Exhibit 99.1

Oasis Petroleum Inc. Announces Quarter Ending September 30, 2012 Earnings

Houston, Texas — November 7, 2012 — Oasis Petroleum Inc. (NYSE: OAS) (“Oasis” or the “Company”) today announced financial results for the quarter ended September 30, 2012.

Highlights for the three months ended September 30, 2012 include:

“The momentum of our operational success continued into the third quarter, as we again exceeded our production guidance and drove down our capital cost per well,” said Thomas B. Nusz, Oasis’ Chairman and Chief Executive Officer. “The team has done a great job minimizing downtime and has continued to deliver on our completion schedule, which has allowed us to bring the total operated wells on first production to 86 for the first nine months of 2012. As production continues to grow, we now believe that the fourth quarter average daily production will range between 26.0 MBoepd and 28.0 MBoepd, and our new full-year guidance is 22.1 MBoepd to 22.6 MBoepd. Operated well costs averaged $9.0 million this quarter, including $0.3 million per well savings related to Oasis Well Services, compared to $10.5 million for the first half of the year. Even before taking into account the benefit of Oasis Well Services, our current well costs are in-line where we said we would be by year-end 2012, at an average cost of $8.8 million per well. Oasis Well Services has proven itself to be a robust value driver for Oasis on numerous fronts, including driving down well costs and increasing the efficiency and quality of our fracs. Additionally, we recently brought wells online in our Indian Hills infill pilot programs in advance of our transition to development mode, which we expect to occur in 2013.”

“We have approximately 60% of our gross operated oil volumes on our third party gathering system and expect this to grow to north of 80% by mid-year 2013 as we connect our wells in East Nesson. This gathering system provides access to numerous rail and pipeline delivery points,” Mr. Nusz added.

Operational and Financial Update

Average daily production for the third quarter of 2012 was 24,257 Boepd, an increase of 109% as compared to 11,583 Boepd in the third quarter of 2011. Sequential quarter-over-quarter average daily production increased 3,904 Boepd, or 19%. In the third quarter of 2012, 93% of production was from oil.

Average daily production by project area is listed in the following table:

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The Company’s average price per barrel of oil, without realized derivatives, was $83.71 in the third quarter of 2012, compared to $83.52 in the third quarter of 2011 and $82.36 in the second quarter of 2012. The Company’s average price differential compared to West Texas Intermediate (“WTI”) crude oil index prices was 9% in the third quarter of 2012, compared to 6% in the third quarter of 2011 and 12% in the second quarter of 2012. The Company’s differentials continued to improve in the third quarter of 2012 compared to the second quarter of 2012 due to higher quoted prices relative to WTI for Bakken crude in markets such as Clearbrook, Minnesota and Guernsey, Wyoming. This was a result of transportation capacity additions in the Williston Basin outpacing production growth along with fewer refinery constraints.

Total revenue for the third quarter of 2012 was $184.7 million compared to $87.6 million for the third quarter of 2011, an increase of 111%. Sequential quarter-over-quarter revenue growth was $35.6 million, or 24%. This increase is primarily due to a 19% increase in production and a $2.1 million increase in well services revenues in the third quarter of 2012 compared to the second first quarter of 2012.

The following table describes the Company’s producing wells by project area in the Williston Basin as of September 30, 2012:

Additionally, the Company also has a backlog of wells waiting on completion and drilling as of September 30, 2012, as shown below:

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Lease operating expenses (“LOE”) per Boe decreased $1.77, or 20%, to $7.23 per Boe in the third quarter of 2012 compared to the third quarter of 2011, and increased $0.74 per Boe, or 11%, in the third quarter of 2012 compared to the second quarter of 2012. Sequential quarter-over-quarter LOE trended up due to increased costs related to wells coming on in areas without infrastructure, and an increase in non-operated LOE in the third quarter of 2012.

Marketing, transportation and gathering expense per Boe was $1.23 in the third quarter of 2012 compared to $0.23 in the third quarter 2011 and $1.06 in the second quarter of 2012. The 16% increase from the second to the third quarter of 2012 is due to higher operated volumes flowing through third party oil gathering pipelines. While transporting volumes through third party oil gathering pipelines increases marketing, transportation and gathering expenses, it improves oil price realizations by eliminating trucking costs, which are reflected in the oil price differential rather than as an expense.

