<PAGE>



                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                   FORM 10-K/A

      For Annual and Transition Reports pursuant to Section 13 or  15(d) of  the
Securities Exchange Act of 1934

(Mark One)

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


                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 1998

                                       OR

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

                           COMMISSION FILE NO. 0-21841

                              3DX TECHNOLOGIES INC.
             (Exact name of registrant as specified in its charter)


      DELAWARE                                           76-0386601
(State of Incorporation)                   (IRS Employer Identification Number)


12012 WICKCHESTER, SUITE 250, HOUSTON, TEXAS                77079
 (Address of principal executive office)                  (Zip Code)


       Registrant's telephone number, including area code: (281) 579-3398


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


      Securities registered pursuant to Section 12(g) of the Exchange Act:
                          Common Stock, $0.01 par value
                                (TITLE OF CLASS)

         Indicate  by check  mark  whether  the  registrant:  (1) has  filed all
reports  required to be filed by Section 13 or 15(d) of the  Exchange Act during
the past 12 months (or for such shorter  period that the registrant was required
to file such reports),  and (2) has been subject to such filing requirements for
the past 90 days. Yes |X| No |_|

         Indicate by check mark if disclosure  of delinquent  filers in response
to Item 405 of Regulation  S-K is not contained in this form,  and no disclosure
will be  contained,  to the best of the  registrant's  knowledge,  in definitive
proxy or information  statements  incorporated  by reference in Part III of this
Form 10-K/A or any amendment to this Form 10-K/A. |X|

         As  of  April  15,  1999,   9,399,353   shares  of  common  stock  were
outstanding.  The  aggregate  market value of the voting and  non-voting  common
equity held by  non-affiliates  computed by  reference to the average of the bid
and ask  price of such  common  equity  on  April  15,  1999  was  approximately
$1,595,000.








<PAGE>



                                TABLE OF CONTENTS


ITEM 10.   DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT..................1

ITEM 11.   EXECUTIVE COMPENSATION..............................................4

ITEM 12.   SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT......9

ITEM 13.   CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS.....................11



SIGNATURES....................................................................12


<PAGE>





ITEM 10.    DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

         The directors of the Company are as follows:
<TABLE>
<CAPTION>

NAME                                   AGE                 PRINCIPAL OCCUPATION               DIRECTOR SINCE
<S>                                   <C>  <C>                                                   <C>

Jon W. Bayless (1) (3) ...........      59    Co-Chairman of the Board of the Company and
                                              General Partner of Sevin Rosen Funds                  1993

C. Eugene Ennis (3)...............      55    Chairman of the Board of the Company and
                                              President and Chief Executive Officer of
                                              Object Reservoir                                      1992

Ronald P. Nowak ..................      46    President and Chief Executive Officer of the
                                              Company                                               1998

C.D. Gray (1) (3).................      64    Petroleum exploration consultant and geologist        1997

Charles E. Edwards (2) (3)........      73    Petroleum technology consultant and
                                              geophysicist                                          1995

Douglas C. Williamson (2) (3).....      48    Managing Director, (Dallas) Venture Capital
                                              Group, BancAmerica Capital Investors                  1995
-----------

</TABLE>

(1)      MEMBER OF THE HUMAN RESOURCES COMMITTEE.
(2)      MEMBER OF THE AUDIT COMMITTEE
(3)      MEMBER OF THE CORPORATE GOVERNANCE COMMITTEE.

         JON W. BAYLESS.  Mr. Bayless  has  been  a director since November 1993
and Vice Chairman of the Board since 1998.  Since 1983,  Mr.  Bayless has been a
general  partner of Sevin Rosen Funds, a venture  capital  investment  firm. Mr.
Bayless is also the sole  stockholder and director of Jon W. Bayless,  Inc., the
general partner of Atlantic  Partners L.P., which is the general partner of Citi
Growth Fund L.P., a venture capital investment firm, and serves as a director of
a number of privately held  companies.  In addition to the Company,  Mr. Bayless
currently serves as Chairman of the Board of Directors of both Ciena Corporation
and Shared Resource  Exchange,  Inc. Shared  Resource  Exchange,  Inc. filed for
reorganization under Chapter 11 of the Federal Bankruptcy Code in August 1996. A
plan of reorganization under Chapter 11 has been approved.

         C. EUGENE  ENNIS.  Mr.  Ennis has served as Chairman of the Board since
1998. Mr. Ennis served as the Company's  President and Chief  Executive  Officer
from the  Company's  inception  in December  1992 until June 1998.  Since August
1998, Mr. Ennis has been a director of Object Reservoir,  a supplier of software
tools for the petroleum industry.  Mr. Ennis has been Chief Executive Officer of
Object  Reservoir  since January 1999. From September 1984 to December 1992, Mr.
Ennis was  President,  Chief  Executive  Officer and a director and from October
1990 to December  1992 was also  Chairman of the Board of  Directors of Landmark
Graphics   Corporation    ("Landmark"),    a   provider   of   interdisciplinary
interpretation  tools for the petroleum industry.  Mr. Ennis holds a Bachelor of
Science in electrical  engineering  from the University of Houston and began his
career in 1969 as a design  engineer  in the  Geophysical  Products  Division of
Texas Instruments where he was employed until 1984.

