RU2286448C2 - Method for water influx isolation in horizontal producing well bores - Google Patents

Abstract

FIELD: oil industry, particularly for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells.

SUBSTANCE: method involves injecting polymeric solution in well bottom zone; forcing the polymeric solution in well; shutting well down for a time necessary for polymer hardening. The polymer is hydrophobic polymeric plugging composition. Before hydrophobic polymeric plugging composition oil and then water-swellable polymer are injected in well. The water-swellable polymer is mixed with mix liquid, namely with fresh water or clay solution and then the polymer is held in vertical well bore section to provide full mix liquid absorption with the water-swellable polymer. Then the water-swellable polymer is slowly forced in horizontal bore with plugging composition to create preventive filtering layer; displacing plugging composition with oil; drilling hardened plugging composition; injecting acid and diesel fuel or mineralized solution in well to remove filtering layer.

EFFECT: increased efficiency of isolation works along with oil containing interval retention.

1 ex

Description

The invention relates to the oil industry and is intended to isolate water inflows in horizontal trunks of production wells.

A known method of processing and isolating the bottom-hole zone of wells, including the injection of an insulating composition based on PAA and acid [1]. The method is not effective in horizontal wells, primarily due to the fact that it is suitable for use when the interval of water inflow is known, and also because of the low blocking ability of PAA, which is "sewn up" in the well, being squeezed into the barrel section.

There is another way to isolate water inflows in horizontal trunks [2]. Fundamentally, the method adopted in the form of a prototype is presented in the following form. The method includes injecting a gelling solution of polyacrylamide and acid first to the far end of the water inflow interval, and then this operation is repeated along the water inflow interval. The method is intended to isolate water inflow when its interval is known.

When watering a horizontal trunk, it is filled with water. The call of fluid inflow by lowering the pressure in the well makes it impossible to determine from which interval the oil comes from, from which water, because the intensity of water occurrence in this case is much greater than oil manifestation. This method cannot be applied because it is not suitable for use when the interval of water inflow is not known where it is located.

Since there are currently no ways to determine the intervals of water inflow in a horizontal well-watered horizontal well, there is a problem of conducting insulating work in a horizontal well with the creation of a selective isolation method in which the injected mixture mainly falls into the water inflow interval with minimal penetration into the oil-saturated part of the horizontal well.

In cold wells at a temperature of + 30 ° C, if the productive rock is filled with viscous oil, pumping the grouting composition to the site of water inflow will not harm the oil reservoir, because at this temperature, in non-washed rocks and channels, viscous oil will have a fairly high resistance to penetration of the composition.

In wells with low-viscosity oil, viscous oil can be specially pumped to obtain a selective effect. It falls into the zone of water inflow with large eroded channels. However, in "hot" wells, all these methods are not applicable, because all viscous oils become fluid and do not create sufficient resistance to penetration into the pores of the cement composition.

The proposed invention solves the problem of isolation in "hot" wells of a limited interval of water inflow in a horizontal wellbore held in an oil reservoir represented by porous or fissured rocks, for example sandstones. Moreover, there is no data on the location of this limited interval of water inflow in the horizontal trunk, because today there are no methods for determining them after watering a horizontal well.

The technical result is an increase in the efficiency of insulation work while maintaining an oil-containing interval.

In the method of isolating water inflows in a horizontal wellbore of production wells, including injecting a polymer solution into the bottomhole zone, injecting a polymer solution, stopping the well while the polymer solution is curing, use a hydrophobic polymer cement slurry composition as a polymer solution; first, oil is pumped into the well before the GPTS is injected then the water-swellable polymer VNP AK-639, sealed with a mixing fluid - fresh water or a clay solution, VNP AK-639 is kept in the vertical part of the well bore d total absorption liquid mixing them, and then it is forced GPTS sustained in horizontal wellbore to generate prophylactic media bed, forced GPTS oil solidified GPTS drilled out, pumped acid or diesel oil, or mineralized solution to remove prophylactic filtration layer.

As GPTS can be used, for example, a composition containing in weight. parts: prepolymer FP-65-2 100, hydrocarbon liquid 50-100, water 2-3, filler 1-10, hardening accelerator UP 606/2 0.1-0.2.

As the acid, for example, hydrochloric acid can be used.

As the mineralized solution, formation water or a specially prepared mineralized solution is used by adding 3 wt.% Calcium chloride to fresh water.

