FORM 10-K405

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                Annual Report Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934

For the fiscal year ended December 31, 1999

Commission File Number 0-16331

                         DYCO OIL AND GAS PROGRAM 1986-X
                             (A LIMITED PARTNERSHIP)
             (Exact name of registrant as specified in its charter)

           Minnesota                                  41-1565819
(State or other jurisdiction of                    (I.R.S. Employer
incorporation or organization)                   Identification Number)

         Samson Plaza
   Two West Second Street
        Tulsa, Oklahoma                                 74103
     (Address of principal                            (Zip Code)
      executive offices)

Registrant's telephone number, including area code: (918) 583-1791

Securities registered pursuant to Section 12(b) of the Act:  None.

Securities registered pursuant to Section 12(g) of the Act:
      Units of limited partnership interest

      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 the
filing requirements for the past 90 days. Yes [X] No [ ]

      Indicate by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained, to the
best of registrant's  knowledge,  in definitive proxy or information  statements
incorporated  by reference in Part III of this Form 10-K405 or any  amendment to
this Form 10-K405. [X]

      The units of  limited  partnership  are not  publicly  traded,  therefore,
registrant cannot compute the aggregate market value of the voting units held by
non-affiliates of the registrant.

      DOCUMENTS INCORPORATED BY REFERENCE:  None.




                                      -1-
<PAGE>





                                  FORM 10-K405

                         DYCO OIL AND GAS PROGRAM 1986-X
                        (a Minnesota limited partnership)


                                TABLE OF CONTENTS


PART I.........................................................................3
      ITEM 1.   BUSINESS.......................................................3
      ITEM 2.   PROPERTIES.....................................................7
      ITEM 3.   LEGAL PROCEEDINGS.............................................11
      ITEM 4.   SUBMISSION OF MATTERS TO A VOTE OF LIMITED PARTNERS...........11
PART II.......................................................................11
      ITEM 5.   MARKET FOR THE REGISTRANT'S LIMITED PARTNERSHIP UNITS
                AND RELATED LIMITED PARTNER MATTERS...........................11
      ITEM 6.   SELECTED FINANCIAL DATA.......................................12
      ITEM 7.   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                CONDITION AND RESULTS OF OPERATIONS...........................14
      ITEM 7A.  QUANTITATIVE AND QUALITATIVE DISCLOSURES
                ABOUT MARKET RISK.............................................18
      ITEM 8.   FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA...................19
      ITEM 9.   CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON
                ACCOUNTING AND FINANCIAL DISCLOSURE...........................31
PART III......................................................................31
      ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT............31
      ITEM 11.  EXECUTIVE COMPENSATION........................................32
      ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS
                AND MANAGEMENT................................................36
      ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS................36
PART IV.......................................................................38
      ITEM 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS
                ON FORM 8-K ..................................................38
      SIGNATURES..............................................................40





                                      -2-
<PAGE>



                                     PART I


ITEM 1.    BUSINESS

      General

      The Dyco Oil and Gas Program 1986-X Limited Partnership (the "Program") is
a Minnesota  limited  partnership  engaged in the production of oil and gas. The
Program  commenced  operations  on December 12, 1986 with the primary  financial
objective of investing its limited  partners'  subscriptions  in the drilling of
oil  and gas  prospects  and  then  distributing  to its  limited  partners  all
available  cash flow from the Program's  on-going  production  operations.  Dyco
Petroleum Corporation ("Dyco") serves as the General Partner of the Program. See
"Item 2. Properties" for a description of the Program's reserves and properties.

      The  limited   partnership   agreement   for  the  Program  (the  "Program
Agreement")  provides  that limited  partners are  allocated  99% of all Program
costs and revenues and Dyco, as General Partner,  is allocated 1% of all Program
costs and  revenues.  Included in such costs is the Program's  reimbursement  to
Dyco of the Program's proportionate share of Dyco's geological, engineering, and
general and administrative expenses.

      Dyco  currently  serves as General  Partner  of 31  limited  partnerships,
including the Program.  Dyco is a wholly-owned  subsidiary of Samson  Investment
Company.  Samson  Investment  Company  and its various  corporate  subsidiaries,
including Dyco, (collectively, "Samson") are primarily engaged in the production
and  development of and exploration for oil and gas reserves and the acquisition
and  operation of  producing  properties.  At December  31,  1999,  Samson owned
interests in approximately  14,000 oil and gas wells located in 17 states of the
United States and the countries of Canada,  Venezuela,  and Russia.  At December
31, 1999,  Samson operated  approximately  3,400 oil and gas wells located in 15
states of the United States, as well as Canada, Venezuela, and Russia.

      As a limited  partnership,  the Program  has no  officers,  directors,  or
employees. It relies instead on the personnel of Dyco and Samson. As of March 1,
2000,  Samson employed  approximately  920 persons.  No employees are covered by
collective bargaining agreements, and management believes that Samson provides a
sound employee relations  environment.  For information  regarding the executive
officers  of Dyco,  see  "Item  10.  Directors  and  Executive  Officers  of the
Registrant."

      Dyco's and the Program's  principal place of business is located at Samson
Plaza, Two West Second Street, Tulsa, Oklahoma 74103, and their telephone number
is (918) 583-1791 or (800) 283-1791.



                                      -3-
<PAGE>



      Funding

      Although the Program  Agreement  permits the Program to incur  borrowings,
the Program's  operations and expenses are currently funded out of the Program's
revenues from oil and gas sales. Dyco may, but is not required to, advance funds
to  the  Program  for  the  same  purposes  for  which  Program  borrowings  are
authorized.


      Principal Products Produced and Services Rendered

      The Program's sole business is the  development  and production of oil and
gas with a  concentration  on gas.  The  Program  does  not  hold  any  patents,
trademarks,  licenses,  or  concessions  and is not a  party  to any  government
contracts.  The  Program  has no backlog of orders and does not  participate  in
research and development  activities.  The Program is not presently encountering
shortages of oilfield tubular goods, compressors,  production material, or other
equipment.


      Oil, Gas, and Environmental Control Regulations

      Regulation  of Production  Operations -- The  production of oil and gas is
subject to  extensive  federal and state laws and  regulations  governing a wide
variety of matters, including the drilling and spacing of wells, allowable rates
of  production,  prevention  of  waste  and  pollution,  and  protection  of the
environment.  In  addition  to the direct  costs  borne in  complying  with such
regulations,  operations and revenues may be impacted to the extent that certain
regulations limit oil and gas production to below economic levels.

      Regulation  of Sales and  Transportation  of Oil and Gas -- Sales of crude
oil and  condensate are made by the Program at market prices and are not subject
to price controls. The sale of gas may be subject to both federal and state laws
and  regulations.  The provisions of these laws and  regulations are complex and
affect all who  produce,  resell,  transport,  or purchase  gas,  including  the
Program.  Although  virtually all of the Program's gas production is not subject
to  price  regulation,   other  regulations   affect  the  availability  of  gas
transportation services and the ability of gas consumers to continue to purchase
or use gas at current levels. Accordingly,  such regulations may have a material
effect  on the  Program's  operations  and  projections  of  future  oil and gas
production and revenues.

      Future  Legislation --  Legislation  affecting the oil and gas industry is
under  constant  review  for  amendment  or  expansion.  Because  such  laws and
regulations  are frequently  amended or  reinterpreted,  management is unable to
predict what additional



                                      -4-
<PAGE>



energy  legislation  may be proposed or enacted or the future cost and impact of
complying with existing or future regulations.

      Regulation of the  Environment -- The Program's  operations are subject to
numerous laws and  regulations  governing  the  discharge of materials  into the
environment or otherwise relating to environmental  protection.  Compliance with
such  laws  and  regulations,   together  with  any  penalties   resulting  from
noncompliance,  may increase the cost of the Program's  operations or may affect
the  Program's  ability  to  timely  complete  existing  or  future  activities.
Management  anticipates  that various local,  state,  and federal  environmental
control agencies will have an increasing impact on oil and gas operations.


      Significant Customers

      Purchases of gas by El Paso Energy  Marketing  Company and  Transok,  Inc.
accounted for approximately 86.4% and 12.6%, respectively,  of the Program's oil
and gas  revenues  during  the year ended  December  31,  1999.  In the event of
interruption  of purchases by these  significant  customers or the  cessation or
material change in availability of open-access  transportation  by the Program's
pipeline transporters, the Program may encounter difficulty in marketing its gas
and in maintaining historic sales levels. Alternative purchasers or transporters
may not be readily available.

      The Program's  principal  customers for crude oil  production are refiners
and other companies which have pipeline facilities near the producing properties
of the Program. In the event pipeline facilities are not conveniently  available
to  production  areas,  crude oil is usually  trucked by  purchasers  to storage
facilities.