         RONALD P. NOWAK. Mr.  Nowak  has  served  as  a  director  since  1998.
Mr.  Nowak has  served as the  Company's  Vice  President  of  Exploration  from
February  through  May 1998 and then  assumed  the role of  President  and Chief
Executive  Officer in June 1998.  Prior to joining the  Company,  Mr.  Nowak was
employed  by Maxus  Energy  Corporation  in Dallas,  Texas from  August  1993 to
January 1998,  where he served as US manager from 1997.  From 1987 to 1993,  Mr.
Nowak was employed by Arco Oil & Gas. Prior to 1987, Mr. Nowak worked with Exxon
Company,  USA where he acted as an independent  geologist working in the onshore
U.S.  Gulf  Coast  region.  Mr.  Nowak  holds a degree in Geology  from  Central
Michigan  University  and a Masters of Science  degree in Geology from  Michigan
State University.

                                      -1-

<PAGE>


         C.D. GRAY. Mr. Gray  has  served  as  a  director  of the Company since
October  1997.  From 1981  until his  retirement  in 1997,  Mr.  Gray  served as
Executive Vice President for CXY Energy, Inc. in Dallas,  Texas. He is currently
an Exploration  Consultant to CXY and other clients.  Mr. Gray holds a degree in
Geology from the  University  of Texas at Austin and spent the first 23 years of
his career with Mobil Oil Corporation and its  predecessor,  Magnolia  Petroleum
Company, prior to joining CXY.

         CHARLES E. EDWARDS. Mr. Edwards has served as a director of the Company
since August  1995.  Since  August 1985 to present,  Mr.  Edwards has acted as a
consultant  in petroleum  technologies.  Prior to August 1985,  Mr.  Edwards was
employed by Chevron  Corp.  for a period in excess of 37 years and most recently
served  as  Chief  Geophysicist  with   responsibility  for  global  exploration
activities.  Mr  Edwards  was  a  founder  in  1987  of  ExploiTech,  a  company
specializing in integrated  multi-disciplinary reservoir description studies for
exploration and exploitation  that merged with Landmark in 1989. Mr. Edwards has
also served as a director for Digicon Inc. and Landmark.

         DOUGLAS C. WILLIAMSON. Mr.  Williamson  has served as a director to the
Company since July 1995. Mr.  Williamson has served for the past nine years as a
Managing  Director in the Venture  Capital Group in the Dallas,  Texas office of
NationsBanc  Capital  Corporation  (now  an  affiliate  of  BancAmerica  Capital
Investors).

         All of  the  Company's  directors  are elected at the annual meeting of
stockholders and hold office until their  respective  successors are elected and
qualified or until their earlier resignation or removal.

BOARD ORGANIZATION AND MEETINGS

         During 1998,  the Board of  Directors  held 9 meetings.  All  directors
attended at least 75% of the total  number of meetings of the Board of Directors
and the  committees of which he was a member.  The Board of Directors  currently
has three  committees,  a Human  Resources  Committee,  an Audit Committee and a
Corporate  Governance  Committee.  The Human Resources Committee consists of Mr.
Bayless  and Mr.  Gray,  each of  whom  are  independent  directors.  The  Human
Resources  Committee reviews general policy matters relating to compensation and
benefits of officers  and  employees  of the Company and  administers  the Stock
Option Plan. The Human Resources  Committee held two meetings in 1998. The Audit
Committee,  established in October 1996, is responsible for  recommending to the
Board of Directors the annual  engagement of a firm of  independent  accountants
and for  reviewing  with the  independent  accountants  the scope and results of
audits, the internal  accounting controls of the Company and audit practices and
professional  services  rendered to the Company by the independent  accountants.
The Audit  Committee  consists of Mr.  Edwards and Mr.  Williamson  and held one
meeting in 1998. The Corporate Governance Committee was established in June 1997
for the purpose of establishing  corporate  governance  policies for the Company
and identifying and recruiting  future board members.  The Corporate  Governance
Committee consists of all independent directors of the Company. No meetings were
held during 1998.

COMPENSATION OF DIRECTORS

         Directors  who are not  employees  are entitled to receive a fee in the
amount of $750 for every  meeting of the Board of Directors  which such director
attends  in  person  or by  telephone  and a fee of $500 for each  meeting  of a
committee of the Board of Directors held separately  which such director attends
in person or by telephone.  Beginning in 1998, the non-employee directors waived
their right to receive fees for attending meetings.  Directors who are employees
of the Company do not receive any additional  compensation for their services as
directors.  All directors are reimbursed for out-of-pocket  expenses incurred in
connection  with their  service as directors.  Under the Stock Option Plan,  the
Company may, from time to time, and in the discretion of the Board of Directors,
grant stock options to directors.

