This document discusses several types of modular penetrometers used for in situ soil reconnaissance at sea, including the Seacalf, Hyson, NGI, Shell, Preussag, and Stingray/Seajack penetrometers. It describes the key components and operating principles of each penetrometer, which are lowered to the sea floor using cables and measure soil properties like tip resistance and lateral friction. The modular penetrometer causes the least disturbance to soils while providing valuable data for soil studies conducted at sea.

2.  in-situ measuring device
 cause least disturbance to soil
 used for reconnaissance of soils at sea
 most of the penetrometers set on sea bed are
in deep water either by
o by divers (Persian Gulf)
o from jack-up platforms
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3. • Some of the types of modular penetrometers are
1. Seacalf penetrometer
2. Hyson penetrometer
3. NGI penetrometer
4. Shell penetrometer
5. Preussag penetrometer
6. Stingray and seajack penetrometers
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4. • lowered to sea bottom by means of bearing cables and remote controlled
from the surface.
• cone of the penetrometer carries two strain gauges
– Tip resistance, 𝑅 𝑝
– Lateral friction resistance, f
o sub-sea system
o surface equipment
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6. 1. Sub Sea Unit
includes
 a ballast frame weighing 10 t
 a hydraulic cylinder - to push in the drilling string tanks
 A string of drill pipes - 36mm dia & about 30m in length -carry
the penetrometer cone.
 an inclinometer to monitor the deviation of the drilling string.
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7. 2. surface equipment comprises
• An operating winch for raising and lowering the sub sea unit
by means of two bearing cables
• A winch for extracting the drill string from the terrain by means
of carrying cable
• A central hydraulic power plant
• A recording instrument connected to the cone of the
penetrometer.
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9. HYSON PENETROMETERS
• Weighs 1500 kg , operated by divers
• held by ballast or anchored to the sea bottom
• The penetrometer cone measures the following
 The tip effort
 The total effort (tip effort + effort due to lateral friction)
• It essentially consists of:
 13 ton thrust device formed by two hydraulic jacks
 A sub sea central hydraulic power plant driven by an electric motor
 A frame carrying jacks, power plant and magazine of drill pipes
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12. NGI PENETROMETER
• developed by The Norwegian Geotechnical Institute (NGI)
• implemented from a jack -up platform
• The penetrometer cone is pushed into the soil in successive
steps by a action of the drilling string.
• The tip resistance is measured by means of a vibrating cord
electric cell.
• The unit essentially consists of
o • A 5-ton module guided and moved by the drilling string.
o • A small diameter drilling string carrying a penetrometer cone.
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13. NGI CPT operation at Ekofisk
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14. SHELL PENETROMETER
• developed by SHELL in 1970
• The unit consists essentially of
– A telescopic jack measuring 3 x 9m carrying cone of the
penetrometers
– A cone of cone angle 60 𝑜,diameter 36 mm
– A system for anchoring the unit to the sea bottom consists of a 3m-
diameter drum held the soil by negative pressure
– A pump for the application and constant maintenance of the negative
pressure inside drum
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15. • the measuring system consists of two strain gauge cells to
measure:
1. The cone resistance, 𝑅 𝑝
2. The lateral force of friction, f
• the unit weights about 6 to 7 t
• these unit is not yet operational.
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16. PREUSSAG PENETROMETER
• fully automatic – operational in 1976
• frame of the penetrometer, which weighs 30 t, is lowered by
5" drilling string
• measures the following parameters
a. The resistance 𝑅 𝑝 of the penetrometer cone.
b. The lateral force of friction, f
c. The inclination of the rods in soil
d. The natural radioactivity of the soil
e. The density of the soil
• pyramid shaped frame of the penetrometer
– height = 4m
– diameter at base = 2.85 m
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17. STRINGRAY AND SEAJACK UNITS
• developed by McClelland Engineers and NGI, in 1975-1976
• Dimensions
 base = 3 x 3m
 height = 3.5m
 Weight = 16 t
• Successfully tested in Gulf of Mexico
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18. Advantages
 least disturbance to soil
 good results in loose & dense sand
 Use of penetrometer is limited by
 excessively loose nature of the sea bottom
 presence of banks of pebbles
 highly dense sand zones where 𝑅 𝑝>5000t/𝑚2
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19. • modular penetrometer is an in situ device
causing least disturbance to soil
• study on different types of penetrometers
conducted
• operating principles & working of each type is
studied
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20. REFERENCES
1. CPT Deployment Systems, TRB Annual Meeting, Washington
DC January2006 Presented By: Mohammad T. Haider, P.E.
Fugro Consultants LP
2. Guide to cone penetration testing Onshore and near shore
By J.J.M.Brouwer(2002,First edition)
3. Fugro Singapore Pte Ltd www.fugro-singapore.com.sg
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