      Competition and Marketing

      The  domestic  oil and gas  industry is highly  competitive,  with a large
number of companies and  individuals  engaged in the exploration and development
of oil and gas properties.  The ability of the Program to produce and market oil
and gas profitably depends on a number of factors that are beyond the control of
the Program.  These factors include worldwide political instability  (especially
in oil-producing regions), United Nations export embargoes, the supply and price
of foreign  imports of oil and gas, the level of consumer  product demand (which
can be heavily  influenced  by weather  patterns),  government  regulations  and
taxes,  the price and  availability of alternative  fuels,  the overall economic
environment,  and the availability and capacity of transportation and processing
facilities.  The effect of these  factors on future oil and gas industry  trends
cannot be accurately predicted or anticipated.



                                      -5-
<PAGE>




      The most important variable affecting the Program's revenues is the prices
received for the sale of oil and gas.  Predicting future prices is not possible.
Concerning past trends,  average yearly wellhead gas prices in the United States
have been volatile for many years.  Over the past ten years such average  prices
have  generally  been in the  $1.40 to  $2.40  per Mcf  range.  Gas  prices  are
currently in the upper end of this range.

      Substantially  all of the  Program's  gas  reserves  are being sold on the
"spot  market."  Prices on the spot  market  are  subject to wide  seasonal  and
regional pricing  fluctuations due to the highly  competitive nature of the spot
market. In addition,  such spot market sales are generally  short-term in nature
and are dependent  upon the  obtaining of  transportation  services  provided by
pipelines.  Spot prices for the Program's gas increased from approximately $1.93
per Mcf at December  31,  1998 to  approximately  $2.24 per Mcf at December  31,
1999.  Such prices  were on an MMBTU  basis and differ from the prices  actually
received  by  the  Program  due  to  transportation  and  marketing  costs,  BTU
adjustments, and regional price and quality differences.

      For the past ten years,  average  oil prices  have  generally  been in the
$16.00 to $24.00 per barrel  range,  but have been  extremely  volatile over the
past two  years.  Due to  global  consumption  and  supply  trends  as well as a
slowdown in Asian energy demand,  oil prices in late 1997 and early 1998 reached
historically low levels,  dropping to as low as approximately  $9.00 per barrel.
However,  production  curtailment  agreements among major oil producing  nations
have  caused  recent  oil  prices  to climb to over  $30.00  per  barrel in some
markets.  It is not known  whether  this  trend  will  continue.  Prices for the
Program's oil increased from approximately $9.50 per barrel at December 31, 1998
to approximately $22.75 per barrel at December 31, 1999.

      Future  prices  for both oil and gas will  likely  be  different  from the
prices in effect on December 31, 1999.  Management is unable to predict  whether
future oil and gas prices will (i) stabilize, (ii) increase, or (iii) decrease.


      Insurance Coverage

      The Program is subject to all of the risks inherent in the exploration for
and production of oil and gas, including blowouts,  pollution,  fires, and other
casualties.  The  Program  maintains  insurance  coverage  as is  customary  for
entities of a similar size engaged in operations similar to that of the Program,
but losses can occur from uninsurable  risks or in amounts in excess of existing
insurance  coverage.  The  occurrence  of an event which is not fully covered by
insurance  could  have a  material  adverse  effect on the  Program's  financial
condition and results of operations.



                                      -6-
<PAGE>




ITEM 2.    PROPERTIES

      Well Statistics

      The  following  table sets forth the  numbers of gross and net  productive
wells of the Program as of December 31, 1999.

                               Well Statistics(1)

                             As of December 31, 1999

                Gross productive wells(2):
                  Oil                           -
                  Gas                           8
                                               ---
                     Total                      8

                Net productive wells(3):
                  Oil                           -
                  Gas                          1.18
                                               ----
                     Total                     1.18

----------
(1)   The designation of a well as an oil well or gas well is made by Dyco based
      on the relative amount of oil and gas reserves for the well. Regardless of
      a well's oil or gas designation,  it may produce oil, gas, or both oil and
      gas.
(2)   As used  throughout  this Annual  Report on Form 10-K  ("Annual  Report"),
      "Gross  Well" refers to a well in which a working  interest is owned.  The
      number  of gross  wells is the  total  number  of wells in which a working
      interest is owned.
(3)   As used throughout this Annual Report, "Net Well" refers to the sum of the
      fractional  working  interests  owned in gross wells.  For example,  a 15%
      working interest in a well represents one Gross Well, but 0.15 Net Well.


      Drilling Activities

      The  Program  participated  in no drilling  activities  for the year ended
December 31, 1999.


      Oil and Gas Production, Revenue, and Price History

      The following table sets forth certain historical  information  concerning
the oil  (including  condensates)  and  gas  production,  net of all  royalties,
overriding royalties, and other third party interests, of the Program,  revenues
attributable to such production, and certain price and cost information.




                                      -7-
<PAGE>




                               Net Production Data

                                        Year Ended December 31,
                                    -----------------------------
                                      1999        1998      1997
                                    --------    --------  --------

Production:
   Oil (Bbls)(1)                         82          264       305
   Gas (Mcf)(2)                      37,339       67,903    80,262

Oil and gas sales:
   Oil                              $ 1,140     $  3,428  $  6,060
   Gas                               84,047      131,652   186,238
                                     ------      -------   -------
      Total                         $85,187     $135,080  $192,298
                                     ======      =======   =======

Total direct operating expenses(3)  $60,752     $ 43,514  $ 57,433
                                     ======      =======   =======

Direct operating expenses as a
   percentage of oil and gas
   sales                              71.3%        32.2%     29.9%

Average sales price:
   Per barrel of oil                 $13.90       $12.98    $19.87
   Per Mcf of gas                      2.25         1.94      2.32

Direct operating expenses per
   equivalent Mcf of gas(4)          $ 1.61       $  .63    $  .70

----------

(1)   As used throughout this Annual Report, "Bbls" refers to barrels of 42 U.S.
      gallons and  represents  the basic unit for  measuring  the  production of
      crude oil and condensate oil.
(2)   As used  throughout  this Annual  Report,  "Mcf" refers to volume of 1,000
      cubic feet under  prescribed  conditions of pressure and  temperature  and
      represents the basic unit for measuring the production of gas.
(3)   Includes lease operating expenses and production taxes.
(4)   Oil production is converted to gas  equivalents at the rate of six Mcf per
      barrel, representing the estimated relative energy content of gas and oil,
      which rate is not  necessarily  indicative of the  relationship of oil and
      gas prices.  The  respective  prices of oil and gas are affected by market
      and other factors in addition to relative energy content.


      Proved Reserves and Net Present Value

      The following table sets forth the Program's  estimated proved oil and gas
reserves and net present value therefrom as of




                                      -8-
<PAGE>




December 31, 1999. The schedule of quantities of proved oil and gas reserves was
prepared by Dyco in accordance  with the rules  prescribed by the Securities and
Exchange  Commission (the "SEC").  Certain  reserve  information was reviewed by
Ryder Scott Company,  L.P. ("Ryder Scott"), an independent petroleum engineering
firm. As used throughout this Annual Report,  "proved  reserves" refers to those
estimated  quantities of crude oil, gas, and gas liquids  which  geological  and
engineering  data  demonstrate  with  reasonable  certainty to be recoverable in
future  years from known oil and gas  reservoirs  under  existing  economic  and
operating conditions.

      Net present  value  represents  estimated  future gross cash flow from the
production and sale of proved reserves,  net of estimated oil and gas production
costs (including  production  taxes, ad valorem taxes, and operating  expenses),
and estimated future development costs, discounted at 10% per annum. Net present
value  attributable to the Program's proved reserves was calculated on the basis
of current costs and prices at December 31, 1999. Such prices were not escalated
except in  certain  circumstances  where  escalations  were  fixed  and  readily
determinable in accordance with applicable contract provisions.  The prices used
by Dyco in  calculating  the net present  value  attributable  to the  Program's
proved  reserves  do not  necessarily  reflect  market  prices  for  oil and gas
production  subsequent to December 31, 1999.  There can be no assurance that the
prices  used in  calculating  the net  present  value  of the  Program's  proved
reserves at December 31, 1999 will actually be realized for such production.

      The process of  estimating  oil and gas  reserves  is  complex,  requiring
significant  subjective  decisions in the  evaluation  of available  geological,
engineering,  and  economic  data  for  each  reservoir.  The  data  for a given
reservoir may change substantially over time as a result of, among other things,
additional development activity, production history, and viability of production
under varying economic conditions;  consequently, it is reasonably possible that
material  revisions to existing reserve  estimates may occur in the near future.
Although  every  reasonable  effort has been made to ensure  that these  reserve
estimates represent the most accurate assessment  possible,  the significance of
the  subjective  decisions  required and variances in available data for various
reservoirs  make these  estimates  generally  less precise than other  estimates
presented in connection with financial statement disclosures.




                                      -9-
<PAGE>




                               Proved Reserves and
                                Net Present Value
                              From Proved Reserves

                           As of December 31, 1999(1)

           Estimated proved reserves:
             Gas (Mcf)                            212,054
             Oil and liquids (Bbls)                   283

           Net present value
             (discounted at 10% per annum)       $156,911

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

(1)   Includes certain gas balancing adjustments which cause the gas volumes and
      net present value to differ from the reserve reports  prepared by Dyco and
      reviewed by Ryder Scott.


