Deposition in the Formation

Streaming Potential, Cooling and Pressure Drop:
When crude oil moves from the formation into the wellbore, there is a significant pressure drop and cooling due to the expansion of oil and gas at the face of the formation. There is also a buildup of streaming potential in the formation due to the flow of oil and gas. Asphaltenes will start depositing at the formation due to the cooling effect, and due to the electrostatic effect contributed by their polar nature and the streaming potential created in the formation. Paraffins soon follow and conglomerate with asphaltenes to form what are known as tarry deposits.

Treatment with Cool Fluid:
Another reason that lead to heavy hydrocarbon buildup in the formation is the sudden cooling of the formation due to certain workover operations, such as acidizing or introducing cold crude oil. into the formation. When the cold acid or crude oil reaches the formation it may cool the formation below the cloud point of the oil (temperature at which paraffin precipitates out of solution). Paraffin and asphaltene will fall out of solution and may be deposited in the formation. Once production is resumed, the formation temperature returns to its normal temperature. However, if the formation temperature is not significantly higher than that of the cloud point of the oil, the deposited wax will stay permanently in the formation, until removed by other means.

Hot Fluid Treatment:
Damage to the formation can also be caused by hot oiling or hot water treatment. This occurs when the hot fluid and the melted wax in the crude oil and from the well bore reaches the formation, and the formation temperature is below the cloud point of the hot fluid, much of the melted paraffin will precipitate in the formation. This will cause a significant permeability decrease and formation damage. Note: By blending PARC400 with the oil it will eliminate formation damage when doing a hot oil job due to the enhanced solvency and crystal modifier properties of PARC 400 Chemical.

Solvent Treatment:
Formation damage can be caused by inferior solvents that have been saturated with paraffin and asphaltene. If the saturated solvent is left in the formation for an extended period of time, much of the dissolved paraffin will come out of solution and recrystallize. This sometimes causes blockage in areas that had no paraffin buildup in the first place.

Deposition in the Production

After oil and gas leaves the formation and move up the well, the pressure and temperature will continue to drop and hydrocarbons will be deposited in the tubing, flowline, production equipment and the storage tanks.

A significant deposit takes place at saturation level. Depending on the oil and gas quality and their temperature, the saturation level may be anywhere between the perforations and the production tank. Generally deposits of wax begin in tubing and increase as the crude oil cools.

It is important to note that once a thin film of hydrocarbon deposit is formed on a surface, the rate of further deposit accumulation is drastically increased, thus an increaded production drop curve associated with waxing off is observed.

It is also important to note that as the well is produced and the crude oil production decreases, the well will usually develop an increase in paraffin and asphaltene problems.

The main factors leading to this behavior.

A) Oil quality changes to a heavier grade which contains more paraffin and asphaltic matter.

B) As the reservoir pressure drops, oil production decreases; thus, the flow rate decreases, resulting in larger temperature gradient in the well conduit. This results in lower temperatures within the well, which leads to more hydrocarbon accumulation.

C) The decrease in production leads to slower flow of oil, which provides more opportunity for accumulation of deposit and less heat transfer from the formation by the slow moving oil.
If these deposits are not removed, the operator / producer will be faced with a decrease in production, pump problems, waxing off of the tubing and other production lines, and a possible total loss of production.

PARC400 Chemical will eliminate this aggravation by eliminating your paraffin and asphaltene problems, thus increasing your profitability and the economic value of PARC 400 Chemical treated wells.

Overview

The deposition of paraffin and asphaltene in oil & gas wells are among the most common problems leading to the deterioration of oil and gas production. However, this problem is one of the easiest to rectify with the proper PARC400 Chemical treatment.

An increase in production of 10%, 30% or even 100%, after a PARC400 Chemical formation treatment, is not uncommon in wells having formation paraffin and asphaltene problems. Some wells that have paraffin / asphaltene problems may also have a combination of other problems.
An increased in production is only possible after the removal of paraffin / asphalterne buildup that has been deposited in the formation and is restricting the inflow of production from the formation. The removal of those deposits in the formation restores permeability and again allows the free flow of oil and gas. The removal of the deposits in the tubing, flow lines, storage tanks, etc. leads to increased efficiency, decreased operational cost and minimized down time.

There are several causes leading to the deposition of paraffin and asphaltene in the formation. Some of those causes occur naturally, others are induced by production practices. 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 the fluids as they enter the well bore. Deposition induced by the production practices include hot oil treatments that do not have a blend of PARC400 Chemical with the hot oil...

Organic deposits (heavy hydrocarbon deposit) associated with reducing oil and gas production in wells are mainly paraffin and asphalterne. While paraffin & asphaltene deposits are usually the major component in these deposits, they are the problems that are readily treated with PARC 400 Chemical. Paraffin & asphaltene deposition in the formation, tubing, flow lines and other production facilities are the main cause to a decrease in production and an increase in operational problems.

No two crudes are the same. Therefore, their paraffin and asphaltene compositions are different. Paraffin deposits, in addition to containing asphaltenes, may contain resins, gums, salt crystals, scales, clays, silts, sand and water.

Paraffins are straight or branched chain nonpolar alkanes of relatively high molecular weight. Their chains usually consist of 20 to 60 carbon atoms with a melting range of 36 - 102°C (98 - 215°F). Asphaltenes, on the other hand, are high molecular weight cyclic aromatic compounds which usually contain nitrogen, oxygen and/or sulfur in their molecular structure. Their melting range is higher than that of paraffins. Asphaltenes are usually negatively charged polar compounds.

In general, the lower the API gravity of the crude, the more asphaltene present, e.g., crude of 9 API gravity contains about 82% asphaltene, whereas a crude of 41 API gravity contains only about 3% asphaltene.

The presence of paraffin and asphaltene in the crude oil does not lead to problems in production or operation. It is their precipitation that leads to those problems. The precipitation and deposits of paraffins and asphaltenes in the formation, tubing, flowline, production equipment (separator, treater, flare knock out, etc.) and especially the production and storage tanks (tank bottom sludge) are generally caused by a change in equilibrium conditions surrounding the produced oil and gas production, i.e., changes in the pressure, temperature, flow rates and/or electrostatic effects.