NL2014082B1

NL2014082B1 - Mud cooling device.

Info

Publication number: NL2014082B1
Application number: NL2014082A
Authority: NL
Inventors: Jean-Paul Richard Meijers Alain-Raymond
Original assignee: Meto Beheer B V
Priority date: 2015-01-05
Filing date: 2015-01-05
Publication date: 2016-09-30
Also published as: EP3242992B1; WO2016111616A1; EP3242992A1; NL2014082A

Abstract

The invention relates to a cooling device (10) for cooling drilling fluids, comprising a first heat exchanger (16) for heat exchange between hot drilling fluid and a coolant passing through a closed second coolant circuit, a second heat exchanger (26) for heat exchange between the coolant and ambient air, wherein the closed second coolant circuit is provided with a coolant subcircuit provided with a third heat exchanger (80) for additional heat exchange between the coolant and a heat exchanging fluid.

Description

MUD COOLING DEVICE

The present invention relates to a cooling device for cooling drilling fluids, in particular a land mud cooler, using air from the environment as a heat exchanging fluid.

During drilling of oil or gas drilling fluid (hereinafter also referred to as mud) is used, which is continuously recycled between the drilling well and the surface, where it is conditioned for renewed use. One of the conditioning steps is cooling of the mud, which is heated as a result of said drilling. If water is abundant, this is typically used as a cooling medium. E.g. in offshore drilling seawater is used for cooling a coolant, such as a mixture of water and glycol, circulating in a closed circuit, in a heat exchanger, while in a second heat exchanger heat exchange between the warm mud and the cold coolant occurs. In situations where water is not present or cannot be used as a cooling medium, frequently air from the environment is used as a cooling medium for cooling the coolant. However, the temperature of the environmental air may vary seriously during a daily cycle, as well as during the various seasons. This is particularly true in areas having a dry air climate such as the Arabic and Middle East countries. It is known that in desserts the temperature difference between day and night may be as large as 20°C or even more. E.g. in the United Arab Emirates the temperature difference during winter may be above 20 °C and during the summer the ambient temperature can be over 50 °C. This high and fluctuating air temperature highly affects the performance of a land mud cooler using environmental air as one of the heat exchanging medium, and therefore the requirements for the mud cooler are complex and may result in overdesigning and overcapacity. Moreover, the temperature differences between the air, coolant and the hot mud may be too small, that is to say outside the optimal range of operating parameters, for efficient heat transfer in the first and second heat exchanger.

The present inventions aims at reducing the above drawbacks, in particular, the invention aims at providing a land mud cooler, which can be adapted to changing climatological conditions during a year. Another object of the invention is to provide a land mud cooler which is easy to install.

According to the invention a cooling device, in particular a land mud cooler, for cooling drilling fluids, comprises a first heat exchanger for heat exchange between hot drilling fluid and a coolant having a first inlet for hot drilling fluid and a first outlet for cooled drilling fluid and a first flow path for the drilling fluid from the first inlet to the first outlet, the first heat exchanger having a coolant outlet and a coolant inlet and a coolant flow path through the first heat exchanger from the coolant inlet to the coolant outlet, a second heat exchanger having a second coolant inlet in fluid communication with the coolant outlet of the first heat exchanger, a second coolant outlet in fluid communication with the coolant inlet of the first heat exchanger via a coolant return conduit, a second coolant flow path through the second heat exchanger from the second coolant inlet to the second coolant outlet, thereby providing a closed second circuit for the coolant through the first heat exchanger and the second heat exchanger, wherein the second heat exchanger is provided with an intake for air from the environment and an air outlet being in fluid communication with each other, wherein the closed second coolant circuit is provided with a coolant subcircuit, wherein the coolant return conduit between the second heat exchanger and the first heat exchanger is provided with a coolant branch supply conduit in fluid communication with a third heat exchanger having a third coolant inlet for coolant and a third coolant outlet for coolant, said third coolant inlet and outlet being in fluid communication with each other via a third coolant flow path through the third heat exchanger, wherein the third coolant outlet is connected to the coolant return conduit via a coolant branch return conduit at a position downstream of the connection between the coolant return conduit and the coolant branch supply conduit, the third heat exchanger also having a heat exchange fluid inlet and a heat exchange fluid outlet being in fluid communication with each other via a third heat exchange fluid flow path through the third heat exchanger, and wherein the conduit part of the coolant return conduit between the connections to the coolant branch supply conduit and coolant branch return conduit is provided with a valve.

