<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

          [X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                For the Quarterly Period Ended September 30, 2004

                                       OR

          [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

   For the Transition Period from ___________________ to _____________________

                         Commission File Number 0-13546

                               ------------------

                     APACHE OFFSHORE INVESTMENT PARTNERSHIP
                     --------------------------------------
             (Exact Name of Registrant as Specified in Its Charter)

                   Delaware                                   41-1464066
       -------------------------------                  ----------------------
       (State or Other Jurisdiction of                     (I.R.S. Employer
       Incorporation or Organization)                   Identification Number)

     Suite 100, One Post Oak Central
  2000 Post Oak Boulevard, Houston, TX                        77056-4400
  ------------------------------------                        ----------
  (Address of Principal Executive Offices)                    (Zip Code)

       Registrant's Telephone Number, Including Area Code: (713) 296-6000

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.

                                   YES [X]  NO [ ]

<PAGE>

                         PART I - FINANCIAL INFORMATION

ITEM 1 - FINANCIAL STATEMENTS

                     APACHE OFFSHORE INVESTMENT PARTNERSHIP
                               STATEMENT OF INCOME
                                   (UNAUDITED)

<TABLE>
<CAPTION>
                                                                     FOR THE QUARTER                  FOR THE NINE MONTHS
                                                                   ENDED SEPTEMBER 30,                 ENDED SEPTEMBER 30,
                                                              ----------------------------        ----------------------------
                                                                 2004             2003              2004               2003
                                                              ----------        ----------        ----------        ----------
<S>                                                           <C>               <C>               <C>               <C>
REVENUES:
   Oil and gas sales                                          $3,440,706        $2,938,759        $9,865,405        $9,145,409
   Interest income                                                13,757             8,626            26,006            18,409
   Other revenue                                                       -            14,567                 -            14,567
                                                              ----------        ----------        ----------        ----------
                                                               3,454,463         2,961,952         9,891,411         9,178,385
                                                              ----------        ----------        ----------        ----------
EXPENSES:
   Depreciation, depletion and amortization                      766,845           753,110         2,140,142         2,198,496
   Asset retirement obligation accretion                          12,272             9,468            36,290            27,997
   Lease operating costs                                         183,885           182,551           609,656           632,169
   Gathering and transportation expense                           33,376            10,115            95,496            99,300
   Administrative                                                102,000            96,000           306,000           306,000
                                                              ----------        ----------        ----------        ----------
                                                               1,098,378         1,051,244         3,187,584         3,263,962
                                                              ----------        ----------        ----------        ----------

OPERATING INCOME BEFORE CUMULATIVE
  EFFECT OF CHANGE IN ACCOUNTING PRINCIPLE                     2,356,085         1,910,708         6,703,827         5,914,423
                                                              ----------        ----------        ----------        ----------
   Cumulative effect of change in accounting principle                 -                 -                 -           302,407
                                                              ----------        ----------        ----------        ----------
NET INCOME                                                    $2,356,085        $1,910,708        $6,703,827        $6,216,830
                                                              ==========        ==========        ==========        ==========
NET INCOME ALLOCATED TO:
   Managing Partner                                           $  603,772        $  508,426        $1,712,934        $1,549,814
   Investing Partners                                          1,752,313         1,402,282         4,990,893         4,667,016
                                                              ----------        ----------        ----------        ----------
                                                              $2,356,085        $1,910,708        $6,703,827        $6,216,830
                                                              ==========        ==========        ==========        ==========
NET INCOME PER INVESTING PARTNER UNIT                         $    1,657        $    1,321        $    4,712        $    4,340
                                                              ==========        ==========        ==========        ==========
WEIGHTED AVERAGE INVESTING PARTNER
   UNITS OUTSTANDING                                             1,057.2           1,061.7           1,059.2           1,075.4
                                                              ==========        ==========        ==========        ==========
</TABLE>

                 The accompanying notes to financial statements
                     are an integral part of this statement.

