RU2236563C1 - Method for extracting oil at finishing stage of wells operation - Google Patents

Abstract

FIELD: oil extractive industry.

SUBSTANCE: method includes lowering of deep sucker-rod pump into the well. To pump continuous reciprocal movement from ground drive is transferred. Pump is mounted in oil layer in upper portion of well in such a way that pump take-in matched with static water level in well in case of lessening of oil layer down to zero during of its extraction. During extraction feed of pump is adjusted dependent on dynamic level. In such way lessening of oil layer is limited to minimally allowed level and presence of certain minimal resource of oil column is provided for excluding take-in of water or air. Static level of water in a well, in case of lessening of oil level down to zero during its extraction, is determined ion basis of analytical expression. Minimally acceptable height of oil layer is determined also on basis of analytical expression.

EFFECT: higher effectiveness of oil extraction due to excluding water cycling, lower metal costs of pump and lower energy costs due to lesser height of liquid raising.

Description

The invention relates to oil production and can be used to increase the efficiency of the oil recovery process at the final stage of operation of low-production wells equipped with sucker-rod pumping units.

A known method of oil production by submersible piston pumps with hydraulic drive, which consists in immersing a pumping unit in a well, communicating to it reciprocating movements with a hydraulic pump, receiving liquid on the surface (Adonin A.N. Choosing a method of oil production. - M .: Nedra, 1971 P.66-67).

The disadvantage of this method is that it is not suitable for highly flooded wells with mechanical impurities, which is inherent in marginal wells.

The closest in terms of the operations performed to the claimed one is the method of oil production, which consists in the fact that a deep borehole plunger pump is lowered into a well on a column of lifting pipes, it is transferred to it continuous reciprocating motion from the pumping unit, and thus provides a rise to the surface of the borehole fluid through a system of suction and discharge valves filling the volume of the lifting pipes (Vasilievsky V.N., Petrov A.I. Technique and technology for determining the parameters of wells and reservoirs. M: Nedra, 1989. S. 46-51).

The disadvantage of this method is the mismatch between the speed of pumping oil and the flow rate of the well. At the beginning of the oil recovery process, when the oil layer is large enough, the pump operates in intensive pumping mode. As the oil decreases, water accumulates in the well, oil rises above the pump intake, and highly watered oil (up to 90% of water) is supplied to the surface. This leads to an excessive consumption of energy, an increase in the metal consumption of the equipment due to the large immersion depth of the pump, a decrease in the overhaul period of the equipment, and an increase in prime cost.

The task is to increase the efficiency of oil recovery by eliminating water circulation, reducing the metal consumption of the pump unit and energy costs by reducing the height of the liquid.

The solution to this problem is achieved by the fact that in the method of oil production from low-production wells equipped with sucker-rod pumping units, which consists in the fact that a deep borehole plunger pump is lowered into the well on a column of lifting pipes, it is transmitted continuously from the rocking machine to it and thus provide a rise to the surface of the borehole fluid filling the volume of the lifting pipes through a system of suction and discharge valves. Unlike the prototype, the pump is installed in the oil layer in the upper part of the well so that the pump intake coincides with the static water level in the well (in the absence of oil), during pumping, regulate the pump performance depending on the dynamic level measured during pumping and limit the decrease oil layer to the minimum acceptable level. The minimum allowable height of the oil layer in the well is determined in accordance with the formula

where H is the depth of the well,

h _st.v - the height of the static water level in the well (in the absence of an oil layer),

x is the depth to the liquid level in the well, y is the depth to the interface,

ρ _n , ρ _in - the density of oil and water, respectively.

Moreover, the static water level in the well in the absence of oil is determined by the expression

where h _st.v - the height of the static water level in the well

(in the absence of a layer of oil),

P _PL - reservoir pressure

ρ _in - the density of water,

g is the acceleration of gravity.

The proposed method is implemented as follows. A downhole level gauge is lowered into the annulus, with which a static liquid level and an oil-water interface are fixed. The deep pump is lowered into the well to a depth at which the pump intake level coincides with the static water level in the well in the absence of oil. They turn on the pump and start pumping at a speed set in the range from minimum to maximum, and the minimum pumping speed ensures a pump flow equal to the flow rate of the well. As the oil layer decreases, its upper and lower boundaries approach from both sides to the pump intake. In order for the pump to work efficiently, it is necessary to limit the reduction of the oil layer to a minimum level. If the oil layer is reduced to zero, the water level rises to the level of pump intake.

During the pumping process, a dynamic level is measured, compared with a predetermined one, depending on the result of the comparison, the pump performance is controlled in such a way as to ensure the presence of a predetermined minimum margin of oil column height at the pump location to exclude water or air intake.

This method can be implemented using known technical means.

The well can be equipped with a sucker rod pump with adjustable capacity (Shangin ES, Tagirova KF Adaptive control system for the operating modes of sucker rod pump units // Mechatronics. 2001. No. 6). A well level gauge can be used as a dynamic level meter (A.S. USSR No. 1154447, class E 21 B 47/04, 1985. Downhole level gauge).

Compared with known methods of oil production, the proposed method has the following advantages:

- allows you to increase the efficiency of oil production from low-yield wells at a late stage of well operation by reducing the height of the liquid and thereby reducing energy costs;

- allows you to increase the amount of oil produced due to the exclusion of water from circulation.

Claims (1)

The method of oil production at the final stage of well operation, namely, that a sucker-rod deep well pump is lowered into the well, and it is provided with a continuous reciprocating motion from a surface drive, characterized in that the pump is installed in the oil layer in the upper part of the well so that the pump intake coincided with the static water level in the well in the case of a decrease in the oil layer to zero during pumping; during pumping, regulate the pump flow depending on the dynamic level, limiting dissolved thereby decrease the layer of oil to a minimum level and ensure the availability of a certain minimum stock oil column to eliminate the intake of water or air, wherein the static water level in the well in the case of reducing the oil layer to zero when it is determined by the expression pumping

where h _cm.c is the height of the static water level in the well in the case of a decrease in the oil layer to zero during its pumping; P _PL - reservoir pressure;

- density of water; g is the acceleration of gravity, and the minimum allowable oil layer height is determined in accordance with the formula

where H is the depth of the well; x is the depth to the liquid level in the well; y is the depth to the interface between oil and water;

- the density of oil and water, respectively.