Independent oil refiner and marketer Marathon Petroleum Corporation MPC is gearing up to release its second-quarter results on Aug 2. This time around, one of the key contributors to the Findlay, OH-based downstream operator’s earnings — its Refining & Marketing division — is likely to have benefited from the ongoing momentum in fuel demand and margins.While Marathon also has a pipeline transportation unit, in this article, we take a look at the factors that could potentially impact the refining unit and its importance in shaping the company’s overall performance.Click here for a complete rundown of the company’s expected Q2 performance.A Look at Marathon’s Refining & Marketing Performance in Q1The Refining & Marketing segment reported an operating income of $768 million, turning around from the year-ago loss of $598 million. The improvement primarily reflects higher year-over-year margins and throughputs.Specifically, the refining margin of $15.31 per barrel improved significantly from $10.16 a year ago. Total refined product sales volumes were 3,293 thousand barrels per day (mbpd), up from the 3,067 mbpd in the year-ago quarter. Throughput rose from 2,565 mbpd in the year-ago quarter to 2,833 mbpd but missed the Zacks Consensus Estimate of 2,846 mbpd. Capacity utilization during the quarter was up from last year’s 83% to 91%.Higher Margins to Boost Q2 Segment IncomeMPC is expected to have benefited from the strength in refining margins. In the first quarter of 2022, the Zacks Rank #1 (Strong Buy) company’s refining margin of $15.31 per barrel improved significantly from $10.16 a year ago. Moreover, throughput rose from 2,565 thousand barrels per day (mbpd) in the first quarter of 2021 to 2,833 mbpd. The positive momentum is most likely to have continued in the second quarter, thanks to a marked improvement in fuel demand on the back of rebounding road and airline travel, which pushed up crude differentials and margins. Consequently, the Zacks Consensus Estimate for Marathon Petroleum’s Refining & Marketing segment operating income is pegged at $3.4 billion, increasing exponentially from the prior-year quarter’s profit of just $224 million. This is likely to have buoyed the second-quarter results of Marathon Petroleum.You can see the complete list of today’s Zacks #1 Rank stocks here.Overall Earnings & Revenue ProjectionsThe Zacks Consensus Estimate for MPC’s second-quarter earnings is pegged at $9.17 per share, suggesting a whopping 1,268.66% surge on the prior-year quarter’s reported figure of 67 cents. For quarterly sales, the consensus mark of $33.3 billion suggests a rise of 11.5% from the year-earlier quarter’s reported number.Important Energy Releases So FarWhile we wait till tomorrow for MPC to come out with its Q2 numbers, let’s take a look at two key energy releases so far.Schlumberger SLB, the largest oilfield contractor, announced second-quarter earnings of 50 cents per share (excluding charges and credits), which beat the Zacks Consensus Estimate of 40 cents. SLB recorded total revenues of $6.8 billion, outpacing the Zacks Consensus Estimate by 7.8%.Schlumberger’s strong quarterly earnings resulted from higher sales of exploration data licensing and strong drilling activities in land and offshore resources in North America and the international market. In further good news for investors, SLB revised its 2022 revenue outlook upward to at least $27 billion. This suggests that it expects year-over-year revenue growth in the high-teens compared with the prior projection of mid-teens. Increased participation in growth of drilling and completion activities across the world brightened Schlumberger’s outlook.U.S. integrated behemoth Chevron CVX reported adjusted second-quarter earnings per share of $5.82, beating the Zacks Consensus Estimate of $5.02 and surging from the year-earlier quarter's profit of $1.71. The outperformance could be attributed to robust commodity prices and product margins, which propelled both CVX segments to better-than-expected bottom line. The company generated revenues of $68.8 billion. The sales figure beat the Zacks Consensus Estimate of $55.8 billion and increased 82.9% year over year.Chevron recorded $13.7 billion in cash flow from operations compared to $7 billion a year ago. The soaring cash flow could be attributed to strong price realizations in the upstream business. Importantly, Chevron’s free cash flow for the quarter was $10.6 billion. Further, Chevron paid $2.8 billion in dividends and bought back $2.5 billion worth of its shares.Europe’s largest oil company Shell plc SHEL reported second-quarter earnings per ADS (on a current cost of supplies basis, excluding items — the market’s preferred measure) — of $3.06. The bottom line came in above the Zacks Consensus Estimate of $2.91 and surged from the year-earlier quarter’s earnings of $1.42 per ADS, backed by stronger commodity prices and refining margins. Shell’s revenues of $103.1 billion were up significantly from second-quarter 2021 sales of $61.8 billion.Meanwhile, Shell repurchased $5.5 billion of shares in the second quarter. The energy group also announced that it completed the $8.5 billion buyback program scheduled for the first half of 2022 on Jul 5. Moreover, SHEL expects another $6 billion of repurchases for the third quarter.Stay on top of upcoming earnings announcements with the Zacks Earnings Calendar. Just Released: Zacks Top 10 Stocks for 2022 In addition to the investment ideas discussed above, would you like to know about our 10 top picks for the entirety of 2022? From inception in 2012 through 2021, the Zacks Top 10 Stocks portfolios gained an impressive +1,001.2% versus the S&P 500’s +348.7%. Now our Director of Research has combed through 4,000 companies covered by the Zacks Rank and has handpicked the best 10 tickers to buy and hold. Don’t miss your chance to get in…because the sooner you do, the more upside you stand to grab.See Stocks Now >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Chevron Corporation (CVX): Free Stock Analysis Report Schlumberger Limited (SLB): Free Stock Analysis Report Marathon Petroleum Corporation (MPC): Free Stock Analysis Report Shell PLC Unsponsored ADR (SHEL): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research