Updated from 1:57 p.m. EDT

Higher prices and consistently strong consumer demand helped several oil and gas companies exceed analysts' quarterly earnings estimates, with

Conoco

( COC.A) reporting that its net income quadrupled and

Enron

( ENE), the nation's largest trader of natural gas as well as electricity, posting a 30% profit increase.

Houston-based Conoco reported net income of $460 million, or 73 cents a diluted share, in its second quarter, up from net income of $114 million, or 18 cents a share, in the comparable quarter a year earlier. Conoco's second-quarter earnings per share were 3 cents higher than the consensus estimate among analysts surveyed by

First Call/ Thomson Financial

.

The integrated oil and gas company cited the increase in crude oil and natural gas prices, a 6% jump in its global production, and stronger demand for refined products for its stellar revenue. Conoco's quarterly revenue rose to $9.5 billion, up 50% from the same period a year ago.

Despite the results, Conoco's Class A shares finished Monday regular trading down 9/16, or 2.5%, at 21 5/8.

Meanwhile, shares of Enron were little changed after the company reported second-quarter net income of $289 million, or 34 cents a diluted share. The Houston-based company, which markets and trades natural gas, wholesale power and other commodities as diverse as coal and fiber-optic bandwidth, reported net income of $222 million, or 27 cents a share, a year earlier. Its current earnings top the Wall Street consensus estimate by 2 cents a share.

Enron's $16.9 billion second-quarter revenue number was 75% higher than the $9.7 billion in revenue reported a year earlier for the same period. The Houston-based company attributed its strong earnings growth to a nearly 40% increase in its wholesale energy business volume. Second-quarter earnings from the wholesale group's commodity sales and services business ballooned to $442 million, a fivefold increase from a year ago.

Enron finished flat at 73.

Independent power producer

Calpine

(CPN)

soared past earnings estimates, with second-quarter net income of $51.7 million, or 37 cents a share, 13 cents above analysts' consensus estimate. The company's quarterly earnings were more than double last year's second-quarter earnings of $17.6 million, or 15 cents a share.

The San Jose, Calif.-based company's revenue number rose to $363.7 million, up nearly 80% from $196.6 million for the same year-ago period. Calpine, which relies on natural gas-fired power generation and is the nation's largest producer of renewable geothermal energy, attributed the jump in its quarterly earnings to increased power demand and higher energy prices in some of its U.S. markets as well as recent acquisitions of geothermal steam fields and energy facilities.

But a bout of profit-taking sent shares in the company down Monday. Calpine closed down 2 7/8, or 4%, at 70. The stock hit a 52-week high of 77 1/2 July 18, but has since slipped.

Calpine also announced Monday that it plans to sell $800 million of a two-part debt offering in a deal expected to be wrapped up by next week. Proceeds from the debt sale will likely be used to finance the construction, development and acquisition of more power generation facilities, and to refinance existing debt, according to company officials.

One company that was unable to benefit fully from higher oil prices in the second quarter was Oklahoma City-based

OGE Energy

(OGE) - Get Report

, whose net income fell from the previous year.

OGE Energy's recently acquired subsidiary, natural gas operator

Enogex

, posted a $1 million, or 20%, jump in net income for the quarter, compared to a year ago. But Enogex's gains were offset by increased operating expenses at OGE's electric utility subsidiary,

OG&E

, and money spent on new retirement program enhancements.

OGE Energy's reported net income of $31.7 million for the second quarter, $6 million less than the same year-ago period. It posted net earnings per share of 41 cents, an 8-cent drop from the previous year and 9 cents below the consensus estimate among Wall Street analysts surveyed by First Call/Thomson Financial.

OGE Energy's quarterly operating revenue was $726.9 million, up sharply from $450.9 million a year earlier. But a $31.6 interest expense related to the company's acquisition of Enogex and increased taxes cut the company's operating income by more than half.

OGE Energy finished down 11/16, or 3.5%, at 18 15/16.