COOK FM

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• General information

  General information

  Attribute	Value
  Lithostrat. unit The lithostratigraphic unit's official name.	COOK FM
  NPDID lithostrat. unit Norwegian Offshore Directorate's unique id for lithostratigraphic units.	24
  Level Indicates the lithostratigraphic unit's level. Legal values: GROUP, FORMATION, MEMBER.	FORMATION
  Lithostrat. unit, parent The parent lithostratigraphic unit's official name. See also level. Will be empty if Level = GROUP.	DUNLIN GP

• Level below

  Level below

  Lithostrat. unit

• Description

  Cook Formation
  
  Name

  Named by Deegan and Scull (1977) who gave it "sub-unit" status.

  Well type section

  UK well 211/29-3 (Shell) from 2887 m to 2950.5 m, coord N 61°08'06", E 01°43'36.5" (Fig 3.10) .

  Well reference sections

  Norwegian wells 33/9-1 (Mobil) from 2715 m to 2801 m, coord N 61°15'07.5", E 01°50'25.8" (Fig 3.11) . 30/6-7 (Norsk Hydro) from 2975 m to 3023 m, coord N 60°38'39.49'' E 02°45'21.74" (Fig 3.12) . 31/2-1 (Shell) from 2093 m to 2134 m, coord N 60°46'19.16'' E 03°33'15.87" (Fig 3.13) . and 30/7-7 (Norsk Hydro) from 4735 m to 4801 m, coord N 60°16'19.30" E 02°16'07.30" (Fig 3.14) .

  Thickness

  63.5 m in the type well, 86 m in 33/9-1 , 66 m in 30/7-7 , 48 m in 30/6-7 and 41 m in 31/2-1 .

  Lithology

  In the type well section the formation is dominantly a marine siltstone with minor grey, silty claystone intercalations. The siltstones and claystones may contain sandy streaks, becoming more prominent away from the type well, especially in Norwegian waters. On the Horda Platform and along its western margin, sandstones are the dominant lithology in the formation. The sands are white to greyish brown, very fine to fine grained, subangular to subrounded and well sorted. Occasionally thin layers of medium to coarse grained sandstones are found. The sandstones are hard to friable. Silica is the most common cement. Mica, glauconite, carbonaceous material and calcareous cement may be present.

  Boundaries

  The formation can be distinguished from the more uniform and more argillaceous sediments above and below by a decrease in gamma ray response and an increase in velocity.

  Distribution

  The formation appears to be present throughout the East Shetland Basin and on the northern part of the Horda Platform.

  Age

  Pliensbachian to Toarcian.

  Depositional environment

  The sandstones can be divided into three types, related to depositional environment and basin geometry. In the Statfjord Field area the sandstones are believed to represent marine shoal sands (e.g. ref. well 33/9-1 ). On the Horda Platform and along its western margin the sandstones represent prograding shelf sands and several cycles can be identified within the formation (ref. 31/2-1 and 30/6-1 ). In the graben area the sands are thinner bedded, and the shale intercalations show no gradations into the sands (ref. 30/7-7 ). These sandstones are believed to represent redeposited sands from the edge of the shelf (the Horda Platform and East Shetland Basin west of the graben area).

  Source

  • Vollset, J. and Doré, A. G. (eds.) 1984: A revised Triassic and Jurassic lithostratigraphic nomenclature for the Norwegian North Sea. NPD-Bulletin No. 3, 53 pp.