      No estimates  of the proved  reserves of the Program  comparable  to those
included  herein have been included in reports to any federal  agency other than
the SEC.  Additional  information  relating to the Program's  proved reserves is
contained in Note 4 to the Program's financial statements, included in Item 8 of
this Annual Report.


      Significant Properties

      As of December 31, 1999,  the  Program's  properties  consisted of 8 gross
(1.18 net)  productive  wells.  The Program  owns an interest in one  additional
well.  Affiliates  of the  Program  operate  8 (89%)  of its  wells.  All of the
Program's reserves are located in the Anadarko Basin of western Oklahoma and the
Texas panhandle, which is an established oil and gas producing basin.


      Title to Oil and Gas Properties

      Management believes that the Program has satisfactory title to its oil and
gas properties. Record title to substantially all of the Program's properties is
held by Dyco as nominee.

      Title  to the  Program's  properties  is  subject  to  customary  royalty,
overriding  royalty,   carried,   working,   and  other  similar  interests  and
contractual  arrangements  customary in the oil and gas  industry,  to liens for
current taxes not yet due, and to other  encumbrances.  Management believes that
such burdens do not materially detract from the value of such properties or from
the Program's  interest  therein or materially  interfere  with their use in the
operation of the Program's business.





                                      -10-
<PAGE>





ITEM 3.    LEGAL PROCEEDINGS

      To the knowledge of the management of Dyco and the Program,  neither Dyco,
the Program,  nor the Program's  properties are subject to any  litigation,  the
results  of which  would  have a  material  effect  on the  Program's  or Dyco's
financial condition or operations.

ITEM 4.    SUBMISSION OF MATTERS TO A VOTE OF LIMITED PARTNERS

      There were no matters  submitted to a vote of the limited  partners during
1999.

                                    PART II

ITEM 5.    MARKET FOR THE REGISTRANT'S LIMITED PARTNERSHIP UNITS
           AND RELATED LIMITED PARTNER MATTERS

      The Program does not have an  established  trading market for its units of
limited  partnership  interest  ("Units").  Pursuant to the terms of the Program
Agreement, Dyco, as General Partner, is obligated to annually issue a repurchase
offer which is based on the  estimated  future net revenues  from the  Program's
reserves and is calculated pursuant to the terms of the Program Agreement.  Such
repurchase offer is recalculated  monthly in order to reflect cash distributions
made to the limited partners and extraordinary  events. The following table sets
forth,  for the  periods  indicated,  Dyco's  repurchase  offer per Unit and the
amount of the Program's  cash  distributions  per Unit for the same period.  For
purposes of this Annual Report,  a Unit  represents an initial  subscription  of
$5,000 to the Program.

                               Repurchase          Cash
                                  Price        Distributions
                               ----------      -------------
      1998:
        First Quarter             $137              $20
        Second Quarter             117                -
        Third Quarter              160               20
        Fourth Quarter             140                -

      1999:
        First Quarter             $140              $ -
        Second Quarter             140                -
        Third Quarter              132                -
        Fourth Quarter             132               20

      2000:
        First Quarter             $112              $ -

      The Program  has 2,000 Units  outstanding  and  approximately  575 Limited
Partners of record.



                                      -11-
<PAGE>




ITEM 6.    SELECTED FINANCIAL DATA

      Selected Financial Data

      The following table presents selected financial data for the Program. This
data should be read in conjunction with the financial statements of the Program,
and the respective notes thereto,  included elsewhere in this Annual Report. See
"Item 8. Financial Statements and Supplementary Data."




                                      -12-
<PAGE>


<TABLE>
<CAPTION>


                                                       December 31,
                                    -------------------------------------------------------
                                      1999        1998        1997       1996        1995
                                    ---------   --------    --------   --------    --------
<S>                                 <C>         <C>         <C>        <C>         <C>
Summary of Operations:
   Oil and gas sales                 $ 85,187   $135,080    $192,298   $191,618    $134,485
   Total revenues                      86,566    135,998     193,485    192,842     135,166

   Lease operating expenses            53,266     33,635      43,348     50,808      58,323
   Production taxes                     7,486      9,879      14,085     13,772       9,521
   General and administrative
      expenses                         20,727     20,576      22,280     21,766      21,713
   Depreciation, depletion, and
      amortization of oil and gas
      properties                       11,706      8,379      16,518      6,950      17,395

   Net income (loss)                (   6,619)    63,529      97,254     99,546      28,214
      per Unit                      (    3.28)     31.43       48.12      49.26       13.96
   Cash distributions                  40,420     80,840      50,525    131,365      40,420
      per Unit                             20         40          25         65          20

Summary Balance Sheet Data:
   Total assets                       117,693    128,068     149,325    133,084     140,704
   Partners' capital                   76,923    123,962     141,273     94,544     126,363

</TABLE>



                                      -13-
<PAGE>




ITEM 7.    MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
           CONDITION AND RESULTS OF OPERATIONS

      Use of Forward-Looking Statements and Estimates

      This Annual Report contains certain forward-looking  statements. The words
"anticipate,"  "believe,"  "expect,"  "plan," "intend,"  "estimate,"  "project,"
"could," "may," and similar expressions are intended to identify forward-looking
statements.  Such statements reflect  management's current views with respect to
future  events and  financial  performance.  This Annual  Report  also  includes
certain information which is, or is based upon, estimates and assumptions.  Such
estimates and assumptions  are  management's  efforts to accurately  reflect the
condition and operation of the Program.

      Use of  forward-looking  statements and estimates and assumptions  involve
risks and uncertainties which include, but are not limited to, the volatility of
oil and gas prices, the uncertainty of reserve  information,  the operating risk
associated with oil and gas properties  (including the risk of personal  injury,
death, property damage, damage to the well or producing reservoir, environmental
contamination,  and other  operating  risks),  the  prospect of changing tax and
regulatory laws, the availability and capacity of processing and  transportation
facilities,  the  general  economic  climate,  the  supply  and price of foreign
imports of oil and gas, the level of consumer product demand,  and the price and
availability  of  alternative  fuels.  Should  one or more  of  these  risks  or
uncertainties  occur  or  should  estimates  or  underlying   assumptions  prove
incorrect,  actual  conditions or results may vary materially and adversely from
those stated, anticipated, believed, estimated, or otherwise indicated.


      General Discussion

      The following  general  discussion  should be read in conjunction with the
analysis of results of operations  provided below.  The most important  variable
affecting the Program's  revenues is the prices received for the sale of oil and
gas. Predicting future prices is not possible.  Concerning past trends,  average
yearly  wellhead  gas prices in the United  States have been  volatile  for many
years.  Over the past ten years such average  prices have  generally been in the
$1.40 to $2.40 per Mcf range.  Gas prices are currently in the upper end of this
range.

      Substantially  all of the  Program's  gas  reserves  are being sold on the
"spot  market."  Prices on the spot  market  are  subject to wide  seasonal  and
regional pricing  fluctuations due to the highly  competitive nature of the spot
market. In addition,  such spot market sales are generally  short-term in nature
and are dependent  upon the  obtaining of  transportation  services  provided by
pipelines. Spot prices for the Program's gas increased from




                                      -14-
<PAGE>



approximately  $1.93 per Mcf at December 31, 1998 to approximately $2.24 per Mcf
at  December  31,  1999.  Such prices were on an MMBTU basis and differ from the
prices  actually  received by the Program due to  transportation  and  marketing
costs, BTU adjustments, and regional price and quality differences.

      For the past ten years,  average  oil prices  have  generally  been in the
$16.00 to $24.00 per barrel  range,  but have been  extremely  volatile over the
past two  years.  Due to  global  consumption  and  supply  trends  as well as a
slowdown in Asian energy demand,  oil prices in late 1997 and early 1998 reached
historically low levels,  dropping to as low as approximately  $9.00 per barrel.
However,  production  curtailment  agreements among major oil producing  nations
have  caused  recent  oil  prices  to climb to over  $30.00  per  barrel in some
markets.  It is not known  whether  this  trend  will  continue.  Prices for the
Program's oil increased from approximately $9.50 per barrel at December 31, 1998
to approximately $22.75 per barrel at December 31, 1999.

      Future  prices  for both oil and gas will  likely  be  different  from the
prices in effect on December 31, 1999.  Management is unable to predict  whether
future oil and gas prices will (i) stabilize, (ii) increase, or (iii) decrease.


