RU2101472C1 - Design of well - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: this relates to operation of deep inclined oil and gas wells located in permafrost ground. Device has string of casing pipes with perforated holes, string of pump-compressor pipes concentrically inserted in it, circulation valve and packer which is located in annular space between string of pump-compressor pipes and string of casing pipes. Packer is installed above perforated holes. Well is provided with seating nipple which is located in string of pump-compressor pipes under packer with possibility of preventing creation of gas cap under it. It is made with holes and their diameter d₁ is determined from following relation:

, where d₂ - inner diameter of above-packer section of pump-compressor pipe string, mm; d₃ - inner diameter of under-packer section of pipe-compressor pipe string, mm; n - number of holes. EFFECT: high efficiency. 1 dwg

Description

 The invention relates to the oil and gas industry, in particular to the operation of deep deviated oil and gas wells located in the permafrost zone (IMF).

Known design of the well, including a casing string with perforated holes, concentrically installed in it tubing string, packer [1]
The disadvantage of this design when used in deviated wells is its low reliability. Due to the location of the underground equipment in an inclined section of the wellbore, reliable transportation from the surface to the installation site and reliable sealing of the annulus of the well are not ensured.

A well-known design of wells for deep inclined wells, including a casing string with perforated holes, a tubing string concentrically installed in it, a packer located in the annular space between the casing string and tubing string above the perforated holes, and underground equipment located in the wellbore [2 ]
The disadvantage of this design when used in deviated wells is its low reliability due to possible deformation of the body and damage to the rubber seals during the descent to the bottom due to friction against the walls of the deviated well, and as a result, penetration of the produced fluid into the annulus and the creation of conditions for thawing the zone MMP. Due to the difference in the flow cross sections of the under-packer and over-packer tubing spaces, throttled products are throttled, liquid and sand deposited on the downhole equipment carried along with the produced fluid, its abrasive and corrosive wear, pressure and temperature losses.

 The challenge facing the creation of the invention is to develop a reliable design for the operation of deep deviated wells located in the IMF zone.

 The technical result achieved by the invention consists in reliably cutting off the annular space of deviated wells from the produced fluid, and therefore, in reducing the probability (degree) of thawing of the IMF zone and the associated negative consequences, in reducing the negative impact of the throttle effect on well operation, in transportation of underground equipment from the day surface to the location without mechanical damage.

где d₂ внутренний диаметр надпакерного участка НКТ, мм;
d₃ внутренний диаметр подпакерного участка НКТ, мм;
n количество отверстий.The task and technical result are achieved by the fact that in a well-known design of the well, including a casing string with perforated holes, a tubing string (tubing) concentrically installed in it, a packer placed in the annular space between the casing string and tubing string above the perforated holes, and underground equipment located in the wellbore, unlike the prototype, the well is equipped with a landing nipple placed in the tubing string under the packer with the possibility of Rotation formation underneath the gas cap and configured with openings, the diameter (d ₁₎ is defined by the relation:

where d _{2 the} inner diameter of the above-packer tubing, mm;
d ₃ inner diameter of the under-packer section of tubing, mm;
n number of holes.

 Based on the foregoing, we can conclude that this invention meets the criterion of "novelty."

 The technical result obtained by using the invention allows to achieve a long-existing production need, attempts to obtain which to the fullest failed. Based on the foregoing, we can conclude that the invention meets the criteria of "inventive step".

 The drawing shows the claimed design of the well.

где d₁ диаметр отверстий, мм
d₂ внутренний диаметр надпакерного участка НКТ, мм;
d₃ внутренний диаметр подпакерного участка НКТ, мм;
n количество отверстий.The well design includes a casing 1 with perforated holes 2, a tubing string consisting of a packer 3 and a packer 4 sections, a circulation valve 5, a packer 6, a fitting nipple 7 with holes 8, a shut-off valve 9, located in the fitting nipple. Underground equipment, with the exception of the sub-packer section 4 of the tubing, is located on the vertical section 11 of the wellbore of a deep inclined well, directly below the MMP zone 12, and the under-packer section 4 of the tubing is on the inclined part 11 of the trunk. The annulus of the well is hermetically separated by the packer 6 into the above-packer 13 and under-packer 14 spaces. The over-pack annular space 14 is filled with a non-freezing sealing fluid. The cross-sectional area of the over-packer pipe space 15 is equal to the total cross-sectional area of the under-packer pipe space 16 and the holes 8 of the landing nipple 7. Moreover, the diameter of the holes 8 is selected from the ratio:

where d _{1 the} diameter of the holes, mm
d ₂ inner diameter of the above-packer section of tubing, mm;
d ₃ inner diameter of the under-packer section of tubing, mm;
n number of holes.

