<PAGE>   1


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    FORM 10-Q

                                Amendment No. 1


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

                For the quarterly period ended September 30, 1999

                                       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 No. 0-22483
                               ------------

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

                            SEVEN SEAS PETROLEUM INC.
             (Exact name of registrant as specified in its charter)

        YUKON TERRITORY                                          73-1468669
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

             SUITE 1700, 5555 SAN FELIPE
                    HOUSTON, TEXAS                                 77056
     (Address of principal executive offices)                    (Zip Code)

       Registrant's telephone number, including area code: (713) 622-8218

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

    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 [ ]
                                    -----     -----

    Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date.

AS OF OCTOBER 31, 1999 THERE WERE 37,833,420 SHARES OF THE REGISTRANT'S COMMON
SHARES, NO PAR VALUE PER SHARE, OUTSTANDING.



<PAGE>   2

                   SEVEN SEAS PETROLEUM INC. AND SUBSIDIARIES
                        (A DEVELOPMENT STAGE ENTERPRISE)
          STATEMENTS OF CONSOLIDATED OPERATIONS AND ACCUMULATED DEFICIT
                  (Unaudited; In thousands, except share data)

<TABLE>
<CAPTION>

                                                                                                                    CUMULATIVE
                                                                                                                    TOTAL FROM
                                                                                                                     INCEPTION
                                                                                                                   (FEBRUARY 3,
                                                         NINE MONTHS ENDED           THREE MONTHS ENDED              1995) TO
                                                            SEPTEMBER 30,                SEPTEMBER 30,             SEPTEMBER 30,
                                                    ----------------------------    ----------------------------   -------------
                                                        1999           1998           1999            1998              1999
                                                    ------------    ------------    ------------    ------------    ------------
<S>                                                 <C>             <C>             <C>             <C>             <C>
REVENUE
     Crude oil sales                                $        308    $         91    $        123    $       --      $      1,337
     Interest income                                       2,403           2,574             705           1,431           7,465
                                                    ------------    ------------    ------------    ------------    ------------
                                                           2,711           2,665             828           1,431           8,802

EXPENSES
     General and administrative                            6,234           5,761           1,610           3,442          28,235
     Oil and gas operating expenses                        1,662             804             151              46           3,764
     Depreciation and amortization                           806             446             292             219           1,777
     Writedown of proved oil & gas properties               --              --              --              --           129,789
     Loss (Gain) on sale of exploration properties           670            (577)           --              (577)            124
     Dry hole and abandonment costs                         --              --              --              --             1,145
     Geological and geophysical                             --              --              --              --                47
     Other (income) expense                                   73             (32)             51              (2)            (49)
                                                    ------------    ------------    ------------    ------------    ------------
                                                           9,445           6,402           2,104           3,128         164,832

NET LOSS BEFORE INCOME TAXES
     AND MINORITY INTEREST                                (6,734)         (3,737)         (1,276)         (1,697)       (156,030)
                                                    ------------    ------------    ------------    ------------    ------------

INCOME TAX EXPENSE                                            30             102              10              72         (45,688)

NET LOSS BEFORE MINORITY INTEREST                         (6,764)         (3,839)         (1,286)         (1,769)       (110,342)
                                                    ------------    ------------    ------------    ------------    ------------

MINORITY INTEREST                                            593             370            --               167           1,729
                                                    ------------    ------------    ------------    ------------    ------------

NET LOSS                                            $     (6,171)   $     (3,469)   $     (1,286)   $     (1,602)   $   (108,613)
                                                    ============    ============    ============    ============    ============

DEFICIT ACCUMULATED DURING THE DEVELOPMENT
  STAGE, BEGINNING OF PERIOD                            (102,442)        (12,243)       (103,546)        (14,110)           --

DEFICIT ACCUMULATED DURING THE DEVELOPMENT
  STAGE, END OF PERIOD                              $   (108,613)   $    (15,712)   $   (104,832)   $    (15,712)   $   (108,613)
                                                    ============    ============    ============    ============    ============

BASIC AND DILUTED NET LOSS PER COMMON SHARE         $      (0.16)   $      (0.10)   $      (0.03)   $      (0.04)   $      (4.27)
                                                    ============    ============    ============    ============    ============

WEIGHTED AVERAGE
  COMMON SHARES OUTSTANDING                           37,806,072      35,706,779      37,833,420      36,724,401      25,408,553
                                                    ============    ============    ============    ============    ============
</TABLE>



