<PAGE>

                                    FORM 10-Q



                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549


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

                  For the quarterly period ended March 31, 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 number 0-20154


                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                            <C>
                  Texas                                    76-0350269
(State or other jurisdiction of organization)  (I.R.S. Employer Identification No.)
</TABLE>


                        16825 Northchase Drive, Suite 400
                              Houston, Texas 77060
                    (Address of principal executive offices)
                                   (Zip Code)

                                  (281)874-2700
              (Registrant's telephone number, including area code)

                                      None
              (Former name, former address and former fiscal year,
                          if changed since last report)


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>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.

                                      INDEX



<TABLE>
<CAPTION>
PART I.    FINANCIAL INFORMATION                                       PAGE
      <S>                                                               <C>
      ITEM 1.    Financial Statements

            Balance Sheets

                - March 31, 1999 and December 31, 1998                   3

            Statements of Operations

                - Three month periods ended March 31, 1999 and 1998      4

            Statements of Cash Flows

                - Three month periods ended March 31, 1999 and 1998      5

            Notes to Financial Statements                                6

      ITEM 2.    Management's Discussion and Analysis of Financial
                     Condition and Results of Operations                10

PART II.    OTHER INFORMATION                                           12


SIGNATURES                                                              13
</TABLE>



<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                                 BALANCE SHEETS



<TABLE>
<CAPTION>
                                                                                          March 31,           December 31,
                                                                                            1999                 1998
                                                                                       --------------       --------------
                                                                                         (Unaudited)
         <S>                                                                           <C>                  <C>           
         ASSETS:

         Current Assets:
              Cash and cash equivalents                                                $        1,678       $        1,671 
              Nonoperating interests income receivable                                         11,942               17,617 
              Nonoperating receivable due to property disposition                                  --               24,303 
              Other                                                                                --                2,992 
                                                                                       ---------------      ---------------
                  Total Current Assets                                                         13,620               46,583 
                                                                                       ---------------      ---------------
         Nonoperating interests in oil and gas
              properties, using full cost accounting                                        4,135,909            4,131,910 
         Less-Accumulated amortization                                                     (3,508,530)          (3,477,234)
                                                                                       ---------------      ---------------
                                                                                              627,379              654,676 
                                                                                       ---------------      ---------------
                                                                                       $      640,999       $      701,259 
                                                                                       ===============      ===============

         LIABILITIES AND PARTNERS' CAPITAL:

         Current Liabilities:
              Accounts Payable                                                         $        8,560       $       42,800 
                                                                                       ---------------      ---------------

         Interest Holders' Capital (3,664,333 Interest Holders' SDIs;
                                   $1.00 per SDI)                                             597,312              626,555 
         General Partners' Capital                                                             35,127               31,904 
                                                                                       ---------------      ---------------
                  Total Partners' Capital                                                     632,439              658,459 
                                                                                       ---------------      ---------------
                                                                                       $      640,999       $      701,259 
                                                                                       ===============      ===============
</TABLE>


                 See accompanying notes to financial statements.

                                        3


<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                            STATEMENTS OF OPERATIONS
                                   (Unaudited)



<TABLE>
<CAPTION>
                                                                                           Three Months Ended
                                                                                             March 31,
                                                                                 ---------------------------------
                                                                                       1999               1998
                                                                                 --------------    ---------------
         <S>                                                                     <C>               <C>
         REVENUES:
             Income from nonoperating interests                                  $        42,077   $        69,425 
             Interest income                                                                 392               239 
                                                                                 ---------------   --------------- 
                                                                                          42,469            69,664 
                                                                                 ---------------   --------------- 
         COSTS AND EXPENSES:
             Amortization                                                                 31,296            37,171 
             General and administrative                                                   18,892            15,379 
                                                                                 ---------------   --------------- 
                                                                                          50,188            52,550 
                                                                                 ---------------   --------------- 
         NET INCOME (LOSS)                                                       $        (7,719)  $        17,114 
                                                                                 ===============   =============== 
</TABLE>

         Limited Partners' net income (loss)
             per SDI

         March 31, 1999                       $            -- 
                                                 ============ 
         March 31, 1998                       $            -- 
                                                 ============ 


                 See accompanying note to financial statements.