 Well design works as follows.

 The casing 1 is lowered into the drilled well, perforated, the under-packer section 4 of the tubing, the landing nipple 7, the packer 6, the circulation valve 5, the over-packer section 3 of the tubing are sequentially lowered, a flow fitting (not shown) is mounted. A call is made to inflow from the reservoir 17 by a decrease in the level of the filling fluid and a decrease in its density. Then, in the landing nipple 7, a blind plug (not indicated) is installed in the place intended for the shutoff valve 9, which closes the wellbore, the super-plug space 15 of the well is filled with technological solution, and the packer 6 is packaged by increasing the pressure in the over-packer tube space 15. After tightness check of the packer 6, the blind plug is removed to the surface, installed in the landing nipple 7, the shut-off valve 9, fill nadpakerny annular space 13 non-freezing sealant liquid. The well is ready for operation.

 During operation, the produced fluid from the reservoir 17 enters the well in two ways: the first through the under-packer pipe space 16, the second through the under-pack annular space 14 and the holes 8 of the landing nipple 7. Then, the fluid flows in a single flow through the shutoff valve 9, packer 6, circulation valve 5 , the over-packer section 3 of the tubing enters the surface in the assembly manifold (not indicated).

 Thus, the holes 8 of the landing nipple 7 can eliminate the conditions for the occurrence of a "gas cap" under the packer, and therefore, eliminate the conditions leading to the depressurization of the packer and the ingress of fluid into the over-pack annular space 13, thereby eliminating the possibility of thawing of the MMP zone 12 due to the movement of the "hot "gas over nadpakerny annular space 13.

 In addition, the holes 8 of the landing nipple 7 make it possible to equalize the flow rates above and below the packer 6, and therefore, to eliminate the conditions for liquid and sand falling in the gas stream to fall onto the downhole equipment and to eliminate its abrasive and corrosive wear.

 In turn, the placement of underground equipment in the vertical section 10 of the wellbore allows you to reliably, without deformation of the body parts and damage to the rubber seals, deliver it to the place of placement, securely seal the annular space 13, and ensure reliable control of the underground equipment using the "cable technique".

 If it is necessary to replace the tubing or carry out repair and maintenance work in the well, the underground equipment is removed as follows.

 First, the shut-off valve 9 is removed using the "rope technique". Then, the well is muffled by periodically feeding the filling fluid into the pipe space 15, 16 and releasing a “gas cap” formed during the well killing from the sub-packer annular space 14 through the openings 8 of the landing nipple 7. After this, the packer 6 is unlocked and the tubing string is tensioned ( nadpakernogo plot 3 tubing) extract the rest of the underground equipment to the surface.

 Due to the absence of a “gas cap” in the under-packer annular space 14 (it is vented through the openings 8 of the landing nipple 7 during the jamming process), the possibility of an emergency discharge of underground equipment during its extraction is eliminated.

 Placing underground equipment, including the landing nipple 7 with holes 8, on the vertical section of the wellbore 10 directly below the MMP zone 12 provides several advantages: the installation and dismantling time of equipment in a deep inclined well is reduced, the reliability of its operation, as well as the reliability of operation and repair of the whole wells.

Sources of information:
1. Equipment for cutting off fountain wells. Catalog. M. TsINTIkhimneftemash, 1980, p. 6-7, fig. 3.

 2. Korotaev Yu. P. Development and operation of gas and gas condensate fields. M. Nedra, 1961, p. 136-137.

Claims (1)

Well design for operating deep inclined oil and gas wells located in the permafrost zone, including a casing string with perforated holes, a tubing string (tubing) concentrically installed in it, a packer located in the annular space between the casing string pipes and tubing string over the perforated holes, and underground equipment located in the wellbore, characterized in that the well is equipped with a landing nipple Placed in the column tubing below the packer with the possibility of preventing the formation underneath the gas cap and configured with openings, the diameter (d ₁ mm) which is determined from the relation

where d _{2 the} inner diameter of the above-packer tubing, mm;
d ₃ inner diameter of the under-packer section of tubing, mm;
n number of holes.