Production taxes as a percent of oil and gas revenues were 9.2% in the third quarter of 2012, 10.1% in the third quarter of 2011, and 9.5% in the second quarter of 2012. The Company’s effective production tax rate decreased in the third quarter of 2012 primarily as a result of additional new Montana wells subject to lower incentivized production tax rates.

Depreciation, depletion and amortization expenses (“DD&A”) totaled $57.7 million in the third quarter of 2012, $20.9 million in the third quarter of 2011, and $44.2 million in the second quarter of 2012. DD&A was $25.85 per Boe in the third quarter of 2012, $19.57 per Boe in the third quarter of 2011, and $23.87 per Boe in the second quarter of 2012. The increase in DD&A of $1.98 per Boe in the third quarter of 2012 over the second quarter of 2012 was a result of the increase in well costs in the first half of 2012 outpacing the increase in associated reserves and the addition of infrastructure assets, including Company-owned salt water disposal assets.

General and administrative expenses (“G&A”) totaled $13.9 million in the third quarter of 2012, $7.3 million in the third quarter of 2011, and $13.5 million in the second quarter of 2012. The overall increase in G&A expenses from the second quarter of 2012 to the third quarter of 2012 was primarily due to higher compensation costs from organizational growth. G&A expenses were $6.22 per Boe in the third quarter of 2012, $6.86 per Boe in the third quarter of 2011, and $7.31 per Boe in the second quarter of 2012. Amortization of restricted stock-based compensation, which is included in the aggregate G&A expense, was $2.7 million, or $1.22 per Boe, in the third quarter of 2012 as compared to $1.0 million, or $0.96 per Boe, in the third quarter of 2011 and $2.3 million, or $1.25 per Boe, in the second quarter of 2012.

As a result of the Company’s derivative activities, it incurred a net cash settlement gain of $5.2 million and a net cash settlement loss of $0.2 million in the third quarters of 2012 and 2011, respectively. In the second quarter of 2012, the Company incurred a net cash settlement loss of $1.2 million. As a result of forward oil price changes, the Company recognized a non-cash unrealized mark-to-market net derivative loss of $27.7 million and a non-cash unrealized mark-to-market net derivative gain of $71.4 million for the third quarters of 2012 and 2011, respectively. The Company recognized a non-cash unrealized mark-to-market net derivative gain of $75.8 million in the second quarter of 2012.

The Company recorded non-cash charges for the impairment of oil and natural gas properties of $36 thousand in the third quarter of 2012 related to unproved property leases that expired during the period or have been forecasted to expire under current drilling plans, as compared to $0.4 million in the third quarter of 2011 and $2.2 million in the second quarter of 2012.

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Interest expense increased $14.2 million to $21.0 million for the third quarter of 2012 compared to the third quarter of 2011 and increased $6.9 million compared to the second quarter of 2012. The $6.9 million increase was the result of additional interest expense from the Company’s issuance of 6.875% senior unsecured notes in July of 2012. Capitalized interest totaled $0.9 million in the third quarter of 2012, $1.1 million in the third quarter of 2011, and $0.8 million in the second quarter of 2012.

Income tax expense was $11.5 million for the three months ended September 30, 2012, resulting in an effective tax rate of 38.5%. The Company’s income tax expense for the three months ended September 30, 2011 was recorded at 37.0% of pre-tax net income. The Company’s effective tax rate is expected to continue to closely approximate the statutory rate applicable to the U.S. and the blended state rate of the states in which the Company conducts business.

Adjusted EBITDA for the third quarter of 2012 was $139.2 million, an increase of $76.3 million, or 121%, over the third quarter of 2011 of $62.9 million, and a 28% increase over the second quarter of 2012 of $108.5 million. For a definition of Adjusted EBITDA and a reconciliation of Adjusted EBITDA to net income and net cash provided by operating activities, see “Non-GAAP Financial Measures” below.

For the third quarter of 2012, the Company reported net income of $18.3 million, or $0.20 per diluted share, as compared to net income of $66.3 million, or $0.72 per diluted share, for the third quarter of 2011. The Company’s third quarter 2012 results were impacted by several non-cash items, including a $27.7 million unrealized loss on derivative instruments and a $36 thousand impairment of oil and gas properties. Excluding these items and their tax effect, the third quarter 2012 Adjusted Net Income (non-GAAP) was $35.4 million, or $0.38 per diluted share. Excluding similar non-cash items and their tax effect, Adjusted Net Income (non-GAAP) for the third quarter of 2011 was $21.6 million, or $0.23 per diluted share. For a definition of Adjusted Net Income and a reconciliation of net income to Adjusted Net Income, see “Non-GAAP Financial Measures” below.

