CYCLOTECH Sand Receiving and Cleaning Systems

Efficient, compact and robust post-separation treatment technology

M-I SWACO designed CYCLOTECH sand receiving and cleaning systems to provide an efficient, compact and robust solution to post-separation treatment. The scope of this post-separation function largely depends on the method of solids disposal. Typically, disposal is accomplished either overboard, through solids re-injection or in dedicated landfills.

The main functions of the CYCLOTECH sand receiving and cleaning systems are:

Receive: Receive raw, dirty sand from a production separator or other solids accumulator via a jetting sequence. All disposal options will require this function
Clean: Remove hydrocarbons from the sand and the associated water. The requirements for this function will be most severe if solids disposal is overboard
Discharge: Discharge clean sand in clean water. This function is straightforward for sea and reservoir disposal options but requires a bagging solution or alternate for the landfill option.

System Design

The main elements of the system are:

CYCLOTECH MC series desanding hydrocyclones. The MC-10 (½-in NB), MC-25 (1-inNB), the MC-50 (2-in.NB) and the MC-100 (4-in.NB), providing particle separation down to sizes ranging from 5 to 40 microns, respectively. Materials of construction are engineering grade alumina ceramic as standard or reaction-bonded silicon carbide for ultimate wear resistance
Integrated Conical-bottomed Solids Accumulator. To collect and process the sand. The accumulator can be sized to provide any solids hold-up requirement and has a conical bottom to maximize solids removal efficiency
CYCLOTECH Sandscape. Proprietary technology designed to draw solids in a controlled concentration from the bottom of the accumulator. The SANDSCAPE boosts the pressure to allow the slurry to be routed back to the CYCLOTECH desanding hydrocyclone inlet. It is located externally to the accumulator. The motive fluid is normally a higher-pressure, clean-water source. The SANSCAPE is constructed usually of carbon steel or stainless steel outer housing with replaceable high wear-resistance reaction-bonded silicon carbide cartridge-style internals.
Typical sand discharge specifications delivered by the CYCLOTECH sand cleaning systems include:

Oil on sand – < 0.5% wt
Oil on water – < 30 mg/l

Cleaning Function

To meet the oil-on-sand specification, the oil-on-sand is removed by:

Attrition forces between the sand and the inner cyclone wall generated by the high-intensity shear fields of the CYCLOTECH MC Series desanding hydrocyclones
Attrition between the sand and the CYCLOTECH Sandscape internals generated by the high-pressure, high-velocity clean-water motive fluid flow.

To meet the oil-in-water specification, the oil in the water is removed by:

Displacement of oily water with clean flush water as the re-circulation progresses. The oily water is removed from the system via the desanding hydrocyclone overflow
As the cleaning cycle progresses, the solids are re-circulated in increasingly cleaner water. Samples can be taken during the re-circulation cleaning cycle to ensure the solids and associated water meet the required specs prior to disposal.

Disposal Function

If the sand is to be disposed to sea or re-injected back into the reservoir, the CYCLOTECH Sandscape system simply pumps the solids at a controlled concentration to either an overboard disposal caisson or a solids re-injection system.

If sand disposal is at a landfill, M-I SWACO offer the following disposal options:

Removable solids accumulator
Transfer to skip. The de-watered and discharge solids are out into a standard mud box or cuttings skip
Solids bagging system. The de-watered and discharge solids are placed in a permeable bag. These bags can then be either transferred to, or emptied into, a skip or mud boxes.

The Benefits

Does not require a slurry pump
CYCLOTECH Sandscape technology controls and limits the sand concentration, regardless of the amount of sand in the accumulator. This prevents blockage problems during the clean and discharge functions and maximizes plant availability
Reduces oil-in-water as well as oil-on-sand to meet all discharge specifications
Simple, reliable, flexible and easily automated.