         In addition,  Mr. Edwards and Mr. Gray provide  consulting  services to
the Company  relating to oil and gas  exploration.  Fees paid to Mr. Edwards and
Mr. Gray during 1998 for these  services were $15,400 and $9,500,  respectively.
Consulting  services are also being provided by Mr. Bayless who is assisting the
Company in obtaining additional financing.  No fees were paid to Mr. Bayless for
consulting  services  rendered to the Company  during 1998.  In January 1998, as
partial compensation for consulting services, the Company granted to each of Mr.
Edwards,  Mr. Gray and Mr. Bayless an option to purchase 20,000 shares of common
stock at an  exercise  price of $2.875  per share.  Fifty  percent of the shares
subject to such options will vest on the first  anniversary of the date of grant


                                      -2-

<PAGE>

and 25 of the shares subject to such options will vest on each of the second and
third  anniversaries  of the date of grant.  These  options were  cancelled  and
reissued on April 20, 1998 at $1.625 per share.

HUMAN RESOURCES COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

         During 1998, Mr. Bayless  and  Mr. Gray  served  on the Human Resources
Committee  of the  Board of  Directors  of the  Company.  No member of the Human
Resources Committee has ever served as an officer of the Company.

EXECUTIVE OFFICERS AND SIGNIFICANT EMPLOYEES

         The  following  table  provides  information  regarding  the  executive
officers and significant  employees of the Company. The executive officers serve
at the discretion of the Board of Directors.

  NAME                            AGE    POSITION

  Ronald P. Nowak...........      46     President, Chief Executive Officer
  Russell L. Allen .........      54     Vice President of Finance, Chief
                                         Financial Officer and Secretary
  Herbert R. Rohloff III....      42     Senior Reservoir Engineer
  Eric B. Gardner...........      35     Project Leader
  Frank C. Sheppard III.....      39     Project Leader
  Peter M. Duncan...........      46     Vice President, Chief Geophysicist
                                         and Treasurer
-----------

         RONALD P. NOWAK.  Mr. Nowak has served as the Company's  Vice President
of  Exploration  from  February  through  May 1998 and then  assumed the role of
President and Chief Executive Officer in May 1998. Prior to joining the Company,
Mr. Nowak was employed by Maxus Energy Corporation in Dallas,  Texas from August
1993 to  January  1998,  where he served as US manager  from 1997.  From 1987 to
1993,  Mr. Nowak was employed by Arco Oil & Gas. Prior to 1987, Mr. Nowak worked
with Exxon Company,  USA where he acted as an independent  geologist  working in
the onshore  U.S.  Gulf Coast  region.  Mr. Nowak holds a degree in Geology from
Central  Michigan  University  and a Masters of Science  degree in Geology  from
Michigan State University.

         RUSSELL L. ALLEN. Mr. Allen is a full  time  management  advisor to the
Company and in that  capacity has served as Vice  President of Finance and Chief
Financial  Officer since June 1998. Prior to that time, Mr. Allen served various
clients in the capacity of  independent  management  advisor.  Mr. Allen holds a
Bachelors  and Masters  Degree in  Accounting  from the  University  of Texas at
Austin and is a Certified Public Accountant.

         HERBERT R. ROHLOFF III.  Mr. Rohloff has served as the Company's Senior
Reservoir  Engineer since joining the Company in January 1995.  Prior to joining
the Company,  Mr. Rohloff was employed by Amoco Production  Company from 1979 to
1993 in various  engineering,  economic and supervisory  positions  beginning in
1979 and served most recently as Project  Manager-Production  New Ventures.  Mr.
Rohloff  holds a  Bachelor  of Science in  Chemical  Engineering  from Texas A&M
University. He is a registered professional engineer in the State of Texas.

         ERIC B. GARDNER.  Mr. Gardner has served as a Senior Explorationist and
Project Leader since joining the Company in September 1994. Mr. Gardner has over
14 years  of  industry  experience  and has  worked  in many  geoscience  areas,
including production,  exploration, seismic technology and research. Mr. Gardner
began  his  career  with  Amoco  Production  Company  in  1985  as  a  technical
geophysicist and served most recently as a staff geophysicist. Mr. Gardner holds
a Bachelor of Science in Engineering Physics from Colorado School of Mines.

         FRANK C. SHEPPARD III.  Mr. Sheppard  joined  the  Company  as a Senior
Explorationist and Project Leader in October 1997. Prior to joining the Company,
Mr. Sheppard was employed by Amoco Production Company where he served since 1985
in a variety of exploration and geophysical  roles throughout the Gulf of Mexico
Basin. Most recently,  Mr. Sheppard managed numerous 3-D seismic exploration and
production  programs for Amoco, and previously served as a 3-D imaging expert in
Amoco's subsalt exploration program. Mr. Sheppard holds a Bachelor of Science in
Earth Sciences from the University of New Orleans.

                                      -3-


<PAGE>

         PETER M. DUNCAN.  Dr. Duncan served as Vice President of Technology and
Treasurer for the Company since its inception  until February 1999, and as Chief
Geophysicist  since February 1998. Prior to joining the Company,  Dr. Duncan was
employed by Landmark Concurrent  Solutions Inc. as Vice President from July 1991
until December 1992.  Dr. Duncan  terminated his employment  with the Company on
March 1, 1999.

SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

         Section  16(a) of the  Securities  Exchange  Act of 1934,  as  amended,
requires the Company's officers and directors, and persons who own more than 10%
of a registered  class of the Company's  equity  securities,  to file reports of
ownership and changes in ownership with the  Commission and the Nasdaq  National
Market.  Officers,  directors and greater than 10%  stockholders are required by
the  regulations  of the  Commission  to furnish the Company  with copies of all
Section 16(a)  reports such persons file.  Based solely on a review of copies of
such reports received by it and written  representation  from certain  reporting
persons that no Forms 5 were required for those  persons,  the Company  believes
that during the year ended December 31, 1998 all filing requirements  applicable
to its officers, directors and greater than 10% stockholders were complied with.


ITEM 11.  EXECUTIVE COMPENSATION

         The  following   table  sets  forth  certain   information   concerning
compensation awarded,  earned or paid for services rendered in all capacities by
the Company's Chief Executive Officer and each of the Company's three other most
highly compensated  executive  officers (the "Named Executive  Officers") during
the past three fiscal years. The table also identifies the principal capacity in
which each of the Named Executive Officers served the Company during 1998.


                                      -4-


<PAGE>
<TABLE>
<CAPTION>

                                                                            Long-Term Compensation
                                           Annual Compensation                       Awards
                                          -----------------------        ---------------------------

                                                                        Restricted    Securities           All Other
                                                                          Stock       Underlying          Compensation
Name and Principal Position           Year   Salary ($)      Bonus ($)   Awards ($)   Options (#)              ($) 
---------------------------           ----   -------        ---------   ----------    ------------      ----------------
<S>                                   <C>    <C>            <C>          <C>           <C>               <C>

  Ronald P. Nowak                     1998    $148,177           -         98,438        150,000           $    -
      President and Chief             1997           -           -              -              -                -
      Executive Officer               1996           -           -              -              -                -

  C. Eugene Ennis                     1998     143,118           -              -        100,000  (a)           -
      President, Chief Executive      1997     171,875           -              -                               -
      Officer (b) and Chairman        1996     150,000           -              -              -                -
      of the Board

  Russell L. Allen                    1998           -           -              -              -           229,800 (c)
      Vice President, Chief           1997           -           -              -              -                -
      Financial Officer, Secretary    1996           -           -              -              -                -

  Peter M. Duncan (d)                 1998     130,289           -              -        100,000  (a)           -
      Vice President, Chief           1997     126,670           -              -                               -
      Geophysicist, Treasurer         1996     103,920           -              -              -                -

     Joseph Schuchardt III (d)        1998     115,087           -              -         10,000 (a)            -
      Vice President of               1997     108,125      27,000              -                               -
      Business Development            1996      95,000      11,875              -              -                -

</TABLE>

(a)  Issued in 1997 and canceled and reissued in 1998.
(b)  Mr. Ennis served as President and Chief Executive Officer until  May  1998.
(c)  Mr.  Allen is an  independent  management  advisor  that has  served as the
     Company's Vice President of Finance and Chief Financial  Officer since June
     1998. Mr. Allen's  compensation is based on hours worked and is paid 60% in
     common  stock of the  Company  at the price in  effect  when  services  are
     rendered and 40% in cash. Of the amount reported above, $137,880 is payable
     in common stock (225,080 shares) to be issued in 1999.
(d)  Mr. Duncan and Mr. Schuchardt  terminated their employment with the Company
     and resigned  their  positions  as executive  officers on March 1, 1999 and
     October 16, 1998, respectively.


CASH BONUS PLAN

         In 1997, the Company adopted the 1997 Incentive  Compensation Plan (the
"Bonus  Plan")  which  provides  for the payment of annual cash  bonuses,  in an
amount up to 40% of the participant's  base salary,  if certain  pre-established
Company-based performance criteria are satisfied. All full-time employees of the
Company are eligible to participate in the Bonus Plan if the Company achieves at
least 80% of its targeted performance criteria,  with the exception of the Chief
Executive  Officer  whose  bonus   compensation  is  determined  solely  at  the
discretion  of the Board of  Directors.  The bonuses are  prorated  based on the
percentage of the targeted performance criteria achieved. The 1997 bonus for Mr.
Schuchardt  was paid  pursuant to the Bonus Plan upon  partial  satisfaction  of
performance  targets.  The bonus  plan was not  renewed in 1998 and no bonus was
paid.

