Exhibit 99.1

TRANSOCEAN LTD. REPORTS SECOND QUARTER 2012 RESULTS

·                  Second quarter 2012 revenues were $2.575 billion compared with $2.337 billion in the first quarter 2012;

·                  Excluding an additional $750 million for estimated loss contingencies associated with the Macondo well incident, second quarter 2012 operating and maintenance expenses were $1.607 billion compared with $1.463 billion in the first quarter 2012;

·                  Second quarter 2012 net loss attributable to controlling interest was $304 million, which included $560 million of net unfavorable items.   This compares with the first quarter 2012 net income attributable to controlling interest of $10 million, which included $181 million of net unfavorable items;

·                  Revenue efficiency(1) was 92.5 percent in the second quarter, compared with 90.6 percent in the first quarter 2012;

·                  Fleet utilization(2) was 66 percent in the second quarter, compared with 61 percent in the first quarter 2012;

·                  Cash flows from operating activities were $459 million in the second quarter, which compares with $540 million in the first quarter 2012;

·                  Second quarter 2012 Annual Effective Tax Rate(3) was 31.1 percent compared with 27.6 percent in the first quarter 2012;

·                  New contracts totaling $4.7 billion were secured in the Fleet Status Report periods April 18, 2012 through July 18, 2012.  Backlog at July 18th was $22.9 billion, a net increase of $2.3 billion.   Since July 18, 2012, additional contracts totaling $144 million were secured; and

·                  Prior period consolidated financial statements have been adjusted to correct for an error primarily related to the recognition of assets for insurance recoveries for legal and other costs associated with the Macondo well incident.  These corrections, described in Appendix A to this release, are immaterial to the prior period consolidated financial statements.

ZUG, SWITZERLAND — Transocean Ltd. (NYSE: RIG) (SIX: RIGN) today reported a net loss attributable to controlling interest of $304 million, or $0.86 per diluted share, for the three months ended June 30, 2012. Second quarter 2012 results included net unfavorable items of $560 million, or $1.58 per

diluted share.  The results compare with net income attributable to controlling interest of $124 million, or $0.39 per diluted share, for the three months ended June 30, 2011.  Second quarter 2011 results included net unfavorable items of $36 million, or $0.11 per diluted share, primarily associated with impairment losses on three standard jackups and charges related to unfavorable discrete tax items.

Net unfavorable items, after tax, impacting the second quarter of 2012 included the following:

·                  $750 million, or $2.12 per diluted share, for estimated loss contingencies associated with the Macondo well incident that the company believes is probable and for which a reasonable estimate can be made at this time.  This estimate will be adjusted to reflect new information and future developments as they become known;

·                  $145 million, or $0.41 per diluted share, associated with discrete tax benefits;

·                  $64 million, or $0.18 per diluted share, net gain on the sale of Transocean Nordic, Transocean Shelf Explorer, Roger W. Mowell, and GSF Adriatic II;

·                  $14 million, or $0.04 per diluted share, loss associated with Quantum’s exchange of its 50 percent interest in Transocean Pacific Drilling Inc. for Transocean Ltd.’s shares;

·                  $12 million, or $0.03 per diluted share, in impairments of long-lived assets classified as held for sale; and

·                  $7 million, or $0.02 per diluted share, primarily associated with a gain on disposal of the discontinued operations of Challenger Minerals Inc.

Operations Quarterly Review

Revenues for the three months ended June 30, 2012 were $2.575 billion, compared with revenues of $2.337 billion during the three months ended March 31, 2012.  Contract drilling revenues increased $170 million mainly due to fewer shipyard days and higher revenue efficiency(1) primarily on High Specification Floaters.  Total fleet revenue efficiency(1) was 92.5 percent for the second quarter, compared with 90.6 percent in the first quarter 2012.  Other revenues increased $68 million to $185 million for the second quarter 2012, compared with $117 million in the prior quarter, primarily due to increased activity levels in the company’s drilling management services reporting unit outside the U.S. GOM.

Excluding $750 million for estimated loss contingencies associated with the Macondo well incident, operating and maintenance expenses totaled $1.607 billion for the second quarter 2012.  This compares with $1.463 billion in the first quarter 2012.  The increase in operating and maintenance expenses was partly due to approximately $82 million in higher costs incurred on rigs undergoing shipyard, maintenance, survey and repair projects.  In addition, drilling management services activity levels outside the U.S. GOM increased operating and maintenance costs by $62 million.

General and administrative expenses were $79 million for the second quarter 2012 compared with $69 million in the previous quarter.  The increase was primarily due to transaction costs associated with the Quantum exchange.

Correction of Prior Period Consolidated Financial Statements

Please note that previously reported consolidated financial statements have been adjusted to reflect prior period corrections primarily related to the recognition of assets for insurance recoveries for legal and other costs associated with the Macondo well incident.  These corrections are immaterial to the prior year consolidated financial statements.

