Definition - What does Unconsolidated Formation mean?
An Unconsolidated Formation is a hydrocarbon formation which contains rock grains that are loosely arranged. These grains do not form a strong adherence bond between the sand and rock grains. If hydrocarbons are produced from unconsolidated formations, there are very high chances that sand will also be produced in large quantities along with the hydrocarbons due to the weak bonding.
Petropedia explains Unconsolidated Formation
A hydrocarbon formation in a reservoir can be either a consolidated formation or an unconsolidated formation. The difference between the two is that in unconsolidated formation, the grain bonding between sand and rocks or stone are loose and do not have a strong bonding between the grains. This makes drilling easy; however, a lot of sand is produced because of loosely packed grains which need to be controlled by implementing sand control procedures. This makes an additional investment to an operator working on the formation.
This is not true in consolidated sandstone. The grains are tightly packed and thus, the production of sand is not that much which is there in the unconsolidated formation, i.e., the sand production during drilling is in a controlled manner.