1998 STOCK OPTION GRANTS

         The following table sets forth certain information regarding options on
the  Company's  common stock which were granted to Named  Executive  Officers in
1998:


                                      -5-

<PAGE>

<TABLE>
<CAPTION>

                                             INDIVIDUAL GRANTS DURING 1998(a)                  POTENTIAL VALUE (b)
                           ------------------------------------------------------------------------------------------
                              NUMBER OF     % OF TOTAL                                        REALIZABLE AT ASSUMED
                             SECURITIES      OPTION                                           ANNUAL RATES OF STOCK
                             UNDERLYING     GRANTS TO        EXERCISE/                        PRICE APPRECIATION FOR
                               OPTIONS      EMPLOYEES        BASE PRICE     EXPIRATION            OPTION TERM
                               GRANTED       IN 1998         PER SHARE        DATE              5%            10%
                            -----------------------------------------------------------------------------------------
<S>                         <C>               <C>          <C>          <C>                <C>           <C>

 Ronald L. Nowak .......       150,000         10.1%         $1.969        03/05/2008          $185,744      $470,700

</TABLE>

(a)  The exercise  price of options is the market price of the Company's  common
     stock on the date of grant.  The  options  vest at the rate of 25% per year
     over four years  (annually  for the first two years and monthly  during the
     last two years).  Stock options are eligible for accelerated vesting upon a
     change of control of the Company.

(b)  These columns show the gains option  holders could realize if the Company's
     common stock appreciates at annual rates of 5% and 10%, respectively. These
     growth rates are arbitrary  assumptions  specified by the Commission and do
     not represent the Company's predictions of future stock price performance.


OPTION EXERCISES AND YEAR-END OPTION VALUES

         The  following  table sets forth  information  regarding  the number of
option  shares  exercised  during  1998 and the  number  and  year-end  value of
unexercised  options held at December 31, 1998,  by each of the Named  Executive
Officers.

<TABLE>
<CAPTION>

                    AGGREGATE OPTION EXERCISES IN FISCAL 1998
                     AND FISCAL 1998 YEAR-END OPTION VALUES

-------------------------------------------------------------------------------------------------------------------------
                                                                       NUMBER OF
                                                                 SECURITIES UNDERLYING         VALUE OF UNEXERCISED
                                     SHARES        VALUE        UNEXERCISED OPTIONS AT      "IN-THE-MONEY" OPTIONS AT
  NAME                             ACQUIRED ON   REALIZED ON       DECEMBER 31, 1998             DECEMBER 31, 1998
                                  EXERCISED (#)  EXERCISE ($)   EXERCISABLE/UNEXERCISABLE   EXERCISABLE/UNEXERCISABLE (1)
<S>                                 <C>          <C>              <C>                      <C>  


  Ronald L. Nowak ........             -         $     -              -        150,000         $  -           $  -
  C. Eugene Ennis.........             -               -         20,144        100,000        3,042              -
  Peter M. Duncan.........             -               -         20,144        100,000        3,042              -
  Joseph Schuchardt III ..       166,381          87,483              -            -              -              -

</TABLE>

(1)  Options  are  "in-the-money"  if the fair  market  value of the  underlying
     securities exceeds the exercise price of the options. The amounts set forth
     represent  the  difference  between the  exercise  price of the options and
     $0.34,  the closing  price for the Common Stock on December 31, 1998 on the
     Nasdaq National Market, multiplied by the applicable number of options.

EMPLOYMENT CONTRACTS, TERMINATION OF EMPLOYMENT AND CHANGE OF CONTROL
ARRANGEMENTS.

         In March 1998, the Company entered into a two-year employment agreement
(the  "Employment  Agreement")  with Mr.  Nowak, pursuant to which Mr. Nowak was
employed as the  Company's  Vice  President  of  Exploration.  Mr.  Nowak became
President and Chief  Executive  OFficer in May 1998.  Pursuant to the Employment
Agreement,  Mr.  Nowak is  entitled  to  annual  compensation  in the  amount of
$150,000,  and was granted an option to purchase 150,000 shares of the Company's
common stock. Additionally, in the event Mr. Nowak is terminated by the Company,
without cause, before the expiration of the term of the Employment Agreement, he
is entitled to receive from the Company his annual salary  compensation  for the
remainder of the two year term.

                                      -6-

<PAGE>


         Also in March 1998, the Company  entered into a Restricted  Stock Award
Agreement with Mr. Nowak (the "Restricted Stock Award  Agreement"),  pursuant to
which Mr. Nowak was granted  50,000  shares of the  Company's  common stock (the
"Restricted  Stock"),  subject to certain  restrictions  (the "Restricted  Stock
Award").  Mr. Nowak's right to the  Restricted  Stock vests on March 6, 2000, so
long as he is  employed  by the  Company  on a  full-time  basis  on that  date.
Furthermore, Mr. Nowak becomes automatically vested in the Restricted Stock upon
a transfer of control of the Company,  so long as Mr. Nowak is actively employed
by the Company as of the date such transfer of control occurs.

REPORT ON REPRICING OF OPTIONS

         It was determined by the Human Resource  Committee during 1998 that the
options  held  by  directors,   executive   officers  and  employees  no  longer
represented an incentive, as the market price of the stock had dropped below the
exercise price of the options.  Therefore,  it was  determined  that the options
should be repriced in line with the current market value.

