RU2386802C1 - Localisation and liquidation technology of oil lens by means of forced facilities - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: localisation and liquidation localisation of oil lens from subsurface layers of soil includes definition of lens boundaries, drilling of wells, localisation of lens and displacement of oil to the surface. Localisation is implemented by means of passing by contour of oil lens of wells or bore pits, after what it is implemented its loading by explosive of such mass and power, at which after explosion it is implemented creation of oil-water-proof of internal envelope, blocking oil lens by means of sealing and melting of ground. Liquidation includes multiple sequential explosions in the same wells or bore pits occurring shocks of which displaces oil lens from soil. It is possible application of additional ground watering with target of increasing of its density and by this increasing of effectiveness of shock impact which directly moves oil lens upwards.

EFFECT: invention increases effectiveness of oil extraction of oil from soil increasing effectiveness of labour, improves ecology, releases soil from oil pollution.

2 cl, 11 dwg

Description

At present, in Russia, and throughout the world, a catastrophic situation has arisen with accidents related to the transportation and storage of oil and oil products. Until recently, few people thought about what environmental damage could be caused by emergency oil spills. Speaking specifically about the types of accidents associated with the transport of oil, it is necessary to note such as accidents on the pipeline, accidents on the railway (overturning of oil tanks) and accidents on roads. And each of these types of accidents brings great environmental damage every year. For example, when a pipeline breaks, a large release of oil occurs in the soil or on the surface of the soil, which is quickly filtered and penetrates to a rather great depth into the bowels of the soil, forming a so-called lens. If oil can be easily collected from the surface of the soil, it is very difficult to eliminate the lens. The soil is affected for many years. On it we will not be able to see the vegetation cover. To date, very few effective, economical, and practical methods for localizing and eliminating an oil lens are known. The main goal was to develop a new way to localize and eliminate an oil lens using explosives.

The method of localization and elimination of an oil lens from the deep layers of the soil using explosives (VV) is primarily used to block and displace the lens from the soil, with the aim of releasing it from oil and further restoring and improving the soil composition, as well as to extract residual oil and its use as a secondary fuel.

After an emergency oil spill, part of it can be collected from the Earth’s surface, the rest penetrates, is filtered into the deeper layers of the soil, and a lens is formed that sometimes cannot be removed. This lens can behave unpredictably, namely, it can begin to drift to the village and penetrate underground sources of drinking water. As a result, oil or its derivatives will be present in drinking water. To prevent this from happening, it is necessary to localize the lens, and then completely displace it from the soil using forced (explosive) means.

As mentioned above, we have two periods in the technology of localization and liquidation of emergency oil spills:

1. Localization of the oil lens.

2. Elimination of the oil lens.

Let's talk first about the first period - localization.

The first period is necessary in order to limit the dangerous spread of the lens.

To implement the first period, you must perform the following operations.

1. Using a gas survey to detect the control boundaries of the lens.

2. Next, it is necessary to drill wells - pits for lowering the charge - and lower the charges of such mass and power in order to only localize the lens.

The explosion of dual use: 1) Localization of the lens (see figure 1).

The explosion of dual use (see figure 2):

1) Localization of the lens.

2) For the forced displacement of oil from the lens.

For this, the features of compaction and melting of the soil in an explosion are taken into account. As a result of the explosion, so-called camouflage cavities are formed. The inner shell is highly melted and watertight. Moreover, during the explosion, a strong compaction of the soil occurs due to the formation of a cavity, which of course enhances the impermeability of the soil between camouflage cavities. This position is confirmed by the formula

,

,

soil volume decreased, density increased. What the scheme proves (see figure 3).

V _G - soil volume before the explosion

V _P - the volume of the cavity after the explosion

V ^* is the volume of compacted soil.

Formula - condition for soil compaction:

Compacted soil formula

V ^* _g - soil volume after the explosion (compacted soil)

V _P - the volume of the cavity after the explosion

V _G - soil volume before the explosion

Two explosion modes:

1) V _g = V _p + V ^*

2) → The seal area is included in the lens area.

