Boring or penetrating the earth – With below-ground tool drive prime mover – Fluid rotary type
Patent
1997-09-23
1999-11-09
Neuder, William
Boring or penetrating the earth
With below-ground tool drive prime mover
Fluid rotary type
175243, 175318, E21B 402
Patent
active
059795727
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a flow control tool for incorporation in an underground string.
The exploration for and production of oil and gas from underground locations requires the drilling of an elongate bore to an underground reservoir. To achieve this, a driven cutting bit is positioned at the leading end of an elongate drilling tube made up from lengths of pipe connected end-to-end, which drilling tube is referred to in the art as a drill string. As the bore is drilled, it is lined with a casing and subsequently, following withdrawal of the drill string, a further tube is inserted into that casing which further tube is also made up from lengths of pipe connected end-to-end. This further tube is referred to in the art as a production string.
Drilling is performed by pumping a liquid (usually referred to as "mud") along the drill string to cause rotation of the drill bit, to cool and lubricate the drill bit, and to clean cuttings out of the drilled bore. An hydraulic motor driving the cutting bit is located at the forward end of the drill string, upstream of the cutting bit, and is operated by the mud pumped from the surface down the string. Upstream of the motor, there is usually located telemetry equipment (known as an MWD unit), powered by a generator driven by the pumped mud and feeding signals back to the surface, concerning various parameters relating to the drilling.
After a period of drilling, it may be necessary to circulate liquid for example to obtain samples of cuttings, thereby to determine the nature of the formation being cut. To achieve this, mud is pumped down the drill string, returning cuttings back to the surface. The life of both the generator for the telemetry equipment and the hydraulic motor for the cutting bits depends upon the operational circulating time and so it is desirable to cease operation of both of these, other than when actual drilling is to be performed. There is therefore a need for a by-pass valve arrangement in the drill string upstream of the hydraulic motor and telemetry equipment, whereby operation of both may be suspended other than when actual drilling is taking place.
In some circumstances, there is a need for a by-pass valve which allows dual flow, wherein part of the flow is circulated, by-passing the hydraulic motor and telemetry equipment, with a reduced flow through the valve to the motor and so on. This has the advantage that the motor will still rotate but at a lower rate in view of the reduced flow, so reducing the likelihood of the bit becoming stuck in the bare hole.
After drilling has been completed, but before production is commenced, there is a cased-hole clean-out phase which may employ a principal string of one diameter and at the far end thereof a further, short string of a smaller diameter. Whilst cleaning the main casing, it is advantageous to use very high flow rates for the clean-out fluid, but the presence of the further short string restricts that to some extent, due to friction pressure losses. It would therefore be advantageous for the clean-out fluid flow to by-pass the further short string until the lowermost part of the bore is to be cleaned out by that string.
There have been various proposals for so-called circulating tools for incorporation in a string, to allow fluid pumped from the surface to issue through the string wall in the region of the tool and so to by-pass equipment downstream of the tool, or to constrain that fluid to continue along the string from the tool. In one such proposal, a valve is operated by dropping into the string a weight which is carried by the fluid flow to the tool and which then changes the state of the valve. Such a tool may be operated only a limited number of times, and typically three or four.
Another proposal is to provide a tool which is operated by axial pressure thereon, caused by the weight of the string above the tool. However, this can subject equipment downstream of the tool to high axial loads and moreover often cannot be used in the case of a bore extending significantly out of vertical.
REFERENCES:
patent: 3025919 (1962-03-01), Angel et al.
patent: 3901333 (1975-08-01), Mori
patent: 4298077 (1981-11-01), Emery
patent: 5174392 (1992-12-01), Reinhardt
patent: 5730222 (1998-03-01), Rike, Jr.
Boyd Mark
Davy Mark Stanley
Neuder William
UWG Limited
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