         Members of the Human Resources Committee:               Jon W. Bayless
                                                                 C.D. Gray
<TABLE>
<CAPTION>
                           TEN-YEAR OPTION REPRICINGS

 --------------------------------------------------------------------------------------------------------------------
                                                                                                     LENGTH OF
                                                                                                      ORIGINAL
                                              NUMBER OF     MARKET                                     OPTION
                                             SECURITIES    PRICE OF      EXERCISE                       TERM
                                             UNDERLYING    STOCK AT      PRICE AT        NEW         REMAINING
                                               OPTIONS      TIME OF       TIME OF      EXERCISE      AT DATE OF
                               DATE OF        REPRICED     REPRICING     REPRICING      PRICE        REPRICING
            NAME              REPRICING          (#)          ($)           ($)          ($)          (MONTHS)
 --------------------------------------------------------------------------------------------------------------------
<S>                           <C>            <C>            <C>            <C>          <C>            <C>

 Ronald L. Nowak
    President and Chief
    Executive Officer            04/20/98       150,000        $1.625        $1.969        $1.625            119
 C. Eugene Ennis
    Chairman of the Board        04/20/98       100,000        $1.625       $11.000        $1.625            111
 Peter M. Duncan
    Vice-President, Chief
    Geophysicist, Treasurer      04/20/98       100,000        $1.625       $11.000        $1.625            111
 Joseph Schuchardt III
    Vice-President of
    Business Development         04/20/98        10,000        $1.625       $11.875        $1.625            106

</TABLE>

In January 1999, the Human Resource  Committee  decided to reprice,  at $0.3125,
the currently outstanding options dated April 20, 1998.

STOCK OPTION PLAN

         In January 1994, the Company  adopted the Stock Option Plan under which
"non-qualified" stock options ("NQSOs") to acquire shares of Common Stock may be
granted to  directors  of and  consultants  to the Company and  incentive  stock
options  ("ISOs") to acquire  shares of Common Stock may be granted to employees
and directors who are also employees of the Company.

         Currently,  the Stock Option Plan  provides for the issuance of up to a
maximum of  2,004,937  shares of Common Stock and is  administered  by the Human
Resources  Committee.  Under the Stock Option Plan,  the option price of any ISO
may not be less than the fair  market  value of a share of  Common  Stock on the
date on which the option is  granted.  The  option  price of an NQSO may be less
than  the fair  market  value on the  date  the  NQSO is  granted  if the  Human
Resources Committee so determines,  but may not in any event be less than 85% of
such fair market value. An ISO may not be granted to a "ten percent stockholder"
(as such term is defined in Section 422A of the  Internal  Revenue Code of 1986,
as amended)  unless the exercise price is at least 110% of the fair market value
of


                                      -7-

<PAGE>

the Common  Stock at the time of grant and the option must be  exercised  within
five years. Options granted pursuant to the Stock Option Plan are evidenced by a
written agreement executed by the Company and the grantee, containing the terms,
provisions  and  conditions  of the grant.  Stock options may not be assigned or
transferred  during the lifetime of the holder except as may be required by law.
The maximum term of each stock option is ten years from the date of grant.

         For  options to qualify  as ISOs,  the  aggregate  fair  market  value,
determined  on the date of grant,  of the shares with  respect to which the ISOs
are  exercisable  for the first time by the grantee during any calendar year may
not exceed $100,000. Payment by option holders upon exercise of an option may be
made (i) in cash, (ii) by tender to the Company of shares of the Company's stock
owned by the optionee  having a fair market  value,  as  determined by the Human
Resources  Committee (but without regard to any restrictions on  transferability
applicable  to such  stock by  reason of  federal  or state  securities  laws or
agreements  with an  underwriter  for the  Company),  not less than the exercise
price,  (iii) by delivery of a  promissory  note made by the  optionee in a form
approved by the  Company,  (iv) by the  assignment  of the proceeds of a sale of
some or all of the shares being acquired upon the exercise of the option, (v) by
the  withholding  of shares being acquired upon exercise of the option bearing a
fair market value, as determined by the Human  Resources  Committee (but without
regard to any restrictions on transferability applicable to such stock by reason
of federal or state  securities  laws or agreements  with an underwriter for the
Company),  not less than the exercise price, or (vi) by any combination thereof.
The Human Resources Committee may at any time or from time to time grant options
which do not permit all of the foregoing  forms of  consideration  to be used in
payment of the exercise price and/or which otherwise  restrict the use of one or
more forms of consideration.  In addition, the Human Resources Committee, in its
sole discretion, may authorize the surrender by an optionee of all or part of an
unexercised stock option and authorize a payment in consideration  thereof of an
amount equal to the  difference  between the aggregate  fair market value of the
Common Stock subject to such stock option and the aggregate option price of such
Common Stock. In the Human Resources Committee's discretion, such payment may be
made in cash,  shares of Common  Stock with a fair  market  value on the date of
surrender equal to the payment amount or some combination thereof.

         The Stock Option Plan provides that  outstanding  options vest in their
entirety and become exercisable in the event of certain mergers,  consolidations
or sales of all or  substantially  all of the assets of the Company,  unless the
successor  corporation assumes such options. As of December 31, 1998, options to
purchase 826,404 shares of Common Stock were outstanding  under the Stock Option
Plan at exercise  prices  ranging  from $0.19 to $1.625 per share,  with 764,421
option shares available for grant.

