Method of excavation of oil and gas-producting wells

Abstract

A method of opening in a well of oil or gas containing layers having a plurality of cracks extending in a predetermined direction, includes forming in a layer a slot intersecting cracks, and orienting the slot so that it extends substantially perpendicular to the direction of the cracks so that the direction of the cracks and the direction of the slot are oriented in a cross-shaped manner.

Description

BACKGROUND OF THE INVENTION

The present invention relates to the oil and gas industry, and more particularly to methods of openings of oil- and gas-productive layers in wells.

A method of increasing efficiency of opening of oil- and gas-productive layers in a well with a casing is known, which utilizes a technology of sand-jet slotting for opening of the layers. This method can increase oil and gas recovery from 1.5 to 10 times as compared with a known method of opening of oil- and gas-containing layers with the use of a cumulative perforation. Conventionally the sand-jet slotting is performed by directing of a cutting jet arbitrarily. It is believed that the existing sand-jet slotting can be further improved to increase its efficiency.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide new method of opening of oil- and gas-productive layers, which is a further improvement of the existing methods.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of opening in a well of oil or gas productive layers having a plurality of cracks extending in a predetermined direction, comprising the steps of forming in a layer a slot which intersects cracks, and orienting the slot so that it extends substantially perpendicular to the direction of the cracks so that the direction of the cracks and the direction of the slot are oriented in a cross-shaped manner.

Another feature of the present invention resides, briefly stated, in that said forming a slot includes orienting a slot azimuthally and at the same time substantially perpendicularly to the direction of extension of the cracks.

Still another feature of the present invention resides, briefly stated, in that said forming a slot includes forming a slot extending through a plurality of cracks extending in the predetermined direction substantially azimuthally.

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the layer having a plurality of cracks and subjected to opening by slotting in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method in accordance with the present invention is performed for opening of layers 1 through which a well 2 extends substantially in a vertical direction.

The opening of the layers is performed to provide a flow of fluid, such as oil or gas from the layers 1 into the well 2 to be subsequently taken from the well. The layers 1 have a plurality of cracks which are identified with reference numerals 3, as shown in FIG. 1.

The opening of the layers is performed by perforating of the layers by means, for example, of sand-jet perforation which is known in the art. FIGURE shows a plan view of one of the layers in which cracks are formed. In the layers the cracks extend in a direction identified with the arrow A, and extending for example between East and West.

In order to provide flowing of oil or gas from the layers 1 into the well 2, the opening of the layers is performed by cutting of slots, for example by means of the above mentioned sand-jet perforator 2.

In accordance with the present invention a slot is produced, for example as identified with reference numeral 21. The slot 21 is oriented in a predetermined direction. In particular, the slot 21 extends in a direction B which is substantially perpendicular to the direction A of extension of the cracks. Therefore, the direction of the slot 21 and the direction of the cracks 3 form a so-called cross, since they are mutually perpendicular.

When the opening of the layer by cutting a slot is performed in the inventive manner, the efficiency of flow of the oil or gas from the cracks 11-17 in the layers 2 into the well 1 is increased, since in this manner the slot extends through a greater number of the cracks.

Therefore the slotting performed in accordance with the present invention provides intersecting of a greater number of cracks and therefore flowing of a greater quantity of oil or gas from the slots into the well.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.

While the invention has been illustrated and described as embodied in a method of opening of oil and gas productive layers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A method of opening in a well of oil or gas containing layers having a plurality of cracks extending in a predetermined direction, comprising the steps of forming in a layer a slot which intersects cracks; and orienting the slot so that it extends substantially perpendicular to the direction of the cracks so that the direction of the cracks and the direction of the slot are oriented in a cross-shaped manner.

2. A method as defined in claim 1, wherein said step of forming a slot includes orienting a slot azimuthally and at the same time substantially perpendicularly to the direction of extension of the cracks.

3. A method as defined in claim 1, wherein said step of forming a slot includes forming a slot extending through a plurality of cracks extending in the predetermined direction substantially azimuthally.