      Results of Operations

                      Year Ended December 31, 1999 Compared
                         to Year Ended December 31, 1998
                      -------------------------------------

      Total oil and gas sales  decreased  $49,893 (36.9%) in 1999 as compared to
1998.  Of this  decrease,  approximately  $59,000  was  related to a decrease in
volumes of gas sold.  This  decrease  was  partially  offset by an  increase  of
approximately  $12,000  related to an increase in the average price of gas sold.
Volumes of oil and gas sold decreased 182 barrels and 30,564 Mcf,  respectively,
in 1999 as compared to 1998.  The decrease in volumes of gas sold was  primarily
due to (i) the  shutting-in  of two  wells  during  1999 in order to  perform  a
workover on each well,  (ii) a negative prior period volume  adjustment  made by
the operator on one well during 1999,  and (iii) normal  declines in production.
Average  oil and gas  prices  increased  to $13.90 per barrel and $2.25 per Mcf,
respectively, in 1999 from $12.98 per barrel and $1.94 per Mcf, respectively, in
1998.

      Oil and gas production  expenses  (including lease operating  expenses and
production  taxes)  increased  $17,238 (39.6%) in 1999 as compared to 1998. This
increase was primarily due to (i) workover expenses incurred on two wells during
1999 in order to improve  the  recovery of  reserves  and (ii) a positive  prior
period  lease  operating  expense  adjustment  made by the  operator on one well
during 1999. As a percentage of oil and gas sales,  these expenses  increased to
71.3% in 1999 from 32.2% in 1998. This




                                      -15-
<PAGE>



percentage  increase  was  primarily  due to the dollar  increase in oil and gas
production expenses.

      Depreciation,  depletion,  and  amortization  of oil  and  gas  properties
increased  $3,327  (39.7%)  in 1999 as  compared  to  1998.  This  increase  was
primarily  due to downward  revisions in the  estimates of remaining oil and gas
reserves at December 31, 1999. This increase was partially  offset by a decrease
primarily  due to the  decreases in volumes of oil and gas sold. As a percentage
of oil and gas sales, this expense increased to 13.7% in 1999 from 6.2% in 1998.
This   percentage   increase  was  primarily  due  to  the  dollar  increase  in
depreciation, depletion, and amortization.

      General and administrative  expenses remained  relatively constant in 1999
as  compared  to 1998.  As a  percentage  of oil and gas sales,  these  expenses
increased  to 24.3% in 1999 from 15.2% in 1998.  This  percentage  increase  was
primarily due to the decrease in oil and gas sales.


                      Year Ended December 31, 1998 Compared
                         to Year Ended December 31, 1997
                      -------------------------------------

      Total oil and gas sales  decreased  $57,218 (29.8%) in 1998 as compared to
1997.  Of this  decrease,  approximately  $29,000  was  related to a decrease in
volumes of gas sold and  approximately  $26,000 was related to a decrease in the
average price of gas sold.  Volumes of oil and gas sold decreased 41 barrels and
12,359 Mcf,  respectively,  in 1998 as compared to 1997. The decrease in volumes
of gas sold resulted  primarily from a negative  prior period volume  adjustment
made during 1998 by the operator on one well which was sold during 1997. Average
oil  and  gas  prices  decreased  to  $12.98  per  barrel  and  $1.94  per  Mcf,
respectively, in 1998 from $19.87 per barrel and $2.32 per Mcf, respectively, in
1997.

      Oil and gas production  expenses  (including lease operating  expenses and
production  taxes)  decreased  $13,919 (24.2%) in 1998 as compared to 1997. This
decrease  resulted  primarily from (i) a decrease in production taxes associated
with the decrease in oil and gas sales and (ii)  workover  expenses  incurred in
1997 on one well in order to improve the recovery of  reserves.  As a percentage
of oil and gas sales,  these  expenses  increased to 32.2% in 1998 from 29.9% in
1997. This percentage increase was primarily due to the decreases in the average
prices of oil and gas sold.

      Depreciation,  depletion,  and  amortization  of oil  and  gas  properties
decreased  $8,139  (49.3%) in 1998 as compared to 1997.  This decrease  resulted
primarily from (i) an upward  revision in the estimate of remaining gas reserves
at  December  31,  1998 and (ii) the  decrease  in  volumes  of gas  sold.  As a
percentage  of oil and gas sales,  this  expense  decreased to 6.2% in 1998 from
8.6% in




                                      -16-
<PAGE>




1997.  This  percentage  decrease was  primarily  due to the dollar  decrease in
depreciation, depletion, and amortization.

      General and  administrative  expenses  decreased  $1,704 (7.6%) in 1998 as
compared to 1997. As a percentage of oil and gas sales, these expenses increased
to 15.2% in 1998 from 11.6% in 1997. This percentage  increase was primarily due
to the decrease in oil and gas sales.


      Liquidity and Capital Resources

      Net  proceeds  from  operations  less  necessary   operating  capital  are
distributed to the limited  partners on a quarterly  basis.  See "Item 5. Market
for the  Registrant's  Limited  Partnership  Units and Related  Limited  Partner
Matters."  The net proceeds  from  production  are not  reinvested in productive
assets, except to the extent that producing wells are improved, or where methods
are employed to permit more efficient recovery of reserves, thereby resulting in
a positive  economic impact.  Assuming 1999 production  levels for future years,
the  Program's  proved  reserve  quantities  at  December  31,  1999  would have
remaining  lives of  approximately  5.7 years for gas reserves and 3.5 years for
oil reserves.  However,  since the Program's  reserve estimates are based on oil
and gas prices at December 31, 1999, it is possible that a significant  decrease
in oil and gas prices from  December  31, 1999 levels will reduce such  reserves
and their corresponding life-span.

      The Program's  available capital from the limited partners'  subscriptions
has been spent on oil and gas drilling activities and there should be no further
material capital resource commitments in the future.  Occasional expenditures by
the Program for well completions or workovers,  however, may reduce or eliminate
cash available for a particular  quarterly cash  distribution.  During 1997, the
Program invested approximately $28,000 in a recompletion on one well in order to
improve  the  recovery  of  reserves.   The   recompletion   was   unsuccessful.
Subsequently,  the well was sold for salvage value of approximately  $8,300. The
unsuccessful  recompletion  expenses incurred by the Program adversely  impacted
the  Program's  cash  flows  during  1997.  Cash for  operational  purposes  has
generally been provided by current oil and gas production.  Management  believes
that cash for ordinary  operational purposes will be provided by current oil and
gas production.

      There can be no  assurance as to the amount of the  Program's  future cash
distributions.   The  Program's  ability  to  make  cash  distributions  depends
primarily  upon the level of  available  cash flow  generated  by the  Program's
operating  activities,  which will be affected (either positively or negatively)
by many factors  beyond the control of the Program,  including  the price of and
demand for oil and gas and other market and economic conditions.  Even if prices
and costs remain stable, the amount of cash



                                      -17-
<PAGE>



available for distributions  will decline over time (as the volume of production
from  producing   properties  declines)  since  the  Program  is  not  replacing
production through acquisitions of producing properties and drilling.


      Inflation and Changing Prices

      Prices obtained for oil and gas production  depend upon numerous  factors,
including the extent of domestic and foreign production, foreign imports of oil,
market  demand,  domestic  and  foreign  economic  conditions  in  general,  and
governmental  regulations  and tax laws.  The general  level of inflation in the
economy did not have a material effect on the operations of the Program in 1999.
Oil and gas prices have  fluctuated  during recent years and generally  have not
followed the same pattern as  inflation.  See "Item 2.  Properties - Oil and Gas
Production, Revenue, and Price History."


      Year 2000 Computer Issues

      The year  2000  issue  refers  to the  inability  of  computer  and  other
information  technology  systems to properly process date and time  information,
stemming from the earlier  programming  practice of using two digits rather than
four to represent the year in a date.  To the knowledge of the General  Partner,
the Program has not experienced  any material  effects from the year 2000 issue.
Costs  incurred by the Program in order to ensure year 2000  compatibility  were
not material to the Program.


ITEM 7A.   QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET
           RISK.

      The Program does not hold any market risk sensitive instruments.



                                      -18-
<PAGE>



ITEM 8.    FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA



      REPORT OF INDEPENDENT ACCOUNTANTS



TO THE PARTNERS

DYCO OIL AND GAS PROGRAM 1986-X LIMITED PARTNERSHIP


      In our opinion, the accompanying balance sheets and the related statements
of operations,  changes in partners'  capital and cash flows present fairly,  in
all material  respects,  the financial  position of the Dyco Oil and Gas Program
1986-X Limited  Partnership,  a Minnesota limited  partnership,  at December 31,
1999 and 1998,  and the results of its operations and its cash flows for each of
the three years in the period  ended  December  31,  1999,  in  conformity  with
accounting  principles  generally accepted in the United States. These financial
statements   are  the   responsibility   of  the   Program's   management;   our
responsibility  is to express an opinion on these financial  statements based on
our audits. We conducted our audits of these financial  statements in accordance
with auditing standards  generally accepted in the United States,  which require
that we plan and perform the audit to obtain reasonable  assurance about whether
the financial  statements are free of material  misstatement.  An audit includes
examining,  on a test basis,  evidence supporting the amounts and disclosures in
the  financial   statements,   assessing  the  accounting  principles  used  and
significant  estimates made by management,  and evaluating the overall financial
statement  presentation.  We believe that our audits provide a reasonable  basis
for the opinion expressed above.