• Wellbores penetrating

  Wellbores penetrating

  Wellbore name	Wellbore completion date	Top depth [m]	Bottom depth [m]
  15/6-11 A	13.03.2011	4286	4291
  15/6-11 S	19.12.2010	3947	3970
  25/2-4	20.10.1975	3927	3965
  25/2-5	04.08.1976	3513	3605
  25/2-12	12.11.1988	3800	3876
  25/2-13	25.01.1990	3565	3645
  29/3-1	15.09.1986	4046	4147
  29/6-1	09.05.1982	4546	4607
  29/9-1	24.02.1984	4487	4530
  30/2-1	12.10.1982	3962	4000
  30/2-3	05.10.1992	4161	4199
  30/3-1 R	26.04.1982	4081	4162
  30/3-2 R	16.02.1981	2982	3121
  30/3-3	30.05.1983	3241	3288
  30/3-4	12.06.1985	3079	3128
  30/3-4 R	18.11.2001	3081	3130
  30/3-5 S	19.06.1992	4424	4494
  30/3-6 S	06.03.1994	5823	5897
  30/3-7 B	04.08.1998	4378	4439
  30/3-7 B	04.08.1998	5897	5970
  30/3-7 BR	17.11.2001	4378	4439
  30/3-7 BR	17.11.2001	5897	5970
  30/3-7 S	12.12.1995	4966	5056
  30/3-7 S	12.12.1995	5138	5197
  30/3-10 S	29.04.2009	3871	3905
  30/4-2	16.05.1980	4127	4208
  30/6-1	22.09.1979	2537	2589
  30/6-2	11.12.1979	2431	2445
  30/6-3	07.03.1980	2689	2768
  30/6-4	11.05.1981	2855	2893
  30/6-5	15.08.1981	3071	3123
  30/6-6	24.03.1982	3152	3225
  30/6-7	24.08.1982	2975	3023
  30/6-8	06.08.1982	3350	3405
  30/6-9	16.12.1982	2821	2878
  30/6-9 R	12.05.1990	2819	2876
  30/6-11	30.03.1983	3752	3768
  30/6-14	08.02.1984	2679	2696
  30/6-15	05.09.1984	3101	3109
  30/6-16	21.01.1985	2920	2946
  30/6-17 A	18.03.1986	2460	2488
  30/6-17 R	04.02.1986	2402	2441
  30/6-19	21.06.1986	3103	3159
  30/6-19 R	25.05.1994	3102	3158
  30/6-20	13.04.1986	2747	2792
  30/6-21	09.04.1987	2854	2922
  30/6-22	13.07.1988	3122	3170
  30/6-22 R	02.06.1994	3121	3169
  30/6-23	01.07.1990	3016	3065
  30/6-29 S	03.03.2015	5534	5592
  30/7-7	01.07.1979	4735	4801
  30/7-8 R	29.01.1982	4325	4366
  30/8-1 S	01.03.1995	4450	4464
  30/8-1 SR	01.03.1996	4450	4464
  30/9-3 A	20.05.1984	3455	3466
  30/9-4 S	30.03.1985	3924	3991
  30/9-5 S	19.07.1985	2447	2466
  30/9-6	21.04.1987	2835	2845
  30/9-7	23.12.1988	3288	3387
  30/9-9	06.11.1989	2575	2591
  30/9-10	21.09.1990	3404	3424
  30/9-12	09.05.1991	2944	2994
  30/9-13 S	11.10.1991	3758	3826
  30/9-13 SR	17.07.2002	3762	3830
  30/9-15	05.01.1994	2461	2489
  30/9-16	08.08.1994	3073	3140
  30/9-28 S	26.02.2016	3488	3515
  30/10-5	01.05.1975	4967	5010
  30/11-3	14.03.1983	4218	4279
  30/11-4	24.07.1984	4210	4273
  30/12-1	07.03.1994	3409	3417
  31/1-1	15.02.2008	2691	2767
  31/1-2 A	29.01.2021	3859	3876
  31/1-2 S	12.01.2021	3446	3494
  31/2-1	09.11.1979	2093	2134
  31/2-1 R	09.11.1981	2094	2135
  31/2-2 R	06.10.1980	2162	2202
  31/2-3	20.07.1980	2010	2055
  31/2-4 R	06.04.1981	2008	2107
  31/2-4 R2	12.11.1982	2008	2107
  31/2-5	21.12.1980	2201	2277
  31/2-5 R	20.07.1981	2194	2270
  31/2-5 R2	22.04.1984	2194	2270
  31/2-8	18.08.1982	2825	2896
  31/2-21 S	04.06.2014	3123	3217
  31/3-1	13.10.1983	1945	1992
  31/4-2	15.11.1979	2479	2533
  31/4-3	11.05.1980	2448	2470
  31/4-4	17.02.1981	2935	2956
  31/4-5	29.07.1981	2482	2521
  31/4-7	11.09.1984	2236	2283
  31/4-8	11.05.1986	2222	2255
  31/4-11	12.09.2000	2957	2985
  31/4-A-13 C	26.07.2022	7426	7490
  31/5-2	11.11.1983	2176	2194
  31/5-2 R	30.08.1984	2176	2194
  31/5-7	06.03.2020	2638	2695
  31/6-1	28.10.1983	1962	1981
  31/6-8	25.05.1985	2025	2138
  31/6-8 R	22.09.1985	2025	2138
  31/7-1	22.06.2016	2598	2618
  31/11-1 S	28.06.2021	2898	2906
  32/4-1	04.12.1996	1733	1783
  33/5-2	18.11.1981	4340	4391
  33/6-1	06.07.1979	3697	3731
  33/6-2	02.01.1997	3815	3856
  33/6-3 S	24.07.2012	4154	4198
  33/9-1	04.06.1974	2715	2801
  33/9-3	14.11.1974	2644	2655
  33/9-6	31.08.1976	3200	3250
  33/9-9	17.11.1977	2528	2558
  33/9-12	03.08.1987	2609	2667
  33/9-13 S	24.12.1987	2855	2919
  33/9-19 A	09.08.1996	3171	3194
  33/9-19 S	23.07.1996	2939	2975
  33/12-6	21.06.1976	3397	3440
  33/12-7	27.04.1989	3387	3472
  33/12-8 S	26.04.2002	3285	3429
  34/2-2 R	08.05.1981	3619	3683
  34/2-4	11.06.1985	3821	3933
  34/3-1 A	30.10.2008	3954	4067
  34/3-1 S	10.09.2008	3866	3958
  34/3-2 S	30.12.2009	4012	4104
  34/3-3 A	03.01.2012	4809	4968
  34/3-3 S	19.11.2011	3908	3996
  34/3-4 A	13.02.2015	4370	4486
  34/3-5	16.04.2015	4140	4222
  34/4-3	30.03.1982	4226	4257