Capital Expenditures

Oasis’ exploration and production (“E&P”) capital expenditures were $316.8 million for the third quarter of 2012 and $872.3 million year-to-date. The following table depicts the Company’s E&P capital expenditures by project area and total capital expenditures by category for the first, second and third quarters of 2012:

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Liquidity

On September 30, 2012, Oasis had total cash and cash equivalents of $280.3 million and short-term investments of $126.2 million. During the third quarter of 2012, Oasis issued $400 million of 6.875% senior unsecured notes due 2023. As of September 30, 2012, the Company had no outstanding indebtedness under its revolving credit facility, which had a $500 million borrowing base on September 30, 2012. Subsequent to the end of the third quarter of 2012, the semi-annual redetermination of the Company’s borrowing base was completed, which resulted in an increase to the borrowing base of its revolving credit facility from $500 million to $750 million. However, the Company elected to have the lenders’ aggregate commitment remain at $500 million.

Hedging Activity

As of November 6, 2012, the Company had the following outstanding commodity derivative contracts, all of which are priced off of NYMEX WTI and settle monthly:

Conference Call Information

Investors, analysts and other interested parties are invited to listen to the conference call:

A recording of the conference call will be available beginning at 1:00 p.m. Central Time on the day of the call and will be available until Thursday, November 15, 2012 by dialing:

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The conference call will also be available for replay for approximately 30 days at www.oasispetroleum.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included in this press release that address activities, events or developments that the Company expects, believes or anticipates will or may occur in the future are forward-looking statements. Without limiting the generality of the foregoing, forward-looking statements contained in this press release specifically include the expectations of plans, strategies, objectives and anticipated financial and operating results of the Company, including the Company’s drilling program, production, derivative instruments, capital expenditure levels and other guidance included in this press release. These statements are based on certain assumptions made by the Company based on management’s experience and perception of historical trends, current conditions, anticipated future developments and other factors believed to be appropriate. Such statements are subject to a number of assumptions, risks and uncertainties, many of which are beyond the control of the Company, which may cause actual results to differ materially from those implied or expressed by the forward-looking statements. These include, but are not limited to, changes in oil and natural gas prices, weather and environmental conditions, the timing of planned capital expenditures, availability of acquisitions, uncertainties in estimating proved reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, the condition of the capital markets generally, as well as the Company’s ability to access them, the proximity to and capacity of transportation facilities, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting the Company’s business and other important factors that could cause actual results to differ materially from those projected as described in the Company’s reports filed with the SEC.

Any forward-looking statement speaks only as of the date on which such statement is made and the Company undertakes no obligation to correct or update any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by applicable law.

About Oasis Petroleum Inc.

Oasis is an independent exploration and production company focused on the acquisition and development of unconventional oil and natural gas resources, primarily operating in the Williston Basin. For more information, please visit the Company’s website at www.oasispetroleum.com.

Contact:

Oasis Petroleum Inc.

Richard Robuck, (281) 404-9600

Director – Finance

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Oasis Petroleum Inc. Financial Statements

Oasis Petroleum Inc.

Condensed Consolidated Balance Sheet

(Unaudited)

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Oasis Petroleum Inc.

Condensed Consolidated Statement of Operations

(Unaudited)

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Oasis Petroleum Inc.

Selected Financial and Operational Statistics

(Unaudited)

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Oasis Petroleum Inc.

Condensed Consolidated Statement of Cash Flows

(Unaudited)

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Non-GAAP Financial Measures

Adjusted EBITDA is a supplemental non-GAAP financial measure that is used by management and external users of the Company’s consolidated financial statements, such as industry analysts, investors, lenders and rating agencies. The Company defines Adjusted EBITDA as earnings before interest expense, income taxes, depreciation, depletion, amortization, exploration expenses and other similar non-cash charges. Adjusted EBITDA is not a measure of net income or cash flows as determined by United States generally accepted accounting principles, or GAAP.

The following tables present a reconciliation of the non-GAAP financial measure of Adjusted EBITDA to the GAAP financial measures of net income and net cash provided by operating activities, respectively.

Adjusted EBITDA Reconciliations