                               PricewaterhouseCoopers LLP








Tulsa, Oklahoma
March 27, 2000



                                      -19-
<PAGE>



                            DYCO OIL AND GAS PROGRAM
                           1986-X LIMITED PARTNERSHIP
                                 Balance Sheets
                           December 31, 1999 and 1998

                                     ASSETS
                                     ------
                                               1999         1998
                                             --------     --------

CURRENT ASSETS:
   Cash and cash equivalents                 $ 12,805     $ 29,249
   Accrued oil and gas sales                   20,962       15,885
                                              -------      -------

      Total current assets                   $ 33,767     $ 45,134

NET OIL AND GAS PROPERTIES, utilizing
   the full cost method                        62,087       71,519

DEFERRED CHARGE                                21,839       11,415
                                              -------      -------

                                             $117,693     $128,068
                                              =======      =======

                        LIABILITIES AND PARTNERS' CAPITAL
                        ---------------------------------

CURRENT LIABILITIES:
   Accounts payable                          $  4,810     $  2,107
   Gas imbalance payable                       18,095         -
                                              -------      -------
      Total current liabilities              $ 22,905     $  2,107

ACCRUED LIABILITY                            $ 17,865     $  1,999

PARTNERS' CAPITAL:
   General Partner, 21 general
       partner units                         $    769     $  1,239
   Limited Partners, issued and
      outstanding, 2,000 Units                 76,154      122,723
                                              -------      -------
      Total Partners' capital                $ 76,923     $123,962
                                              -------      -------

                                             $117,693     $128,068
                                              =======      =======




                   The accompanying notes are an integral part
                         of these financial statements.




                                      -20-
<PAGE>




                            DYCO OIL AND GAS PROGRAM
                           1986-X LIMITED PARTNERSHIP
                            Statements of Operations
              For the Years Ended December 31, 1999, 1998, and 1997


                                      1999        1998      1997
                                    ---------  ---------  --------

REVENUES:
   Oil and gas sales                 $ 85,187   $135,080  $192,298
   Interest                             1,379        918     1,187
                                      -------    -------   -------

                                     $ 86,566   $135,998  $193,485

COSTS AND EXPENSES:
   Lease operating                   $ 53,266   $ 33,635  $ 43,348
   Production taxes                     7,486      9,879    14,085
Depreciation, depletion, and
      amortization of oil and gas
      properties                       11,706      8,379    16,518
   General and administrative          20,727     20,576    22,280
                                      -------    -------   -------

                                     $ 93,185   $ 72,469  $ 96,231
                                      -------    -------   -------

NET INCOME (LOSS)                   ($  6,619)  $ 63,529  $ 97,254
                                      =======    =======   =======

GENERAL PARTNER (1%) -
   NET INCOME (LOSS)                ($    66)   $    635  $    973
                                     =======     =======   =======

LIMITED PARTNERS (99%) -
   NET INCOME (LOSS)                ($  6,553)  $ 62,894  $ 96,281
                                      =======    =======   =======

NET INCOME (LOSS) per Unit          ($   3.28)  $  31.43  $  48.12
                                      =======    =======   =======

UNITS OUTSTANDING                       2,021      2,021     2,021
                                      =======    =======   =======







                     The accompanying notes are an integral
                      part of these financial statements.




                                      -21-
<PAGE>




                            DYCO OIL AND GAS PROGRAM
                           1986-X LIMITED PARTNERSHIP
                   Statements of Changes in Partners' Capital
             For the Years Ended December 31, 1999, 1998, and 1997


                                  General     Limited
                                  Partner    Partners       Total
                                 --------   ----------   ----------

Balances at Dec. 31, 1996         $  944     $ 93,600     $ 94,544
   Cash distributions            (   505)   (  50,020)   (  50,525)
   Net income                        973       96,281       97,254
                                   -----      -------      -------

Balances at Dec. 31, 1997         $1,412     $139,861     $141,273
   Cash distributions            (   808)   (  80,032)   (  80,840)
   Net income                        635       62,894       63,529
                                   -----      -------      -------

Balances at Dec. 31, 1998         $1,239     $122,723     $123,962
   Cash distributions            (   404)   (  40,016)   (  40,420)
   Net loss                      (    66)   (   6,553)   (   6,619)
                                   -----      -------      -------

Balances at Dec. 31, 1999         $  769     $ 76,154     $ 76,923
                                   =====      =======      =======




                     The accompanying notes are an integral
                      part of these financial statements.




                                      -22-
<PAGE>




                            DYCO OIL AND GAS PROGRAM
                           1986-X LIMITED PARTNERSHIP
                            Statements of Cash Flows
              For the Years Ended December 31, 1999, 1998, and 1997

                                             1999        1998         1997
                                          ---------   ---------    ---------
CASH FLOWS FROM OPERATING ACTIVITIES:
   Net income (loss)                      ($ 6,619)    $63,529      $97,254
   Adjustments to reconcile net
      income (loss) to net cash provided
      by operating activities:
      Depreciation, depletion, and
        amortization of oil and gas
        properties                          11,706       8,379       16,518
      (Increase) decrease in accrued
        oil and gas sales                 (  5,077)     19,092        5,828
      (Increase) decrease in
        deferred charge                   ( 10,424)      1,779     (    172)
      Increase (decrease) in
        accounts payable                     2,703    (    530)    ( 26,761)
      Increase in gas
        imbalance payable                   18,095        -            -
      Increase (decrease) in
        accrued liability                   15,866    (  3,416)    (  3,727)
                                            ------      ------       ------
   Net cash provided by operating
      activities                           $26,250     $88,833      $88,940
                                            ------      ------       ------

CASH FLOWS FROM INVESTING ACTIVITIES:
   Proceeds from sale of oil and
      gas properties                       $  -        $  -         $ 8,846
   Additions to oil and gas properties    (  2,274)       -        ( 34,801)
                                            ------      ------       ------
   Net cash used by investing
      activities                          ($ 2,274)    $  -        ($25,955)
                                            ------      ------       ------

CASH FLOWS FROM FINANCING ACTIVITIES:
   Cash distributions                     ($40,420)   ($80,840)    ($50,525)
                                            ------      ------       ------
   Net cash used by financing
      activities                          ($40,420)   ($80,840)    ($50,525)
                                            ------      ------       ------
NET INCREASE (DECREASE) IN CASH
   AND CASH EQUIVALENTS                   ($16,444)    $ 7,993      $12,460

CASH AND CASH EQUIVALENTS AT
   BEGINNING OF PERIOD                      29,249      21,256        8,796
                                            ------      ------       ------
CASH AND CASH EQUIVALENTS AT
   END OF PERIOD                           $12,805     $29,249      $21,256
                                            ======      ======       ======

                     The accompanying notes are an integral
                      part of these financial statements.




                                      -23-
<PAGE>




               DYCO OIL AND GAS PROGRAM 1986-X LIMITED PARTNERSHIP
                          Notes to Financial Statements
              For the Years Ended December 31, 1999, 1998, and 1997


1.    ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

      Organization and Nature of Operations

           The  Dyco  Oil  and  Gas  Program  1986-X  Limited  Partnership  (the
      "Program"),  a Minnesota  limited  partnership,  commenced  operations  on
      December  12, 1986.  Dyco  Petroleum  Corporation  ("Dyco") is the General
      Partner  of the  Program.  Affiliates  of Dyco  owned 705  (35.3%)  of the
      Program's Units at December 31, 1999.

           The Program's sole business is the  development and production of oil
      and gas with a concentration  on gas.  Substantially  all of the Program's
      gas reserves are being sold  regionally  in the "spot  market." Due to the
      highly  competitive  nature of the spot market,  prices on the spot market
      are  subject  to wide  seasonal  and  regional  pricing  fluctuations.  In
      addition,  such spot market sales are  generally  short-term in nature and
      are dependent upon the obtaining of  transportation  services  provided by
      pipelines.  The prices  received for the Program's oil and gas are subject
      to influences such as global consumption and supply trends.


      Cash and Cash Equivalents

           The Program  considers all highly liquid  investments with a maturity
      of three  months  or less  when  purchased  to be cash  equivalents.  Cash
      equivalents  are not  insured,  which  cause the  Program to be subject to
      risk.


      Credit Risk

           Accrued oil and gas sales which are due from a variety of oil and gas
      purchasers  subject the Program to a concentration of credit risk. Some of
      these purchasers are discussed in Note 3 - Major Customers.