                                       3

<PAGE>   3

                   SEVEN SEAS PETROLEUM INC. AND SUBSIDIARIES
                        (A DEVELOPMENT STAGE ENTERPRISE)
                      STATEMENTS OF CONSOLIDATED CASH FLOWS
                            (Unaudited; In thousands)

<TABLE>
<CAPTION>
                                                                                                      CUMULATIVE
                                                                                                      TOTAL FROM
                                                                                                       INCEPTION
                                                                                                     (FEBRUARY 3,
                                                                                                        1995) TO
                                                                   NINE MONTHS ENDED SEPTEMBER 30,   SEPTEMBER 30,
                                                                       1999              1998            1999
                                                                   --------------    -------------   -------------
<S>                                                                  <C>               <C>              <C>
OPERATING ACTIVITIES
     Net loss                                                        $ (6,171)         $ (3,469)        $(108,603)
     Add (subtract) items not requiring (providing) cash:
     Compensation expense                                                  --                --             2,140
     Minority interest                                                   (593)             (370)           (1,729)
     Common stock contribution to 401(k) retirement plan                   --                --                79
     Depreciation and amortization                                        806               449             1,782
     Writedown of proved oil & gas properties                              --                --           129,789
     Loss on sale of exploration property                                 670              (577)              124
     Dry hole and abandonment costs                                        --                --             1,140
     Gain on sale of marketable securities                                 --                (6)               (6)
     Deferred income taxes benefit                                         --                --           (45,727)
     Amortization of investments                                       (1,048)               --            (1,048)
     Changes in working capital excluding changes to cash and cash
        equivalents:
        Accounts receivable                                             2,115               867            (3,565)
        Interest receivable                                               442              (495)              (90)
        Inventory                                                          27                --            (1,289)
        Prepaids and other, net                                           172                53               (53)
        Accounts payable                                               (3,513)           (5,299)           (2,197)
        Other accrued liabilities                                        (223)              339               346
                                                                     --------          --------         ---------
Cash Flow Used in Operating Activities                                 (7,316)           (8,508)          (24,513)
                                                                     --------          --------         ---------
INVESTING ACTIVITIES
     Exploration of oil and gas properties                            (20,427)          (24,324)          (92,772)
     Purchase of land                                                      (1)           (1,591)           (1,258)
     Purchase of investments                                           (8,818)          (56,069)          (47,119)
     Proceeds from acquisition                                             --                --               630
     Payment to withdraw from property                                   (250)            1,163               997
     Proceeds from sale of marketable securities                           --                50                50
     Proceeds from sale of investments                                 13,080                --            13,080
     Notes receivable from employees                                     (236)               --              (436)
     Other asset additions                                               (216)           (1,150)           (1,972)
                                                                     --------          --------         ---------
Cash Flow Used in Investing Activities                                (16,868)          (81,921)         (128,800)
                                                                     --------          --------         ---------
FINANCING ACTIVITIES
     Proceeds from special warrants issued                                 --               284            12,393
     Proceeds from share capital issued                                    --             2,619            15,466
     Proceeds from additional paid-in capital contributed                  --                --                 1
     Proceeds from issuance of  long-term debt                             --           110,000           135,000
     Costs of issuing long-term debt                                       --            (4,248)           (5,821)
     Contributions by minority interest                                 1,386             5,416            11,623
                                                                     --------          --------         ---------
Cash Flow Provided by Financing Activities                              1,386           114,071           168,662
                                                                     --------          --------         ---------
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS                  (22,798)           23,642            15,349
Cash and cash equivalents, beginning of period                         38,147            18,067                --
CASH AND CASH EQUIVALENTS, END OF PERIOD                             $ 15,349          $ 41,709         $  15,349
                                                                     ========          ========         =========
</TABLE>


    Supplemental disclosures of cash flow information:
    The Company incurred interest costs of $10.3 million and $7.0 million for
the nine month periods ended September 30, 1999 and 1998, respectively. Such
amounts were capitalized during the respective periods.
    Cash paid for interest for the nine month periods ended September 30, 1999
and 1998 was $6.9 million, $0.9 million, respectively.
    The Company paid zero and $30,000 for estimated income taxes during the nine
month periods ended September 30, 1999 and 1998, respectively. The accompanying
notes are an integral part of these financial statements.