                                        4


<PAGE>
                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)


<TABLE>
<CAPTION>
                                                                                           Three Months Ended
                                                                                                March 31,
                                                                                ---------------------------------------
                                                                                      1999                    1998
                                                                                ----------------        ---------------
<S>                                                                             <C>                     <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
    Income (loss)                                                               $         (7,719)       $        17,114 
    Adjustments to reconcile income (loss) to
      net cash provided by operations:
      Amortization                                                                        31,296                 37,171 
      Change in assets and liabilities:
        (Increase) decrease in nonoperating interests income receivable                    5,675                  1,477 
        (Increase) decrease in other current assets                                       27,295                     -- 
        Increase (decrease) in accounts payable                                          (34,240)                (1,024)
                                                                                  --------------         -------------- 
                 Net cash provided by (used in) operating activities                      22,307                 54,738 
                                                                                  --------------         -------------- 
CASH FLOWS FROM INVESTING ACTIVITIES:
        Additions to nonoperating interests in oil and gas properties                     (4,005)               (10,813)
        Proceeds from sale of nonoperating interests in oil and gas properties                 6                 37,977 
                                                                                  --------------         -------------- 
                 Net cash provided by (used in) investing activities                      (3,999)                27,164 
                                                                                  --------------         -------------- 
CASH FLOWS FROM FINANCING ACTIVITIES:
      Cash distributions to partners                                                     (18,301)               (81,895)
                                                                                  --------------         -------------- 
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS                                           7                      7 
                                                                                  --------------         -------------- 
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD                                           1,671                  1,585 
                                                                                  --------------         -------------- 
CASH AND CASH EQUIVALENTS AT END OF PERIOD                                      $          1,678        $         1,592 
                                                                                  ==============         ==============
</TABLE>


                 See accompanying notes to financial statements.

                                        5


<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                          NOTES TO FINANCIAL STATEMENTS
                                   (UNAUDITED)

(1)  General Information -

                  The financial statements included herein have been prepared by
        the  Partnership  and are  unaudited  except  for the  balance  sheet at
        December  31,  1998  which has been  taken  from the  audited  financial
        statements at that date. The financial  statements reflect  adjustments,
        all of which were of a normal recurring nature, which are in the opinion
        of the  managing  general  partner  necessary  for a fair  presentation.
        Certain  information  and  footnote  disclosures  normally  included  in
        financial  statements  prepared in accordance  with  generally  accepted
        accounting  principles  have  been  omitted  pursuant  to the  rules and
        regulations  of the  Securities  and Exchange  Commission  ("SEC").  The
        Partnership  believes adequate disclosure is provided by the information
        presented.  The financial  statements should be read in conjunction with
        the audited  financial  statements  and the notes included in the latest
        Form 10-K.

(2)  Organization and Terms of Partnership Agreement -

                  Swift Energy Pension  Partners  1991-C,  Ltd., a Texas limited
        partnership  ("the  Partnership"),  was formed on December 30, 1991, for
        the purpose of  purchasing  net  profits  interest,  overriding  royalty
        interests and royalty interests (collectively, "nonoperating interests")
        in producing oil and gas properties within the continental United States
        and Canada. Swift Energy Company ("Swift"), a Texas corporation, and VJM
        Corporation ("VJM"), a California corporation, serve as Managing General
        Partner and Special  General Partner of the  Partnership,  respectively.
        The sole limited partner of the Partnership is Swift Depositary Company,
        which has assigned all of its beneficial  (but not of record) rights and
        interest  as  limited  partner  to  the  investors  in  the  Partnership
        ("Interest  Holders"),   in  the  form  of  Swift  Depositary  Interests
        ("SDIs").

                  The Managing  General  Partner has paid or will pay out of its
        own corporate funds (as a capital  contribution to the  Partnership) all
        selling commissions,  offering expenses,  printing, legal and accounting
        fees and other  formation costs incurred in connection with the offering
        of SDIs and the  formation  of the  Partnership,  for which the Managing
        General  Partner  will  receive  an  interest  in  continuing  costs and
        revenues of the Partnership. The 350 Interest Holders made total capital
        contributions of $3,664,333.

                  Generally,   all  continuing  costs  (including   general  and
        administrative  reimbursements  and direct  expenses)  and  revenues are
        allocated  85  percent  to the  interest  holders  and 15 percent to the
        general  partners.   After   partnership   payout,  as  defined  in  the
        Partnership  Agreement,  continuing costs and revenues will be shared 75
        percent by the interest holders, and 25 percent by the general partners.

(3)  Significant Accounting Policies -

       Use of Estimates --

                  The  preparation  of financial  statements in conformity  with
        generally accepted  accounting  principles  requires  management to make
        estimates and assumptions that affect the reported amounts of assets and
        liabilities  at the date of the  financial  statements  and the reported
        amounts of revenues and expenses  during the  reporting  period.  Actual
        results could differ from estimates. 