      Oil and Gas Properties

           Oil and gas  operations  are accounted for using the full cost method
      of accounting. All productive and non-productive costs associated with the
      acquisition,  exploration,  and  development  of oil and gas  reserves are
      capitalized.  Capitalized  costs are depleted on the gross revenue  method
      using estimates of proved reserves. The full




                                      -24-
<PAGE>




      cost  amortization  rates per  equivalent  Mcf of gas produced  during the
      years ended  December  31, 1999,  1998,  and 1997 were $0.31,  $0.12,  and
      $0.20, respectively. The Program's calculation of depreciation, depletion,
      and amortization  includes estimated future expenditures to be incurred in
      developing  proved  reserves and estimated  dismantlement  and abandonment
      costs, net of estimated  salvage values. In the event the unamortized cost
      of oil and gas properties  being  amortized  exceeds the full cost ceiling
      (as defined by the Securities and Exchange  Commission ("SEC")) the excess
      is charged to expense in the year during which such excess  occurs.  Sales
      and  abandonments  of  properties  are  accounted  for as  adjustments  of
      capitalized costs with no gain or loss recognized, unless such adjustments
      would significantly  alter the relationship  between capitalized costs and
      proved oil and gas reserves.


      Deferred Charge

           The Deferred  Charge at December 31, 1999 and 1998  represents  costs
      deferred for lease  operating  expenses  incurred in  connection  with the
      Program's  underproduced  gas  imbalance  positions.   The  rate  used  in
      calculating  the deferred  charge is the average of the annual  production
      costs per Mcf. At December 31, 1999,  cumulative  total gas sales  volumes
      for  underproduced  wells were less than the Program's  pro-rata  share of
      total gas production from these wells by 21,569 Mcf,  resulting in prepaid
      lease  operating  expenses of $21,839.  At December 31,  1998,  cumulative
      total  gas  sales  volumes  for  underproduced  wells  were  less than the
      Program's  pro-rata  share of total gas  production  from  these  wells by
      22,631 Mcf, resulting in prepaid lease operating expenses of $11,415.


      Accrued Liability

           The  Accrued  Liability  at  December  31,  1999 and 1998  represents
      charges accrued for lease operating  expenses  incurred in connection with
      the  Program's  overproduced  gas  imbalance  positions.  The rate used in
      calculating the accrued  liability is the average of the annual production
      costs per Mcf. At December 31, 1999,  cumulative  total gas sales  volumes
      for overproduced  wells exceeded the Program's pro-rata share of total gas
      production  from these wells by 17,644  Mcf,  resulting  in accrued  lease
      operating expenses of $17,865. At December 31, 1998,  cumulative total gas
      sales volumes for overproduced wells exceeded the Program's pro-rata share
      of total gas  production  from  these  wells by 3,964  Mcf,  resulting  in
      accrued lease operating expenses of $1,999.




                                      -25-
<PAGE>



      Oil and Gas Sales

           The Program's oil and  condensate  production is sold,  title passed,
      and revenue  recognized  at or near the Program's  wells under  short-term
      purchase  contracts at prevailing  prices in accordance with  arrangements
      which are  customary in the oil industry.  Sales of gas  applicable to the
      Program's interest in producing oil and gas leases are recorded as revenue
      when the gas is metered  and title  transferred  pursuant to the gas sales
      contracts  covering the Program's  interest in gas  reserves.  During such
      times as the  Program's  sales of gas exceed its pro rata  ownership  in a
      well,  such sales are recorded as revenue unless total sales from the well
      have  exceeded  the  Program's  share  of  estimated  total  gas  reserves
      underlying  the  property  at which  time  such  excess is  recorded  as a
      liability.  At December 31, 1999, total sales exceeded the Program's share
      of estimated  total gas reserves on one well by $18,095 (12,063 Mcf). This
      imbalance  was recorded in accordance  with the sales method.  At December
      31, 1998, no such liability was recorded.


      Use of Estimates in Financial Statements

           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 and
      disclosure  of  contingent  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 those
      estimates.  Further, the deferred charge and the accrued liability involve
      estimates which could materially differ from the actual amounts ultimately
      realized or incurred in the near term.  Oil and gas reserves  (see Note 4)
      also involve significant  estimates which could materially differ from the
      actual amounts ultimately realized.


      Income Taxes

           Income or loss for income tax  purposes is  includable  in the income
      tax returns of the partners. Accordingly, no recognition has been given to
      income taxes in the accompanying financial statements.




                                      -26-
<PAGE>



2.    TRANSACTIONS WITH RELATED PARTIES

           Under the terms of the Program Agreement, Dyco is entitled to receive
      a reimbursement  for all direct  expenses and general and  administrative,
      geological,  and engineering  expenses it incurs on behalf of the Program.
      During the years ended December 31, 1999,  1998,  and 1997,  such expenses
      totaled $20,727, $20,576, and $22,280,  respectively, of which $16,080 was
      paid each year to Dyco and its affiliates.

           Affiliates   of  the  Program   operate   certain  of  the  Program's
      properties.  Their policy is to bill the Program for all customary charges
      and cost  reimbursements  associated with these activities,  together with
      any  compressor  rentals,  consulting,  or other services  provided.  Such
      charges are  comparable to third party charges in the area where the wells
      are located and are the same as charged to other working  interest  owners
      in the wells.


3.    MAJOR CUSTOMERS

           The following purchaser individually accounted for 10% or more of the
      combined oil and gas revenues of the Program for the years ended  December
      31, 1999, 1998, and 1997:

           Purchaser           1999       1998      1997
           -------------       -----      -----     -----

           El Paso Energy
             Marketing Company 86.4%      86.9%     85.4%
           Transok, Inc.       12.6%      10.5%     11.9%

           In the  event of  interruption  of  purchases  by  these  significant
      customers  or  the  cessation  or  material   change  in  availability  of
      open-access  transportation by the Program's  pipeline  transporters,  the
      Program may encounter  difficulty in marketing its gas and in  maintaining
      historic sales levels.  Alternative  purchasers or transporters may not be
      readily available.




                                      -27-
<PAGE>




4.    SUPPLEMENTAL OIL AND GAS INFORMATION

           The  following  supplemental  information  regarding  the oil and gas
      activities  of  the  Program  is  presented  pursuant  to  the  disclosure
      requirements promulgated by the SEC.


      Capitalized Costs

           The  Program's   capitalized  costs  and  accumulated   depreciation,
      depletion,  amortization, and valuation allowance at December 31, 1999 and
      1998 were as follows:


                                               December 31,
                                         ------------------------
                                            1999          1998
                                         ----------    ----------

      Proved properties                 $9,216,416     $9,214,142

      Less accumulated depreciation,
        depletion, amortization, and
        valuation allowance            ( 9,154,329)    (9,142,623)
                                         ---------      ---------

      Net oil and gas properties        $   62,087     $   71,519
                                         =========      =========


      Costs Incurred

           The  Program  incurred  no  oil  and  gas  property   acquisition  or
      exploration  costs  during 1999,  1998,  and 1997.  Costs  incurred by the
      Program in connection with its oil and gas property development activities
      during 1999, 1998, and 1997 were as follows:


                                             December 31,
                                    ----------------------------
                                     1999        1998      1997
                                    ------       ----     -------

           Development costs        $2,274       $ -      $34,801
                                     =====       ====      ======

      Quantities of Proved Oil and Gas Reserves - Unaudited

           Set forth below is a summary of the changes in the net  quantities of
      the Program's proved oil and gas reserves for the years ended December 31,
      1999,  1998,  and  1997.  Proved  reserves  were  estimated  by  petroleum
      engineers employed by



                                      -28-
<PAGE>



      affiliates  of Dyco.  Certain  reserve  information  was reviewed by Ryder
      Scott Company, L.P., an independent petroleum engineering firm. All of the
      Program's  reserves  are  located  in the  United  States and there are no
      proved undeveloped  reserves.  The following  information includes certain
      gas balancing  adjustments  which cause the gas volumes to differ from the
      reserve information prepared by Dyco and reviewed by Ryder Scott.





                                      -29-
<PAGE>

<TABLE>
<CAPTION>



                                  1999                  1998                   1997
                           -------------------   -------------------    -------------------
                             Oil         Gas       Oil         Gas        Oil         Gas
                           (Bbls)       (Mcf)    (Bbls)       (Mcf)     (Bbls)       (Mcf)
                           -------    ---------  -------    ---------   -------    ---------
<S>                        <C>        <C>        <C>        <C>         <C>        <C>
Proved reserves,
   beginning of year        905        580,740    1,294      405,846     1,333      526,455

Revisions of previous
   estimates               (540)      (331,347)  (  125)     242,797       266     ( 40,347)


Production                 ( 82)      ( 37,339)  (  264)    ( 67,903)   (  305)    ( 80,262)
                            ---        -------    -----      -------     -----      -------

Proved reserves,
   end of year              283        212,054      905      580,740     1,294      405,846
                            ===        =======    =====      =======     =====      =======

Proved developed reserves:
   Beginning of year        905        580,740    1,294      405,846     1,333      526,455
                            ---        -------    -----      -------     -----      -------
   End of year              283        212,054      905      580,740     1,294      405,846
                            ===        =======    =====      =======     =====      =======

</TABLE>



                                      -30-
<PAGE>




           The process of estimating oil and gas reserves is complex,  requiring
      significant   subjective   decisions  in  the   evaluation   of  available
      geological,  engineering,  and economic data for each reservoir.  The data
      for a given reservoir may change  substantially  over time as a result of,
      among other things,  additional development activity,  production history,
      and  viability  of   production   under   varying   economic   conditions;
      consequently,  it  is  reasonably  possible  that  material  revisions  to
      existing  reserve  estimates may occur in the near future.  Although every
      reasonable  effort  has been made to  ensure  that the  reserve  estimates
      reported  herein  represent the most  accurate  assessment  possible,  the
      significance  of  the  subjective  decisions  required  and  variances  in
      available data for various reservoirs make these estimates  generally less
      precise  than other  estimates  presented  in  connection  with  financial
      statement disclosures.  The Program's reserves were determined at December
      31,  1999 using oil and gas prices of $22.75 per barrel and $2.24 per Mcf,
      respectively.


