Removal of paraffin, a waxy compound found in many crude oil formations, from producing oil wells is of critical economic importance. As pointed out by the U.S. Department of Energy, "thousands of oil wells have been abandoned prematurely leaving in some instances up to 90-percent of the oil" in the formation because paraffin problems reduced well production below economically feasible levels. Unless removed, according to Halliburton oilfield services, "paraffin gradually builds up in a well bore restricting the flow of oil until it is shut off altogether."
- Skill level:
Things you need
- Laboratory analysis of produced oil
- Hot-oil service truck
Analyse the composition of the oil produced from the well where paraffin is suspected as the cause of declining production. As noted by research at the Texas Tech Department of Petroleum Engineering a different hydrocarbon compound asphaltene, often found in crude oil where paraffin is present, causes similar problems. Test the produced crude to determine that paraffin and not asphaltene is the real issue. Methods used to control and remove paraffin are not effective in controlling and removing asphaltene. As an example thermal methods are often effective in treating a paraffin problem because paraffin melts at a temperature between 40-120 degrees C. Asphaltene however does not melt and does not decompose below temperatures of above 149 degrees Celsius.
Utilise the most simple and economical method for controlling and removing paraffin before trying a more complex and expensive method in the interest of profitability. According to the Petroleum Engineering Department at Texas Tech University, the thermal method, involving the introduction of an external source of heat into the well-bore to melt paraffin deposits is the most widely used technique due to simplicity and low-cost.
Perform a hot oil treatment using an oilfield service company that provides these services. The process involves circulating oil heated to 65.6 to 149 degrees Celsius down the casing, the large diameter pipe that lines an oil well-bore and back up the tubing, the smaller piping inside the casing through which oil is moved from the producing formation to the surface. The hot oil pumped down-hole melts paraffin deposits inside the tubing, allowing it to be lifted up and out of the well with the produced oil. Produced oil stored on-site is used for the process. The oil is heated and pumped by a truck-mounted boiler and pump brought to the site by a contractor.
Review and evaluate production rates from the well periodically after the well has been treated. Hot-oiling should restore production levels significantly and should be repeated whenever production declines notably. Periodic treatments should control and remove paraffin effectively, maximising well production.
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- U.S. Department of Energy: Microbial Cleanup of Paraffins.
- Halliburton Oilfield Services: Paraffin and Asphaultene Control.
- Texas Tech Department of Petroleum Engineering: Review of Paraffin Control and Removal in Oil Wells Using Southwestern Petroleum Short Course.
- One Petro: Formation Damage Related to Hot Oiling Abstract.