                                       1

<PAGE>

                     APACHE OFFSHORE INVESTMENT PARTNERSHIP
                             STATEMENT OF CASH FLOWS
                                   (UNAUDITED)

<TABLE>
<CAPTION>
                                                                                 FOR THE NINE MONTHS ENDED
                                                                                        SEPTEMBER 30,
                                                                              -------------------------------
                                                                                 2004                 2003
                                                                              -----------         -----------
<S>                                                                           <C>                 <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
   Net income                                                                 $ 6,703,827         $ 6,216,830
   Adjustments to reconcile net income to net cash
      provided by operating activities:
         Depreciation, depletion and amortization                               2,140,142           2,198,496
         Asset retirement obligation accretion                                     36,290              27,997
         Cumulative effect of change in accounting principle                            -            (302,407)
         Dismantlement and abandonment cost                                      (187,160)                  -
         Changes in operating assets and liabilities:
             (Increase) decrease in accrued revenues receivable                    31,144              17,154
             Increase (decrease) in accrued operating expenses                      3,932              24,716
             (Increase) decrease in receivable from Apache Corporation            (82,198)           (142,800)
                                                                              -----------         -----------
         Net cash provided by operating activities                              8,645,977           8,039,986
                                                                              -----------         -----------
CASH FLOWS FROM INVESTING ACTIVITIES:
   Additions to oil and gas properties                                         (1,706,329)         (1,647,803)
                                                                              -----------         -----------
         Net cash used in investing activities                                 (1,706,329)         (1,647,803)
                                                                              -----------         -----------

CASH FLOWS FROM FINANCING ACTIVITIES:
   Repurchase of Partnership Units                                                (41,321)           (285,936)
   Distributions to Investing Partners                                         (2,121,466)           (542,445)
   Distributions to Managing Partner                                           (1,745,962)         (1,591,827)
                                                                              -----------         -----------
         Net cash used in financing activities                                 (3,908,749)         (2,420,208)
                                                                              -----------         -----------
NET INCREASE IN CASH AND CASH EQUIVALENTS                                       3,030,899           3,971,975

CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR                                    2,271,495             915,891
                                                                              -----------         -----------

CASH AND CASH EQUIVALENTS, END OF PERIOD                                      $ 5,302,394         $ 4,887,866
                                                                              ===========         ===========
</TABLE>

                 The accompanying notes to financial statements
                     are an integral part of this statement.

                                       2

<PAGE>

                     APACHE OFFSHORE INVESTMENT PARTNERSHIP
                                  BALANCE SHEET
                                   (UNAUDITED)

<TABLE>
<CAPTION>
                                                                                    SEPTEMBER 30,        DECEMBER 31,
                                                                                       2004                  2003
                                                                                   -------------         -------------
<S>                                                                                <C>                   <C>
                                      ASSETS
CURRENT ASSETS:
   Cash and cash equivalents                                                       $   5,302,394         $   2,271,495
   Accrued revenues receivable                                                           610,066               641,210
   Receivable from Apache Corporation                                                    168,415                86,217
                                                                                   -------------         -------------
                                                                                       6,080,875             2,998,922
                                                                                   -------------         -------------

OIL AND GAS PROPERTIES, on the basis of full cost accounting:
   Proved properties                                                                 184,152,528           182,173,899
   Less - Accumulated depreciation, depletion and amortization                      (175,638,831)         (173,498,689)
                                                                                   -------------         -------------
                                                                                       8,513,697             8,675,210
                                                                                   -------------         -------------
                                                                                   $  14,594,572         $  11,674,132
                                                                                   =============         =============

                        LIABILITIES AND PARTNERS' CAPITAL

CURRENT LIABILITIES:
   Distributions payable                                                           $   4,228,869         $           -
   Accrued development costs                                                             419,880               334,740
   Accrued operating expenses                                                             56,008                52,076
                                                                                   -------------         -------------
                                                                                       4,704,757               386,816
                                                                                   -------------         -------------
ASSET RETIREMENT OBLIGATION                                                              848,810               812,520
                                                                                   -------------         -------------

PARTNERS' CAPITAL:
   Managing Partner                                                                      134,182               167,210
   Investing Partners (1,057.2 and 1,060.7 units outstanding, respectively)            8,906,823            10,307,586
                                                                                   -------------         -------------

                                                                                       9,041,005            10,474,796
                                                                                   -------------         -------------
                                                                                   $  14,594,572         $  11,674,132
                                                                                   =============         =============
</TABLE>

                 The accompanying notes to financial statements
                     are an integral part of this statement.