ITEM 9.    CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING
           AND FINANCIAL DISCLOSURE

      None.

                                    PART III

ITEM 10.   DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

      The Program is a limited  partnership  and has no  directors  or executive
officers.  The following  individuals  are  directors and executive  officers of
Dyco, the General Partner.  The business address of such directors and executive
officers is Two West Second Street, Tulsa, Oklahoma 74103.

            NAME          AGE           POSITION WITH DYCO
      ----------------    ---    --------------------------------

      Dennis R. Neill      48    President and Director

      Patrick M. Hall      41    Chief Financial Officer

      Judy K. Fox          49    Secretary

      The  director   will  hold  office  until  the  next  annual   meeting  of
shareholders of Dyco or until his successor has been duly elected and qualified.
All executive officers serve at the discretion of the Board of Directors.

      Dennis R. Neill joined Samson in 1981, was named Senior Vice President and
Director of Dyco on June 18, 1991,  and was named  President of Dyco on June 30,
1996. Prior to joining Samson,  he was associated with a Tulsa law firm,  Conner
and Winters, where




                                      -31-
<PAGE>




his  principal  practice was in the  securities  area. He received a Bachelor of
Arts degree in political  science from  Oklahoma  State  University  and a Juris
Doctorate  degree from the University of Texas.  Mr. Neill also serves as Senior
Vice  President of Samson  Investment  Company and as President  and Director of
Samson Properties Incorporated,  Samson Hydrocarbons Company, Berry Gas Company,
Circle L Drilling Company,  Compression,  Inc., and Geodyne Resources,  Inc. and
its subsidiaries.

      Patrick M. Hall joined Samson in 1983,  was named a Vice President of Dyco
on June 18,  1991,  and was named  Chief  Financial  Officer of Dyco on June 30,
1996. Prior to joining Samson he was a senior  accountant with Peat Marwick Main
& Co. in Tulsa.  He holds a  Bachelor  of  Science  degree  in  accounting  from
Oklahoma State  University and is a Certified Public  Accountant.  Mr. Hall also
serves as Senior Vice President - Controller of Samson Investment Company.

      Judy K. Fox joined Samson in 1990 and was named  Secretary of Dyco on June
30, 1996.  Prior to joining Samson,  she served as Gas Contract  Manager for Ely
Energy  Company.  Ms.  Fox is also  Secretary  of Berry  Gas  Company,  Circle L
Drilling  Company,  Compression,   Inc.,  Samson  Hydrocarbons  Company,  Samson
Properties Incorporated, and Geodyne Resources, Inc. and its subsidiaries.

      Section 16(a) Beneficial Ownership Reporting Compliance

      To the best  knowledge  of the Program and Dyco,  there were no  officers,
directors,  or ten  percent  owners who were  delinquent  filers  during 1999 of
reports required under Section 16(a) of the Securities and Exchange Act of 1934.


ITEM 11.   EXECUTIVE COMPENSATION

      The Program is a limited  partnership and,  therefore,  has no officers or
directors.  The following  table  summarizes  the amounts paid by the Program as
compensation and  reimbursements  to Dyco and its affiliates for the three years
ended December 31, 1999:





                                      -32-
<PAGE>





              Compensation/Reimbursement to Dyco and its affiliates
                       Three Years Ended December 31, 1999

Type of Compensation/Reimbursement (1)             Expense
--------------------------------------    -------------------------
                                           1999     1998     1997
                                          -------  -------  -------
Compensation:
   Operations                               (2)      (2)      (2)

Reimbursements:
   General and Administrative,
      Geological, and Engineering
      Expenses and Direct
      Expenses(3)                         $16,080  $16,080  $16,080

----------
(1)   The  authority  for  all of such  compensation  and  reimbursement  is the
      Program Agreement.  With respect to the Operations activities noted in the
      table, management believes that such compensation is equal to or less than
      that  charged by  unaffiliated  persons in the same  geographic  areas and
      under the same conditions.
(2)   Affiliates of the Program  serve as operator of a substantial  majority of
      the  Program's  wells.  Dyco,  as  General  Partner,  contracts  with such
      affiliates  for  services  as  operator of the wells.  As  operator,  such
      affiliates are  compensated at rates provided in the operating  agreements
      in effect and charged to all parties to such agreement.  The dollar amount
      of such  compensation paid by the Program to such affiliates is impossible
      to quantify as of the date of this Annual Report.
(3)   The  Program  reimburses  Dyco  and  its  affiliates  for  reasonable  and
      necessary general and administrative, geological, and engineering expenses
      and direct  expenses  incurred in  connection  with their  management  and
      operation of the Program. The directors,  officers,  and employees of Dyco
      and its  affiliates  receive no direct  remuneration  from the Program for
      their services to the Program. See "Salary Reimbursement Table" below. The
      allocable general and administrative, geological, and engineering expenses
      are apportioned on a reasonable  basis between the Program's  business and
      all other oil and gas  activities  of Dyco and its  affiliates,  including
      Dyco's  management  and  operation  of  affiliated  oil  and  gas  limited
      partnerships. The allocation to the Program of these costs is made by Dyco
      as General Partner.


      As noted in the  Compensation/Reimbursement  Table above,  the  directors,
officers,  and  employees  of  Dyco  and  their  affiliates  receive  no  direct
remuneration  from the Program for their services.  However,  to the extent such
services represent direct




                                      -33-
<PAGE>




involvement with the Program,  as opposed to general corporate  functions,  such
persons'  salaries  are  allocated  to  and  reimbursed  by  the  Program.  Such
allocation  to  the  Program's  general  and  administrative,   geological,  and
engineering  expenses of the salaries of directors,  officers,  and employees of
Dyco and its affiliates is based on internal records  maintained by Dyco and its
affiliates,   and  represents  investor  relations,   legal,  accounting,   data
processing,  management, gas marketing and other functions directly attributable
to  the  Program's   operations.   When  actual  costs  incurred  benefit  other
partnerships   and  affiliates,   the  allocation  of  costs  is  based  on  the
relationship  of the  Program's  reserves  to the  total  reserves  owned by all
partnerships  and  affiliates.  The following  table  indicates the  approximate
amount of general and administrative  expense reimbursement  attributable to the
salaries of the  directors,  officers,  and employees of Dyco and its affiliates
for the three years ended December 31, 1999:




                                      -34-
<PAGE>

<TABLE>
<CAPTION>



                                         Salary Reimbursement

                                  Three Years Ended December 31, 1999

                                                                 Long Term Compensation
                                                             -------------------------------
                                 Annual Compensation                Awards           Payouts
                              ---------------------------    ---------------------   -------
                                                                           Securi-
                                                    Other                   ties                  All
     Name                                           Annual   Restricted    Under-                Other
      and                                          Compen-     Stock       lying      LTIP      Compen-
   Principal                  Salary     Bonus     sation     Award(s)    Options/   Payouts    sation
   Position           Year      ($)       ($)        ($)        ($)        SARs(#)     ($)        ($)
---------------       ----    -------   -------    -------   ----------   --------   -------    -------
<S>                   <C>     <C>         <C>        <C>       <C>          <C>        <C>        <C>
Dennis R. Neill,
President(1)          1997      -         -          -         -            -          -          -
                      1998      -         -          -         -            -          -          -
                      1999      -         -          -         -            -          -          -
All Executive
Officers,
Directors,
and Employees
as a group(2)         1997    $9,606      -          -         -            -          -          -
                      1998    $9,516      -          -         -            -          -          -
                      1999    $9,822      -          -         -            -          -          -
----------
(1)   The  general  and  administrative   expenses  paid  by  the  Program  and  attributable  to  salary
      reimbursements do not include any salary or other compensation attributable to Mr. Neill.
(2)   No  officer  or  director  of Dyco or its  affiliates  provides  full-time  services to the
      Program and no individual's  salary or other  compensation reimbursement from the Program equals
      or exceeds $100,000 per annum.
</TABLE>




                                      -35-
<PAGE>




      Samson  maintains  necessary  inventories of new and used field equipment.
Samson may have provided  some of this  equipment for wells in which the Program
has an interest. This equipment was provided at prices or rates equal to or less
than  those  normally  charged  in the  same or  comparable  geographic  area by
unaffiliated  persons or companies  dealing at arm's  length.  The  operators of
these  wells  bill the  Program  for a  portion  of such  costs  based  upon the
Program's interest in the well.