                                       6


<PAGE>


                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                    NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                                   (UNAUDITED)


     Nonoperating Interests in Oil and Gas Properties --

                  The Partnership accounts for its ownership interest in oil and
        gas properties using the proportionate consolidation method, whereby the
        Partnership's  share of assets,  liabilities,  revenues  and expenses is
        included in the appropriate classification in the financial statements.

                  For financial  reporting purposes the Partnership  follows the
        "full-cost"  method of accounting for nonoperating  interests in oil and
        gas property costs. Under this method of accounting,  all costs incurred
        in the acquisition of  nonoperating  interests in oil and gas properties
        are capitalized.  The unamortized cost of nonoperating  interests in oil
        and gas  properties is limited to the "ceiling  limitation"  (calculated
        separately for the Partnership,  limited partners and general partners).
        The  "ceiling  limitation"  is  calculated  on  a  quarterly  basis  and
        represents the estimated future net revenues from nonoperating interests
        in proved  properties  using current  prices  discounted at ten percent.
        Proceeds from the sale or disposition of  nonoperating  interests in oil
        and  gas  properties  are  treated  as a  reduction  of the  cost of the
        nonoperating  interests  with no gains or  losses  recognized  except in
        significant transactions.

                  The Partnership computes the provision for amortization of oil
        and gas properties on the units-of-production method. Under this method,
        the provision is calculated by multiplying the total unamortized cost of
        oil and gas  properties  by an overall rate  determined  by dividing the
        physical  units of oil and gas  produced  during the period by the total
        estimated  units of proved oil and gas reserves at the  beginning of the
        period.

                  The calculation of the "ceiling  limitation" and the provision
        for  depreciation,  depletion and  amortization is based on estimates of
        proved reserves. There are numerous uncertainties inherent in estimating
        quantities  of proved  reserves  and in  projecting  the future rates of
        production,  timing and plan of development. The accuracy of any reserve
        estimate  is a  function  of  the  quality  of  available  data  and  of
        engineering  and  geological  interpretation  and  judgment.  Results of
        drilling,  testing and production subsequent to the date of the estimate
        may justify revision of such estimate.  Accordingly,  reserve  estimates
        are  often  different  from  the  quantities  of oil  and gas  that  are
        ultimately recovered.

(4)  Related-Party Transactions -

                  The  Partnership  entered  into a Net Profits  and  Overriding
        Royalty  Interest  Agreement  ("NP/OR   Agreement")  with  Swift  Energy
        Operating Partners 1991-C, Ltd. ("Operating Partnership"), an affiliated
        partnership  managed  by Swift  for the  purpose  of  acquiring  working
        interests in producing  oil and gas  properties.  Under the terms of the
        NP/OR  Agreement,  the  Partnership  has been  conveyed  a  nonoperating
        interest in the  aggregate net profits  (i.e.,  oil and gas sales net of
        related  operating  costs)  of  the  properties  acquired  equal  to the
        Partnership's proportionate share of the property acquisition costs.


                                       7


<PAGE>


                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                    NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                                   (UNAUDITED)


(5)  Vulnerability Due to Certain Concentrations -

                  The  Partnership's  revenues are primarily the result of sales
        of its oil and natural gas production.  Market prices of oil and natural
        gas may fluctuate and adversely affect operating results.

                  In the normal  course of  business,  the  Partnership  extends
        credit,  primarily in the form of monthly oil and gas sales receivables,
        to various  companies  in the oil and gas  industry  which  results in a
        concentration  of credit risk. This  concentration of credit risk may be
        affected by changes in economic or other  conditions and may accordingly
        impact the  Partnership's  overall  credit risk.  However,  the Managing
        General  Partner  believes  that  the  risk is  mitigated  by the  size,
        reputation, and nature of the companies to which the Partnership extends
        credit.  In  addition,   the  Partnership  generally  does  not  require
        collateral or other security to support customer receivables.

(6)  Fair Value of Financial Instruments -

                  The Partnership's  financial  instruments  consist of cash and
        cash equivalents and short-term  receivables and payables.  The carrying
        amounts  approximate  fair value due to the highly  liquid nature of the
        short-term instruments.

