Aug 18 (Reuters) - Private investment firm Raisa Energy

is selling a package of oil and gas wells across numerous U.S.

shale basins that may fetch around $1.5 billion, people familiar

with the matter said.

The sale, which is in its early stages, is not guaranteed

and the final price could fluctuate depending on market

conditions and other factors, these sources said, asking not to

be named because the process is confidential.

TPH, the energy-focused investment banking arm of boutique

advisor Perella Weinberg Partners ( PWP ), is advising Raisa on

the effort, they added.

Raisa did not respond to a comment request. Perella Weinberg ( PWP )

declined comment.

The assets being marketed by Raisa are known in the oil and

gas industry as non-op, meaning the owner contributes a portion

of the drilling costs and other expenses and gets a share of the

revenue from the sale of hydrocarbons in return. Meanwhile,

another producer takes charge of the wells' day-to-day

operation.

Such non-op positions are attractive to energy producers

that specialize in such assets, or financial investors who can

pocket steady returns without needing operating knowledge.

Roughly half of the production from the Raisa assets

is natural gas, with total net production around 63,000 barrels

of oil equivalent per day, one of the sources added.