After the explosion, the volume of soil is equal to the volume of compacted soil V ^*.

We call this soil - compacted soil, it was compacted due to the formation of a cavity V _p .

In addition, it must be added that the charges must be located at such a distance from each other that, in the event of the explosion of two adjacent charges of a certain power, the jumper between the camouflage cavities is maximally compacted and impermeable to the contents of the lens. This will provide an oil-tight casing, which will block and thereby localize the lens (see Fig. 4, 5, 6).

The creation of a compacted zone is the most important effect of an explosion in the soil, especially valuable in the conditions of localization of an oil lens, since it is a kind of antifiltration screen.

Under dynamic, including explosive, loading, soil compaction occurs mainly as a result of air compression (reduction of free porosity), i.e. as a result of repackaging of skeleton particles with their mutual displacement. Due to the decrease in free porosity in clay soil, pore sizes and their number are reduced due to the combination of adsorption films surrounding mineral particles, which leads to an increase in viscous resistance and a decrease in the filtration area.

According to the results of studies on the explosion of cylindrical and spherical charges, the following dependences of the radii of the cylindrical and spherical cavities were obtained, respectively, on the linear weight of the camouflage charge (C _p ) and total weight (C)

R _C - the radius of the cylindrical cavity

R _c is the radius of the spherical cavity

K is the coefficient of compliance (compressibility)

With _p - linear weight camouflage charge

C is the total weight of the camouflage charge

We denote the weight of the effective concentrated charge by C _eff , then we write formula (B) like this:

Comparing formulas (A) and (B), we obtain

The location of the center of the spherical charge is determined by the formula

The second period is the elimination of an oil lens using an explosion.

It is intended for forced displacement of oil from the lens. To do this, it is necessary that the sealing zone is included in the zone of the lens. This is done by selecting charges of greater power or by varying the distances between charges of a certain power (see Fig. 7).

To displace the lens from the soil, it is necessary to create ΔР - pressure, shock wave. This will create the necessary piston effect.

In drilled wells (pits) lower charges (explosives) of greater mass and, accordingly, greater power. They produce a series of directed and powerful explosions. The upper parts of the boreholes (pits) are tightly sealed for energy concentration and shock wave amplification. In this case, the seal area is more likely to be included in the lens area. And in the end, we seek to displace the lens from the soil, i.e., eliminate the lens.

To achieve a higher effect (more successful displacement of the lens from the soil), it is necessary to apply the following technology related to watering and soaking the soil.

1st method

1. Using a gas survey to determine the boundaries of the lens.

2. Drill wells - pits for lowering the charge (explosive).

3. Lower the charges.

4. Over the area of the lens, it is recommended to irrigate or soak the soil and fill the wells with water. To do this, arrange the so-called dam, which is filled with water and left for 20-30 days.

A slightly different process is allowed - first the soil is soaked, and then wells are drilled in the already soaked soil - pits (see Fig. 8), which are then additionally filled with water.

This is done in order to increase the piston effect - the effect of displacing the lens with the help of a blast wave. Since the soil is a porous medium, there is air in the pores. The density of air is less than the density of water (ρ Air <ρ Water). When soil is soaked, the pores are filled with water. As a result, the density of the soaked soil is higher than the density of the porous soil. This means that a denser medium transmits a shock wave more significantly. Next, we consider the effect of an explosion in water-saturated soil. The physical nature of hydroexplosive compaction consists in the fact that preliminary soaking of the soil causes a weakening of non-water-resistant and weak-water-resistant structural bonds of the transition type, and subsequent deep explosions destroy the primary weakened bonds and contribute to a denser re-arrangement of particles and the formation of new structural bonds. When the soil is soaked to a degree of humidity S _r > 0.80, the water content in it is so great that the colloidal bonds weaken significantly, and adhesion becomes small. Soaked soil has a number of properties different from those of a solid soil, and the deformations that occur during the explosion of an explosive charge are completely different than in solid soil.

