RU2439273C1 - Well cluster construction method - Google Patents

Abstract

FIELD: gas and oil production.

SUBSTANCE: construction of well cluster involves location of production and injection well mouths in the form of cluster or battery, drilling in solid rock and reinforcement of vertical, sloping and/or curved wellbores, exposure of production bed in specified points. Construction of the first well of a cluster involves drilling of mine by bit of 630 mm diameter to 10-20 m depth, lowering of casing pipe of 500-540 mm diameter, cementing of annular space, further directional drilling in laminar mode using drilling mud not eroding well walls, with maximum water loss under 6 cm³ in 30 minutes, viscosity of 50 s or higher, specific weight of ca. 1.35 g/cm³, using rotor drilling method with rotor torque up to 100 rpm. Rock samples are taken over each metre of direction tunnelling and analysed for crumbling. Sampling continues until solid hard rock is reached. After directional drilling, casing string is lowered, and annular space is cemented. Well construction is continued to the design mark. Next wells of the cluster or battery are drilled in the same way, but rock sampling and analysis is performed when directional drilling approaches solid hard rock.

EFFECT: safe drilling of well cluster in karst gap conditions in immediate vicinity of the ground surface at drilling start.

Description

The invention relates to the oil industry and may find application in the construction of a cluster of wells.

There is a method of preventing the meeting of trunks during cluster drilling of oil and gas wells, according to which the elastic vibrations coming from the vibration of the bit during the drilling of the well are recorded using instruments, amplify the received signal, and then transmit it to the recording device. Additionally, filtering the incoming signal with the selection of the signal from the bit and digitizing the selected signal. Then, the approximation or removal of the wellbore meeting is determined by comparing the incoming signal with the threshold values of the signal from the bit. Information about the signal from the bit is simultaneously transmitted to a recording device and a warning device (RF Patent No. 2232861, publ. 04/27/2003).

The method allows to prevent the occurrence of trunks during drilling, but it does not allow to protect against the formation of karst dips in the immediate vicinity of the earth's surface at the beginning of well drilling.

Closest to the proposed invention in technical essence is a method of developing fluid fields, including laying the mouths of production and injection wells in the form of a bush or battery, drilling in a rock mass and fixing the trunks of vertical, deviated and / or curved wells, opening them with a productive formation in predetermined points and field development over the entire area or in separate blocks. The production and injection wells of each bush or battery are placed in the central part of the field or the block under development so that their paths pass in the zone of horizontal displacements of the rock mass that is deformed due to the risk of shear disturbance of the casing, deforming during the extraction of fluids (RF Patent No. 2199002, publ. 02/20/2003 - prototype).

The known method allows to protect the wells during operation from shifts of the rock mass, deforming during the extraction of fluids, however, the method does not allow to secure drilling equipment and workers from the formation of karst dips in the immediate vicinity of the earth's surface at the beginning of well drilling.

The proposed invention solves the problem of ensuring safe drilling of a wellbore under conditions of formation of karst dips during drilling in the immediate vicinity of the earth's surface at the beginning of well drilling.

The problem is solved in that in a method for constructing a wellbore, including laying the mouths of production and injection wells in the form of a bush or battery, drilling in a rock mass and securing vertical, deviated and / or curved wells, opening a producing formation at specified points, according to When constructing the first well of the bush, they first drill the mine with a chisel with a diameter of 630 mm to a depth of 10-20 m, lower the casing with a diameter of 500-540 mm, cement the annulus, then drill the direction to l laminar mode using mud without scouring the borehole wall, with fluid loss is not more than 6 cm ^3/30 min, a viscosity of not lower than 50, a specific gravity of about 1.35 g / cm ³ using a rotary while drilling with the drilling method quantity rotor revolutions of not more than 100 rpm, rock samples are taken through each meter of penetration and analyzed for fallability, sampling is continued until a solid and dense rock is reached, after drilling the direction, the casing is lowered and the annulus is cemented, the builder continues Well bore to the design mark, drilling subsequent wells of the bush or battery is carried out, as well as the first, but sampling and analysis of the rock while drilling the direction is carried out when the direction of drilling is close to a solid and dense rock.

SUMMARY OF THE INVENTION

During construction of a well, fragile, easily moving sections of soil can occur, which can form pits, dips, cavities, etc. of considerable size. karst dips. The dimensions of such dips can reach 10 m in diameter and depth, and even more than that. Drilling a well under such conditions provokes the formation of a karst dip. In this case, the soil from under the drilling equipment leaves, the drilling equipment tilts or even falls into a failure. Deformation and scattering of drilling equipment occurs. There may be injury to workers or even death. Existing methods of well construction do not take into account the possibility of karst failure under drilling equipment. The proposed invention solves the problem of ensuring safe drilling of a wellbore in the event of possible formation of karst dips during drilling in the immediate vicinity of the earth's surface at the beginning of well drilling. The problem is solved as follows.

