RU2256783C1 - Well completion method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes forming a depression on bed by gassing column of well liquid due to interaction of acid with alkali metal in well. With decrease of specific weight of well liquid for 20-40% from its basic specific weight well is periodically sealed at mouth. Well is sealed for different time spans. These periods are set by random law to provide for cyclic non-stationary mode of well operation. Such mode is maintained until gassed liquid leaves well and bed fluid debit stabilizes.

EFFECT: lower costs, broader functional capabilities, higher efficiency.

7 cl, 1 ex

Description

The invention relates to gas and oil wells and is intended mainly for use at the operational stage of the said wells to increase the flow of fluid from the reservoir. The method can also find private application, for example, in well development.

It is known that during the operation of wells, their production rate decreases over time, for example, for technological reasons (imperfections in opening the reservoir) or due to the properties of the produced fluid.

Various methods are used to increase the flow of fluid into the well at the operational stage.

There is a method of increasing the influx of fluid from a reservoir by swabbing (see, for example, Muravyev I.M. et al., Technology and technique for oil and gas production, Moscow, Nedra, 1971, p.90).

The disadvantage of this method is that it requires special equipment, high labor costs and is dangerous, with the use in gas wells, for emergency emissions (fountains).

A known method of increasing the flow of fluid from a reservoir by depression due to aeration of a liquid column in a well (see, for example, Muravyev I.M. et al., Technology and technique for oil and gas production, Moscow, Nedra, 1971, p. 92) .

The disadvantage of this method is its low efficiency, due to the fact that it also requires special equipment, considerable labor costs, but does not provide filtering conditions (drainage) of the fluid of the reservoir over its entire thickness.

The technical result of the invention is the expansion of factors affecting the reservoir with a decrease in energy costs, an increase in the degree of coverage by drainage of the reservoir in thickness and depth.

The required technical result is achieved by the fact that a method of increasing fluid flow from a producing formation involves creating a depression on the formation by aerating a column of well fluid due to the interaction of acid with an alkaline earth metal in the well and, while reducing the specific gravity of the well fluid by 20-40% of its initial specific gravity periodically shutting the well at the wellhead for periods of different durations, which are set by a random law to provide a cyclic unsteady regime p well operation, which is maintained until the flow of carbonated fluid from the well and stabilization of the production fluid flow rate.

Moreover:

as an alkaline earth metal, calcium or magnesium or barium is used;

alkaline earth metal is used as a suspension of its particles in the hydrocarbon phase;

gasoline or alcohol, or condensate, or diesel fuel, or oil, or diesel fuel is used as the hydrocarbon phase;

hydrochloric acid of a concentration of 10-25% is used as an acid;

initially acid is supplied to the well, and then alkaline earth metal;

initially alkaline earth metal is fed into the well, and then acid;

if it is necessary to repair the well, the well is pre-muffled with its subsequent development, which is carried out simultaneously with an increase in fluid inflow from the reservoir in comparison with its inflow before repair;

well killing is carried out by a hydrocarbon phase;

Well killing is carried out by a hydrocarbon phase with a suspension of alkaline earth metal particles in it.

The essence of the invention lies in the fact that the proposed invention provides the possibility of multifactorial effects not only on the well fluid, but also on the reservoir. In this case, the effect is carried out both on the matrix - the skeleton of the reservoir, and on the fluid of the reservoir. The impact is carried out in such a way as to ensure the filtration of the fluid of the reservoir at the micro and macro levels, i.e. pores and cracks of the reservoir over its entire thickness under the influence of temperature, pressure, gas.

For this, the reaction between the alkaline earth metal, for example, calcium or magnesium, or barium with an acid, such as hydrochloric acid, is ensured under borehole conditions. The reaction produces gas - hydrogen. For each gram equivalent (g-equiv) of alkaline earth metal, 22.4 liters of hydrogen (about 100 m ^{3 of} hydrogen per 100 kg of metal under normal conditions) are released, which does not dissolve in water at any pressure. As a result, in a well, for example, at a depth of 1000 m, the specific gravity of the liquid becomes 0.3 g / cm ³ , and at a depth of 2000 m - 0.6 g / cm ³ . In addition to gas evolution, the aforementioned reaction is characterized by heat generation (more than 300 kcal per g-eq of alkaline earth metal), which leads to a significant increase in gas volume and a further decrease in the specific gravity of the liquid. Such indicators are a powerful tool for aerating well fluid and providing depression in the well.

To prevent water from entering the reservoir, which may become a water trap in the pores of this reservoir, a hydrocarbon phase is used to drain fluid from the reservoir to deliver alkaline earth metal to the well. As the hydrocarbon phase, gasoline or alcohol, or condensate, or diesel fuel, or oil is used. Acid, in some cases, is taken in excess than is necessary for the reaction with an alkaline earth metal. In this case, conditions are created for the interaction of acid with the rock of the reservoir, the mud in the pores and fractures of the reservoir, for example, from the liquid used to kill the well at the stages of its repair.