                                       3

<PAGE>

                     APACHE OFFSHORE INVESTMENT PARTNERSHIP
                          NOTES TO FINANCIAL STATEMENTS
                                   (UNAUDITED)

     The financial statements included herein have been prepared by the Apache
Offshore Investment Partnership (the Partnership), without audit, pursuant to
the rules and regulations of the Securities and Exchange Commission, and reflect
all adjustments which are, in the opinion of management, necessary for a fair
statement of the results for the interim periods, on a basis consistent with the
annual audited financial statements. All such adjustments are of a normal,
recurring nature. Certain information, accounting policies, and footnote
disclosures normally included in financial statements prepared in accordance
with generally accepted accounting principles have been omitted pursuant to such
rules and regulations, although the Partnership believes that the disclosures
are adequate to make the information presented not misleading. These financial
statements should be read in conjunction with the financial statements and the
summary of significant accounting policies and notes thereto included in the
Partnership's latest annual report on Form 10-K.

1. RECEIVABLE FROM APACHE CORPORATION

     The receivable from Apache Corporation, the Partnership's managing partner
(Apache or the Managing Partner), represents the net result of the Investing
Partners' revenue and expenditure transactions in the current month. Generally,
cash in this amount will be paid by Apache to the Partnership in the month after
the Partnership's transactions are processed and the net results of operations
are determined.

2. RIGHT OF PRESENTMENT

         As provided in the Partnership Agreement, as amended (the Amended
Partnership Agreement), a first right of presentment offer for 2004 of $11,518
per Unit, plus interest to the date of payment, was made to Investing Partners
in April 2004, based on a valuation date of December 31, 2003. As a result, the
Partnership purchased 3.5 Units in June for a total of $41,321. A second right
of presentment offer for 2004 of $8,988 per Unit, plus interest to the date of
payment, was made to Investing Partners on October 22, 2004, based on a
valuation date of June 30, 2004. The Investing Partners have until the close of
business on November 22, 2004 to present their Units for repurchase by the
Partnership. The Partnership will determine by December 15, 2004, whether or not
to accept each Unit offered during this election period.

     The Partnership is not in a position to predict how many Units will be
presented for repurchase during the fourth quarter of 2004 and cannot, at this
time, determine if the Partnership will have sufficient funds available to
repurchase any Units. The Partnership has no obligation to purchase any Units
presented to the extent it determines that it has insufficient funds for such
purchases. The Amended Partnership Agreement contains limitations on the number
of Units that the Partnership can repurchase, including a limit of 10 percent of
the outstanding Units on an annual basis.

3. ASSET RETIREMENT OBLIGATIONS

     Effective January 1, 2003, the Partnership adopted Statement of Financial
Accounting Standards (SFAS) No. 143, "Accounting for Asset Retirement
Obligations," which requires that an asset retirement obligation (ARO)
associated with the retirement of a tangible long-lived asset be recognized as a
liability in the period in which it is incurred and becomes determinable, with
an offsetting increase in the carrying amount of the associated asset. The cost
of the tangible asset, including the initially recognized ARO, is depleted such
that the cost of the ARO is recognized over the useful life of the asset. The
ARO is recorded at fair value, and accretion expense will be recognized over
time as the discounted liability is accreted to its expected settlement value.
The fair value of the ARO is measured using expected future cash outflows
discounted at the company's credit-adjusted risk-free interest rate. The
Partnership's asset retirement obligations primarily relate to the plugging and
abandonment of oil and gas properties.

     Upon adoption, the Partnership recorded an increase to net oil and gas
properties of $1.1 million and additional liabilities related to asset
retirement obligations of $.8 million. These amounts reflect the ARO of the
Partnership had the provisions of SFAS No. 143 been applied since inception and
resulted in a non-cash cumulative effect increase to 2003 earnings of $.3
million.

                                       4

<PAGE>
         The Partnership's increase in ARO liability from December 31, 2003 was
attributable to accretion expense of $36,290.