                                       4

<PAGE>   4


prospects are uncertainties inherent in estimating oil and gas reserves and
future hydrocarbon production and cash flows, particularly with respect to wells
that have not been fully tested and with wells having limited production testing
histories; access to additional capital; changes in the price of oil and natural
gas, services and equipment; the limited exploration of the concessions; the
status of existing and future contractual relationships with Ecopetrol; foreign
currency fluctuation risks; Seven Seas' substantial indebtedness; the presence
of competitors with greater financial resources and capacity; and difficulties
and risks associated with operating in Colombia.


2. BASIS OF PRESENTATION

    The accompanying unaudited, condensed consolidated financial statements
include the accounts of Sevens Seas Petroleum Inc. and its subsidiaries after
elimination of intercompany balances and transactions.

    The unaudited, condensed consolidated financial statements of the Company
for the periods indicated herein have been prepared by the Company pursuant to
the rules and regulations of the Securities and Exchange Commission and in
accordance with generally accepted accounting principles (GAAP) for interim
financial reporting. Accordingly, they do not include all of the information and
footnotes required by GAAP for complete financial statements. In the opinion of
management, all adjustments, consisting of normal recurring accruals, necessary
to present fairly the information in the accompanying condensed consolidated
financial statements have been included. Interim period results are not
necessarily indicative of the results of operations or cash flows for a full
year period. The condensed financial statements included herein should be read
in conjunction with the audited financial statements and notes thereto included
in the Company's Annual Report on Form 10K for the year ended December 31, 1998.

    Certain minor reclassifications have been made in prior years to conform to
current reporting practices.


3. OPERATIONS BY GEOGRAPHIC AREA


    The Company has one operating and reporting segment. Information about the
Company's operations for the nine months ended September 30, 1999 and 1998 and
by geographic area is shown below (In thousands):

<TABLE>
<CAPTION>

                                                                                  OTHER
                                                        UNITED                   FOREIGN
                                             CANADA     STATES     COLOMBIA       AREAS      TOTAL
<S>                                         <C>        <C>         <C>           <C>      <C>
   Nine months ended  September 30, 1999
     Revenues.............................. $  2,311   $      9    $     391     $    --  $   2,711
     Operating Income (Loss)...............    1,124     (2,569)      (4,599)       (690)    (6,734)
     Capital Expenditures..................       --         61        8,822         250      9,133
     Identifiable Assets...................   74,453      1,080      183,243          81    258,857
     Depreciation and Amortization               455        251          100          --        806
   Nine months ended  September 30, 1998
     Revenues.............................. $  2,481   $      9    $     175     $    --  $   2,665
     Operating Income (Loss)...............    1,861     (3,729)      (2,432)        563     (3,737)
     Capital Expenditures..................       --        937       27,415          54     28,406
     Identifiable Assets...................  106,152      1,384      299,257         469    407,262
     Depreciation and Amortization.........      334         80           32          --        446
</TABLE>

4. NOTES RECEIVABLE FROM EMPLOYEES

    In April 1999, the Company loaned funds totaling $0.2 million to several
non-executive employees for the purpose of purchasing the Company's common
shares. These notes bear a 4.99% interest rate and are due 36 to 44 months from
origination. The Company recognized interest income of $4,000 for the nine
months ended September 30, 1999.

5. MINORITY INTEREST


    In June 1999, Seven Seas Petroleum Inc. ("SSPI") completed the
reorganization of certain of its subsidiaries, three of which owned working
interests in the Dindal and Rio Seco Association Contracts, through a series of
tax-free transactions. Prior to these transactions, Seven Seas Petroleum
Holdings Inc. (SSPH), a wholly owned subsidiary of SSPI, owned 100% of the stock
of Seven Seas Petroleum Colombia Inc. ("SSPC") and 50% of Esmeralda L.L.C. SSPC
owned the remaining 50% of Esmeralda L.L.C. and 62.963% of Cimarrona L.L.C. with
MTV Investments Ltd. ("MTV"), the minority interest owner in Cimarrona L.L.C.,
owning the remaining 37.037%. In the reorganization transactions, SSPH first
assigned its membership interest in Esmeralda L.L.C. to SSPC as a capital
contribution, giving SSPC 100% ownership of Esmeralda L.L.C. Next, Esmeralda
L.L.C. was merged into Cimarrona L.L.C. SSPH continued to own 100% of the stock
of SSPC. Cimarrona L.L.C. and its members, MTV and SSPC, entered into an
agreement whereby the assets, obligations, and liabilities of Cimarrona L.L.C.
which were proportionately attributable to SSPC (through the



                                       6
<PAGE>   5

Company's interests in Esmeralda L.L.C. and Cimarrona L.L.C.) were merged into
SSPC in exchange for SSPC's interest in Cimarrona L.L.C. As a result, MTV became
the sole member of Cimarrona L.L.C. and accordingly, Cimarrona L.L.C. is no
longer a consolidated subsidiary of the Company. MTV maintained its
proportionate interest in the Dindal and Rio Seco Association Contracts as a
working interest owner and Seven Seas' net interest in the Association Contracts
was not changed.