(7)  Year 2000 -

                  The  Year  2000  issue  results  from  computer  programs  and
        embedded computer chips with date fields that cannot distinguish between
        the years 1900 and 2000.  The  Managing  General  Partner  is  currently
        implementing  the steps necessary to make its operations and the related
        operations of the Partnership capable of addressing the Year 2000. These
        steps include upgrading, testing and certifying its computer systems and
        field   operation   services   and   obtaining   Year  2000   compliance
        certification  from  all  important  business  suppliers.  The  Managing
        General Partner formed a task force during 1998 to address the Year 2000
        issue and prepare its business  systems for the Year 2000.  By mid-1999,
        the Managing  General Partner expects the mission critical systems to be
        either replaced or updated and testing to be virtually completed.

                  The Managing  General  Partner's  business  systems are almost
        entirely  comprised of  off-the-shelf  software.  Most of the  necessary
        changes in computer  instructional  code can be made by  upgrading  this
        software.  The Managing  General  Partner is currently in the process of
        either upgrading the off-the-shelf  software or receiving  certification
        as to Year 2000  compliance from vendors or third party  consultants.  A
        testing phase is being conducted as the software is updated or certified
        and is expected to be completed by mid-1999.


                                       8

<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                    NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                                   (UNAUDITED)


                  The  Managing  General  Partner  does not  believe  that costs
        incurred  to address  the Year 2000 issue with  respect to its  business
        systems  will have a  material  effect on the  Partnership's  results of
        operations,  or its  liquidity and  financial  condition.  The estimated
        total cost to the Managing  General  Partner to address Year 2000 issues
        is  projected  to be less  than  $150,000,  most of which  will be spent
        during  the  testing  phase.  The  Partnership's  share of this  cost is
        expected to be insignificant.

                  The  failure  to correct a material  Year 2000  problem  could
        result  in an  interruption,  or  failure  of  certain  normal  business
        activities or  operations.  Based on  activities  to date,  the Managing
        General  Partner  believes that it will be able to resolve any Year 2000
        problems  concerning  its financial and  administrative  systems.  It is
        undeterminable  how all the  aspects  of the Year 2000 will  impact  the
        Partnership.  The most  reasonably  likely  worst  case  scenario  would
        involve a prolonged disruption of external power sources upon which core
        equipment   relies,   resulting  in  a   substantial   decrease  in  the
        Partnership's  oil and  gas  production  activities.  In  addition,  the
        pipeline  operators  to whom the  Managing  General  Partner  sells  the
        Partnership's  natural gas, as well as other  customers  and  suppliers,
        could be prone to Year  2000  problems  that  could not be  assessed  or
        detected by the Managing General  Partner.  The Managing General Partner
        is contacting  its major  purchasers,  customers,  suppliers,  financial
        institutions  and others  with whom it conducts  business  to  determine
        whether  they will be able to resolve  in a timely  manner any Year 2000
        problems directly  affecting the Managing General Partner or Partnership
        and to inform them of the Managing General Partner's internal assessment
        of its Year 2000  review.  There  can be no  assurance  that such  third
        parties will not fail to appropriately address their Year 2000 issues or
        will not  themselves  suffer a Year 2000  disruption  that  could have a
        material  adverse  effect  on the  Partnership's  activities,  financial
        condition  or  operating  results.  Based upon these  responses  and any
        problems  that arise  during the  testing  phase,  contingency  plans or
        back-up systems would be determined and addressed.

                                       9


<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                       CONDITION AND RESULTS OF OPERATIONS

GENERAL

      The  Partnership  was formed for the purpose of investing in  nonoperating
interests in producing oil and gas  properties  located  within the  continental
United States and Canada.  In order to accomplish  this,  the  Partnership  goes
through two distinct yet  overlapping  phases with respect to its  liquidity and
results of  operations.  When the  Partnership  was  formed,  it  commenced  its
"acquisition"  phase,  with all funds  placed in  short-term  investments  until
required for the acquisition of nonoperating interests.  Therefore, the interest
earned on these pre-acquisition investments becomes the primary cash flow source
for  initial  Interest  Holder   distributions.   As  the  Partnership  acquires
nonoperating  interests  in  producing  properties,  net cash from  ownership of
nonoperating  interests  becomes  available  for  distribution,  along  with the
investment   income.   After  all  partnership   funds  have  been  expended  on
nonoperating  interests in producing  oil and gas  properties,  the  Partnership
enters its  "operations"  phase.  During  this phase,  income from  nonoperating
interests  in oil  and gas  sales  generates  substantially  all  revenues,  and
distributions  to Interest  Holders  reflect those  revenues less all associated
partnership expenses.  The Partnership may also derive proceeds from the sale of
nonoperating interests in acquired oil and gas properties, when the sale of such
interests is economically appropriate or preferable to continued operations.