4. CHANGE IN CRITICAL ACCOUNTING POLICY

         In September 2004, the Securities and Exchange Commission issued Staff
Accounting Bulletin No. 106 (SAB 106) to provide new guidance on how asset
retirement obligations should impact the calculation of the "ceiling test" or
limitation on the amount of properties that can be capitalized on the balance
sheet under the full cost method of accounting for oil and gas companies. The
new guidance dictates that since the asset retirement obligation is now
reported on the balance sheet, related costs in the future net cash flow
calculation should be omitted to avoid double-counting these costs. As allowed
under existing guidance, the Partnership includes such costs in its future net
cash flow calculation, but adjusts the corresponding amount on the balance
sheet. The Partnership does not believe that adoption of SAB 106 will have a
material impact on financial results. The Partnership will apply the new
guidance outlined in SAB 106 prospectively.

                                       5
<PAGE>
ITEM 2 -   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
           RESULTS OF OPERATIONS

RESULTS OF OPERATIONS

NET INCOME AND REVENUE

     The Partnership earned $2.4 million during the third quarter of 2004, 23
percent above the net income reported in the third quarter a year ago on the
strength of higher oil and gas prices. Net income per Investing Partner Unit
increased to $1,657 in the third quarter of 2004 from $1,321 in the third
quarter of 2003.

     Net income for the first nine months of 2004, totaled $6.7 million or
$4,712 per Investing Partner Unit. Net income for the same period in 2003
totaled $6.2 million or $4,340 per Investing Partner Unit. As a result of higher
oil and gas prices in 2004, net income in 2004 was 13 percent higher than the
2003 net income before the cumulative effect of a change in accounting
principle.

     Total revenues for the third quarter increased 17 percent from a year ago,
increasing from $3.0 million in 2003 to $3.5 million in 2004. For the nine
months ending September 30, 2004, revenues were $9.9 million, or eight percent
above the revenues for the same period in 2003 on higher oil and gas prices.

     The Partnership's oil and gas production volume and price information is
summarized in the following table (gas volumes presented in thousand cubic feet
(Mcf) per day):

<TABLE>
<CAPTION>
                                  FOR THE QUARTER ENDED SEPTEMBER 30,      FOR THE NINE MONTHS ENDED SEPTEMBER 30,
                                  -----------------------------------      -------------------------------------
                                                            INCREASE                                  INCREASE
                                     2004         2003     (DECREASE)        2004          2003      (DECREASE)
                                  ---------    ---------   ----------      ---------    ---------    ----------
<S>                               <C>          <C>         <C>             <C>          <C>          <C>
Gas volume - Mcf per day              3,891        4,125           (6%)        3,761        3,989           (6%)
Average gas price - per Mcf       $    5.85    $    5.13           14%     $    5.93    $    5.83            2%
Oil volume - barrels per day            286          366          (22%)          312          336           (7%)
Average oil price - per barrel    $   42.83    $   29.43           46%     $   38.45    $   30.43           26%
NGL volume - barrels per day             93            -            -             69            -            -
Average NGL price - per barrel    $   25.71            -            -      $   24.77            -            -
</TABLE>

OIL AND GAS SALES

         Natural gas production revenues for the third quarter of 2004 totaled
$2.0 million, up seven percent from the third quarter of 2003. The Partnership's
average realized natural gas price for the third quarter of 2004 increased 14
percent compared to the year-earlier period. The $.72 per Mcf increase in gas
price from a year ago positively impacted sales by approximately $.3 million.
Natural gas volumes on a daily basis decreased six percent from a year ago as a
result of natural declines at South Timbalier 295 and Matagorda 681/682. These
production declines were partially offset by new production from the completion
of the Ship Shoal 258 JB-6 well in mid-April, the Ship Shoal 259 JA-3 well in
late May, the Ship Shoal 258/259 JA-7 well in late July, and the Ship Shoal
258/259 JA-8 well in late September. Production from Ship Shoal 258/259 and
South Timbalier 295 was shut-in for three days in mid-September as Hurricane
Ivan passed through the Gulf of Mexico. The Partnership's properties did not
sustain significant damage from the hurricane.