The cooling device according to the invention comprises at least three heat exchangers, i.e. a first heat exchanger for heat exchange between hot mud and a coolant, typically water, which coolant is contained and recycled in a closed loop; a second heat exchanger wherein the coolant that is heated in the first heat exchanger transfers its heat to environmental air under forced airflow conditions, and a third heat exchanger incorporated in an additional loop on the main coolant loop for further reduction of the coolant temperature by heat exchange with a heat exchanging fluid. Thus the second and third heat exchanger are arranged in series with regard to the coolant. Preferably, the heat exchanging fluid in the third heat exchanger is a liquid. Suitable examples of such a heat exchanging liquid comprise Freon, R407C. R410A and R22. In order to direct the coolant into the additional loop suitable valving is provided in the main coolant return conduit and preferably in the additional loop as well.

Under normal design conditions the cooling device according to the invention is able to operate using environmental air as its only cooling fluid for heat exchange with the coolant. When circumstances require additional cooling, the third heat exchanger is also employed, e.g. the incoming heat exchanging fluid has a temperature of about 7 °C while the outgoing heat exchange fluid is at about 12 °C.

Thus the operation of the cooling device according to the invention is easily adapted to changing conditions during the seasons.

Advantageously, the first and third heat exchangers are heat exchangers of the plate exchanger type. The third heat exchanger preferably has a design comprising multiple plate packs, which are easily mounted and demounted. This allows for further possibilities to modify the capacity and performance of the third heat exchanger in view of varying average temperature conditions over a year. In a further advantageous embodiment the second heat exchanger is a heat exchanger of the radiator type, which is provided with one or more fans for circulating air from the environment over the radiator, such as a finned radiator.

In a preferred embodiment the land mud cooler according to the invention comprises a bypass conduit in the coolant subcircuit between the coolant branch supply conduit and the cooling branch return conduit for bypassing the third heat exchanger. This bypass is particularly relevant for controlling the heat exchange capacity in the third heat exchanger. Typically the land mud cooler according to the invention is set to standard operating conditions for the first and second heat exchangers. During operation these standard conditions including flow rates and the like are essentially maintained, even when the air temperature conditions or requirements change. Then the third heat exchanger can be adapted to the changing conditions, e.g. adding a plate pack to the heat exchanger or removing therefrom.

In a further preferred embodiment thereof the coolant branch supply conduit is provided with a temperature controlled 3-way valve, which is controlled by a temperature sensor for determining the temperature of the heat exchange fluid at the heat exchange fluid outlet or at least downstream the heat exchanger. Actively controlling the 3-way valve as a control means for the operation of the whole system, while other parameters are mainly invariably maintained, allows a relatively simple and single control of the cooling device according to the invention.

In another preferred embodiment the cooling device according to the invention comprises also a chiller for temperature control of the heat exchanging fluid in the third heat exchanger. In a particular embodiment thereof the heat exchange fluid inlet and outlet of the third heat exchanger are in fluid communication with an inlet and outlet of an evaporator of a refrigerant (second cooling fluid) chilling device comprising a refrigerant evaporator, compressor, condensor and expansion device in a closed circuit. The chiller device is an efficient means for providing and controlling the relatively low temperature required for the heat exchanging fluid in the third heat exchanger. Typical examples of a suitable refrigerant include again Freon, R407C. R410A and R22.

Preferably the cooling device according to the invention has a modular design, wherein the modules comprises standard sized containers, e.g. 20 or 40 foot containers, housing the respective module components, and provided with suitable connecting flanges. Such portable modules are easy to ship and transport by conventional transport means, like ships, railroad and lorries. They are also easily couples to one another.

In a preferred embodiment a modular cooling device according to the invention comprises at least a first, advantageously portable, module comprising the first and second heat exchanger including part of the coolant circuit, the branching supply conduit and branching return conduit, having suitable connecting flanges, and a second, advantageously portable, module comprising the refrigerant chilling device, wherein the heat exchange fluid inlet and outlet of the evaporator are provided with flanges. The third heat exchanger including the bypass conduit and the temperature sensor equipment and control can be designed as a third module.

