RU2698759C1 - Drilling string arrangement for construction of horizontal sections of large length - Google Patents

Abstract

FIELD: soil or rock drilling; mining.

SUBSTANCE: invention relates to drilling and can be used in construction and construction of oil and gas wells, offshore wells and wells with large horizontal length. Drill string arrangement includes a bit, a drill string and a rotor-controlled system. In the part of the layout, where the zenith angle is greater than 60°, the drill string consists of light-alloy drill pipes (LDP), or of LDP in combination with steel drill pipes (SDP). In upper part of well shaft, where zenith angle is less than 60°, drilling string consists of SDP in combination with weighted drill pipes (WDP).

EFFECT: such arrangement leads to increase of well flow rate, quality of cleaning of well bottom, efficiency of drill cuttings removal and makes it possible to perform drilling operations on horizontal sections of large length with possibility of drilling from floating and stationary facilities, minimizing risks of string sticking and excluding "sliding" drilling mode.

1 cl, 1 dwg

Description

The invention relates to drilling and can be used in the wiring and construction of oil and gas wells, offshore wells and wells with a large horizontal length.

A known layout of the bottom of the drill string for drilling directional and horizontal wells with a downhole motor, consisting of a drill string, a bit and a downhole motor (patent RU 2280748, IPC ЕВВ 7/04, published on July 27, 2006, bull. 21).

The disadvantages of this device are the complexity of the layout of the bottom of the drill string, the high likelihood of sticking of the drill string due to accumulation of drill cuttings in a directional or horizontal section of the well, high friction losses that occur during sliding of the drill string along the borehole during drilling.

A known method of assembling a drill string for drilling deep wells, which is a prototype, including a bit, a drill string containing steel drill pipes (SBT) and alloy drill pipes (LBT), a downhole motor (Fayn G.M., Research, development and implementation of pipes from aluminum-based alloys for drilling deep wells, UDC 622.24.05, M., 1994).

The disadvantage of this method is the "sliding" drilling mode, the reason for which is the use of a downhole motor. In this mode, only the chisel rotates, and the drill string simply follows the guide assembly. During the drilling process, the drill string slides along the lying wall of the well, the flushing fluid moves unevenly around it, which reduces the carrying capacity of the solution and increases the risk of sticking the string. Also due to slipping decreases

net power used to rotate the bit, which, combined with sliding friction, reduces the speed of penetration. In addition, driven motorized drilling is characterized by low barrel quality, undulating bumps and sharp bends.

The technical objectives of the proposal are to increase the technical and economic indicators (TEC) of drilling horizontal sections in order to increase the filtration surface, which leads to an increase in the flow rate of wells, an increase in the quality of cleaning the bottom of the well, and the efficiency of removal of drill cuttings. The main objective of the invention is to increase the horizontal section of the wells, the possibility of drilling offshore wells with floating and stationary means.

The stated technical problems are solved by the assembly of a drill string consisting of a drill bit, a drill string with alloy drill pipes (LBT) or LBT in combination with steel drill pipes (SBT) in the lower part of the wellbore, where the zenith angle is greater than 60 ° and SBT with weighted drill pipes (UBT) at the top of the wellbore where the zenith angle is less than 60 °. Also, a rotary-controlled system is installed in the lower part of the wellbore.

In FIG. 1 shows the layout of the drill string for the construction of horizontal sections of long length, in which:

1 - rock cutting tool (chisel);

2 - rotary controlled system;

3 - telemetry system;

4 - LBT or LBT + SBT;

5 - SBT;

6 - UBT.

The layout of the drill string for the construction of horizontal sections of long length is used as follows.

When a flushing fluid is supplied, under pressure in a rotary-controlled system 2, either the assembly or a large part of it is repelled from the well wall relative to the axis, causing pressure on the side surface of the bit 1 in a certain predetermined direction (the system is “Push the bit”), or positioning of bit 1, which is achieved by shifting the drive shaft relative to the layout or by changing its curvature, which causes a change in the angle (Point the bit system). In this case, data on changes in the parameters acting on the layout of the bottom of the drill string are recorded by devices on the surface. After that, the combined drill string is fed, consisting in the lower part - LBT (or in combination with SBT), in the upper part - SBT + UBT, and the loading cycle is repeated. LBT is used to facilitate the assembly of the drill string in its lower part, by reducing the coefficient of friction against the borehole wall. In the upper part, SBT + UBT are used to create the corresponding load on the bit, which contribute to the increase in penetration and mechanical speed, depending on the strength and other rock characteristics, and subject to the condition that the circulation rate of the washing fluid increase is necessary and sufficient to completely clean the face from the drill bit breed. Replacing a downhole screw motor with a rotary-driven system allows you to maintain precise control of drilling parameters in the process and achieve a smooth well path.

The proposed arrangement can be effectively used when drilling complex wells with a long horizontal section, since the use of light drill pipes significantly lightens the weight of the entire drill string assembly, which means we can increase penetration and the rotary-controlled system, avoiding the "sliding" drilling mode, minimizes the risk of column sticking.

Claims (1)

An assembly of a drill string for the construction of horizontal sections of long length, consisting of a bit, a drill string, characterized in that a rotary-controlled system is installed in the lower part of the wellbore, in the part of the arrangement where the zenith angle is greater than 60 °, light-alloy drill pipes (LBT) are installed or light-alloy drill pipes (LBT) with steel drill pipes (SBT), and in the upper part of the wellbore, where the zenith angle is less than 60 °, steel drill pipes (SBT) with weighted drill pipes are installed mi (UBT).

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