To prepare a clay solution, 2-3 wt.% Clay powder is introduced into fresh water.

The essence of the method is as follows.

In a method involving the injection of GPTS, first a preventive filtration layer of a visco-plastic material is created on its surface in a horizontal wellbore, the excess of which is filtered into large washed out channels in the interval of water inflow. This is due to the fact that the penetration of a viscoplastic fluid into porous oily rocks is limited due to the small pore size, while its penetration into blurry channels (pores) in the interval of water inflow does not cause difficulties. The appearance of blurred (drained) channels is a consequence of the long-term operation of wells with a high percentage of water produced along with oil. Typically, repair and insulation work in horizontal wells is carried out when the volume of water reaches 95-98% of the volume of produced fluid.

The implementation of the method of isolation of the interval of water inflow using a viscoplastic material to create a preventive filtration layer is as follows. First, oil is pumped into the well in the form of a buffer for separating GNP from water into the horizontal wellbore, then AK-639 water-swelling polymer is injected into the vertical part of the wellbore, shut at a ratio of not less than 1: 100 in fresh water or in a clay solution, for example, bentonite clay. It is aged in it before being squeezed into a horizontal trunk for the time necessary until complete absorption of water, but not less than 0.5 hours. Then the viscoplastic composition is pressed into the horizontal trunk.

The water-swelling polymer AK-639 is used in practice mainly of 2 grades: B-416 and B-615. Their water absorption capacity per 1 g of polymer is more than 100 g of fresh water. Moreover, the water-absorbing polymer of grade B-615 needs 15 minutes to absorb 100 g of fresh water, the polymer of grade B-415 needs 30 minutes. After holding the water-swellable polymer in the wellbore, it is pressed into the horizontal wellbore while the hydrophobic polymer grouting composition of the HPS is pumped behind it. Selling is carried out slowly to maximize the ability of viscoplastic fluids to provide high selectivity as long as they retain maximum viscosity properties.

In the presence of a preventive filtration layer, the GPTS is forced into the interval of water development. Moreover, the sale on the horizontal trunk is oil. A change in the injection pressure will indicate that large water-drained channels in the interval of water inflow are filled with GPTS.

Execution example.

The tubing is lowered into a horizontal well before entering the horizontal wellbore. First, a buffer of oil is pumped into the tubing, then a water-swellable polymer in fresh water, and it is kept until it completely absorbs mixing water. Then uploaded to the tubing GPTS. At the same time, GNP is pressed into the horizontal trunk. Selling is carried out at the 1st speed of the CA-320, i.e. slow down. This allows the GNP to be delivered to the horizontal trunk in the form of a viscoplastic structured fluid that creates a filter layer along the barrel with permeable rock. With the further sale of the gas transport system by oil, the insulating material goes to the water inflow zone, where the rock with large channels canalized by the water drained along with the produced water is located. After curing of the GPTS, a bit with tubing is lowered into the horizontal shaft and the hardened composition is drilled. After development, if insufficient oil production is noted, acid or mineralized solution is pumped into the well. Under the influence of an acid or a mineralized solution, the preventive filtration layer is destroyed. Well production is increasing.

The advantage of the claimed method is to increase the efficiency of eliminating an undetermined site of water inflow in a horizontal well (especially in a “hot” well) of a flooded well due to a previously created preventive filtration layer from a viscoplastic composition, which allows you to save the productive part of the horizontal well. Moreover, this method uses selective features of injection of viscoplastic fluids into the permeable rock, manifested at a low pumping speed.

Information sources

1. A.S. USSR, No. 836340, class E 21 B 43/27, 1981

2. RF patent No. 2101484, cl. E 21 In 43/27, 1997 (prototype).

Claims (1)

A method of isolating water inflows in a horizontal well of production wells, including injecting a polymer solution into the bottomhole zone, pumping a polymer solution, shutting down a well for the duration of curing of a polymer solution, characterized in that a hydrophobic polymer grouting composition of a GPTS is used as a polymer solution; first oil, then water-swellable polymer GNP AK-639, sealed with a mixing fluid - fresh water or a clay solution, GNP AK-639 is kept in a vertical part and the wellbore until the mixing fluid is completely absorbed by it, then GPTS is pressed slowly into the horizontal well to create a prophylactic filtration layer, GPTS is pressed through with oil, the cured GPTS is drilled, acid or diesel fuel or mineralized solution is injected to remove the preventive filtration layer.