Chart:
POR-1a and POR-1b (Gamma Ray Environmental Corrections - Mud Weight and Borehole Size)
Applications:
To determine the approximate correction applied to HDS1 and CWR Gamma readings due to mud weight and borehole size.
Directions:
1.
Find the chart for the correct tool size (4.75", 6.75", 8.0", or 9.5") and tool position (centered or eccentered).
2. Enter the chart on the Borehole Diameter axis at the correct borehole diameter. 3. Project vertically to the curve corresponding to the correct value of the mud weight, then project horizontally to the GRcor/GR axis and read off the correction factor. 4. Multiply the log value of the Gamma reading by the correction cor rection factor. Example:
Assume that a Gamma log taken with a 6.75 inch collar centered in a 9 inch borehole reads 65 API and was drilled with a 12 lb/gal mud. The chart (third down on POR-1a) indicates that the correction factor is 1.12. The corrected reading is then 65*1.12 = 72.8
Notes:
1.
Under the standard reference conditions for PathFinder Gamma Ray tools, the tool is centered in an 8.5 inch borehole, and both the tool and the borehole are filled with fresh water. In the field, however, the conditions are usually not standard, and the field logs are generally not presented with gamma ray values corrected for borehole size and mud weight.
2. Apply any potassium chloride (KCl) correction (charts POR-1c through POR-1j) before correcting for mud weight and borehole size.
104 LWD Log Interpretation Charts PathF PathFinder inder Energy Services, Services, Inc., 2002
Gamma Ray Mud Weight and Borehole Size Corrections 4.75 inch and 6.75 inch Tools
2.5 2.3 2.1 R 1.9 1.7 G / r o 1.5 c R 1.3 G 1.1 0.9 0.7 0.5
4.75 in tool, centered
18 lb/gal
16 12 8
6
7
8
9 10 11 Borehole Diameter (in)
12
13
14
2.00
4.75 in tool, eccentered
1.75
18 lb/gal
16
R G1.50 / r o c
12
R1.25 G
8
1.00 0.75
6
7
8
9 10 11 Borehole Diameter (in)
12
13
14
3.0
6.75 in tool, centered
2.5
18 lb/gal
16
R 2.0 G / r
12
R 1.5 G
8
o c
1.0 0.5
8
9
10
11 12 13 Borehole Diameter (in)
14
15
16
2.00 18 lb/gal
6.75 in tool, eccentered
1.75
16
R 1.50 G /
12
r o c
8
1.25 R G 1.00 0.75
8
9
10
11 12 13 Borehole Diameter (in)
14
15
16
POR-1a LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
Gamma Ray Mud Weight and Borehole Size Corrections 8.0 inch and 9.5 inch Tools
3.5
8.0 in tool, centered
3.0
18 lb/gal 16
R2.5 G / r
12
R G1.5
8
2.0
o c
1.0 0.5
10
11
12
13 14 15 Borehole Diameter (in)
16
17
18
2.50
8.0 in tool, eccentered
2.25
18 lb/gal
16
2.00
R G 1.75 /
12
r o c
1.50
R G 1.25
8
1.00 0.75
10
11
12
13
14
15
16
17
18
Borehole Diameter (in) 4.0
9.5 in tool, centered
3.5
18 lb/gal
16
R3.0 G / r o c
2.5
12
R G2.0
8
1.5 1.0
12
13
14
15 16 17 Borehole Diameter (in)
18
19
20
3.0
9.5 in tool, eccentered
18 lb/gal
2.5
16
R G / r
2.0
o c
12
R G
1.5
8
1.0
12
13
14
15 16 17 Borehole Diameter (in)
18
19
20
POR-1b LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
Chart:
POR-1c through 1j (Gamma Ray Environmental Corrections - Potassium Mud)
Applications:
To determine the approximate correction applied to HDS1 Gamma readings due to potassium chloride (KCl) in the drilling mud.
Directions:
1.
