Drilling process monitor

This application claims the benefit of U.S. Provisional Application No. 60/234,535, filed Sep. 22, 2000, and incorporates the Provisional Application by reference.

FIELD OF THE INVENTION

The present invention relates to systems for drilling holes in the ground.

BACKGROUND

In a drilling operation, a drilling assembly is used to drill a hole in the earth. It is sometimes desirable to monitor the progress of the drilling operation.

SUMMARY OF THE INVENTION

An apparatus is used with a drilling assembly for drilling a borehole. The drilling assembly has a drill head. An impact device of the drilling assembly is linked to the drill head. The impact device is powered by a first fluid under a first pressure to impart a percussive force to the drill head. The percussive force is a function of the first pressure. A thruster of the drilling assembly is also linked to the drill head. The thruster is powered by a second fluid under a second pressure to impart a thrust force to the drill head. The thrust force is a function of the second pressure. Additionally, a rotator of the drilling assembly is linked to the drill head. The rotator is powered by a third fluid under a third pressure to impart a torque to the drill head. The torque is a function of the third pressure. The apparatus includes a first pressure sensor communicating with the first fluid to output a first electrical signal that is a function of the first pressure. A second pressure sensor communicates with the second fluid to output a second electrical signal that is a function of the second pressure. A third pressure sensor communicates with the third fluid to output a third electrical signal that is a function of the third pressure. A position sensor outputs a fourth electrical signal that is a function of depth of the drill head relative to a reference location. A device monitors the first, second, third and fourth signals. The device produces respective graph traces of functions of the percussive force, the thrust force, the torque and the depth.

In a preferred embodiment, the device produces the graph traces in real time during the drilling operation. The first, second and third electrical signals are analog signals. The fourth electrical signal is a digital signal. The graph traces are indicative of the occurrence of downward drilling, drilling stoppage, raising of the drill head, and addition of drilling rods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a schematic view of a drilling system according to the present invention; and

FIGS. 2-9

are graphs produced by the drilling system of FIG.

1

.

DESCRIPTION

An example of a preferred embodiment of the present invention is shown schematically in FIG.

1

. The preferred embodiment is a drilling system

10

that includes a drilling assembly

14

and a monitoring system

16

. The drilling assembly

14

performs a drilling operation defined by drilling a borehole

20

in the earth

22

. The monitoring system

16

measures and displays dynamic parameters related to the drilling operation.

In this embodiment, the drilling assembly

14

is a pneumatic percussive rotary drilling machine. The drilling assembly

14

has a drill head

24

at the end of a drill string

26

defined by a series of drilling rods. During the drilling operation, the drill head

24

rotates and vibrates while being thrust into the bottom end

28

of the borehole

20

.

The drill head

24

is linked to an impact device

30

in a known manner. The impact device

30

applies a percussive force, indicated by arrow

32

, which is transmitted through the drill string

26

to the drill head

24

to fragment soil and drive the drill head

24

into the bottom end

28

of the borehole

20

. The impact device

30

is powered by a first fluid

36

under a first pressure. The percussive force at the drill head

24

is a function of the first pressure.

The drill head

24

is also linked to a thruster

42

. The thruster

42

can apply a downward force, indicated by arrow

44

, that is transmitted through the drill string

26

to the drill head

24

to thrust the drill head

24

into the earth

22

. The thruster

42

can also apply an upward force, indicated by arrow

46

, that is transmitted through the drill string

26

to the drill head

24

to raise the drill head

24

. The thruster

42

is powered by a second fluid

48

under a second pressure and a third fluid

50

under a third pressure. The downward force is a function of the second pressure. The upward force is a function of the third pressure.

The drill head

24

is further linked to a rotator

54

. The rotator

54

can apply a forward torque, indicated by arrow

56

, that is transmitted through the drill string

26

to the drill head

24

to rotate the drill head

24

in a forward direction. Rotation of the drill head

24

in the forward direction causes the drill head

24

to abrade, and to be driven downward through, the bottom end

28

of the borehole

20

. The rotator

54

can also apply a reverse torque, indicated by arrow

58

, that is transmitted through the drill string

26

to the drill head

24

. Rotation of the drill head

24

in the reverse direction assists in removing the drill head

24

from the bottom end

28

of the borehole

20

. The rotator

54

is powered in the forward direction by a fourth fluid

60

under a fourth pressure. The rotator

54

is powered in the reverse direction by a fifth

62

fluid under a fifth pressure. The forward torque is a function of the fourth pressure. The reverse torque is a function of the fifth pressure.

In this embodiment, each of the first, second, third, fourth and fifth fluids

36

,

48

,

50

,

60

and

62

is a gas. However, for use with hydraulic drilling assemblies, these fluids would be liquids. These fluids

36

,

48

,

50

,

60

and

62

are compressed from a common fluid supply

64

into a manifold

66

by a compressor

68

and are delivered to the corresponding devices

30

,

42

and

54

. Delivery of each of these fluids

36

,

48

,

50

,

60

and

62

to the respective device

30

,

42

and

54

is controlled by a controller

70

.

