RU2490429C1 - Construction method for slim-hole well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method drilling, casing and anchoring of pipe, surface pipe and production string. While drilling the production string a well is drilled with a natural water suspension. When a water-containing formation is open transfer is done to a dense mud in order to prevent spilling of formation water; when the formation is open and after complete loss of mud transfer is done to a natural water suspension maintaining volume of the mud in the upper part over the formation with complete loss of mud. As the well does deeper, volume of mud becomes less in the upper part of the well and intermittent changes in level and spills of borehole fluid occur then volume of mud is added in the upper part of the well till intermittent changes and spills are stopped.

EFFECT: increased efficiency of method.

1 ex

Description

The invention relates to the oil industry and may find application in the construction of small-diameter wells in difficult geological conditions.

A known method of construction, operation, conservation and liquidation of a well, including drilling a wellbore in a given direction, lowering and securing several casing strings, including the last one, a “liner”, a small production casing, and pumping an active insulating material — a water seal. The first casing string is lowered, fastened with a fastening unit and isolated with a hydraulic seal close to the viscoplastic mass, the well is deepened, the hydraulic seal obtained from the drilling fluid is added by adding binders and neutralizing agents using a small-sized device - the unit for preparing and pumping cement to the required parameters depending on the stability and permeability of the rocks passed, lower the next next at least one casing, fasten it from below with a fastening unit, and the last the casing, the lower end of which is perforated outside the well and equipped with a coarse filter, is lowered above the oil-water circuit and fastened with a fastening unit above the roof of the reservoir, last but not least, pre-pumped by a water seal, a small production string equipped with a packer with an anchor and a secondary filter, install the packer over the reservoir and cause swab inflow, operate the well, and then, if necessary, preserve and / or liquidate (Public Number NII 2005123568, publ. 2007.01.02).

The known method requires large costs for drilling, the design of the well is metal-intensive.

Closest to the proposed invention in technical essence is a method of building a small diameter well, including drilling a wellbore in a given direction, lowering and securing several casing strings. The first part of the wellbore - the direction is drilled with a bit with a diameter of 245-296 mm, the second part - the conductor is drilled with a bit with a diameter of 178-216 mm, the third part is drilled with a bit with a diameter of 144-156 mm, the fourth part is drilled with a bit with a diameter of 93-114 mm, as a drilling mud using process water density of 1,00-1,09 kg / m ^3, enriched with suspended particles of solid drilling cuttings, consumption and industrial water pressure is set greater than the absorption process water absorption zones, autopsy production interval are using pecifications water-additive mixture ML 81B brand surfactants in an amount of 1-3%, after drilling the borehole from the bottom to the mouth, or to the absorption zone is filled with mud density of 1,12-1,16 kg / m ³ carried logging investigations , lower the layout for drilling, pump technical water and rotate the drill bit 2-4 times the interval of the reservoir at a speed of 20-30 m / h, lower the production casing and cement the annular space of the well, while in the first parts use a column with an outer diameter of 245 mm, in the second part with a diameter of 178 mm, in the third part with a diameter of 114 mm, in the fourth part with a diameter of 102 mm, providing a wall thickness of the cement ring of at least 19 mm. If there is an absorption zone, cementing is carried out in the direction from the bottom to the absorption zone and from the mouth to the absorption zone (RF Patent No. 2393320, publ. 06/27/2010 - prototype).

Due to the small diameter of the well, the known method requires less drilling costs, the design of the well is less metal-intensive. However, the method does not provide for the construction of a well in difficult geological conditions.

The proposed invention solves the problem of building a small diameter well in difficult geological conditions.

The problem is solved in that in the method of constructing a small-diameter well, including drilling, casing and fixing the direction, the conductor and the production string, according to the invention, when drilling the production string, they drill a well on a natural water suspension (EMU), when opening the pouring formation, they switch to a solution with density, which prevents the outflow of formation fluid, and when the formation is opened with the drilling fluid completely leaving, they switch to EMU while maintaining the volume of drilling fluid in the upper part of the well above the reservoir ohm full withdrawal mud, the deepening of the borehole, reducing the volume of mud in the upper part of the well and wellhead appearance pulsating changes in the level and overflow wellbore fluid supplement volume of drilling fluid into the top of the well to exclude fluctuations and overflow.

SUMMARY OF THE INVENTION

The construction of a small diameter well reduces construction costs while maintaining the flow rate or injectivity of the well. However, the small diameter imposes restrictions on the possibility of building a well in difficult geological conditions, when during drilling at some horizons there are poured formations and absorption of drilling fluid or drilling fluid until it is completely gone. The small diameter of the wellbore imposes restrictions on the use of traditional measures to isolate complex formations, and sometimes makes the construction of small-diameter wells impossible. The proposed invention solves the problem of building a small diameter well in difficult geological conditions. The problem is solved as follows.

