FIELD OF INVENTION
The present invention generally relates to testing of oil rigs for on-shore drilling.
More particularly, the invention relates to a device for testing operability of a
traveling block in an oil rig.
BACKGROUND OF INVENTION
A drilling rig (oil Rig) is a machine which creates holes (usually called boreholes)
in the ground. It is a heavy steel structural body consisting of a plurality of sub
assemblies which are releasably assembled to each other to drill oil wells or
natural gas extraction wells. It consists of following main components and sub
assemblies as shown in Figures 1 to 8.
(A) A MAST (1)
A mast (1) is one of the important components of an oil rig. The mast (1) is used
to support crown block (2) and the drill string (9). Masts (1) are usually
rectangular or trapezoidal in shape and allow rigs to land whose mast is laid
down when the rig is moved. It is a tall structure made up of high strength low
alloy steel material. It is light in weight for easy lifting, lowering and
transportation. It consists of six sections of mast panels each on DS.l (Driller
side) and ODS-1 (Off Driller Side). These are connected with the help of
spreaders and braces. Its main function is to extract the drill pipes (3) after the
drilling operation. It gives support to the drill string while drilling. It gives the
support for stacking of drill pipes (3) through Racking board (4) and Belly board
(5). It also supports High Pressure mud line which sends the drilling fluid through
traveling block-Swivel (6).
(B) A SUBSTRUCTURE (8)
A substructure (8) is also one of the important components in the oil rig. It is
made up of high strength low alloy steel material. It is light in weight for easy
lifting, lowering and transportation. It supports the drilling machinery. It also
works as a platform to carry out the drilling operation.
(C) A CROWN BLOCK (2)
The Crown Block (2) has at least seven cluster sheaves with 50"/60" minimum
diameter and corresponding number of (fast line assembly) with 50"/60"
minimum diameter, all with tapered roller bearings and grooved for 1-1/4" or 1-
3/8" or 1-1/2" diameter wire line (9). It supports the Travelling block (6) with the
help of the wire lines (9). A fixed set of pulleys (called sheaves) are located at
the top of the derrick or mast (1), over which the drilling line is threaded. The
companion blocks to these pulleys are the traveling blocks (6). By using two sets
of blocks in this fashion, a great mechanical advantage is gained, enabling the
use of a relatively small drilling line (1¼ to 1½ in. diameter steel cable) to hoist
loads many times heavier than the cable could support as a single strand.
(D) A TRAVELLING BLOCK (6)
A traveling block (6) constitutes a set of sheaves that move up and down in the
derrick. The wire rope threaded through the sheaves is "reeved" back to the
stationary crown blocks (2) located on the top of the derrick to form a pulley
system which provides mechanical advantage to the action of the wire rope
drilling line, and allow heavy loads (drill string, casing and liners) to be lifted out
of or lowered into the well bore.
A Travelling block being set of sheaves mounting of the traveling block for
testing is difficult. The known practice followed is to raise the complete mast (1)
and the substructure (8) along with the crown block (2) including the traveling
block (6). Then a concrete block (18) weighing in tons as per requirement is
hooked on the traveling block (6) and load testing of the traveling block is
completed. For this a foundation with a huge set up is required. This is time
consuming and needs a complete rig for testing of traveling block (6).
OBJECTS OF INVENTION
It is therefore an object of the invention to propose a device for testing
operability of a traveling block in an oil rig, which eliminates the disadvantages of
prior art.
Another an object of the invention to propose a device for testing operability of a
traveling block in an oil rig, which is enabled to test the traveling block alone
without the necessity of mounting the entire oil rig on the test set-up.
A still another an object of the invention to propose a device for testing
operability of a traveling block in an oil rig, which eliminates the requirement for
providing a huge structure for testing of the traveling block.
A further an object of the invention to propose a device for testing operability of
a traveling block in an oil rig, which takes much lesser time to conduct a testing
of the traveling block.
A still further an object of the invention to propose a device for testing
operability of a traveling block in an oil rig, which is enabled to conduct test of
several types and capacities of traveling block.
Yet further an object of the invention to propose a device for testing operability
of a traveling block in an oil rig, which is simple in construction and easy to
handle.
SUMMARY OF INVENTION
According to the invention, the testing system consists of top assembly and a
bottom assembly. The load capacity is simulated using the wire rope and at least
four hydraulic Jacks.
The device is designed as a self straining type, where all the loads are contained
within the structure. This type of design is unique in nature. In this design the
free body diagram is such that all the loads and reactions are kept within the
system structure. No load is transferred to ground. Hence no foundation is
required for placing the system. Also all the rig components are not required for
testing. A Travelling block alone can be load tested. Four numbers of hydraulic
jacks are used to get the required load. The traveling block is hung from a
cluster sheave system supported at the top assembly a using casing line (1-3/8
inches wire line). The traveling block is pinned to the bottom assembly.
Strain gauges are connected at three points on the traveling block to measure
actual strains during loading. To verify the load test results with design values,
traveling block side plate is analyzed by using ANSYS software.
DETAIL DESCRIPTION OF THE INVENTION
As shown in figure 10, the device consists of a Bottom Assly (14), a Top Assly
(13) and a Crown Assly (2). A Travelling Block (6) is hung from the cluster
sheave of the Crown Assembly (2) using Wire Rope (12) of suitable size. The
Travelling Block (6) is pinned to the Bottom Assly (14) using link plate (16).
Strain gauges are mounted on to the side plate of traveling Block (6) to measure
the stress at critical points. Required load is simulated by using at least four
Hydraulic Jack (10) located on four corners of the device. When a load is applied
the Top Assly (13) along with the Travelling block (6) moves upward, while the
Bottom assly (14) remains stationary. This load is experienced by the traveling
block (6) as it is tied at the top and pinned at the bottom. This way Travelling
block of various capacities can be tested on this Test device.
WE CLAIM :
1. A device for testing operability of a traveling block (6) in an oil rig,
comprising:
- a bottom assembly (14) accommodating the traveling block (6) adapting a
link plate (14);
- a top assembly (13) vertically movable on application of load along with
the traveling block, and supporting the traveling block (6) via a wire rope
(12);
- at least four hydraulic jacks (10) disposed on four sides of the device, the
jacks (10) being capable to simulate load on the traveling block (6) at
critical points; and
- at least one strain gauge sideably mounted on the traveling block (6) to
measure the stress at the critical points of the traveling block (6) on
application of load.
2. A device for testing operability of a traveling block (6) in an oil rig, as
substantially described and illustrated herein with reference to the
accompanying drawings.

The invention relates to a device for testing operability of a traveling block (6) in
an oil rig, comprising a bottom assembly (14) accommodating the traveling block
(6) adapting a link plate (15); a top assembly (13) vertically movable on
application of load alongwith the traveling block, and supporting the traveling
block (6) via a wire rope (12); at least four hydraulic jacks (10) disposed on four
sides of the device, the jacks (10) being capable to simulate load on the traveling
block (6) at critical points; and at least one strain gauge sideably mounted on
the traveling block (6) to measure the stress at the critical points of the traveling
block (6) on application of load.