LIQUIDITY AND CAPITAL RESOURCES

      Oil and gas reserves are depleting  assets and therefore often  experience
significant  production  declines each year from the date of acquisition through
the end of the life of the  property.  The primary  source of  liquidity  to the
Partnership comes almost entirely from the income generated from the sale of oil
and gas produced from ownership  interests in oil and gas  properties.  Net cash
provided  by  operating  activities  totaled  $22,307  and $54,738 for the three
months ended March 31, 1999 and 1998, respectively. This source of liquidity and
the related results of operations, and in turn cash distributions,  will decline
in  future  periods  as the oil and gas  produced  from  these  properties  also
declines while production and general and administrative costs remain relatively
stable making it unlikely that the  Partnership  will hold the properties  until
they are fully depleted,  but will likely liquidate when a substantial  majority
of the reserves  have been  produced.  The  Partnership  has expended all of the
partners' net commitments available for property acquisitions and development by
acquiring producing oil and gas properties. The partnership invests primarily in
proved  producing  properties with nominal levels of future costs of development
for  proven  but  undeveloped  reserves.  Significant  purchases  of  additional
reserves or extensive drilling activity are not anticipated.  Cash distributions
totaled  $18,301 and $81,895 for the three months ended March 31, 1999 and 1998,
respectively.

      The  Partnership  does  not  allow  for  additional  assessments  from the
partners or interest holders to fund capital  requirements.  However,  funds are
available  from  partnership  revenues or proceeds from the sale of  partnership
property.  The  Managing  General  Partner  believes  that the  funds  currently
available to the Partnership  will be adequate to meet any  anticipated  capital
requirements.

RESULTS OF OPERATIONS

      Income  from  nonoperating  interests  decreased  39  percent in the first
quarter of 1999 when  compared  to the same  quarter in 1998.  Oil and gas sales
declined $45,323 or 44 percent in the first quarter of 1999 when compared to the
corresponding  quarter in 1998,  primarily due to the normal production  decline
from the  Partnership's  wells in  conjunction  with lower oil  prices.  Current
quarter gas and oil production declined 11 percent and 3 percent,  respectively,
when compared to first quarter 1998 production volumes. Gas prices remained flat
at an average $1.66/MCF,  however, oil prices declined 51 percent or $6.16 to an
average  $6.04/BBL  for the  quarter,  further  contributing  to the  decline in
revenues.  The  majority  of the  Partnership's  oil  production  is  located in
Wyoming, which saw a significant drop in oil prices during the quarter.

      Corresponding  production costs per equivalent MCF decreased 50 percent in
the  first  quarter  of 1999  compared  to the  first  quarter  of 1998 as total
production  costs  decreased  54  percent,  offsetting  a portion of the revenue
decline.

      Total amortization expense decreased 16 percent or $5,875 in 1999 compared
to first quarter 1998

                                       10

<PAGE>


                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                 CONDITION AND RESULTS OF OPERATIONS (CONTINUED)


      The Partnership records an additional provision in depreciation, depletion
and amortization when the present value, discounted at ten percent, of estimated
future net revenues  from oil and gas  properties,  using the  guidelines of the
Securities and Exchange  Commission,  is below the fair market value  originally
paid for oil and gas  properties.  Using prices in effect at March 31, 1999, the
Partnership would have recorded an additional provision at March 31, 1999 in the
amount of $22,204.  However,  these temporarily low quarter-end prices rebounded
and by using prices in effect at the filing date, the Partnership's  unamortized
cost of oil and gas properties were not limited by this calculation.

      During 1999,  partnership  revenues  and costs will be shared  between the
Interest Holders and general partners in an 85:15 ratio.


                                       11


<PAGE>

                   SWIFT ENERGY PENSION PARTNERS 1991-C, LTD.
                           PART II - OTHER INFORMATION




ITEM 5.    OTHER INFORMATION


                                     -NONE-



                                       12


<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.


                                         SWIFT ENERGY PENSION
                                         PARTNERS 1991-C, LTD.
                                         (Registrant)

                              By:        SWIFT ENERGY COMPANY
                                         Managing General Partner


Date:     May 5, 1999         By:        /s/ John R. Alden
          -----------                    --------------------------------
                                         John R. Alden
                                         Senior Vice President, Secretary
                                         and Principal Financial Officer

Date:     May 5, 1999         By:        /s/ Alton D. Heckaman, Jr.
          -----------                    --------------------------------
                                         Alton D. Heckaman, Jr.
                                         Vice President, Controller
                                         and Principal Accounting Officer


                                       13