting the pressure and the injection amount of high-pressure gas to enable a gas-liquid interface to rise and be kept above the salt rock top plate, and enabling brine to be in contact with the surface of the salt rock top plate and to be dissolved upwards;

step 4), when the solution is dissolved for a period of time and the solution is not sufficiently corroded, the discharge capacity of the injected clear water is adjusted upwards;

step 5), when the upward dissolution meets a mudstone interlayer, the gas-liquid interface is lowered below the mudstone interlayer to form an air cushion, so that salt rock below the mudstone interlayer is fully dissolved, and when the transverse dimension of a cavity below the mudstone interlayer reaches the standard, the gas-liquid interface is lifted to be kept between the upper surface and the lower surface of the mudstone interlayer, so that brine is fully contacted with the mudstone interlayer, and the permeation, softening and collapse of the brine to the mudstone interlayer are promoted;

step 6), after the mudstone interlayer completely collapses, keeping a gas-liquid interface above the salt rock top plate to ensure that the cavity is mainly dissolved; after the transverse dimension of the cavity reaches the standard, a gas-liquid interface is lowered below a rock stratum top plate to form an air cushion, so that the rock stratum between the salt rock top plate and brine is subjected to side dissolution; and circulating according to the steps 3-6.

As a further limitation of the invention, the salt rock is a high impurity salt rock having an impurity content of: 20-40%.

As a further limitation of the invention, the transverse dimension of the cavity in the steps 3), 5) and 6) reaches the standard by calculation according to the brine extraction amount and the brine concentration, and the total volume of the dissolving cavity is obtained by comprehensive calculation based on the Moore's law and according to the shape of the inverted cone-shaped dissolving cavity obtained by a dissolution experiment as a calculation model.

As a further limitation of the invention, if the concentration of the brine collected in the step 4) is reduced, the corrosion is insufficient, the injected clean water is adjusted up to increase the injection amount by 20-50%, and the change of the concentration of the brine collected on site is specifically determined; if the total concentration of brine is reduced to below 300g/l, the soluble substance contact surface at the top or side of the cavity is determined to be too small.

As a further limitation of the present invention, when the brine in step 5) is sufficiently contacted with the mudstone interlayer, the injection of the clean water can be stopped, and the gas pressure and the brine pressure are increased, but the gas-liquid interface is maintained above the bottom surface of the mudstone interlayer.

Compared with the prior art, the invention has the beneficial effects that: the invention provides a brine mining method, which can effectively prevent brine from contacting a salt rock top plate by injecting air cushion when encountering a high-impurity salt rock stratum, thereby ensuring that side dissolution occurs, and requiring to improve the discharge of injected clear water in the high-impurity salt rock stratum so as to ensure that the high-impurity salt stratum is fully dissolved; when an interlayer is encountered, the air cushion is used for preventing dissolution, so that the transverse size below the interlayer is ensured to be large enough, and the interlayer has enough collapse size, and then the interlayer is soaked in high-pressure brine by lifting a gas-liquid interface and properly increasing the pressure of the brine and the gas, so that the interlayer is prevented from collapsing too early due to insufficient pressure in a dissolution cavity; on the other hand, the soaking time of the interlayer in the brine is promoted, so that the softening and the collapse of the interlayer are ensured; when the size of the upper part of the cavity is reached, the lifting of a gas-liquid interface is properly accelerated, the purpose of reducing the increase of side dissolution and the dissolution is achieved, and the upper part of the cavity is ensured to be in a dome shape with good stability; in the process of brine collection and cavity construction, the shape of the cavity and the propulsion speed of brine collection and cavity construction are well controlled, and the cavity with large volume and regular shape can be obtained to meet the requirement of oil-gas storage; in the whole process of brine collection and cavity construction, high-pressure gas is used as a dissolution inhibitor, and the collected brine is refined brine, so that a good sale price can be obtained, and the economic benefit of brine collection is improved.