Find the chart for the correct tool size (4.75", 6.75", 8.0", or 9.5"), tool position (centered or eccentered), and mud weight (10, 12, 14, or 16 lb/gal). If you need corrections for a mud weight other than those given, find the corrections for the given mud weights and interpolate linearly to the needed mud weight.
2. Enter the chart on the Borehole Diameter axis at the correct borehole diameter. 3. Project vertically to the curve corresponding to the correct value of the KCl concentration, then project horizontally to the KCl Correction axis and read off the correction. 4. Subtract the correction from the log value of the Gamma reading.. Example:
Assume that a Gamma log taken with a 4.75 inch collar eccentered in an 8 inch borehole reads 97 API and that the 12 lb/gal drilling mud was made with 10% KCl by weight. The chart (POR-1d, second down) indicates that the KCl correction is 18 API, so the corrected reading is 97 - 18 = 79 API. Assume that a Gamma log taken with a 8.0 inch collar centered in a 12 inch borehole reads 135 API and that the 12.6 lb/gal drilling mud was made with 15% KCl by weight. The 12 lb/gal chart on POR-1g indicates an 79 API correction, and the 14 lb/gal chart on POR-1g indicates a 68 API correction for 14 lb/gal mud. The interpolated correction for 12.6 lb/gal is (12.6 - 12) Corection = 79 + (68 - 79) = 76 API (14 - 12) The corrected log reading is then 135 - 76 = 59 API.
Notes:
1.
KCl corrections must be applied before mud weight and hole size corrections.
2. If you have the potassium concentration in terms of pounds per barrel (ppb) KCl or mg/liter potassium ion (K+), use the following equations to convert to % KCl by weight: (% KCI) = -0.000378*(ppb KCI)2 + 0.2818*(ppb KCI) + 0.0247 +
(ppb KCI) = (mg/liter K )/1500
LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 4.75 inch Tool, Centered
140
) I P120 A ( 100 n o i t 80 c e 60 r r o C 40 l C 20 K
10 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0
6
7
8
9
10
11
12
13
14
13
14
13
14
13
14
Borehole Diameter (inches) 120 ) I P A100 ( n 80 o i t c 60 e r r o 40 C l 20 C K
12 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0
6
7
8
9
10
11
12
Borehole Diameter (inches) 100
) I 90 P 80 A (
14 lb/gal mud, centered tool 25% KCl
n 70 o 60 i t c e r r o C l C K
50 15% KCl
40 30 20
5% KCl
10 0 6
7
8
9
10
11
12
Borehole Diameter (inches) 80
) I 70 P A ( 60 n o 50 i t c 40 e r r 30 o C20 l C10 K
16 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 6
7
8
9
10
11
12
Borehole Diameter (inches)
POR-1c LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 4.75 inch Tool, Eccentered
120
) I P 100 A ( n 80 o i t c 60 e r r o 40 C l C 20 K
10 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 6
7
8
9
10
11
12
13
14
Borehole Diameter (inches) 90
) I 80 P A70 ( n 60 o i t 50 c e 40 r r o 30 C l 20 C K10
12 lb/gal mud, eccentered tool
25% KCl
15% KCl
5% KCl
0 6
7
8
9
10
11
12
13
14
Borehole Diameter (inches) 80
) I 70 P A60 ( n o 50 i t c 40 e r r 30 o C20 l C10 K
14 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 6
7
8
9
10
11
12
13
14
Borehole Diameter (inches) 70
) I P 60 A ( 50 n o i t 40 c e 30 r r o C20 l C10 K
16 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 6
7
8
9
10
11
12
13
14
Borehole Diameter (inches)
POR-1d LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 6.75 inch Tool, Centered 180
) I 160 P 140 A ( n 120 o i t 100 c e 80 r r o 60 C l 40 C K 20
10 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
Borehole Diameter (inches)
14
15
16
15
16
15
16
15
16
160
) I 140 P A120 ( n o 100 i t c 80 e r r 60 o C 40 l C 20 K
12 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
14
Borehole Diameter (inches) 140
) I P 120 A ( 100 n o i t 80 c e 60 r r o C 40 l C 20 K
14 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
