Purasolve PWD is designed to clear up problems associated with paraffin and asphaltene. Purasolve PWD is a non-evaporative, non-petroleum biobased solvent developed to “thin or dissolve” paraffin and asphaltene deposits safely which improves pumping efficiency of crude oils. It is the ideal solution for paraffin wax in oil wells.
Benefits of Purasolve PWD
Purasolve PWD is a powerful non-evaporative solvent that can replace hazardous solvents. It is a new counteracting formulation comprised of plant-based ingredients. Contradictory to the traditional solvents, the benefits of Purasolve PWD include the following features:
- Non-toxic – Safe for workers to use
- Non-hazardous – Safe to transport and store
- Non-flammable – Flashpoint 73° C (164° F)
- Ultimately biodegradable – Safe for the environment
- 100% Biobased – Derived from renewable resources
- Removed in normal refining procedures
Purasolve PWD is a safe and effective substitute for eliminating paraffin and asphaltene deposits. It can be used as either a stand-alone solvent-based treatment or concurrently with hot oiling methods.
How Purasolve PWD Works
Purasolve PWD makes the hot-oiling method more effective as it escalates the solvency development of the hot oil and holds the melted paraffin in solution even after the oil cools down. Depending upon the amount of paraffin and/or asphaltenes present Purasolve PWD may be introduced into a hot-oiling process at 100% concentration at a varying ratio of 0.5% to 5% of the crude oil volume.
Purasolve PWD will “thin and dissolve” the paraffin and asphaltene deposits so that the discharge is greater through the tubing, lines, pumps and valves without causing damage. By melting the deposit, paraffin and asphaltenes can be efficiently extracted from storage tanks, shipping containers and tanker trucks. As a result of the nature of the biobased solvents, Purasolve PWD does not need to be removed from the melted deposits and can enhance the production process of crude oil.
Oil Production Wells & Paraffin Build-Up
There are several contributing reasons why oil wells may have reduced production. Some of the factors are naturally occurring, but others are caused by poor production or are well-specific and can often be fixed by adding Purasolve PWD. Natural causes include streaming potential due to the flow of the oil and temperature drop at the face of the formation due to the expansion of fluids as they enter the wellbore. Two wells adjacent in the same field may have two differing crude oil characteristics pumping from the same reservoir, therefore, crude oil paraffin and asphaltene content and their impact on production are “well-specific” in nature. Additional to the paraffin deposits, while containing asphaltenes, they may also contain resins, gum, salt crystals, scales, clay, silts, sand, and water emulsions.
Further contributors to the deposition may be poor production practices such as attempting to pump more than the well’s capacity, or the injection of cool fluids including surfactants, acids and solubilisers. Although hazardous solvents such as Benzene, Xylene and Toluene have traditionally been used to remove deposits, they have been known to create other problems related to worker and environmental safety.
Therefore, where paraffin and asphaltene deposits are the primary reason for a decline in production, the introduction of Purasolve PWD as part of the treatment process is designed to eliminate these deposits in flow lines, tubing, valves, pumps, tanks, etc. with minimal downtime, and will improve life-cycle maintenance costs of equipment parts.
Characteristics of Paraffins
Paraffins are straight or branched chain non-polar alkanes of relatively high molecular weight. Their chains usually consist of 20 to 60 carbon atoms with a melting range of 36° to 102° C (98° to 215° F). Asphaltenes are different; they are high molecular weight cyclic aromatic compounds that usually contain nitrogen, oxygen and/or sulfur in their molecular structure and melt at a higher range than paraffins. Asphaltenes are usually negatively charged polar compounds. In general, the lower the API gravity of the crude, the more asphaltene is present, for example, a crude of 9 API gravity contains about 82% asphaltene, whereas a crude of 41 API gravity contains only about 3% asphaltene.
It is the precipitation of these two hydrocarbons which leads to the problems in production or operation, not their mere presence in the crude oil. The precipitation and deposit of paraffin and asphaltenes are generated by a change in equilibrium conditions surrounding the production of petroleum, including pressure, temperature, flow rates and/or electrostatic effects.
Causes of Paraffin Build-Up
There is a significant pressure drop and cooling when the crude oil moves from the formation into the wellbore which is due to the expansion of oil and gas at the face of the production. There is also a buildup of streaming potential due to the flow of petroleum. Due to this cooling and the electrostatic effects of the polar nature of the asphaltenes, they can start to deposit at the formation. Often, heavy hydrocarbon buildup in the formation is further caused by the sudden cooling of the formation due to certain work-over operations such as acidizing or other operations that introduce cold fluids. When the cold acid, or other fluid, reaches the formation it may cool the formation below the cloud point of the oil (the temperature at which the paraffin precipitates out of solution). The paraffin and asphaltene may be deposited into the formation if they fall out of the solution. Once production is resumed, the formation temperature returns to its normal ambient temperature.
Methods for Removing Paraffin
A common method used to remove paraffin and asphaltene is hot fluid treatment. This treatment removes these deposits by using hot oil/diesel, hot water or steam. Although these traditional methods perform by melting the deposits, melted paraffin and asphaltenes can deposit in the formation when the hot oil introduced into the formation becomes saturated with the paraffin and asphaltenes, and the formation temperature becomes lower than the cloud point of the hot oil.
As a result under these circumstances, precipitation will occur and can cause permeability reduction and damage to the formation.
The most popular method for removing paraffin and asphaltene deposits has historically been the use of solvents such as Benzene, Xylene, Toluene and Chlorinated Solvents. This method is also the most dangerous. While effective at removing these deposits, they are extremely hazardous for workers and the environment. For example, Carbon Disulfide has been banned in some countries because it is explosive with a flashpoint of -30° C (-22° F), and is highly toxic.
Other complications associated with traditional solvents include:
- Benzene is extremely flammable and is a carcinogenic compound.
- Xylene is highly flammable, may cause damage to the liver and kidneys, and affects the central nervous system.
- Toluene is highly flammable, produces toxic decomposition products, may cause damage to the liver and kidneys, and affects the central nervous system.
- Chlorinated Solvents also have fire and health hazards, but in addition to the safety issues, they damage the catalyst used in the refinery process.
In addition to the health and safety problems associated with “traditional” solvents, if the solvents are not removed from the well when they reach their saturation level, the melted paraffin will precipitate out of the solution and lead to “clogging” problems. Therefore, these solvents should be removed quickly with extreme caution.
Although naturally occurring heavy hydrocarbons such as paraffin, wax, asphaltene and tar are often referred to as heavy deposits they are among the easiest to solve by improving your pumping solutions. By introducing Purasolve PWD into the treatment process, production efficiencies can be increased from 25% to 75% or even 100%.