For the three months ended March 31, 2012, the corrections reduced income from continuing operations by $55 million and net income attributable to controlling interest by $32 million.  For the

three months ended June 30, 2011, the corrections reduced income from continuing operations by $31 million, and net income attributable to controlling interest by $31 million.  Additional details of these corrections, as well as required reconciliations, are provided in Appendix A.

Income Taxes

Transocean’s second quarter Effective Tax Rate(4) was 8.6 percent compared with 47.2 percent in the first quarter 2012.  The decrease in the Effective Tax Rate(4) was due to favorable changes in estimates mainly for settlement of prior year’s tax liabilities.  Transocean’s Annual Effective Tax Rate (3) for the second quarter 2012, which excludes various favorable discrete items totaling $145 million, was 31.1 percent.  This compares with 27.6 percent for the prior quarter.  The increase was primarily due to changes in the blend of income that is taxed based on gross revenues versus pre-tax income and rig movements between taxing jurisdictions, among other things.  Second quarter 2012 income tax expense included an adjustment of $5 million, or $0.01 per diluted share, required to reflect an increase in the Annual Effective Tax Rate(3) to 29.6 percent for the six months ended June 30, 2012, from 27.6 percent for the first quarter of 2012.

Other Items

For the second quarter, interest expense, net of amounts capitalized, was $183 million, compared with $180 million in the first quarter 2012.  Capitalized interest for the second quarter 2012 was $12 million compared with $13 million in the prior quarter.   Interest income decreased to $13 million in the second quarter, compared with $15 million in the first quarter 2012.

Cash flows from operating activities were $459 million for the second quarter compared with $540 million for the first quarter 2012.  Capital expenditures decreased to $236 million for the second quarter compared with $260 million in the first quarter of 2012. The lower capital expenditures were primarily due to timing of shipyard milestone payments associated with the company’s newbuild program.

Forward-Looking Statements

Statements included in this news release, including those regarding estimates of Transocean’s goodwill or long-lived asset impairments and the estimated loss contingencies associated with the Macondo well incident, are forward-looking statements that involve certain assumptions. These statements are based on currently available competitive, financial, and economic data along with our current operating plans and involve risks and uncertainties including, but not limited to, market conditions, Transocean’s results of operations, the effect and results of litigation, assessments and contingencies, and other factors detailed in “Risk Factors” and elsewhere in Transocean’s filings with the Securities and Exchange Commission. Should one or more of these risks or uncertainties materialize (or the other consequences of such a development worsen), or should underlying assumptions prove incorrect, actual outcomes may vary materially from those forecasted or expected. Transocean disclaims any intention or obligation to update publicly or revise such statements, whether as a result of new information, future events or otherwise.

Conference Call Information

Transocean will conduct a teleconference call at 10:00 a.m. EDT, 4:00 p.m. CEST, on Thursday, August 2, 2012. To participate, dial +1 719-325-4929 and refer to confirmation code 4582389 approximately 10 minutes prior to the scheduled start time of the call.

In addition, the conference call will be simultaneously broadcast over the Internet in a listen-only mode and can be accessed by logging onto Transocean’s website at www.deepwater.com and selecting “Investor Relations.” A file containing four charts that may be discussed during the conference call, titled “2Q12 Charts,” has been posted to Transocean’s website and can also be found by selecting “Investor Relations/Quarterly Toolkit.” The conference call may also be accessed via the Internet at www.CompanyBoardroom.com by typing in Transocean’s New York Stock Exchange trading symbol, “RIG.”

A telephonic replay of the conference call should be available after 1:00 p.m. EDT, 7:00 p.m. CEST, on August 2, 2012, and can be accessed by dialing +1 719-457-0820 or +1 888-203-1112 and referring to the confirmation code 4582389. Also, a replay will be available through the Internet and can be accessed by visiting either of the above-referenced internet addresses. Both replay options will be available for approximately 30 days.

About Transocean

Transocean is a leading international provider of offshore contract drilling services for oil and gas wells.  We own or have partial ownership interests in and operate a fleet of 128 mobile offshore drilling units consisting of 49 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh-Environment semisubmersibles and drillships), 25 Midwater Floaters, 10 High-Specification Jackups, 43 Standard Jackups and one swamp barge.  In addition, we have two Ultra-Deepwater Drillships and three High-Specification Jackups under construction.  The company specializes in technically demanding sectors of the global offshore drilling business with a particular focus on deepwater and harsh environment drilling services, and believes that it operates one of the most versatile offshore drilling fleets in the world.

(1) Revenue efficiency is defined as actual revenue divided by the highest amount of total revenue which could have been earned during the relevant period(s). See the accompanying schedule entitled “Revenue Efficiency.”

(2) Utilization is defined as the total actual number of revenue earning days in the period as a percentage of the total number of calendar days in the period for all drilling rigs in the company’s fleet. See the accompanying schedule entitled “Utilization.”