The invention is illustrated by means of the drawings, wherein the single Figure 1 shows a process diagram representing an embodiment of the mud cooling device according to the invention.

In Figure 1 the cooling device according to the invention is indicated in its entirety by reference numeral 10. Hot mud is derived from mud pits or ponds and supplied via mud supply line 12 to the mud inlet 14 of a first heat exchanger 16 of the plate exchange type.

Heat is transferred from the mud that flows along a first flow path 18 from the mud inlet 14 to a mud outlet 20, to a coolant. After heat exchange the mud thus cooled is returned to the mud pits via mud return line 22. The mud inlet 14 and mud outlet 20 of the first heat exchanger 16 are provided with flanges 24 for connecting to mating flanges of the mud supply line 12 and mud return line 22. Suitable valves and branching conduits allowing reversing the mud flow are provided between the mud inlet 14 and mud outlet 20 and the mud flow path 18 in the first heat exchanger 16.

The coolant for cooling the mud in the first heat exchanger 16 circulates between the first heat exchanger 16 and a second heat exchanger 26 in a closed loop. This loop comprises a first coolant outlet 28 of the first heat exchanger 16, a first coolant circulation conduit 30 connected to the outlet 28 and a second coolant inlet 32 of the second heat exchanger 26, which is in fluid communication with a second coolant flow path 34 within the second heat exchanger 26, which flow path 34 is connected to a second coolant outlet 36, which on its turn connects to a coolant return conduit 38 for returning the coolant that is cooled in the second heat exchanger 26 to the first coolant inlet 40 at the first heat exchanger 16, comprising coolant flow path 42. The first coolant circulation conduit 30 and the coolant return conduit 38 are provided with valves 44, as well as branching conduits 46 having valves 48 allowing reversal of flow of the coolant. A bypass conduit 50 provided with a valve 52 is provided between the first coolant circulation conduit 30 and the coolant return conduit 38, which conduit 50 allows for bypassing the second heat exchanger 26. As indicated the coolant flowing in the second coolant flow path 34 of the second heat exchanger 26 is cooled by air from the environment, that is drawn into the heat exchanger 26 by means of a fan 53 or multiple fans via air intake 54. The air flows out of the second heat exchanger 26 via air outlet 56.

As due to the seasonal and climatological (day night rhythm) temperatures may vary considerably, the performance of this way of cooling mud may be insufficient.

According to the invention an additional subcircuit is provided for lowering the temperature of the coolant. In particular, the coolant return conduit 38 is provided with a coolant branch supply conduit 60 and is also connected to a coolant branch return conduit 62 at a position downstream of the coolant branch supply conduit 60, both provided with suitable valves 64 and connecting flanges 66. In order to prevent a shortcut, valve 68 is provided in the conduit part 70 of the coolant return conduit 38 between the connections to the branch conduits 60 and 62. A third heat exchanger 80 in the subcircuit receives the coolant from the coolant branch supply line 60 at the third coolant inlet 82. In the third heat exchanger 80 the coolant is passed along a third coolant flow path 84 for heat exchange with a further heat exchange fluid and exits via third coolant outlet 86 into the coolant branch return conduit 62. The heat exchange fluid circulates in its own closed loop between the third heat exchanger 80 and an evaporator 90 of a chiller 92. The closed loop comprises a third heat exchange fluid flow path 94 in the third heat exchanger 80 in fluid communication with a third heat exchange fluid inlet 96 and outlet 98 respectively, which are both provided with a connecting flange 99 for connecting to loop conduits 100 and 102. These loop conduits 100 and 102 themselves are connected via suitable flanges 104 to the heat exchange fluid inlet 106 and heat exchange fluid outlet 108 of the evaporator 90 of the chiller 92. The chiller 92 is based on a vapour compression cycle and comprises in addition to the evaporator 90, where evaporation (vaporization) of a refrigerant occurs, a compressor 120 for raising the pressure of the refrigerant allowing condensing of the vaporized refrigerant at a higher temperature in a condensor 122, and an expansion device 124 for returning the refrigerant to its original condition.