6. CONTINGENCIES

    The Company is, from time to time, party to certain legal actions and claims
arising in the ordinary course of business. While the outcome of these events
cannot be predicted with certainty, management does not expect these matters to
have a material adverse effect on the financial position or results of
operations or cash flows of the Company.

Colombian forest reserve


         Inderena, the predecessor to the current Ministry of Environment,
declared a forest reserve in the 1980's in an area that includes a portion of
the Dindal and Rio Seco Association Contracts. The existence of this reserve may
make obtaining permits for drilling wells and building facilities more
difficult, but does not preclude oil and gas activity. In fact, we were granted
an environmental permit and drilled the Escuela 1 well on this area in 1993.
More recently, the Guaduas municipality has, independently of the Ministry of
Environment, declared a forest reserve in the same area. This latest reserve
proclamation would prohibit drilling. Colombian counsel has advised us that the
right to declare forest reserves is the exclusive right of the Ministry of
Environment. We intend to discuss this matter with representatives of the
municipal council and the mayor. In the event we do not obtain satisfactory
results, we have also engaged Colombian counsel to proceed before an appropriate
tribunal to have the municipal declaration ruled invalid. We are advised that
the resolution could take from 12 to 18 months. We will also seek an order from
the tribunal suspending the municipal declaration until final resolution. We are
advised that this process would take four to six months. The earliest we would
otherwise intend to drill in this area would be June 2000.


         The forest reserve includes approximately 6,250 acres of our 109,000
total acreage under the Rio Seco and Dindal association contracts. The forest
reserve should not preclude us from recovering our proved oil and gas reserves.
There is a surface location for the deeper subthrust structure well that can
be drilled outside the forest reserve. Further, the existence of the forest
reserve will not impede our development of the shallow Cimarrona reservoir
of the Guaduas field.

Environmental penalties


         On June 8, 1998 the Ministry of Environment required our subsidiary,
GHK Company Colombia, to perform some remedial works on the El Segundo 6-E
location and access road. GHK Company Colombia performed the works, and
thereafter reported to the Ministry of Environment that all the works had duly
been completed. In various site visits, ministry officials have confirmed that
the alleged violations have been properly remedied. On July 8, 1999 GHK Company
Colombia filed all the documentation which confirmed total compliance to the
requirements. Although we cannot be certain, we do not expect any fines or
penalties to be imposed in connection with the alleged El Segundo 6-E
environmental violations.


         On August 30, 1999, the Ministry of Environment issued a resolution
against our subsidiary, GHK Company Colombia, declaring it in violation of a
1997 decree in connection with the construction of the El Segundo 7-E well. The
resolution imposed a fine of approximately $215,000. We have filed an appeal for
a reversal of the resolution, including 379 pages of documentary evidence
supporting our position. We believe that we have corrected the environmental
violations claimed by the Ministry of Environment and that the fine may be
reduced or eliminated. However, the appeal process can take up to two years. The
El Segundo No. 7 well has been restored and we do not currently have any
drilling activities planned at this location.

Contract area

    The Dindal Association Contract was issued in March 1993 and provides for a
maximum six-year exploration period followed by a maximum 22-year production
period, with partial relinquishment of acreage, excluding commercial fields,
required commencing at the end of the sixth year of the Association Contract.
The exploration period under the Dindal Association Contract will be extended to
September 23, 2000, provided the Associates commit to an additional $2.0 million
of exploration work. In September 2000, we must relinquish 50% of the contract
area or all lands that fall outside a five kilometer buffer zone around the area
designated to be the commercial field or negotiate another one year extension by
committing to additional exploration work, if applicable.

                                       7

<PAGE>   6

     If additional funds become available from borrowings or otherwise, we would
next drill exploration wells on the multiple prospects within the Rosablanca and
Montecristo blocks, which we operate.