ITEM 12.   SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

      The following table provides information as to the beneficial ownership of
the Program's Units as of March 1, 2000 by each beneficial owner of more than 5%
of  the  issued  and  outstanding  Units  and by the  directors,  officers,  and
affiliates  of Dyco.  The address of each of such persons is Samson  Plaza,  Two
West Second Street, Tulsa, Oklahoma 74103.


                                          Number of Units
                                           Beneficially
                                          Owned (Percent
             Beneficial Owner             of Outstanding)
      -------------------------------     ---------------

      Samson Resources Company             705   (35.3%)

      All directors, officers, and
        affiliates of Dyco as a group
        and Dyco (5 persons)               705   (35.3%)


ITEM 13.   CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

      Certain affiliates of Dyco engage in oil and gas activities  independently
of the Program  which  result in  conflicts  of interest  that cannot be totally
eliminated.  The allocation of acquisition  and drilling  opportunities  and the
nature of the compensation  arrangements between the Program and such affiliates
also create potential conflicts of interest.  An affiliate of the Program owns a
significant  amount of the  Program's  Units and  therefore  has an  identity of
interest  with other  limited  partners  with respect to the  operations  of the
Program.

      In order to attempt to assure  limited  liability for limited  partners as
well as an orderly  conduct of business,  management of the Program is exercised
solely by Dyco. The Program Agreement grants Dyco broad discretionary  authority
with  respect  to  the  Program's   participation  in  drilling   prospects  and
expenditure and control of funds,  including  borrowings.  These  provisions are
similar to those contained in prospectuses and partnership  agreements for other
public oil and gas partnerships. Broad



                                      -36-
<PAGE>



discretion as to general management of the Program involves  circumstances where
Dyco has conflicts of interest and where it must allocate costs and expenses, or
opportunities, among the Program and other competing interests.

      Dyco does not devote all of its time, efforts,  and personnel  exclusively
to the  Program.  Furthermore,  the  Program  does not have any  employees,  but
instead relies on the personnel of Samson. The Program thus competes with Samson
(including  other  oil and gas  programs)  for the  time and  resources  of such
personnel.  Samson  devotes  such time and  personnel to the  management  of the
Program as are indicated by the  circumstances and as are consistent with Dyco's
fiduciary duties.

      Affiliates  of the Program  are solely  responsible  for the  negotiation,
administration,  and  enforcement of oil and gas sales  agreements  covering the
Program's  leasehold  interests.  Because  affiliates of the Program who provide
services to the  Program  have  fiduciary  or other  duties to other  members of
Samson,  contract  amendments and  negotiating  positions taken by them in their
effort to enforce  contracts with purchasers may not  necessarily  represent the
positions that the Program would take if it were to administer its own contracts
without involvement with other members of Samson. On the other hand,  management
believes that the Program's  negotiating strength and contractual positions have
been enhanced by virtue of its affiliation with Samson.

      Samson  Resources  Company,  an  affiliate  of  Dyco,  ("Resources")  owns
approximately  35% of the Program's  outstanding  Units as of March 1, 2000. The
Program Agreement permits Resources to independently vote its Units.  Resources'
significant  Unit ownership will therefore  likely  determine the outcome of any
matter submitted for a vote of the Limited Partners.



                                      -37-
<PAGE>




                                    PART IV


ITEM 14.   EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K

      (a)  Financial Statements, Financial Statement Schedules, and Exhibits.

           (1)  Financial Statements: The following financial statements for the
                Program as of December 31, 1999 and 1998 and for the years ended
                December  31,  1999,  1998,  and 1997 are  filed as part of this
                report:

                     Report of Independent Accountants
                     Balance Sheets
                     Statements of Operations
                     Statements of Changes in Partners' Capital
                     Statements of Cash Flows
                     Notes to Financial Statements

           (2)  Financial Statement Schedules:

                     None.

           (3)  Exhibits:

                4.1  Drilling   Agreement  dated  November  25,  1986  for  Dyco
                     Drilling  Program  1986-X,  a Limited  Partnership,  by and
                     between Dyco Oil and Gas Program  1986-X and Dyco Petroleum
                     Corporation  filed as Exhibit 4.1 to Annual  Report on Form
                     10-K for the year ended  December 31, 1991 on April 1, 1992
                     and is hereby incorporated by reference.

                4.2  Program  Agreement dated November 25, 1986 for Dyco Oil and
                     Gas   Program   1986-X  by  and  between   Dyco   Petroleum
                     Corporation  and the  Participants  filed as Exhibit 4.2 to
                     Annual Report on Form 10-K for the year ended  December 31,
                     1991  on  April  1,  1992  and is  hereby  incorporated  by
                     reference.

                4.3  Amendment to Program Agreement for Dyco Oil and Gas Program
                     1986-X  dated  December  31,  1989 filed as Exhibit  4.3 to
                     Annual Report on Form 10-K for the year ended  December 31,
                     1991  on  April  1,  1992  and is  hereby  incorporated  by
                     reference.



                                      -38-
<PAGE>




                4.4  Certificate of Limited  Partnership,  as amended,  for Dyco
                     Oil and Gas Program  1986-X  Limited  Partnership  filed as
                     Exhibit  4.4 to  Annual  Report  on Form  10-K for the year
                     ended  December  31,  1991 on April 1,  1992 and is  hereby
                     incorporated by reference.

               *23.1 Consent of Ryder Scott  Company,  L.P. for Dyco Oil and Gas
                     Program 1986-X Limited Partnership.

               *27.1 Financial  Data  Schedule   containing   summary  financial
                     information  extracted  from the  Dyco Oil and Gas  Program
                     1986-X  Limited  Partnership's  financial  statements as of
                     December 31, 1999 and for the year ended December 31, 1999.

                All other Exhibits are omitted as inapplicable.


                ------------------
                *  Filed herewith.


      (b)  Reports on Form 8-K filed during the fourth quarter of 1999.

                None.




                                      -39-
<PAGE>



                                   SIGNATURES

Pursuant to the requirements of Sections 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 organized.

                               DYCO OIL AND GAS PROGRAM 1986-X
                               LIMITED PARTNERSHIP

                               By:  DYCO PETROLEUM CORPORATION
                                    General Partner

                                    March 28, 2000


                               By:  //s// Dennis R. Neill
                                    ------------------------------
                                    Dennis R. Neill
                                    President

Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following  persons on behalf of the  registrant and
in the capacities on the dates indicated.

By: //s// Dennis R. Neill  President and            March 28, 2000
    -------------------    Director (Principal
       Dennis R. Neill     Executive Officer)

    //s// Patrick M. Hall  Chief Financial          March 28, 2000
    -------------------    Officer (Principal
       Patrick M. Hall     Financial and
                           Accounting Officer)

    //s// Judy K. Fox      Secretary                March 28, 2000
    -------------------
       Judy K. Fox



                                      -40-
<PAGE>



                          INDEX TO EXHIBITS


Exhibit
Number     Description
-------    -----------

4.1        Drilling  Agreement dated November 25, 1986 for Dyco Drilling Program
           1986-X,  a  Limited  Partnership,  by and  between  Dyco  Oil and Gas
           Program 1986-X and Dyco Petroleum Corporation filed as Exhibit 4.1 to
           Annual  Report on Form 10-K for the year ended  December  31, 1991 on
           April 1, 1992 and is hereby incorporated by reference.

4.2        Program  Agreement  dated  November  25,  1986  for  Dyco Oil and Gas
           Program  1986-X by and between  Dyco  Petroleum  Corporation  and the
           Participants  filed as Exhibit 4.2 to Annual  Report on Form 10-K for
           the year  ended  December  31,  1991 on April 1,  1992 and is  hereby
           incorporated by reference.

4.3        Amendment to Program  Agreement  for Dyco Oil and Gas Program  1986-X
           dated December 31, 1989 filed as Exhibit 4.3 to Annual Report on Form
           10-K for the year  ended  December  31,  1991 on April 1, 1992 and is
           hereby incorporated by reference.

4.4        Certificate of Limited Partnership,  as amended, for Dyco Oil and Gas
           Program  1986-X  Limited  Partnership  filed as Exhibit 4.4 to Annual
           Report on Form 10-K for the year ended  December 31, 1991 on April 1,
           1992 and is hereby incorporated by reference.

*23.1      Consent of  Ryder Scott  Company, L.P. for Dyco  Oil and  Gas Program
           1986-X Limited Partnership.

*27.1      Financial  Data Schedule  containing  summary  financial  information
           extracted   from  the  Dyco  Oil  and  Gas  Program   1986-X  Limited
           Partnership's  financial  statements  as of December 31, 1999 and for
           the year ended December 31, 1999.


------------------
*  Filed herewith.


                                      -41-
<PAGE>