REPORT OF THE HUMAN RESOURCES COMMITTEE OF THE BOARD OF DIRECTORS

         The Human  Resources  Committee of the Board of Directors  oversees the
compensation policies applicable to all employees of the Company,  including its
executive   officers.   The  Human   Resources   Committee   also  has   primary
responsibility for administering stock-based compensation plans of the Company.

         The Company seeks to provide a compensation program which will allow it
to attract and retain highly qualified and motivated employees. Its compensation
program is also designed to enhance  stockholder value by providing  significant
incentives for employees to achieve the Company's goals. The Company is striving
to promote an  entrepreneurial  environment  which  encourages  all employees to
focus on the  continuing  long-term  growth of the  Company.  Specifically,  the
compensation plan includes the following components:

         BASE SALARY.  It is the goal of the Human Resources  Committee that the
primary element of compensation result from the achievement of performance-based
objectives which contribute in a meaningful way to long-term  stockholder value.
However, the Company must also provide a base salary and employee benefits which
are  competitive  with  compensation  offered  by other oil and gas  exploration
companies  similar to the Company.  The Human Resources  Committee  expects that
base salary will not exceed the average paid by the Company's peers.

         STOCK OPTION PLAN. The Stock Option Plan is a broad-based  stock option
plan covering all employees  which is designed to motivate and retain  employees
and allow all employees to benefit from  performance  which  enhances  long-term
stockholder  value.  All stock options granted to employees have exercise prices
which equal the fair market  value of the Common  Stock on the date of grant and
vest ratably  over a period of four years.  Accordingly,  the options  provide a
significant incentive for superior long-term performance and continued retention

                                      -8-

<PAGE>


of employees by the Company.  For stock  options  awarded to executive  officers
during 1998, refer to the section "Stock Option Grants".

COMPENSATION OF THE CHIEF EXECUTIVE OFFICER

         As discussed  above,  the  Company's  compensation  philosophy  for all
employees,  including the Chief Executive  Officer,  is to provide a competitive
base salary and incentive compensation based on the Company's  performance.  Mr.
Nowak  did not  receive a bonus  for  1998.  The  bonus for the Chief  Executive
Officer is  discretionary  under the Bonus Plan and reflects factors in addition
to the objective performance measures in the Bonus Plan.

         Members of the Human Resources Committee:           Jon W. Bayless
                                                             C.D. Gray

PERFORMANCE GRAPH

The following  graph compares the  cumulative  total  stockholder  return on the
Common Stock with the cumulative  total return of (i) the Media General Industry
Group Index No. 123, "Oil and Gas  Drilling/Exploration"  ("MG Group Index") and
(ii) the NASDAQ  Market  Value Index from the first day of trading of the Common
Stock,  December 20, 1996 through  December 31, 1998. The graph assumes that the
value of an  investment  in the Common Stock and each index was $100 at December
20, 1996 and that any dividends were  reinvested.  Numerical values used for the
six month  period end plot  points in the graph are set forth in the table under
the graph.


        Comparison of Cumulative Total Return for 3DX Technologies Inc.,
                     NASDAQ Market Index and MG Group Index



                                    [GRAPH]

<TABLE>
<CAPTION>


                            12/20/96   12/31/96   06/30/97   12/31/97   06/30/98   12/31/98
                            --------   --------   --------   --------   --------   --------

<S>                          <C>        <C>        <C>       <C>         <C>        <C>

3DX Technologies Inc.         100.00     100.00      90.91      36.36      14.77       3.13
NASDAQ Market Index           100.00     100.00     112.29     122.67     147.48     172.79
MG Group Index                100.00     100.00     119.74     147.23     110.82      59.83

</TABLE>

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

         As of April 15,  1999,  there  were  9,399,353  shares of Common  Stock
outstanding  and  entitled  to vote.  The  following  table sets  forth  certain
information  regarding the beneficial ownership of Common Stock, as of April 15,
1999, by (i) each person known to the Company to own  beneficially 5% or more of
the  Company's  outstanding  shares of Common  Stock,  (ii) each director of the
Company,  (iii) each of the Named Executive  Officers,  as defined in "Executive

                                      -9-

<PAGE>

Compensation," and (iv) all executive officers and directors of the Company as a
group. The information with respect to beneficial ownership is based on the most
recent  filings  with the  Securities  and Exchange  Commission  which have been
furnished to the Company by the respective stockholders of the Company.