The main feature of water-saturated soil from the moment of its moistening to the final stabilization is the continuous redistribution of stresses in it and the continuous repackaging of its particles. With a charge explosion, a blast wave will propagate in all directions - a region of high pressures. The shape of the front of the blast wave will depend on the shape of the charge and its location relative to the open surface of the soil. The speed of propagation of a blast wave in a water-saturated soil will be greater than the speed of its propagation in soil in a solid (low-moisture) state. A very large pressure will be created along the front of the blast wave, under the influence of which the internal bonds of the soil are destroyed.

Due to the destruction of the internal bonds of the soil, its equilibrium state as a system is disturbed. Mineral particles and aggregates that remained undestroyed, already under the influence of gravitational forces, tend to occupy the most stable position under these conditions. There is a subsidence of mineral particles and aggregates that are not interconnected by internal bonds, their denser packing (see Fig.9).

Since the aqueous medium has a certain viscosity, it resists the movement of particles, friction forces arise between adjacent contacting particles. The process of repackaging mineral particles and aggregates after a blast wave passes over water-saturated soil requires a certain amount of time. This process cannot be instantaneous, although it is much more rapid than the process that occurs without exposure to the blast wave. As a result, after some time, the soil acquires a density significantly higher than in its natural state. However, the process of changing the density is fundamentally different from the compression deformation of the soil in the usual sense. The passage of a blast wave through water-saturated soil causes deeper destruction of internal bonds in it, sharply accelerates the process of repackaging mineral soil particles. As a result, the compaction by explosions of water-saturated soil is achieved faster and with greater effect than dry. Monitoring of soil moisture is carried out by the radioisotope method.

The estimated amount of water Q for soil soaking is determined by the formula:

where n is the weighted average value of porosity;

V is the volume of the soaked soil, m ³ ;

S _r - weighted average value of the degree of humidity of natural soil.

The volume of soil soaked before explosions is determined by the formula:

where V ₁ is the volume of soil within the soaked pit, equal to the area of the pit, multiplied by the thickness of the soaked soil;

V ₂ - the total volume of soil within the zones of water distribution at an angle β to the sides of the soaked pit.

At the time of the explosion, the resulting gaseous products act with great force on the liquid layer adjacent to the charge, compressing it. Compression wave - a shock wave with a speed corresponding to the speed of sound in a compressed liquid propagates through water, breaking away from the products of the explosion. The expansion of the gas bubble formed at the site of the charge causes a displacement of the boundary of the surrounding fluid.

The second method for eliminating an oil lens based on its localization with the help of an explosion and further watering (soaking the soil) is proposed. In this case, explosives are necessary for compaction and melting of the soil, creating an oil-tight barrier on the lower and side boundaries of the lens.

For this, it is first necessary to detect the boundaries of the lens, to drill wells - pits. Lower the charges of such mass and power, so that only block the lens to further fill it with water. In this case, the soil around the lens will be compacted and melted. Next, we perform the operation - water flooding, i.e. Soak the soil with a specially constructed dam.

In the process of soaking, water and oil are mixed. And since the density of oil is less than the density of water, water will gradually displace oil from the lens. The oil will partially float up and exit to the surface, where it will be pumped out and separated from the water using special pumps (see Fig. 10).

Claims (2)

1. The method of localization and liquidation of an oil lens from the deep layers of the soil, including detecting the boundaries of the lens, drilling wells, localizing the lens and displacing oil to the surface, characterized in that the localization is carried out by sinking wells or pits along the contour of the oil lens, after which they are charged explosive of such mass and power at which, after the explosion, an oil-impermeable inner shell is created that blocks the oil lens by compaction and melting of the soil, and Ia includes multiple consecutive explosions in the same wells or pits, the resulting shock waves from which displace the oil lens from the soil. 2. The method according to claim 1, characterized in that it includes additional watering of the soil, in order to increase its density, and thereby increase the efficiency of the shock wave, which directionally shifts the oil lens up.

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