During the construction of small-diameter wells, drilling, casing and fixing of the direction, conductor and production casing are carried out. Use bits and casing of small diameters. For example, when drilling under an production casing, bits with a diameter of 155.6 mm are used, after drilling, a production casing with a diameter of 114 mm (4 inches) is lowered to the design level and the annulus is cemented.

Such small diameters make it possible to speed up and reduce the cost of well construction, but they often make it impossible to use classic diameters for well construction in these conditions. Particularly acute is the question of conducting a wellbore through flowing formations and formations with the absorption of drilling fluid or drilling fluid until it is completely gone.

Zones of complications such as absorbing formations or zones of complete liquid withdrawal are mainly encountered when drilling under a production casing. When drilling a production casing, EMC is used as a washing liquid, which is water with impurities of drill cuttings. Water is defended in barns, but some of the rock particles remain in the water in the form of suspensions. Such a liquid is called EMU. At the opening of the outflow formation, i.e. water-saturated reservoir with high pressure switch from EMU to a solution with a density that prevents the outflow of formation fluid. In each case, this solution has its own density, however, summarizing the drilling data, we can say that this is usually a solution with a density of the order of 1.25-1.35 g / cm ³ . Next, a well is drilled on such a solution. When the formation is opened with complete drilling mud leaving, they switch to EMU while maintaining the volume of drilling fluid in the upper part of the well above the formation with complete drilling mud leaving. In this case, the entire volume of EMU is pumped into the zone of complete fluid withdrawal. As the well deepens, there is a gradual decrease in the volume of drilling fluid in the upper part of the well and the appearance of a pulsating change in the level of the well fluid and overflow of the well fluid at the wellhead. The volume of drilling fluid is supplemented at the top of the well until pulsations and overflow are eliminated. Drill the well to the design level, casing and fasten, i.e. cement the annulus. As a result, it is possible to build a small diameter well in complicated geological conditions.

Concrete example

Build a small diameter well. The first part of the wellbore - the direction is drilled with a bit with a diameter of 296 mm, cased with a column with a diameter of 245 mm, the annulus is cemented. The second part - the conductor is drilled with a chisel with a diameter of 216 mm, cased with a column with a diameter of 178 mm, cemented annulus. The third part - under the production casing, they drill a bit with a diameter of 144-156 mm, casing it with a production casing with a diameter of 114 mm, cement the annulus. EMC i.e. natural aqueous suspension, which is industrial water with a density of 1.00-1.09 kg / m ³ , enriched during drilling with solid suspended particles of drill cuttings. When drilling production casing, the pouring layer is opened at depths of 700-800 m. They switch to a solution with a density that prevents the outflow of formation fluid equal to 1.25 g / cm ³ . Drilling is continued at a drilling fluid density of 1.25 g / cm ³ . The absorbing layer is opened with complete drilling mud leaving at depths of 750-850 m. Switching to EMC with preserving the volume of drilling mud in the upper part of the well above the drilling reservoir with complete drilling mud leaving. The entire volume of EMU is sent to the absorbing layer, i.e. to the complete care zone. As the well deepens, the volume of the drilling fluid decreases in the upper part of the well, and a pulsating change in the level and overflow of the well fluid appears at the wellhead, the drilling fluid with a density of 1.25 g / cm ³ is added to the upper annular part of the well, reaching the level of the absorbing formation. Ripples and overflows are eliminated. When cementing the annulus of the production casing, cementing is carried out in the direction from the bottom to the absorption zone and from the mouth to the absorption zone.

As a result, a small diameter well was constructed in complicated geological conditions.

Application of the proposed method will solve the problem of building a small diameter well in difficult geological conditions.

Claims (1)

A method of constructing a small-diameter well, including drilling, casing and fixing the direction, conductor and production casing, characterized in that when drilling the production casing, a well is drilled on a natural water suspension, when the pouring formation is opened, they switch to a solution with a density that prevents the outflow of formation fluid, and when the formation is opened with the drilling fluid completely leaving, they switch to a natural aqueous suspension while maintaining the volume of the drilling fluid in the upper part of the well above the formation with olnym leaving mud, the deepening of the borehole, reducing the volume of mud in the upper part of the well and wellhead appearance pulsating changes in the level and overflow wellbore fluid supplement volume of drilling fluid into the top of the well to exclude fluctuations and overflow.