Exhibit 99.1

Oasis Petroleum Inc. Announces Quarter and Year Ending December 31, 2011 Earnings and Provides an

Operational Update

Houston, Texas — February 22, 2012 — Oasis Petroleum Inc. (NYSE: OAS) (“Oasis” or the “Company”) today announced quarter and year ending December 31, 2011 financial results and provided an operational update.

Highlights in 2011:

“Production more than doubled and reserves nearly doubled in 2011, as we significantly grew the business in the midst of some tough operating conditions,” said Thomas B. Nusz, Oasis’ Chairman and Chief Executive Officer. “We currently have nine rigs running and three dedicated frac crews. Three more rigs are under contract for delivery in 2012, and we expect to begin operations for Oasis Well Services at the end of this quarter. The Williston Basin continues to experience significant growth, as the overall rig count is now around 210. Over the past five years, oil production in North Dakota alone has grown from 115,142 barrels per day in December 2006 to a new record of 534,884 barrels per day in December 2011. The oil-prone Williston Basin is a highly attractive area for a growth company like ours. Our growth strategy is on target, as we grew our average daily production rate in 2011 to 10,724 barrels of oil equivalent per day, up 106% from 5,206 equivalent barrels per day in 2010.”

Financial Update

Total revenue for the fourth quarter of 2011 was $116.9 million compared to $49.1 million for the fourth quarter of 2010, an increase of 138%. Sequential quarter-over-quarter revenue growth was $29.3 million, or 33%. Total revenue for the full year 2011 was $330.4 million compared to $128.9 million in 2010.

Lease operating expenses for the fourth quarter of 2011 totaled $12.1 million, or $8.63 per Boe, a 9% increase per Boe over the fourth quarter of 2010 of $7.92 per Boe. Lease operating expenses for the full year 2011 totaled $34.1 million, or $8.70 per Boe, a 13% increase per Boe over the full year 2010 of $7.67 per Boe. This year-over-year increase was primarily due to increased costs associated with water production, salt water disposal and the continuing effects of the inclement weather during the first half of 2011. We have $57.0 million of capital in our 2012 budget allocated to infrastructure, primarily for building salt water disposal infrastructure, which is currently being deployed in our key operating areas. This infrastructure is expected to reduce the need for trucks and simplify operational logistics. We are projecting unit operating costs in 2012 to range between $6.00 to $8.00 per Boe compared to $8.70 per Boe in 2011.

Production taxes for the fourth quarter of 2011 totaled $11.8 million, or 10.1% of revenue. For the full year 2011, production taxes totaled $33.9 million, or 10.2% of revenue. Production taxes decreased in 2011 compared to 2010, at 10.7% of revenue, primarily due to the increased weighting of oil revenues in Montana, which imposes a lower production tax rate than North Dakota. Our production taxes for the year ended December 31, 2010 were primarily for oil and natural gas sales revenue associated with properties in the North Dakota portion of our West Williston project area, which generates revenue subject to an 11.5% production tax rate.

Depreciation, depletion and amortization for the fourth quarter of 2011 totaled $27.2 million, or $19.40 per Boe, compared to $13.4 million, or $19.46 per Boe, in the fourth quarter of 2010. Depreciation, depletion and amortization for the full year 2011 totaled $75.0 million, or $19.16 per Boe, compared to $37.8 million, or $19.91 per Boe, for the full year 2010. The $37.2 million increase in depreciation, depletion and amortization expense for the year ended December 31, 2011 was primarily a result of our production increases and well completions during 2011. The $0.75 per Boe decrease was due to the lower cost of reserve additions associated with our 2011 drilling activities.

General and administrative expenses for the fourth quarter of 2011 totaled $9.6 million, or $6.82 per Boe, compared to $7.6 million, or $11.05 per Boe, in the fourth quarter of 2010. General and administrative expenses for the full year 2011 totaled to $29.4 million, or $7.52 per Boe, as compared to $19.7 million, or $10.39 per Boe, for the full

year 2010. Of this $9.7 million year-over-year increase, approximately $6.5 million was due to the impact of our organizational growth on employee compensation and approximately $2.4 million was due to the amortization of our restricted stock awards. As of December 31, 2011, we had 146 full-time employees compared to 62 full-time employees as of December 31, 2010.

As a result of our derivative activities, we incurred a net cash settlement gain of $1.0 million in the fourth quarter of 2011 and a net cash settlement loss of $0.1 million in the fourth quarter of 2010. As a result of forward oil price changes, we recognized non-cash unrealized mark-to-market derivative losses of $66.5 million and $7.4 million for the fourth quarter of 2011 and 2010, respectively. For the years ended December 31, 2011 and 2010, we incurred net cash settlement losses of $3.8 million and $0.1 million, respectively. In addition, as a result of forward oil price changes, we recognized a $5.4 million non-cash unrealized mark-to-market derivative gain during the year ended December 31, 2011 and a $7.5 million non-cash unrealized mark-to-market derivative loss during the year ended December 31, 2010.

Adjusted EBITDA for the fourth quarter of 2011 was $85.9 million, an increase of $54.7 million, or 176%, over the fourth quarter of 2010 of $31.2 million. Adjusted EBITDA for the full year 2011 was $234.5 million, an increase of $152.3 million, or 185%, over the full year 2010 of $82.2 million.

