<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 June 30, 1997

                                       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 0-17023


                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                          <C>
                  Texas                                   76-0208087
(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 INCOME PARTNERS 1986-D, LTD.

                                      INDEX



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

            Balance Sheets

                - June 30, 1997 and December 31, 1996                                   3

            Statements of Operations

                - Three month and six month periods ended June 30, 1997 and 1996        4

            Statements of Cash Flows

                - Six month periods ended June 30, 1997 and 1996                        5

            Notes to Financial Statements                                               6

      ITEM 2.    Management's Discussion and Analysis of Financial
                     Condition and Results of Operations                                7

PART II.    OTHER INFORMATION                                                           9


SIGNATURES                                                                             10
</TABLE>


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                                 BALANCE SHEETS



<TABLE>
<CAPTION>
                                                                                            June 30,           December 31,
                                                                                              1997                 1996
                                                                                       ---------------      ---------------
                                                                                          (Unaudited)
         <S>                                                                           <C>                  <C>           
         ASSETS:

         Current Assets:
              Cash and cash equivalents                                                $        1,041       $        1,029
              Oil and gas sales receivable                                                    198,017              199,066
              Receivable due to property disposition                                               --              105,380
                                                                                       ---------------      ---------------
                   Total Current Assets                                                       199,058              305,475
                                                                                       ---------------      ---------------

         Oil and Gas Properties, using full cost
              accounting                                                                   12,898,885           12,897,927
         Less-Accumulated depreciation, depletion
              and amortization                                                            (10,608,332)         (10,534,127)
                                                                                       ---------------      ---------------
                                                                                            2,290,553            2,363,800
                                                                                       ---------------      ---------------
                                                                                       $    2,489,611       $    2,669,275
                                                                                       ===============      ===============

         LIABILITIES AND PARTNERS' CAPITAL:

         Current Liabilities:
             Accounts payable and accrued liabilities                                  $       81,884       $      105,215
                                                                                       ---------------      ---------------

         Deferred Revenues                                                                    125,281              126,636

         Partners' Capital                                                                  2,282,446            2,437,424
                                                                                       ---------------      ---------------
                                                                                       $    2,489,611       $    2,669,275
                                                                                       ===============      ===============
</TABLE>


                 See accompanying notes to financial statements.

                                        3


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                            STATEMENTS OF OPERATIONS
                                   (Unaudited)




<TABLE>
<CAPTION>
                                                        Three Months Ended               Six Months Ended
                                                             June 30,                        June 30,
                                             ----------------------------------  ---------------------------------
                                                   1997              1996              1997               1996
                                              ---------------   ---------------  ---------------   ---------------
<S>                                           <C>               <C>              <C>               <C>            
REVENUES:
   Oil and gas sales                          $       105,760   $       191,319  $       260,279   $       504,511
   Interest income                                        673               486            1,102               919
   Other                                                1,200             6,510            2,595             8,187
                                              ---------------   ---------------  ---------------   ---------------
                                                      107,633           198,315          263,976           513,617
                                              ---------------   ---------------  ---------------   ---------------

COSTS AND EXPENSES:
   Lease operating                                     53,257            47,220          101,879           134,937
   Production taxes                                     3,651             9,324           11,586            19,021
   Depreciation, depletion
      and amortization                                 39,321            52,026           74,205           128,071
   General and administrative                          30,251            30,815           62,848            61,984
   Interest expense                                        --             3,129               --            11,289
                                              ---------------   ---------------  ---------------   ---------------
                                                      126,480           142,514          250,518           355,302
                                              ---------------   ---------------  ---------------   ---------------
NET INCOME (LOSS)                             $       (18,847)  $        55,801  $        13,458   $       158,315
                                              ===============   ===============  ===============   ===============



Limited Partners' net income (loss)
   per unit                                   $         (1.33)  $          3.95  $           .95   $         11.21
                                              ===============   ===============  ===============   ===============
</TABLE>


                 See accompanying note to financial statements.

                                        4


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                                                            Six Months Ended
                                                                                                June 30,
                                                                               ----------------------------------------
                                                                                     1997                     1996
                                                                               ---------------          ---------------
<S>                                                                             <C>                     <C>            
CASH FLOWS FROM OPERATING ACTIVITIES:
    Income (loss)                                                               $       13,458          $       158,315
    Adjustments to reconcile income (loss) to
      net cash provided by operations:
      Depreciation, depletion and amortization                                          74,205                  128,071
      Change in gas imbalance receivable
          and deferred revenues                                                         (1,355)                 (12,019)
      Change in assets and liabilities:
        (Increase) decrease in oil and gas sales receivable                              1,049                   27,270
        (Increase) decrease in receivable due to property disposition                  105,380                       --
        Increase (decrease) in accounts payable
          and accrued liabilities                                                      (23,331)                (407,300)
                                                                               ---------------          ---------------
      Net cash provided by (used in) operating activities                              169,406                 (105,663)
                                                                               ---------------          ---------------
CASH FLOWS FROM INVESTING ACTIVITIES:
    Additions to oil and gas properties                                                 (3,059)                 (22,748)
    Proceeds from sales of oil and gas properties                                        2,101                  209,069
                                                                               ----------------         ---------------
      Net cash provided by (used in) investing activities                                 (958)                 186,321
                                                                               ---------------          ---------------
CASH FLOWS FROM FINANCING ACTIVITIES:
    Cash distributions to partners                                                    (168,436)                 (55,529)
    Payments on note payable                                                                --                  (25,000)
                                                                               ---------------          ---------------
      Net cash provided by (used in) financing activities                             (168,436)                 (80,529)
                                                                               ---------------          ---------------
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS                                        12                      129
                                                                               ---------------          ---------------
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD                                         1,029                    1,854
                                                                               ---------------          ---------------
CASH AND CASH EQUIVALENTS AT END OF PERIOD                                      $        1,041          $         1,983
                                                                               ===============          ===============
Supplemental disclosure of cash flow information:
   Cash paid during the period for interest                                     $           --          $        11,917
                                                                               ===============          ===============
</TABLE>