    Subject to obtaining adequate additional funding, our next priority is to
continue to delineate and develop our principal property in the Guaduas field.
The Company plans to focus its resources on placing the Guaduas field on
production by increments in order to achieve cash flow as soon as possible.
First production from the Guaduas field, Increment I, should be achieved through
the construction of a Portable Trucking Facility ("PTF" -- subsequently to
become part of the permanent facilities) for the trucking of between 4,000
Bbls/d and 6,000 Bbls/d to a local refinery located approximately 80 miles from
the Guaduas field. The estimated net capital cost to the Company for these
facilities is approximately $1.0 million. The Company estimates that it can
commence PTF production in early 2000. Increment II, Early Pipeline Production,
includes the construction of facilities for the production of 20,000 Bbls/d to
30,000 Bbls/d and is scheduled to go on line in early-2001. Increment II
facilities will include the construction of a 36-mile pipeline that will connect
with the existing regional OAM pipeline. Contemporaneously, the Company will
drill additional development wells and one gas injection well. The Company
estimates that the net capital cost of the pipeline, the production facilities
and drilling the necessary wells will be approximately $12.6 million. The net
cost of the pipeline will range from $4.3 million to $6.1 million, depending on
the size. Whether the Company can achieve the Increment I and II objectives on
schedule and with the Company's existing capital resources is dependant upon a
number of factors, many of which are not within its control, such as timely
environmental permitting, securing pipeline rights-of-way, obtaining Ecopetrol's
agreement to commerciality under the Association Contracts and timely payments
by the co-participants of their share of these costs as well as the market price
of oil field equipment and services. If the Company experiences delays or cost
overruns, which must be considered possible, the Company will seek other sources
of financing, including project financing, industry joint ventures or like
arrangements with industry service companies, commercial bank borrowings and
traditional debt and equity financing. The Company's expenditures for Increment
II, Early Pipeline Production, may be substantially reduced by having a third
party construct the Guaduas pipeline (connecting to the OAM regional pipeline),
in which case the Company may have little or no equity, thereby obligating the
Company to pay only a per barrel tariff on its oil transported through the
pipeline and none of the capital expenditures that are currently budgeted by the
Company for the construction of the pipeline.

    Furthermore, the Company will be required to obtain additional sources of
financing to meet its other, multiple objectives of accelerating incremental
production from the Guaduas field beyond Increment II and delineation and
exploratory drilling. Each additional increment of field production (Increments
III through V) will require additional production facilities, a pipeline
expansion, and the expansion of proved oil reserves through successful
development and delineation drilling of the shallow Cimarrona reservoir.


    We are obligated to conduct seismic operations on the Rosablanca and
Montecristo blocks during 1999 and the first quarter of 2000 at a net cost of
$2.1 million.


LIQUIDITY AND CAPITAL RESOURCES

         We had working capital, net of restricted investments, of $24.3
million, and unrestricted cash resources, including short-term investments, of
$24.2 million as of September 30, 1999. Our non-discretionary capital
commitments for the remainder of 1999, as of September 30, 1999, are
approximately $3.8 million.

         Our activities from inception through September 30, 1999 were funded
primarily by the proceeds from private placements of our securities, including
our common shares, warrants and notes, resulting in aggregate cash proceeds of
$157.0 million. Recent transactions include:

   o     Exchangeable Notes. In August 1997, we issued $25.0 million of 6%
         exchangeable notes in a private transaction with institutional and
         accredited investors. The exchangeable notes accrued interest at a rate
         of 6% per annum and were payable on December 31 and June 30 in each
         year, commencing December 31, 1997. The exchangeable notes were
         scheduled to mature on August 7, 2003.

   o     Convertible Debentures. The exchangeable notes were exchanged for a
         like principal amount of 6% convertible debentures on August 5, 1998.
         The 6% convertible debentures were converted on August 6, 1998 into
         units consisting of 2,173,901 common shares and warrants exercisable
         for 1,086,957 common shares.