The Company reported a net loss of $13.4 million in the fourth quarter of 2011 compared to net income of $1.6 million in the fourth quarter of 2010. For the full year 2011, Oasis reported net income of $79.4 million, or $0.86 per weighted average diluted share.

Capital Expenditures

Oasis’ capital expenditures (“CapEx”) were $249.6 million for the fourth quarter of 2011 and $666.0 million for the year ending December 31, 2011. The following table depicts the Company’s CapEx by Exploration & Production (“E&P”), Oasis Well Services, Field Office and Other Non-E&P:

Leasehold Position and Drilling Locations

Oasis built its leasehold position in West Williston, East Nesson and Sanish project areas through acquisitions and development activities and, as of December 31, 2011, had 307,430 net acres in the Williston Basin. Based on results to date and the delineation of the Bakken formation throughout much of its acreage, Oasis believes it has 1,313 gross

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(571.1 net) remaining primary drilling locations. This drilling inventory is based on the assumption that there are 464 substantially delineated and economically viable spacing units across the Company’s acreage position. Identified gross and net drilling locations are based on mostly 1,280 acre spacing units. For the primary inventory, each spacing unit assumes three Bakken wells (excluding wells previously drilled) and in certain areas, such as Indian Hills and parts of South Cottonwood where initial Three Forks wells were believed to be economic, each spacing unit assumes three Three Forks wells (excluding wells previously drilled). Additionally, the Company assumes that the Sanish project area includes up to three Bakken wells and two Three Forks wells (excluding wells previously drilled) per spacing unit in the primary inventory.

In addition to its primary drilling locations, the Company believes it has additional remaining potential drilling locations based on three Three Forks wells per spacing unit in spacing units that did not include Three Forks wells in the primary inventory. There were 941 gross (472.3 net) potential drilling locations remaining as of December 31, 2011. Throughout the Williston Basin, the Company believes it has an aggregate of 2,254 gross (1,043.4 net) remaining drilling locations targeting the Bakken and Three Forks formations.

In the West Williston project area, we have identified 731 gross (345.0 net) primary drilling locations remaining in the Bakken formation and 97 gross (51.3 net) primary drilling locations remaining in the Three Forks formation. In the East Nesson project area, we have identified 263 gross (137.3 net) primary drilling locations remaining in the Bakken formation and 95 gross (28.5 net) primary drilling locations remaining in the Three Forks formation. In the Sanish project area, we have identified 43 gross (4.2 net) primary drilling locations remaining in the Bakken formation and 84 gross (4.8 net) primary drilling locations remaining in the Three Forks formation.

The following table presents remaining drilling locations for each primary project area as of December 31, 2011:

Differentials Update

In February 2012, the quoted prices for oil coming out of the Williston Basin on pipeline (typically quoted at Clearbrook, Minnesota and Guernsey, Wyoming) (“Bakken Crude Oil”) was substantially less than prices quoted for WTI due to refinery and transportation constraints. Transportation constraints were largely due to increased volumes produced in North Dakota in the second half of 2011. In December 2011, oil production in North Dakota was approximately 535,000 barrels per day compared to approximately 386,000 barrels per day in June 2011. Oil from Canada also put pressure on the existing pipeline infrastructure that terminates in Mid-West refineries. Although there was 300,000 barrels per day of railcar transportation capacity in place as of December 31, 2011, these railcar facilities are not running at nameplate capacity due to limited availability of railcars. We believe the operators of these railcar facilities have railcars on order and expect utilization on these facilities to increase substantially during the first half of 2012. Additionally, during 2012 we expect to begin transporting a portion of our crude oil on gathering systems, originating at the wellhead, in the West Williston, which will eliminate the need to transport barrels by truck from the wellhead. The gathering system is expected to provide us access to multiple pipelines and rail outlets where we can sell our crude oil.

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Hedging Activity

As of February 22, 2012, the Company had the following outstanding commodity derivative contracts, all of which settle monthly:

Conference Call Information

The Company will host a conference call on Thursday, February 23, 2012 at 11:00 a.m. Central Time to discuss its fourth quarter and full year 2011 financial and operational results. Investors, analysts and other interested parties are invited to listen to the conference call by dialing 877-621-0256 (U.S.) or 706-634-0151 (International) using the Conference ID 46774975 or via the Company’s website at www.oasispetroleum.com. A recording of the conference call will be available by dialing 855-859-2056 (U.S.) or 404-537-3406 (International), using the Conference ID 46774975, beginning at 2:00 p.m. Central Time on the day of the call, and available until Friday, March 2, 2012 via the Company’s website. 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, derivatives activities, 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 changes in oil and natural gas prices, 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.

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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

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Oasis Petroleum Inc. Financial Statements

OASIS PETROLEUM INC.

CONSOLIDATED BALANCE SHEET

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OASIS PETROLEUM INC.

CONSOLIDATED STATEMENT OF OPERATIONS

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OASIS PETROLEUM INC.

SELECTED FINANCIAL AND OPERATIONAL STATS

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OASIS PETROLEUM INC.

CONSOLIDATED STATEMENT OF CASH FLOWS

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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 (loss) and net cash provided by operating activities, respectively.

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