The monitoring system

16

includes five individual pressure sensors

71

,

72

,

73

,

74

and

75

for measuring the pressure of the five fluids

36

,

48

,

50

,

60

and

62

, respectively. The pressure sensors

71

,

72

,

73

,

74

and

75

are in communication with the respective fluids

36

,

48

,

50

,

60

and

62

through fluid lines

80

. The pressure of each fluid

36

,

48

,

50

,

60

and

62

is conducted through the respective fluid line

80

to the respective pressure sensor

71

,

72

,

73

,

74

and

75

. Each pressure sensor

71

,

72

,

73

,

74

and

75

produces an analog electrical signal that is a function of the pressure of the respective fluid

36

,

48

,

50

,

60

and

62

. The signals are output onto respective electrical lines

81

,

82

,

83

,

84

and

85

.

A position sensor

86

is operative to measure the depth of the drill head

24

relative to a reference location. The reference location is a fixed location

92

on the surface of the earth

22

. Alternatively, the reference location can be a fixed location (not shown) on the drilling assembly

14

. The depth measurement may be accomplished in any suitable manner known in the art. The position sensor

86

produces a digital signal representing a value that is a function of the depth of the drill head

24

. The digital signal is output on an electrical line

96

.

The five analog signals and the one digital signal are communicated over the lines

81

,

82

,

83

,

84

,

85

and

96

to a micro-processor controller

98

. The micro-process controller

98

converts the five analog signals and the one digital signal to six corresponding digital data typically in RS232 format. The micro-process controller

98

functions as a data buffer to manipulate the data and change data format. The micro-process controller

98

also controls the data collection of the six electrical signals in real time simultaneously via the six lines

81

,

82

,

83

,

84

,

85

and

96

. The micro-process controller

98

can continuously store the digital data on a disk drive (not shown) in real time.

In the present embodiment, the micro-process controller

98

outputs the digital data over an electrical line

99

to a computer

100

, which in the present embodiment is a personal computer. During the drilling operation, the computer

100

continuously stores the digital signals on a disk drive (not shown) in real time and can continuously produce graphs of the respective digital signals in real time. Each graph is displayed on a suitable medium, such as a sheet of paper.

FIGS. 2-7

show graphs

102

,

103

,

104

,

105

,

106

and

107

corresponding to the first, second, third, fourth, fifth and sixth digital signals, respectively, for a first typical drilling operation.

FIGS. 8 and 9

show graphs

108

and

109

corresponding to the first and sixth signals, respectively, for a second typical drilling operation.

The graphs

102

,

103

,

104

,

105

,

106

,

107

,

108

and

109

in

FIGS. 2-9

have many features in common. These features can be explained with reference to the graph

102

of FIG.

2

. Graph

102

includes a vertical axis

122

representing signal magnitude. The vertical axis

122

is graduated in terms of pressure in units of kPa. A horizontal axis

124

represents elapsed time relative to a start time designated as zero. The horizontal axis

124

is graduated in units of seconds. Graph

102

also includes a trace

126

based on the first digital signal corresponding to percussive force. The vertical position of each point along the trace

126

is a function of the first pressure at the time that point was measured.

In graph

103

of

FIG. 3

, the trace

126

is based on the second digital signal. The trace

126

is thus a function of the second pressure, corresponding to downward thrust. Similarly, the trace

126

of the graph

104

of

FIG. 4

is based on the third digital signal and is therefore a function of the third pressure, corresponding to upward thrust. Likewise, the trace

126

of the graph

105

of

FIG. 5

is based on the fourth digital signal. It is consequently a function of the fourth pressure, corresponding to forward torque. The trace

126

of the graph

106

of

FIG. 6

is based on the fifth digital signal. It is thus a function of the fifth pressure, corresponding to reverse torque.

In graph

107

of

FIG. 7

, the vertical axis

122

is graduated in terms of depth in units of meters. This is in contrast to the graphs

102

,

103

,

104

,

105

and

106

(

FIGS. 2-6

, respectively) in which the vertical axes

122

are graduated in terms of pressure. In graph

107

of

FIG. 7

, the trace

126

is based on the sixth digital signal. The vertical position of each point along the trace

126

is consequently a function of depth of the drill head

24

(

FIG. 1

) at the time that point was measured.

The graph

108

of

FIG. 8

is similar to the graph

102

of

FIG. 2

, but is for the second drilling operation. Likewise, the graph

109

of

FIG. 9

is similar to the graph

107

of

FIG. 7

, but is for the second drilling operation.

In this embodiment, the traces

126

are plotted on separate graphs

102

,

103

,

104

,

105

,

106

,

107

,

108

and

109

(FIGS.

2

-

9

), each having a separate horizontal axis

124

. However, the horizontal axes

124

of graphs relating to the same operation are the same in size and in time scale. For example, the horizontal axes

124

of the graphs in

FIGS. 2-7

all have the same time scale, 0-4000 seconds.

During and after the drilling operation, an operator can interpret the graphs shown in

FIGS. 2-9

to assess the progress of the drilling operation, to note any irregularity in the operation, and to discern the subsurface profile and properties. The operator can also interpret these graphs to determine when different operations have been performed. For example, referring to graph

109

in

FIG. 9

, section A corresponds to downward drilling, section B corresponds to drilling stoppage, section C corresponds to raising of the drill head

124

, and section D corresponds to addition of drilling rods.

The invention has been described with reference to preferred embodiments. Those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications are intended to be within the scope of the claims.