Drawings

Fig. 1 is a schematic diagram of the principle of the present invention.

FIG. 2 is a schematic of the present invention for treating the up-and side-dissolving of high impurity salt formation.

FIG. 3 is a schematic diagram of the method for treating salt rock side dissolution at the lower part of a mudstone interlayer and inducing interlayer collapse by soaking the interlayer with high-pressure brine.

FIG. 4 is a schematic view of the upper portion of the chamber of the present invention showing reduced lateral flow and increased lateral flow to ensure that the chamber has a domed top.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

An air cushion type bittern collecting method for a salt rock stratum containing high-impurity salt rocks and a mudstone interlayer adopts an air cushion type bittern collecting device shown in figure 1, wherein the air cushion type bittern collecting device comprises a three-layer sleeve, the three-layer sleeve is respectively a clear water central pipe, a bittern central pipe and a cavity-making outer pipe which are sequentially sleeved from inside to outside, the clear water central pipe is used for injecting clear water into a conventional cavity, the bittern central pipe is used for collecting bittern from the cavity, the cavity-making outer pipe is used for injecting gas into the cavity, a bittern collecting channel is formed between the bittern central pipe and the clear water central pipe, and a gas injection channel is formed between the cavity-making outer pipe and the bittern central pipe; the bittern collecting method comprises the following steps:

step 1) initializing a process, establishing a dissolving cavity, injecting high-pressure gas (such as nitrogen) between an outer tube of the cavity and a brine central tube through a ground air compressor, forming an air cushion with the thickness of not less than 20cm on the upper part of brine, preventing a salt rock top plate of the cavity from contacting brine, and only allowing the salt rock top plate of the cavity to be subjected to side dissolving, as shown in fig. 2;

step 2) calculating the transverse dimension of the cavity to reach the standard according to the brine extraction amount and the brine concentration, and adjusting the pressure and the gas injection amount through a ground air compressor to enable a gas-liquid interface to rise, so that brine is in contact with the surface of a top plate of high-impurity rock salt (particularly, the impurity content is 20-40%) and is dissolved upwards;

step 3) when the high-impurity rock salt stratum is dissolved, closely monitoring the concentration of the produced brine, and if the concentration is reduced, indicating that the corrosion is insufficient, at the moment, properly adjusting the discharge capacity of the injected clear water, specifically, improving the discharge capacity of the clear water by 20-50%, and determining by combining the concentration change of the brine produced on site;

step 4) if the upper solution meets the interlayer, increasing the thickness of the air cushion properly below the interlayer to ensure that the salt rock below the interlayer is fully dissolved, lifting the gas-liquid interface when the transverse dimension of the cavity below the interlayer reaches the standard, and allowing the brine to be fully contacted with the interlayer, at the moment, stopping injecting the clear water properly, and simultaneously properly increasing the gas pressure and the brine pressure (but keeping the gas-liquid interface above the bottom surface of the interlayer) to promote the brine to permeate, soften and collapse the interlayer, so that the brine is slowly distributed and collapsed, and the tubular column cannot be damaged and lifted due to collapse, as shown in fig. 3;

step 5) after the interlayer is completely collapsed, keeping a gas-liquid interface above the top plate to ensure that the gas-liquid interface is mainly dissolved, as shown in fig. 4; after the requirement is met, increasing the gas injection amount, and generating side dissolution on a rock stratum between a salt rock top plate and brine;

step 6), when high-impurity salt rocks and interlayers are encountered, repeating the steps 1), 2), 3), 4) and 5), and ensuring that the vertical and transverse sizes of the cavity meet the design requirements;

and 7) when the brine is collected and the cavity reaches the designed upper part of the cavity, gradually reducing the injection amount of the air cushion so as to reduce the side dissolution amount and increase the upper dissolution amount and ensure that the upper part of the cavity forms a dome shape with good self-stability.

The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.