  34/4-5	06.04.1984	3416	3520
  34/4-10 R	18.04.2000	4066	4186
  34/4-14 S	19.05.2015	4494	4519
  34/5-1 A	10.04.2010	4274	4356
  34/5-1 S	13.03.2010	3629	3696
  34/5-2 S	04.07.2018	3588	3674
  34/6-1 S	28.08.2002	3807	3932
  34/6-2 A	12.12.2012	3702	3974
  34/6-2 S	05.11.2012	3654	3777
  34/6-3 A	01.11.2014	3603	3717
  34/6-3 S	24.09.2014	3851	4001
  34/6-4	02.03.2016	3952	4067
  34/6-5 S	08.06.2021	3654	3772
  34/7-5	16.03.1985	2696	2768
  34/7-12	17.12.1987	2462	2518
  34/7-13	13.04.1988	2670	2742
  34/7-14	02.12.1989	2543	2629
  34/7-16	13.08.1990	2603	2660
  34/7-16 R	15.10.1990	2604	2661
  34/7-16 R2	05.07.1994	2603	2660
  34/7-17	07.04.1991	2789	2818
  34/7-19	27.12.1991	2740	2800
  34/7-19 R	12.07.1994	2747	2807
  34/7-20	27.08.1992	2882	2919
  34/8-1	08.03.1986	3044	3163
  34/8-2	17.11.1986	2923	2934
  34/8-3	14.09.1988	3007	3118
  34/8-3 A	31.10.1988	3227	3230
  34/8-5	01.04.1991	3122	3186
  34/8-7	16.07.1992	4808	4953
  34/8-7 R	10.02.1993	4808	4953
  34/8-8	24.08.1992	3123	3260
  34/8-8 R	09.03.1993	3122	3260
  34/8-9 S	28.12.1992	3009	3113
  34/8-10 S	09.12.1993	2932	2939
  34/8-11	08.02.1994	3072	3140
  34/8-13 A	13.05.2009	3495	3593
  34/8-13 S	26.06.2009	3972	4085
  34/8-17 S	14.03.2014	4098	4199
  34/8-19 S	20.06.2018	3671	3943
  34/8-19 S	20.06.2018	5582	5672
  34/8-19 S	20.06.2018	5738	5893
  34/10-1	08.09.1978	2023	2081
  34/10-2	08.12.1978	3172	3200
  34/10-3	07.06.1979	2201	2326
  34/10-3 R	10.10.1987	2198	2323
  34/10-4	15.10.1979	2025	2165
  34/10-5	02.01.1980	2240	2381
  34/10-7	23.03.1980	1810	1937
  34/10-7 R	14.07.1983	1807	1934
  34/10-8	25.05.1980	2133	2214
  34/10-9	09.05.1980	2083	2200
  34/10-9 R	03.07.1980	2083	2203
  34/10-12	12.09.1981	2350	2470
  34/10-14	19.03.1982	2159	2203
  34/10-15	12.12.1982	1870	2034
  34/10-16	11.04.1983	3556	3602
  34/10-16 R	27.09.1983	3553	3599
  34/10-17	08.07.1983	3108	3220
  34/10-18	30.08.1983	2688	2785
  34/10-19	06.12.1983	1779	1830
  34/10-21	22.10.1984	3632	3763
  34/10-23	13.10.1985	4413	4515
  34/10-30	12.05.1986	2950	2983
  34/10-32	13.07.1987	3236	3286
  34/10-32 R	10.08.1987	3236	3286
  34/10-33	15.12.1988	3514	3629
  34/10-34	31.05.1991	2357	2410
  34/10-35	01.07.1992	3965	4048
  34/10-36	13.07.1992	3565	3640
  34/10-38 S	29.05.1995	3112	3211
  34/10-39 S	20.06.1995	2900	2985
  34/10-41 S	28.08.1997	3000	3099
  34/10-42 S	19.09.1999	4485	4520
  34/10-43 S	11.04.2001	3434	3544
  34/10-48 A	15.02.2005	4891	5008
  34/10-48 S	22.12.2004	4891	5008
  34/10-49 B	21.05.2006	2740	2925
  34/10-49 B	21.05.2006	3482	3618
  34/10-49 B	21.05.2006	3747	3935
  34/10-49 S	08.05.2006	2740	2925
  34/10-53 S	24.03.2011	4065	4234
  34/10-54 A	18.04.2014	4238	4299
  34/10-54 S	11.02.2014	4177	4230
  34/10-55 S	26.03.2017	7223	7240
  34/11-1	25.10.1994	4289	4338
  34/11-2 S	17.05.1996	4433	4478
  34/11-3	16.01.1997	4261	4304
  34/11-4	14.04.1999	4410	4438
  34/12-1	30.04.2008	4607	4713
  35/1-1	18.07.2002	3970	4087
  35/1-2 S	19.12.2010	3923	3961
  35/3-2	26.10.1980	3920	3946
  35/3-4	06.06.1981	3963	4069
  35/3-5	31.03.1982	3999	4052
  35/4-1	24.05.1997	4434	4515
  35/4-3	17.05.2022	4614	4707
  35/7-1 S	15.08.2011	4669	4771
  35/8-1	24.01.1981	3831	3982
  35/8-2	21.05.1982	3932	4064
  35/9-6 S	07.12.2010	3624	3691
  35/9-9	18.11.2013	3128	3171
  35/9-11 A	21.05.2014	3624	3701
  35/9-11 S	15.04.2014	3624	3701
  35/10-1	16.01.1992	3509	3649
  35/10-2	22.08.1996	4368	4450
  35/10-4 S	10.10.2018	3845	4010
  35/10-7 A	27.12.2021	3584	3605
  35/10-7 S	11.12.2021	3489	3545
  35/11-1	06.08.1984	2648	2684
  35/11-2	04.12.1987	3615	3712
  35/11-3 S	09.09.1989	3693	3764
  35/11-4	29.12.1990	2825	2918
  35/11-4 R	27.01.1992	2835	2928
  35/11-5	03.11.1991	3467	3533
  35/11-6	20.04.1992	3773	3864
  35/11-7	29.09.1992	2592	2687
  35/11-10	23.06.1997	2818	2950
  35/11-17	01.05.2014	2847	2889
  35/11-18	27.09.2015	3711	3759
  35/11-18 A	16.12.2015	3808	3928
  35/11-20 B	15.09.2016	4900	5075
  35/11-21 A	17.10.2018	2897	2931
  35/11-21 S	05.09.2018	2771	2800
  35/11-22 S	02.02.2019	3495	3565
  35/11-23	06.11.2019	2911	2977
  35/12-1	24.04.1992	2921	3003
  35/12-4 S	26.06.2011	3324	3534