                 See accompanying notes to financial statements.

                                        5


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, 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,  1996  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)  Gas Imbalances -

                  The  gas  imbalance   receivable  and  deferred  revenues  are
        accounted  for on  the  entitlements  method,  whereby  the  Partnership
        records its share of revenue,  based on its entitled amount. Any amounts
        over or under  the  entitled  amount  are  recorded  as an  increase  or
        decrease  to the  gas  imbalance  receivable  or  deferred  revenues  as
        applicable.

(3)  Vulnerability Due to Certain Concentrations -

                  The  Company'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.

                  The Partnership extends credit 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.

(4)  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.


                                       6


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                       CONDITION AND RESULTS OF OPERATIONS


GENERAL

      The  Partnership  was formed for the purpose of investing in producing oil
and gas properties  located within the  continental  United States.  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  is formed,  it commences its  "acquisition"  phase,  with all funds
placed in short-term  investments until required for such property acquisitions.
The interest  earned on these  pre-acquisition  investments  becomes the primary
cash flow source for initial partner distributions.  As the Partnership acquires
producing   properties,   net  cash  from  operations   becomes   available  for
distribution,  along with the investment  income.  After  partnership funds have
been expended on producing oil and gas properties,  the  Partnership  enters its
"operations" phase. During this phase, oil and gas sales generate  substantially
all revenues,  and  distributions  to partners  reflect those  revenues less all
associated  partnership expenses.  The Partnership may also derive proceeds from
the sale of acquired oil and gas properties, when the sale of such properties is
economically appropriate or preferable to continued operation.

LIQUIDITY AND CAPITAL RESOURCES

      The  Partnership  has  completed  acquisition  of  producing  oil  and gas
properties,  expending  all  of  limited  partners'  commitments  available  for
property acquisitions.

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

RESULTS OF OPERATIONS

      The  following  analysis  explains  changes  in the  revenue  and  expense
categories  for the quarter ended June 30, 1997 (current  quarter) when compared
to the quarter  ended June 30,  1996  (corresponding  quarter),  and for the six
months ended June 30, 1997  (current  period),  when  compared to the six months
ended June 30, 1996 (corresponding period).

Three Months Ended June 30, 1997 and 1996

      Oil and gas sales declined  $85,559 or 45 percent in the second quarter of
1997 when  compared  to the  corresponding  quarter  in 1996,  primarily  due to
decreased gas and oil production.  A decline of 53 percent in oil production and
25  percent  in  gas  production   had  a  significant   impact  on  partnership
performance.  Also,  current  quarter gas prices declined 15 percent or $.32/MCF
when  compared  to second  quarter  1996 gas  prices,  further  contributing  to
decreased revenues.

      Associated depreciation expense decreased 24 percent or $12,705.



                                       7


<PAGE>

                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                 CONDITION AND RESULTS OF OPERATIONS (CONTINUED)


Six Months Ended June 30, 1997 and 1996

      Oil and gas sales decreased $244,232 or 48 percent in the first six months
of 1997 over the  corresponding  period in 1996.  A decline of 34 percent in gas
production and 52 percent in oil production were major  contributing  factors to
the  decreased  revenues for the period.  Increased  gas prices of 19 percent or
$.39/MCF partially offset the production declines.

      Associated depreciation expense declined 42 percent or $53,866.

      During 1997,  partnership  revenues  and costs will be shared  between the
limited partners and general partners in a 90:10 ratio.


                                       8


<PAGE>


                    SWIFT ENERGY INCOME PARTNERS 1986-D, LTD.
                           PART II - OTHER INFORMATION




ITEM 5.    OTHER INFORMATION


                                     -NONE-



                                       9


<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 INCOME
                                             PARTNERS 1986-D, LTD.
                                             (Registrant)

                                  By:        SWIFT ENERGY COMPANY
                                             Managing General Partner

Date:     August 4, 1997          By:        /s/ John R. Alden
          --------------
                                             ---------------------------------
                                             John R. Alden
                                             Senior Vice President, Secretary
                                             and Principal Financial Officer

Date:     August 4, 1997          By:        /s/ Alton D. Heckaman, Jr.
         ---------------
                                             ---------------------------------
                                             Alton D. Heckaman, Jr.
                                             Vice President, Controller
                                             and Principal Accounting Officer


                                       10