As shown the coolant subcircuit is provided with a bypass conduit 130 between the coolant branch supply conduit 60 and the coolant branch return conduit 62. This bypass conduit 130 allows to bypass the third heat exchanger 80. The 3-way valve 132 in the coolant branch supply conduit 60 is controlled based on a temperature measurement by a temperature sensor 134 of the temperature of the heat exchanging fluid downstream of the third heat exchanger 80 in the loop conduit 100.

The modular design of the basic mud cooler is indicated by broken lines.

Claims

A cooling device (10) for cooling drilling fluids, comprising a first heat exchanger (16) for heat exchange between hot drilling fluid and a cooling means, with a first inlet (14) for hot drilling fluid and a first outlet (20) for cooled drilling fluid and a first flow path (18) for the drilling fluid from the first inlet (14) to the first outlet (20), the first heat exchanger (16) having a coolant outlet (28) and a coolant inlet (40) and a coolant flow path ( 42) through the first heat exchanger (16) from the coolant inlet (40) to the coolant outlet (28), a second heat exchanger (26) with a second coolant inlet (32) in fluid communication with the coolant outlet (28) of the first heat exchanger (16), a second refrigerant outlet (36) in fluid communication with the refrigerant inlet (40) of the first heat exchanger (16) via a refrigerant return line (38), a second refrigerant flow path (34) through the second heat Exchanger (26) from the second coolant inlet (32) to the second coolant outlet (36), thereby providing a closed second coolant circuit through the first heat exchanger (16) and the second heat exchanger (26), the second heat exchanger (26) is provided with an inlet (54) for ambient air and an air outlet (56) which are in fluid communication with each other, the closed second circuit for the coolant being provided with a coolant subcircuit, the coolant return line ( 38) between the second heat exchanger (26) and the first heat exchanger (16) is provided with a coolant branch supply line (60) in fluid communication with a third heat exchanger (80) with a third coolant inlet (82) for coolant and a third coolant outlet ( 86) for refrigerant, the third refrigerant inlet (82) and outlet (86) being in fluid communication with each other via a third refrigerant flow path (84) through the third heat exchanger (80), wherein the third refrigerant outlet (86) is connected to the refrigerant return line (38) via a refrigerant branch return line (62) at a position downstream of the connection between the refrigerant return line (38) and the refrigerant branch supply line (60) wherein the third heat exchanger (80) also has a heat exchange fluid inlet (96) and a heat exchange fluid outlet (98) in fluid communication with each other via a third heat exchange fluid flow path (94) through the third heat exchanger (80), and wherein the conduit portion (70) of the coolant return line (38) between the connections to the coolant branch supply line (60) and coolant branch return line (62) is provided with a valve (68).

The cooling device of claim 1, further comprising a bypass (130) in the refrigerant subcircuit between the refrigerant branch supply line (60) and the refrigerant branch return line (62) for bridging the third heat exchanger (80).

The cooling device of claim 2, wherein the refrigerant branch supply line (60) includes a temperature controlled valve (132) controlled by a temperature sensor (134) for determining the temperature of the heat exchange fluid at the heat exchange fluid outlet (98) .

Cooling device according to one of the preceding claims, wherein the first and third heat exchangers (16, 80) are plate type heat exchangers.

Cooling device according to one of the preceding claims, wherein the second heat exchanger (26) is a radiator type heat exchanger, provided with a fan (53) for circulating air from the environment via the radiator of the second heat exchanger (26).

Cooling device according to any of the preceding claims, wherein the heat exchange fluid inlet (96) and outlet (98) of the third heat exchanger (80) in fluid communication with an outlet (108) and inlet (106) of an evaporator (90) of a refrigerant cooling device (92) comprising a refrigerant evaporator (90), compressor (120), condenser (122), and expansion device (124) in a closed circuit.

Cooling device according to one of the preceding claims with a modular design, comprising at least a first module comprising the first and second heat exchangers (16; 26) including a part of the cooling system, the branch supply line (60) and branch return line (62) with connecting flanges (24, 66), and a second module comprising the coolant cooling device (92), wherein the heat exchange fluid inlet (106) and outlet (108) of the evaporator (90) are provided with flanges (104).