An essential feature of the proposed invention is that it provides the possibility of combining operations to enhance the flow of fluid from the reservoir with the development of the well. In some cases, during the operation of the well, it becomes necessary to repair it and, consequently, to develop it after repair.

The invention allows to combine well development with increased fluid inflow from the reservoir (or, conversely, increased inflow with well development) when the inflow rates after well repair, in particular development, exceed those before well repair.

In some cases, the claimed invention can be characterized as well development.

This is ensured by the fact that with a decrease in the specific gravity of the wellbore fluid by 20-40% of the initial specific gravity, periodic shutoff of the well at the wellhead is carried out for periods of time of different durations. The range of acceptable values of the specific gravity of the well fluid was obtained empirically and indicates that the carbonation process is irreversible and the initial conditions for the implementation of the method are implemented.

The time periods for the duration of the overlapping of the well are set by a random law, for example, by a mathematical sensor of a random number generator that are placed in a series of numbers characterizing the duration of the flow of carbonated liquid from the well.

This mode provides a cyclic non-stationary nature of the well’s operation, when repression alternates with depression of stably different pressure values. The response of the reservoir accompanying these quantities is characterized by multidirectional movements of the reservoir fluid in the near-wellbore zone. The deep non-stationarity of the process eliminates the possibility of the development of the usual channels of fluid filtration of the reservoir. The initial processes of fluid filtration through macrochannels are connected to the filtering processes by microchannels.

Under the influence of pressure, which is provided by the reaction conditions and the mode of operation of the well in the range of 0.7-0.9 hydraulic fracturing pressure of the reservoir, natural vertical cracks in the reservoir are opened. These cracks combine all the heterogeneities of the formation by its thickness. As a result, the productive formation filters (drains) the fluid throughout its thickness. The unsteady mode is maintained until the carbonated fluid completely flows out of the well, using the fluid as a working fluid with more stringent factors of dynamic impact on the reservoir.

The unsteady mode is maintained, for the first time, and on the fluid of the reservoir until stabilization of the flow rate of this fluid.

Stabilization of the fluid flow rate of the reservoir indicates that all the reserves of its filtration are involved and the necessary technical result is achieved.

A specific example of the implementation of the method.

Gas well No. 1333 of the Urengoy field is characterized by the following indicators:

well depth - 1240 m;

perforation interval - 1218-1230 m.

The well was in disrepair. Intercolumn gas manifestations were discovered in it. Before the repair, the well was characterized by a low flow rate.

To eliminate the intercolumnar gas manifestations, the well was plugged.

To increase gas inflow and at the same time, wells were pumped with tubing, with their funnel at a depth of 1222 m, 3 m ^{3 of} industrial hydrochloric acid with a concentration of 10%. After that, 2 m ^{3 of a} suspension of granular calcium, prepared on the basis of diesel fuel, with a concentration of 3% in the solid phase was pumped. The well at the mouth was blocked. As a result of the reaction, the buffer pressure in the well increased to 4 MPa, and the specific gravity decreased by 20% of the initial specific gravity. This indicated an irreversible and predetermined development of the reaction. Pressure bleed. After that, the well was shut off for 30 minutes. Again, increased pressure pitted again. After that, the well was shut off for 15 minutes. These operations were repeated 3 more times with the establishment of the time for shutting off the well according to a random law until the carbonated liquid expired from the well and stabilization of gas production from the well. This flow rate exceeded the well flow rate before its repair by 1.5 times.

Claims (7)

1. The method of well development, including creating a depression on the formation by aerating a column of well fluid due to the interaction of hydrochloric acid with an alkaline earth metal in the well and with a decrease in the specific gravity of the well fluid by 20-40% of its initial specific gravity, periodically shuts the well at the wellhead for periods time of different durations, which are set by a random law to ensure a cyclic unsteady mode of operation of the well, which is maintained until the carbonated fluid expires from wells and stabilization of formation fluid flow rate. 2. The method according to claim 1, characterized in that as the alkaline earth metal using calcium, or magnesium, or barium. 3. The method according to claim 1 or 2, characterized in that the alkaline earth metal is used in the form of a suspension of its particles in the hydrocarbon phase. 4. The method according to claim 3, characterized in that gasoline, or alcohol, or condensate, or diesel fuel, or oil, or diesel fuel is used as the hydrocarbon phase. 5. The method according to claim 1, characterized in that use of hydrochloric acid concentration of 10-25%. 6. The method according to claim 1, characterized in that initially hydrochloric acid and then alkaline earth metal are fed into the well. 7. The method according to claim 1, characterized in that initially the alkaline earth metal and then hydrochloric acid are fed into the well.