(3) Annual Effective Tax Rate is defined as income tax expense from continuing operations excluding various discrete items (such as changes in estimates and tax on items excluded from income before income tax expense) divided by income from continuing operations before income tax expense excluding gains on sales and similar items pursuant to the accounting standards for income taxes. See the accompanying schedule entitled “Supplemental Effective Tax Rate Analysis.”

(4) Effective Tax Rate is defined as income tax expense from continuing operations divided by income from continuing operations before income taxes. See the accompanying schedule entitled “Supplemental Effective Tax Rate Analysis.”

For more information about Transocean, please visit the website at www.deepwater.com.

TRANSOCEAN LTD. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(In millions, except per share data)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(In millions, except share data)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOW

(In millions)

(Unaudited)

TRANSOCEAN LTD. AND SUBSIDIARIES

FLEET OPERATING STATISTICS

(1)          Average daily revenue is defined as contract drilling revenue earned per revenue earning day in the period.  A revenue earning day is defined as a day for which a rig earns dayrate after commencement of operations.

TRANSOCEAN LTD. AND SUBSIDIARIES

FLEET OPERATING STATISTICS (continued)

(2)          Utilization is defined as the total actual number of revenue earning days in the period as a percentage of the total number of calendar days in the period for all drilling rigs in our fleet.

(3)          Revenue efficiency is defined as actual revenue divided by the highest amount of total revenue which could have been earned during the relevant period(s).

TRANSOCEAN LTD. AND SUBSIDIARIES

SUPPLEMENTAL EFFECTIVE TAX RATE ANALYSIS

(In US$ millions, except percentages)

TRANSOCEAN LTD. AND SUBSIDIARIES

APPENDIX A

Correction of Errors in Previously Reported Consolidated Financial Statements

We perform assessments of our contingencies and corresponding assets for insurance recoveries on an ongoing basis to evaluate the appropriateness of our balances and disclosures for such contingencies and insurance recoveries.  We establish liabilities for estimated loss contingencies when we believe a loss is probable and the amount of the probable loss can be reasonably estimated.  We recognize corresponding assets for those loss contingencies that we believe are probable of being recovered through insurance.  In performing these assessments in the three months ended June 30, 2012, we identified an error in our previously issued financial statements for the year ended December 31, 2011 and the three months ended March 31, 2012 related to the recognition of assets for insurance recoveries related to legal and other costs totaling $67 million and $37 million, respectively, which we have concluded should not have been recorded because they were not probable of recovery.

We assessed the materiality of this error in accordance with SEC Staff Accounting Bulletin (“SAB”) No. 99, Materiality and SAB No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements (“SAB 108”), using both the rollover method and the iron curtain method, as defined in SAB 108, and concluded the error, inclusive of other adjustments discussed below, was immaterial to prior years but could be material to the current year.  Under SAB 108, if the prior year error that, if corrected in the current year, would be material to the current year, the prior year financial statements should be corrected, even though such correction previously was immaterial to the prior year financial statements.  Correcting prior year financial statements for immaterial errors does not require our previously filed reports to be amended, but rather these corrections will be made the next time we file the prior period consolidated financial statements.

In addition to the adjustments in 2011 and 2012 related to the assets for insurance recoveries, we recorded other adjustments related to the years ended December 31, 2011 and 2010 and the three months ended March 31, 2012 to correct for immaterial errors for repair and maintenance costs, income taxes, discontinued operations, and the allocation of net income attributable to noncontrolling interest.  These other adjustments were not previously recorded in the appropriate periods, as we concluded that they were immaterial to our previously issued consolidated financial statements.

For the three months ended March 31, 2012, the correction of these errors reduced income from continuing operations by $55 million and net income attributable to controlling interest by $32 million.  For the three and six month periods ended June 30, 2011, correction of these errors reduced income from continuing operations by $31 million and $34 million, respectively, and net income attributable to controlling interest by $31 million and $22 million, respectively.  For the year ended December 31, 2011, correction of these errors increased loss from continuing operations by $31 million and net loss attributable to controlling interest by $29 million.  For the year ended December 31, 2010, correction of these errors reduced income from continuing operations by $19 million and net income attributable to controlling interest by $35 million.  The summary of adjustments for increases and (decreases) to net income (loss) from continuing operations and net income (loss) attributable to controlling interest for the applicable periods were as follows (in millions):

The effects of the corrections of the errors on our consolidated statements of operations and balance sheets are presented in the tables below.  The corrections of the errors had no effect on our consolidated statements of comprehensive income (loss) other than the effect of the changes to net income (loss) for each period.  The corrections of the errors had no effect on the previously reported amounts of operating, investing, and financing cash flows in our consolidated statements of cash flows.

TRANSOCEAN LTD. AND SUBSIDIARIES

APPENDIX A

Correction of Errors in Previously Reported Consolidated Financial Statements (continued)