SAND CLEANING STATFJORD C FIELD TESTSAND CLEANING STATFJORD C FIELD TEST

Stavanger 18 – 19 January 2006Stavanger 18 – 19 January 2006Henrik Dannström, MATOR ASHenrik Dannström, MATOR AS

CURRENT PRACTICE ON THE NORWEGIAN SHELFCURRENT PRACTICE ON THE NORWEGIAN SHELF

Solids are normally handled in dedicated treatment units.

In most cases jetting water and associated solids are treated separate from main produced water stream.

Solids are reinjected, treated to achieve discharge quality or sent onshore for disposal.

BACKGROUNDBACKGROUNDDischarge quality governed by

REGULATIONS RELATING TO CONDUCT OF ACTIVITIES IN THE PETROLEUM ACTIVITIES (THE ACTIVITIES REGULATIONS) Section 59 discharge of cuttings, sand and solid particles

Cuttings from drilling and well activities, sand and other solid particles shall not be discharged to sea if the oil content of formation oil, other oil or base fluid in organic drilling fluid is more than ten grams per kilogram of dry matter.

Dedicated sand treatment not available on Statfjord C. Statoil therefore wanted in 2005 to investigate sand treatment

methods utilising existing equipment (Flash Tank CD2015).

CONCEPT STAGESCONCEPT STAGES

1. Theoretical evaluation optional cleaning methods

(mechanical, steam, chemical) suitability of CD2015 for selected

method (pressure, temperature, materials, instrumentation etc)

sampling and analysing methods→ Decision to investigate condensate wash

2. Laboratory test washing of sand with condensate

→ Decision to proceed with field test

TEST SET-UP, PILOT SCALETEST SET-UP, PILOT SCALE

Process and test separator jetting water and –sand routed batchwise in to CD2015. Excess water drained between jettings.

TEST CONDITIONS, PILOT SCALETEST CONDITIONS, PILOT SCALE

Volumetric flow rate to ensure fluidisation of sand in one of three jetting sections

Fluidisation factor (F) to be higher than 0.0011)

gDLdpnFls

)(22

2

1) Tippets, R Priestman G ”Liquid Jet Fluidisation and Solids Wash Out”

TEST CONDITIONS, PILOT SCALETEST CONDITIONS, PILOT SCALE

Operating pressure to ensure liquid phase condensate in wash section

TEST CONDITIONS, PILOT SCALETEST CONDITIONS, PILOT SCALE

Mixing of condensate and sand / water- in–line mixer used

Condensate flow rate to fit purpose- tested with 0.1 – 0.2 vol-% of water flow rate

Recirculation- until desired oil-on-sand concentration achieved

Disposal of hydrocarbons- flashing / disposal through flare and skimming to reclaimed oil sump

TEST SET-UP, PILOT SCALETEST SET-UP, PILOT SCALE

ANALYZING METHODSANALYZING METHODS

Sampling Concentration and analysis Filtering 1.2 µm / 5.0 µm Weighing (correction for OiW) – washing – re-weighing Method accurate down to 0.2 wt%. Method to be modified for floating installations

Retorte – accuracy down to 0.5 – 1.0 wt%, requires larger sample volumes

IR / Infracal for OiW

TEST RESULTS, PILOT SCALETEST RESULTS, PILOT SCALE

Inlet separator sand.Condensate 0,1 vol-%

0,0

20,0

40,0

60,0

80,0

100,0

120,0

140,0

160,0

180,0

00:00 00:14 00:28 00:43 00:57 01:12 01:26 01:40 01:55 02:09

Runtime (hr:min)

(mg/

l)

-

10,0

20,0

30,0

40,0

50,0

60,0

(%)

Sand+oil (mg/l)

Sand (mg/l)

Oil [wt-%]

Start kondensat

TEST RESULTS, PILOT SCALETEST RESULTS, PILOT SCALE

Test separator + CD 2072 sand.Condensate 0,2 vol-%

0,0

20,0

40,0

60,0

80,0

100,0

120,0

140,0

160,0

180,0

00:00 00:14 00:28 00:43 00:57 01:12 01:26

Runtime (hr:min)

(mg/

l)