14
Borehole Diameter (inches) 120
) I P 100 A ( n 80 o i t c 60 e r r o 40 C l C 20 K
16 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
14
Borehole Diameter (inches)
POR-1e LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 6.75 inch Tool, Eccentered
160
) I 140 P A120 ( n o 100 i t c 80 e r r 60 o C 40 l C 20 K
10 lb/gal mud, eccentered tool
25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
14
15
16
15
16
15
16
15
16
Borehole Diameter (inches) 140
) I P 120 A ( 100 n o i t 80 c e r 60 r o C 40 l C 20 K
12 lb/gal mud, eccentered tool
25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
14
Borehole Diameter (inches) 120
) I P 100 A ( n 80 o i t c 60 e r r o 40 C l C 20 K
14 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 8
9
10
11
12
13
Borehole Diameter (inches)
14
100
) I P A ( n o i t c e r r o C l C K
16 lb/gal mud, eccentered tool
90
25% KCl
80 70 60 50
15% KCl
40 30 20
5% KCl
10 0 8
9
10
11
12
13
Borehole Diameter (inches)
14
POR-1f LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 8.0 inch Tool, Centered
250
) I P A200 ( n o i 150 t c e r 100 r o C l 50 C K
10 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
17
18
17
18
17
18
17
18
Borehole Diameter (inches) 250
) I P A200 (
12 lb/gal mud, centered tool 25% KCl
n o 150 i t c e r 100 r o C l 50 C K
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches) 180
) I 160 P A140 ( n 120 o i 100 t c e r 80 r o 60 C l 40 C K 20
14 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches) 160
) I 140 P A120 ( n 100 o i t c 80 e r r 60 o C 40 l C 20 K
16 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches)
POR-1g LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 8.0 inch Tool, Eccentered
250
) I P 200 A ( n o 150 i t c e r 100 r o C l 50 C K
10 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
17
18
17
18
17
18
17
18
Borehole Diameter (inches) 200
) I 180 P A160 ( 140 n o 120 i t c 100 e r r 80 o 60 C l 40 C K 20
12 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches) 160
) I 140 P A120 ( n 100 o i t c 80 e r r 60 o C 40 l C 20 K
14 lb/gal mud, eccentered tool
25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches) 140
) I P 120 A ( 100 n o i t 80 c e 60 r r o C 40 l C 20 K
16 lb/gal mud, eccentered tool
25% KCl
15% KCl
5% KCl
0 10
11
12
13
14
15
16
Borehole Diameter (inches)
POR-1h LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 9.5 inch Tool, Centered 400
) I 350 P A ( 300 n 250 o i t c 200 e r r 150 o C100 l C 50 K
10 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
19
20
19
20
19
20
19
20
Borehole Diameter (inches) 350
) I P 300 A ( 250 n o i t 200 c e 150 r r o C100 l C 50 K
12 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches) 300
) I P 250 A ( n 200 o i t c 150 e r r o 100 C l C 50 K
14 lb/gal mud, centered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches) 250
) I P A200 ( n o 150 i t c e r r 100 o C l 50 C K
16 lb/gal mud, centered tool
25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches)
POR-1i LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
HDS1 Gamma Ray Potassium Mud Corrections 9.5 inch Tool, Eccentered
400
) I 350 P A ( 300 n o 250 i t c 200 e r r 150 o C100 l C 50 K
10 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
19
20
19
20
19
20
19
20
Borehole Diameter (inches) 350
) I P 300 A ( 250 n o i t 200 c e 150 r r o C100 l C 50 K
12 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches) 300
) I P 250 A ( n 200 o i t c 150 e r r o 100 C l C 50 K
14 lb/ al mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches) 250
) I P 200 A ( n o 150 i t c e r r 100 o C l 50 C K
16 lb/gal mud, eccentered tool 25% KCl
15% KCl
5% KCl
0 12
13
14
15
16
17
18
Borehole Diameter (inches)
POR-1j LWD Log Interpretation Charts PathFinder Energy Services, Inc., 2002
