Damage during drilling

1-Tubing Damage
2-Matrix Damage
3-Deposition within Porous Formation
Reason for Scale Control: Tubing Damage
•Tubing ID Restriction
1-Constrained production
2-Often layered with scale, wax, asphaltene, etc.
•Completion components blocked with scale
1-Gas Lift Mandrels
2-SSSV
3-Nipples, ..etc
•Corrosion under scale deposition
1-Bacterial / H2S
2-Pitting
3-Loss of steel integrity
Reason for Scale Control: Matrix Damage
1-Hydrocarbon flow through water-saturated matrix
2-Scale deposition restricts flow
3-Scale reduces matrix permeability
4-Complete scaling of pore throat not likely; however,
5-Small quantity of scale =large loss in permeability
6-Large loss in permeability =significant reduction in productivity
Organic Deposit
A type of damage in which heavy hydrocarbons precipitate when temperature or pressure is reduced.
1-These deposits are commonly located in the tubing,gravel pack and perforations, or inside the formation . The injection of cold treating fluids promotes the formation of organic deposits.
2-Organic deposits such as paraffins or asphaltenes are resolubilized using aromatic organic solvents such as toluene or xylene.
3-Small amounts of alcohol help to further dissolve asphaltenes.
Organic deposits are heavy hydrocarbons (paraffins or asphaltenes) that precipitate as the pressure or temperature is reduced.
They are typically located in the tubing, perforations or formation.
1. Paraffins: (dissolved in oil)
Paraffins are the simplest of hydrocarbons. They are composed of only carbon and hydrogen atoms, and the carbons occur as an unbranded chain.
2. Asphaltenes: (undissolved, but suspended as a colloid in oil)
Asphaltenes are organic materials consisting of condensed aromatic and naphthenic ring compounds with molecular weights of several hundred to several thousand. In “solution,” they usually exist as a colloidal suspension,
3. Tar:
-Tar is simply an asphaltene or other heavy-oil deposit. It cannot be removed by acid or mutual solvents. Removal requires dispersion in an aromatic solvent, and energy is typically necessary to achieve removal.
4. Resins :
-(Peptizing agent, dissolved in oil, help suspend asphaltene in oil)
5. Wax:
-A combined deposit of paraffins, asphaltenes, resins, mixed with clays, sand, and debris (dissolved in oil)