During the construction of a cluster of wells, drilling is carried out in a rock mass and the shafts of vertical, deviated and / or curved wells are fastened. During the construction of the first well of the bush, the mine is first drilled with a chisel with a diameter of 630 mm to a depth of 10-20 m, a casing pipe with a diameter of 500-540 mm is lowered, and the annulus is cemented. Shallow mine helps to fix the rocks in close proximity to the surface of the earth and reduce the impact of drilling on soils. Then the direction of the drilled using a laminar flow of drilling fluid without scouring the borehole wall, with fluid loss is not more than 6 cm ^3/30 min, a viscosity of not lower than 50, a specific gravity of about 1.3-1.4 g / cm ^3, with using when drilling a rotary method of drilling with a rotor speed of not more than 100 rpm Through each meter of driving, rock samples are taken and analyzed for fallability. Continue sampling until a solid and dense breed is achieved. After drilling, the casing string is lowered and the annulus is cemented. Well construction continues to the design level. Drilling subsequent wells of a bush or battery is carried out, like the first, but sampling and analysis of the rock while drilling the direction is carried out when the direction of drilling is closer to a strong and dense rock.

The above conditions help minimize the impact of drilling on weak soils. Laminar drilling mode eliminates the active influence of the drilling fluid on the walls of the well. Application mud without scouring the borehole wall, with fluid loss is not more than 6 cm ^3/30 min, a viscosity of not lower than 50, a specific gravity of about 1.3-1.4 g / cm ³ enables to keep the borehole wall against erosion. Specific figures are selected from drilling practice. The use of a rotary drilling method when drilling with a rotor speed of not more than 100 rpm has less impact on the bottom of a well being drilled than a layout with a downhole motor. A drilling fluid that does not erode the walls of the well is used after analyzing the composition of the rocks and determining the effect of various fluids on the rocks. So, clay drilling fluids are used to eliminate erosion of fragile sandstone, polymer drilling fluids or anhydrous-based muds, etc. are used to exclude erosion of clay rocks.

Through each meter of driving, rock samples are taken and analyzed for fallability. Shedding is determined visually when rubbing the rock in the hands. Sampling is continued until a solid and dense rock is reached that does not form sand when rubbed in the hands. After drilling, the casing string is lowered and the annulus is cemented. Well construction continues to the design level. Drilling subsequent wells of a bush or battery is carried out as the first, but sampling and rock analysis when drilling directions are carried out when the direction of drilling is closer to a strong and dense rock.

As a result, it is possible to build a well bush in conditions of karst dips.

Concrete example

A well bush is built with the following characteristics: indicate that it is possible, for example, the nature of the soil, the depth and size of karst occurrences, the geometry of the well cluster, how many wells, how they are located, what kind of wells, etc.

During the construction of the first well of the bush, the mine is first drilled with a chisel with a diameter of 630 mm to a depth of 15 m, a casing pipe with a diameter of 520 mm is lowered, and the annulus is cemented. Then, the direction is drilled to a depth 124 m in the laminar regime mud pump performance of 16 l / sec, as the fluid loss mud with 6 cm ^3/30 min, a viscosity of 52 seconds by the viscometer B3-4, specific gravity of 1.35 g / cm ³ , using a rotary drilling method when drilling with a rotor speed of 80 rpm. Through each meter of penetration, rock samples are taken at the mouth and analyzed for fallability. It is determined that rocks with increased crumbling are located at depths of up to 120 m. Continue sampling until a solid and dense rock is reached at a depth of 124 m. The casing with a diameter of 426 mm is lowered and the annulus is cemented. The conductor is drilled to a depth of 280 m, a string of pipes with a diameter of 324 mm is lowered into the well and the annulus is cemented. Drill the technical string of the well to a depth of 1220 m, lower the string of pipes with a diameter of 245 mm and cement the annulus. A well is drilled to the design level of 2090 m, a production casing with a diameter of 146 mm is lowered and the annulus is cemented.

Drilling of subsequent wells in the cluster is carried out, like the first, but sampling and analysis of the rock while drilling the direction is carried out when the direction of drilling is closer to a strong and dense rock.

When drilling in this area of the well, the prototype led to the formation of a karst dip, loss of stability, and an unacceptable inclination of the drilling rig. This necessitated the dismantling of equipment, the elimination of the failure and the transfer of drilling equipment several meters from the failure. At the new location, the proposed method of drilling the well was applied, as a result of which it was possible to avoid the formation of a hole and bring the well to the design depth.

The application of the proposed method will solve the problem of ensuring safe drilling of a wellbore in the conditions of formation of karst dips during drilling in the immediate vicinity of the earth's surface at the beginning of well drilling.

Claims (1)

A method of constructing a well cluster, including laying the mouths of production and injection wells in the form of a bush or battery, drilling in a rock mass and attaching vertical, deviated and / or curved wells, opening a producing formation in predetermined locations, characterized in that during the construction of the first wells in the bush initially drill a mine with a chisel with a diameter of 630 mm to a depth of 10-20 m, lower the casing with a diameter of 500-540 mm, cement the annulus, then drill the direction in laminar mode using iem mud without scouring the borehole wall, with fluid loss is not more than 6 cm ^3/30 min, a viscosity of not lower than 50, a specific gravity of about 1.35 g / cm ³ using a rotary while drilling with the drilling method number of revolutions of the rotor is not more than 100 rpm, rock samples are taken through each meter of drilling and analyzed for crumbling, sampling is continued until a solid and dense rock is reached, after drilling the direction, they lower the casing and cement the annulus, continue well construction until design mark, the subsequent drilling of wells bush or the battery is carried out as the first, but the sampling and analysis of rock during the drilling direction is carried out at the approach to the drilling direction of a strong and tight.