• Wellbores with cores

  Wellbores with cores

  Wellbore name	Wellbore completion date	Core length [m]
  30/3-2 R	16.02.1981	47
  30/3-4	12.06.1985	42
  30/3-5 S	19.06.1992	17
  30/6-2	11.12.1979	3
  30/6-11	30.03.1983	12
  30/6-16	21.01.1985	23
  30/6-17 A	18.03.1986	22
  30/6-17 R	04.02.1986	24
  30/6-22	13.07.1988	28
  30/6-23	01.07.1990	27
  30/7-7	01.07.1979	9
  30/9-5 S	19.07.1985	11
  31/4-2	15.11.1979	5
  31/5-7	06.03.2020	52
  34/2-2 R	08.05.1981	10
  34/2-4	11.06.1985	11
  34/3-1 S	10.09.2008	61
  34/3-2 S	30.12.2009	27
  34/3-3 S	19.11.2011	80
  34/4-5	06.04.1984	58
  34/5-1 S	13.03.2010	48
  34/6-2 S	05.11.2012	54
  34/6-3 S	24.09.2014	75
  34/6-5 S	08.06.2021	103
  34/8-1	08.03.1986	21
  34/10-7	23.03.1980	54
  34/10-9	09.05.1980	37
  34/10-15	12.12.1982	36
  34/10-19	06.12.1983	2
  34/10-35	01.07.1992	66
  34/10-38 S	29.05.1995	0
  34/10-54 A	18.04.2014	14
  34/10-54 S	11.02.2014	20
  34/11-2 S	17.05.1996	16
  35/3-2	26.10.1980	2
  35/4-1	24.05.1997	28
  35/9-6 S	07.12.2010	12
  35/9-11 A	21.05.2014	41
  35/10-1	16.01.1992	84