                                       10
<PAGE>   7


   o     Purchase Warrants. On February 5, 1999, purchase warrants for 1.1
         million of our common shares expired without exercise. We received
         proceeds of $0.3 million from the exercise of 18,913 warrants. These
         purchase warrants had been issued in association with the exchange and
         conversion of our previously outstanding $25 million issue of 6%
         exchangeable notes.

   o     Senior Notes. In May 1998, we completed the offering of $110 million of
         12 1/2% senior notes due May 15, 2005 and received net proceeds of
         approximately $106 million. Approximately $37.8 million of the proceeds
         has been held in a separate account or in escrow to provide for the
         first three years of interest payable under the senior notes. Interest
         on the senior notes is payable semi-annually on May 15 and November 15
         of each year, commencing November 15, 1998. The senior notes mature on
         May 15, 2005. The senior notes are redeemable at our option, in whole
         or in part, at any time on or after May 15, 2002, at the prescribed
         redemption price, plus accrued and unpaid interest, liquidated damages
         and additional amounts, if any, to the date of redemption.
         Notwithstanding the foregoing, at any time prior to May 15, 2001, we
         may redeem up to 33 1/3% of the original aggregate principal amount of
         the senior notes at a redemption price of 112.50% of the principal
         amount redeemed with a portion of the net proceeds of an equity or
         strategic investor offering, provided that at least 66 2/3% of the
         original aggregate principal amount of the senior notes remains
         outstanding immediately after the redemption. In the event of certain
         changes affecting withholding taxes applicable to certain payments on
         the senior notes, the senior notes may be redeemed at our option, in
         whole but not in part, at any time at a redemption price equal to 100%
         of the principal amount thereof plus accrued and unpaid interest,
         liquidated damages and additional amounts, if any, to the redemption
         date. Upon the occurrence of a change of control:

                  (1)      Unless we redeem the senior notes as provided in (2)
                           below, we will be required to offer to purchase the
                           senior notes at a purchase price equal to 101% of the
                           aggregate principal amount thereof, plus accrued and
                           unpaid interest, liquidated damages and additional
                           amounts, if any, to the date of purchase; and

                  (2)      We will have the option, at any time prior to May 15,
                           2002, to redeem the senior notes, in whole but not in
                           part, at a redemption price equal to 100% of the
                           principal amount thereof plus the applicable premium
                           and accrued and unpaid interest, liquidated damages
                           and additional amounts, if any, to the date of
                           redemption.

         The senior notes are senior obligations of Seven Seas and rank pari
passu in right and priority of payment with all of our existing and future
senior indebtedness.

COLOMBIA


         In 1995, we acquired a 15% interest in the Dindal and Rio Seco
association contracts through our participation in El Segundo 1-E, the Guaduas
field discovery well. In 1996, we acquired an additional 36.7% in the Dindal and
Rio Seco association contracts in exchange for the issuance of our common shares
valued at $153.1 million in the aggregate at that time. In 1997, we acquired an
additional 6% in the Dindal and Rio Seco association contracts in exchange for
the issuance of our common shares valued at $18.6 million in the aggregate at
that time. From inception through September 30, 1999, we had cash expenditures
for the exploration of oil and gas properties of $92.8 million.


         Our estimated capital expenditures assume that each of the associates
in the association contracts approves and pays its proportionate share of
capital expenditures. Under the terms of the association contracts, if a
commercially feasible discovery is made, Ecopetrol may acquire a 50% interest in
the property, and the interests of all other parties to the contract will be
reduced by 50%. Ecopetrol will bear 50% of the associated development costs and
will reimburse the other associates for 50% of certain exploration activities.
The association contracts require Ecopetrol's participation in the production
facilities. We expect that Ecopetrol will participate in the extent of 50% of
the pipeline and infrastructure costs. We cannot be sure, however, that an
agreement will be reached and we may be required to fund amounts greater than
the amounts presented as our net share. Ecopetrol retains the right not to
participate initially in the development. In this case, the associates can
develop the Guaduas field under a sole risk provision, and will be required to
invest 100% of the development costs. After the associates have recovered 200%
of the costs invested for development plus 50% of certain exploration costs,
Ecopetrol will become a participant in the project with a 50% interest.

         To date, all oil revenues have been due to our share of crude oil
produced during production testing of our wells on the Guaduas field. Although
we intend to continue selling oil from production tests, significant commercial
production is not expected until we drill, or redrill and complete, additional
wells and construct production and pipeline transportation facilities.

         We have contracted to acquire 100 kilometers of new 2-D seismic on the
Rosablanca association contract at a net cost of approximately $1.1 million. We
estimate the cost to conduct seismic operations on the Montecristo and
Rosablanca association


                                       11

<PAGE>   8


                                   SIGNATURES


                                           SEVEN SEAS PETROLEUM INC.



    Date: April 13, 2000                    By:  Larry A. Ray
                                                 Executive Vice President,
                                                 Chief Operating Officer and
                                                 Chief Financial Officer
                                                 Sir Mark Thomson, Bt. President











                                       15