         The Partnership's crude oil production revenues for the third quarter
of 2004 totaled $1.1 million, a 14 percent increase from the third quarter of
2003. A $13.40 per barrel, or 46 percent, increase in the Partnership's average
realized oil price increased oil revenues by $.5 million. Oil production was 22
percent lower than a year ago as declines at South Timbalier 295 more than
offset production additions from drilling at Ship Shoal 258/259. As noted above,
Hurricane Ivan caused Ship Shoal 258/259 and South Timbalier 295 to be shut-in
for three days in September.

                                       6
<PAGE>

         Gas sales for the first nine months of 2004 of $6.1 million declined
four percent, when compared to the same period in 2003. The Partnership's
average realized gas prices increased $.10 per Mcf, when compared with the first
nine months of 2003. Daily gas production for the first nine months of 2004
decreased six percent when compared to the same period in 2003. The lower sales
volumes in 2004 reflected natural depletion at South Timbalier 295 and Matagorda
681/682.

     For the nine months ended September 30, 2004, oil sales increased 18
percent from a year ago to $3.3 million. The Partnership's oil sales revenues
were favorably impacted by an 26 percent increase in the average realized oil
price. Oil production declined seven percent from a year ago as a result of
natural depletion. The recompletion of the Ship Shoal 258 JB-5 well in February
2004 and new drilling at Ship Shoal 258/259 during 2004 partially offset the
decline in production.

     During the fourth quarter of 2003, the Partnership began processing a
portion of its natural gas production through onshore plants operated by third
parties. The Partnership sold an average of 93 barrels per day of natural gas
liquids from processing gas during the third quarter of 2004 and 69 barrels per
day of natural gas liquids during the first nine months of 2004.

     Declines in oil and gas production can be expected in future periods due to
natural depletion. Given the small number of producing wells owned by the
Partnership, and their natural depletion, the Partnership's future production
will be subject to more volatility than those companies with greater reserves
and longer-lived properties.

OPERATING EXPENSES

     The Partnership's depreciation, depletion and amortization (DD&A) rate,
expressed as a percentage of oil and gas sales, was approximately 22 percent
during the third quarter of 2004 compared to 26 percent during the same period
in 2003. This decline in rate reflected the impact of higher oil and gas prices
in the current year. The Partnership recognized $12,272 of accretion expense on
the asset retirement obligation during the third quarter of 2004 and $36,290 for
the first nine months of 2004.

     Lease operating expense (LOE) in the third quarter of 2004 was essentially
even with the third quarter of 2003. During the first nine months of 2004, LOE
totaled $.6 million, down four percent from the same period in 2003 on lower
repair and maintenance costs.

     Gathering and transportation costs include amounts paid by the Partnership
to third parties to transport oil and gas to a purchaser-specified delivery
point. Such costs vary based on the volume and distance shipped, and the fee
charged by the transporter, which may be price sensitive. The transportation
cost may also vary from period to period based on marketing and delivery options
utilized by the Partnership to realize the highest net price (gross price less
transportation) for either oil or gas. Gathering and transportation costs during
the third quarter were up from the third quarter of 2003 as a result of
increased volumes from Ship Shoal 258/259. Gathering and transportation costs
during the first nine months of 2004 were down from a year ago as a result of
decreased volumes from Matagorda Island 681/682.

CASH FLOW, LIQUIDITY AND CAPITAL RESOURCES

CAPITAL RESOURCES AND LIQUIDITY

     The Partnership's primary capital resource is net cash provided by
operating activities, which totaled $8.6 million for the first nine months of
2004. Net cash provided by operating activities in 2004 was eight percent above
the $8.0 million reported a year ago, reflecting increases in oil prices from
2003. Future cash flows will be influenced by fluctuations in product prices,
production levels and operating costs.

     The Partnership's future financial condition, results of operations and
cash from operating activities will largely depend upon prices received for its
oil and natural gas production. A substantial portion of the Partnership's
production is sold under market-sensitive contracts. Prices for oil and natural
gas are subject to fluctuations in response to changes in supply, market
uncertainty and a variety of factors beyond the Partnership's control. These
factors include worldwide political instability (especially in the Middle East),
the foreign supply of oil and natural gas, the price of foreign imports, the
level of consumer demand, and the price and availability of alternative fuels.
With natural gas accounting for 62 percent of the Partnership's production for
the first nine months of 2004 and 62 percent of total proved reserves at


                                       7
<PAGE>

December 31, 2003, on an energy equivalent basis, the Partnership is affected
more by fluctuations in natural gas prices than in oil prices.