-

10,0

20,0

30,0

40,0

50,0

60,0

(%)

Sand+oil (mg/l)

Sand (mg/l)

Oil [wt-%]

Start condensate

TEST RESULTS, PILOT SCALETEST RESULTS, PILOT SCALE

POSITIVE: Promising results in terms of cleaning

efficiency, although 10 g/kg not was achieved

CD2015 well suited for purpose Full scale test may easily be carried out

based on same principle

NEGATIVE: Mechanical failure (leakage) led to

modifications on site and reduced capacity

Reduced sand concentration over time

CONCLUSION:Results promising enough to proceed with full scale

field test

TEST SET-UP, FULL SCALETEST SET-UP, FULL SCALE

Major changes to pilot test:

- all three jetting sections utilised

- larger flow rate (larger pump, hoses, lines, valves)

- more instrumentation

- longer test period

- more analysing equipment

TEST SET-UP, FULL SCALETEST SET-UP, FULL SCALE

Pump210 m3/h 10 barg

Condensate feedto in-line mixer

TEST CONDITIONS, FULL SCALETEST CONDITIONS, FULL SCALE

Volumetric flow rate to ensure fluidisation of all sand in vessel

Tie-in such that all water and sand in vessel are circulated

Operating pressure to ensure liquid phase condensate in wash section

Mixing of condensate and sand / water. In-line mixer used.

Water level 50% - 70% of vessel height Condensate flow rate to fit purpose Recirculation Disposal of hydrocarbons

TEST RESULTS, FULL SCALETEST RESULTS, FULL SCALE

Results from 1:st sand batch circulation

Test 1Condensate 0,1 - 0,15 vol-%

33

8 100

910 18

75

9777

136

95

1619 13 11

148

0

20

40

60

80

100

120

140

160

180

200

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00

Runtime (hr:min)

Oil

on s

and

(g/k

g)

-10

40

90

140

190

240

Oil

in w

ater

(mg/

l)

Oil on sand

OiW

Start condensate

Stop condensateSkimming of oil

TEST RESULTS, FULL SCALETEST RESULTS, FULL SCALE

Results from 2:nd sand batch circulation

Test 2Condensate 0,1 - 0,15 vol-%

32

75

7

61

11 20

0

20

40

60

80

100

120

140

160

180

200

00:00 01:00 02:00 03:00 04:00

Runtime (hr:min)

Oil

on s

and

(g/k

g)

0

20

40

60

80

100

120

140

160

180

200

Oil

in w

ater

(mg/

l)

Oil on sand

OiW

Start condensate

TEST RESULTS, FULL SCALETEST RESULTS, FULL SCALE

Results from flow regime testClampon sand data

0

0,5

1

1,5

2

2,5

15:00 16:00 17:00 18:00

Time

Leve

l

Sand rate (g/s)CloseOutlet 1,2

CloseOutlet 3

CloseOutlet 4

Stop

Open Outlet 4

Open Outlet 3

Open Outlet 2

Open Outlet 1

CloseInlet 3

TEST RESULTS, FULL SCALETEST RESULTS, FULL SCALE

SUMMARY

Demonstrated ability to achieve discharge quality for oil wetted sand by means of condensate washing.

Associated water quality well below discharge requirements.

Overall condensate consumption to achieve cleaning of 1 week of accumulated jetting solids approximately 1 m3, of which 20 - 30% reclaimed.

BATCH PROCESS REQUIREMENTSBATCH PROCESS REQUIREMENTS

Vessel with holding capacity for separator / process vessel jetting inventory

Pumparound system for vessel inventory, with pump discharge pressure above condensate flash point

Flow capacity and internal distribution arrangement to ensure fluidisation of solids

Suitable mixer and choke Condensate with appropriate qualities Means for discharge of flashed and gravity

separated hydrocarbons

CONCLUSIONCONCLUSION

Client objective of finding alternative means of solids treatment identified.

Concept is oil extraction from sand using condensate. This can be achieved in several configurations. One batch configuration found suitable for Statfjord C.

Technology qualification next step towards implementation as permanent installation.

Implementation of concept on other facilities subject to feasibility evaluation.