So-called sludge is the deposit of crude oil and its heavy fractions on storage units. This sludge causes many troubles in the handling of crude oil whether in pipelines, storage tanks, or in refineries. It leads to block pipelines, especially in cold weather and also causes blockage of the nozzles of burners.

Petroleum sludge consist of organic materials such as paraffin waxes, asphaltenes, resinous materials and other materials such as cotton pieces. Beside the organic materials, there are inorganic substances as dust, scales and water.

The factors controlling the sludge formation in petroleum storage units are oxidation, -βiectrostatic charging, coagulation, volatility and the precipitation of wax and solid components.

The technical problems attributed to sludge deposition in storage units are wasting resource, reducing holding capacity, pump malfunctioning, false measurements, corrosion, plugging, blockage and affecting basis of payment. Background Art

The previous methods did not work properly to find a radical and effective solution for this problem leading to huge economically, human and environmental losses.

Comiβntional methods are mainly manual methods as labors used to break down the sludge bonds (after opening the tank and leaving it to be gas free) then dump all the sludge inside pits causing many environmental problems besides loss of huge quantities of crude oil that can be recovered and sold by our new method or mechanical method where moving the sludge from tank to another that leads to transporting and spreading the problem without presenting a final solution.

Traditional methods require that the tank is taken out of service for long periods, thus the holding capacity of the tank will be minimized .Using these

traditional methods, labors are exposed to high risk resultant by the petroleum gases they inhale. Disclosure of invention

The main target of the invention is to reclaim and recover the hydrocarbons from the sludge accumulated in oil storage structures ( tank, tankers and gas separators) into crude oil conformable to specs , reducing the economic losses, also to expand the holding capacity of these storage units by removing the sludge and taking use of the spaces it occupy in these units.

For the first time, cleaning tanks and another storage units is a profitable process for the petroleum companies by selling the sludge in a typical crude oil form confirmable to specs which means gaining more than the normal cleaning processes costs. Closed circuit system without opening the tank accordingly no spill occurs or any poisonous gas evolves leading to protect workers from any danger they may face, like suffocation for example. Also Tanks and any other storage units are no longer taken out of service for long time, and it can be back into operation immediately if necessary. Finally, environment is completely protected by finding a radical and effective solution for the pits and the basins existing in the companies fields for sludge collecting purpose by recovering this sludge into crude oil, which means that the sludge is no longer dumped to the environment nor polluted the soil and under ground water that affects cultivating and other activities. The method proposed can be described in general as thermo-chemical method. Chemical, because the chemical introduced in the sludge to break the sludge into three components (hydrocarbon, water and inorganic sediments). In addition, all the hydrocarbon contents of sludge will be provided with a permanent floating ability for dissolving into crude oil. Thermal, in order to achieve the optimum working of the chemical in the sludge within an acceptable time. The sludge is stirred ^" and v^alme^lϊpTFόFt^

heat exchangers are temporarily piped to storage tanks, So by elevating the temperature of the mixture, the sludge will be pumped and liquefied, then at 50-60 ⁰ C the chemical will start to act as a surfactant.

Sjtep by Step Method

1- The volume of contents of the storage units is reduced to leave a 1:1 mix of sludge and crude oil.

2- Installation of closed mechanical hydraulic-Thermal circuit around the unit consist of steam boiler, pipes for pumping and drawing (usually 4 inches) , pipes for steam (usually 3 inches ), Heat exchanger where the crude oil is warmed through the steam, filter to prevent any undesirable material and gear pump for drawing and pumping.

3- Start circulating and heating after connecting the circuit on the storage unit connections , crude oil is pumped through the heat exchanger to be warmed up and raising its temperature to 50-60 ° C.

4- When the temperature raise to 50:60 ° C the chemical injected with a certain dose .

5- Repeating these steps until the sludge is broken into three components hydrocarbon, water and inorganic sediments. 6- Water is drained from the tank. The crude oil and the treated sludge is blended with another crude with mixing ratio calculated to conform the standards, sometimes the blending occurs on the same unit.

7- After transferring the treated quantity, steps from 3-6 are repeated (batch wise) until treating all the sludge in the unit. 8- In some cases the legs supporting the roof are taken out and replaced by mixers or submerged jets to help the process of the circulation and stirring.

Figure (1) Explanation

- Steam Boiler - Steam Coil - Sludge - Open Pit - Gear, Diaphragm pump - Tank - Filter - Gear pump - Heat Exchanger 0-Chemical Injection 1- Shipping Tank

Figure (2 ) Explanation

- Tank - Filter - Gear pump - Heat Exchanger - Water condensed tank - Steam Boiler - Chemical Injection