     The Partnership's oil and gas reserves and production will also
significantly impact future results of operations and cash from operating
activities. The Partnership's production is subject to fluctuations in response
to remaining quantities of oil and gas reserves, weather, pipeline capacity,
consumer demand, mechanical performance and workover, recompletion and drilling
activities. Declines in oil and gas production can be expected in future years
as a result of normal depletion and the Partnership not participating in
acquisition or exploration activities. Based on production estimates from
independent engineers and current market conditions, the Partnership expects it
will be able to meet its liquidity needs for routine operations in the
foreseeable future. The Partnership will reduce capital expenditures and
distributions to partners as cash from operating activities declines.

     In the event that future short-term operating cash requirements are greater
than the Partnership's financial resources, the Partnership may seek short-term,
interest-bearing advances from the Managing Partner as needed. The Managing
Partner, however, is not obligated to make loans to the Partnership.

     On an ongoing basis, the Partnership reviews the possible sale of lower
value properties prior to incurring associated dismantlement and abandonment
cost.

CAPITAL COMMITMENTS

     The Partnership's primary needs for cash are for operating expenses,
drilling and recompletion expenditures, future dismantlement and abandonment
costs, distributions to Investing Partners, and the purchase of Units offered by
Investing Partners under the right of presentment. The Partnership had no
outstanding debt or lease commitments at September 30, 2004.

         During the first nine months of 2004, the Partnership invested $1.7
million in oil and gas properties as the Partnership participated in drilling
activities at Ship Shoal 258/259. During the third quarter, the Partnership
participated in the successful completion of two wells at Ship Shoal 258/259,
the JA-7 and the JA-8. The JA-7 well was brought on production in late July
while the JA-8 well was completed as a producer in late September. During the
second quarter, the Partnership participated in the successful completion of the
Ship Shoal 259 JA-3 ST1, which was brought on production in late May, and the
Ship Shoal 258 JB-6 well, which was brought on production in mid-April. During
the first quarter, the Partnership participated in the recompletion of the South
Timbalier 295 A-13 and Ship Shoal 258 JB-5 wells.

     On March 17, 2004, the Partnership paid distributions to Investing Partners
totaling $2.1 million, or $2,000 per Investing Partner unit. The Partnership
made a cash distribution to Investing Partners during the first nine months of
2003 of $500 per Investing Partner Unit. The Partnership declared a distribution
of $4,000 per Investing Partner Unit on September 2, 2004, that was paid to
Unitholders on October 7, 2004. The amount of future distributions will be
dependent on actual and expected production levels, realized and expected oil
and gas prices, expected drilling and recompletion expenditures, and prudent
cash reserves for future dismantlement and abandonment costs that will be
incurred after the Partnership's reserves are depleted.

     As provided in the Amended Partnership Agreement, a first right of
presentment offer for 2004 of $11,518 per Unit, plus interest to the date of
payment, was made to Investing Partners in April 2004, based on a valuation date
of December 31, 2003. As a result, the Partnership purchased 3.5 Units in June
2004 for a total of $41,321. A second right of presentment offer for 2004 of
$8,988 per Unit, plus interest to the date of payment, was made to Investing
Partners on October 22, 2004 based on a valuation date of June 30, 2004. The
Investing Partners have until the close of business on November 22, 2004 to
present their Units for repurchase by the Partnership. The Partnership will
determine by December 15, 2004, whether or not to accept each Unit offered
during this election period.

     The Partnership is not in a position to predict how many Units will be
presented for repurchase during the fourth quarter of 2004 and cannot, at this
time, determine if the Partnership will have sufficient funds available to
repurchase any Units. The Partnership has no obligation to purchase any Units
presented to the extent it determines that it has insufficient funds for such
purchases. The Amended Partnership Agreement contains limitations on the number
of Units that the Partnership can repurchase, including a limit of 10 percent of
the outstanding Units on an annual basis.


                                       8
<PAGE>
ITEM 3 - QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

     The Partnership's major market risk exposure is in the pricing applicable
to its oil and gas production. Realized pricing is primarily driven by the
prevailing worldwide price for crude oil and spot prices applicable to its
natural gas production. Prices received for oil and gas production have been and
remain volatile and unpredictable. The Partnership has not used derivative
financial instruments or otherwise engaged in hedging activities during 2003 or
the first six months of 2004.

     The information set forth under "Commodity Risk" in Item 7A of the
Partnership's Form 10-K for the year ended December 31, 2003, is incorporated by
reference. Information about market risks for the current quarter is not
materially different.

ITEM 4 - CONTROLS AND PROCEDURES

     G. Steven Farris, the Managing Partner's President, Chief Executive Officer
and Chief Operating Officer, and Roger B. Plank, the Managing Partner's
Executive Vice President and Chief Financial Officer, evaluated the
effectiveness of the Partnership's disclosure controls and procedures as of the
end of the period covered by this report. Based on that evaluation and as of the
date of that evaluation, these officers concluded that the Partnership's
disclosure controls to be effective, providing effective means to insure that
information it is required to disclose under applicable laws and regulations is
recorded, processed, summarized and reported in a timely manner. Also, no
significant changes were made in the Partnership's internal controls over
financial reporting during the fiscal quarter ending September 30, 2004 that
have materially affected, or are reasonably likely to materially affect, the
Partnership's internal control over financial reporting.

FORWARD-LOOKING STATEMENTS AND RISK

     Certain statements in this report, including statements of the future
plans, objectives, and expected performance of the Partnership, are
forward-looking statements that are dependent on certain events, risks and
uncertainties that may be outside the Partnership's control, and which could
cause actual results to differ materially from those anticipated. Some of these
include, but are not limited to, the market prices of oil and gas, economic and
competitive conditions, inflation rates, legislative and regulatory changes,
financial market conditions, political and economic uncertainties of foreign
governments, future business decisions, and other uncertainties, all of which
are difficult to predict.

     There are numerous uncertainties inherent in estimating quantities of
proved oil and gas reserves and in projecting future rates of production and
timing of development expenditures. The total amount or timing of actual future
production may vary significantly from reserves and production estimates. The
drilling of exploratory wells can involve significant risks, including those
related to timing, success rates and cost overruns. Lease and rig availability,
complex geology and other factors can affect these risks. Fluctuations in oil
and gas prices, or a prolonged period of low prices, may substantially adversely
affect the Partnership's financial position, results of operations and cash
flows.


                                       9
<PAGE>

                           PART II - OTHER INFORMATION

ITEM 1.      LEGAL PROCEEDINGS

             None.

ITEM 2.      CHANGES IN SECURITIES, USE OF PROCEEDS AND ISSUER PURCHASES OF
             EQUITY SECURITIES

             None.

ITEM 3.      DEFAULTS UPON SENIOR SECURITIES

             None.

ITEM 4.      SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

             None.

ITEM 5.      OTHER INFORMATION

             None.

ITEM 6.      EXHIBITS AND REPORTS ON FORM 8-K

             a.   Exhibits

                  31.1 - Certification of Chief Executive Officer

                  31.2 - Certification of Chief Financial Officer

                  32.1 - Certification of Chief Executive Officer and Chief
                         Financial Officer

             b.   Reports filed on Form 8-K - None.


                                       10
<PAGE>

                                   SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange
Act of 1934, the registrant has duly caused this report to be signed on its
behalf by the undersigned thereunto duly authorized.

                              APACHE OFFSHORE INVESTMENT PARTNERSHIP
                              By:  Apache Corporation, General Partner

Dated: November 8, 2004       /s/ Roger B. Plank
                              --------------------------------------------------
                              Roger B. Plank
                              Executive Vice President and Chief Financial
                              Officer

Dated: November 8, 2004       /s/ Thomas L. Mitchell
                              --------------------------------------------------
                              Thomas L. Mitchell
                              Vice President and Controller
                              (Chief Accounting Officer)

<PAGE>

                                 EXHIBIT INDEX

Exhibits

31.1    -    Certification of Chief Executive Officer

31.2    -    Certification of Chief Financial Officer

32.1    -    Certification of Chief Executive Officer and Chief
             Financial Officer