<TABLE>
<CAPTION>



                                                                         BENEFICIAL OWNERSHIP
                                                                         -------------------

NAME AND ADDRESS (1)                                                   NUMBER OF SHARES(2)  PERCENT
--------------------                                                   ----------------     -------
<S>                                                                     <C>                  <C> 

Ronald P. Nowak ..............................................                50,000 (3)    *
Jon W. Bayless................................................               754,195 (4)     8.0%
Charles E. Edwards............................................                25,267 (5)     *
C. Eugene Ennis...............................................               289,411         3.1%
C.D. Gray.....................................................                     -         *
Douglas C. Williamson.........................................               727,073 (6)     7.7%
Russell L. Allen .............................................                     -        *
Peter M. Duncan ..............................................               375,592         4.0%
Joseph Schuchardt III ........................................               207,278         2.2%

All directors and executive officers as a group (9 persons)...             2,428,816        25.8%

CWS Limited-Liability Company ................................             1,172,270        12.5%
    One Rockefeller Plaza, 31st Floor
    New York, NY  11002

Citi Growth Fund L.P..........................................               727,477         7.7%
   c/o CitiGrowth Funds, Sycamore Partners
   989 Lenox Drive
   Lawrenceville, New Jersey 08648

NationsBanc Capital Corporation...............................               721,903         7.7%
   (Affiliate of BancAmerica Capital Investors)
   901 Main Street
   Dallas, Texas 75202
</TABLE>
--------
 *       Represents beneficial ownership of less  than  1%  of  the  outstanding
         shares of Common Stock.

(1)      Unless otherwise indicated,  the address of each stockholder identified
         in the table is at the  principal  executive  offices of the Company at
         12012 Wickchester, Houston, Texas 77079.

(2)      Beneficial  ownership is determined in accordance with the rules of the
         Securities and Exchange Commission (the "Commission"). In computing the
         number of shares of Common Stock beneficially owned by a person and the
         percentage ownership of that person,  shares of Common Stock subject to
         options and warrants held by that person that are currently exercisable
         or exercisable within 60 days of April 15, 1998 are deemed outstanding.
         Such shares,  however,  are not deemed  outstanding for the purposes of
         computing  the  percentage  ownership  of any other  person.  Shares of
         Common Stock issuable upon exercise of stock options  granted  pursuant
         to the  Company's  1994 Stock  Option Plan (the "Stock  Option  Plan"),
         which are currently  exercisable or exercisable within 60 days of April
         15, 1999,  include  20,144 shares for Mr.  Ennis,  5,170 shares for Mr.
         Bayless, 5,170 shares for Mr. Edwards, 5,170 shares for Mr. Williamson,
         and 35,654 shares for all directors and executive  officers as a group.
         Except as indicated in the footnotes hereto,  each stockholder named in
         the table has sole  voting and  investment  power  with  respect to the
         shares set forth beside such stockholder's name.

                                      -10-

<PAGE>


(3)      Subject to the Restricted Stock Award discussed in Item 11, "Employment
         Contracts, Termination of Employment and Change of Control
         Arrangements."
         
(4)      Includes 727,477 shares beneficially owned by Citi Growth Fund L.P. Mr.
         Bayless is the sole  stockholder  and director of Jon W. Bayless  Inc.,
         the general  partner of Atlantic  Partners L.P., the general partner of
         Citi Growth Fund L.P.

(5)      Includes 1,200 shares of Common Stock owned by Mr. Edwards' spouse.

(6)      Includes  721,903  shares of Common Stock held by  NationsBanc  Capital
         Corporation  (an affiliate of Bank of America Capital  Investors).  Mr.
         Williamson  is a Managing  Director  in the  Venture  Capital  Group of
         NationsBanc  Capital  Corporation  (an  affiliate  of Bank  of  America
         Capital Investors).

TEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

         None.













                                      -11-

<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.

                                        3DX TECHNOLOGIES INC.



                                        By:    /s/ Russell L. Allen
                                        ----------------------------------------
                                        Vice President, Finance, Chief Financial
                                        Officer and Secretary

         Know All Men By These Presents,  that each  individual  whose signature
appears  below hereby  constitutes  and appoints  Ronald P. Nowak and Russell L.
Allen  and each of them  individually,  his true and  lawful  agent,  proxy  and
attorney-in-fact, with full power of substitution and resubstitution, for him in
his name,  place and stead, in any and all  capacities,  to (i) act on, sign and
file with the Securities and Exchange  Commission any and all amendments to this
report together with all schedules and exhibits  thereto,  (ii) act on, sign and
file with the  Securities  and Exchange  Commission any exhibits to this report,
(iii) act on, sign and file such certificates, instruments, agreements and other
documents as may be necessary or  appropriate  in connection  therewith and (iv)
take any and all actions  which may be necessary or  appropriate  in  connection
therewith,  granting unto such agents, proxies and attorneys-in-fact and each of
them individually, full power and authority to do and perform each and every act
and thing  necessary  or  appropriate  to be done,  as fully for all intents and
purposes  as he might or could do in person,  hereby  approving,  ratifying  and
confirming all that such agents, proxies and  attorneys-in-fact,  any of them or
any of his or their  substitute  or  substitutes  may lawfully do or cause to be
done by virtue hereof.

         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 and on the dates indicated.


   DATE                SIGNATURE                            TITLE(S)

April 30, 1999    /s/ Ronald P. Nowak       Pesident and Chief Executive Officer
                  ---------------------     (Principal Executive Officer)
                  Ronald P. Nowak


April 30, 1999   /s/ Russell L. Allen        Vice President, Finance and Chief 
                 -----------------------     Financial Officer
                 Russell L. Allen            (Principal Financial and Accounting
                                             Officer)


                                             Director
                 -----------------------
                 Jon W. Bayless 


                                              Director
                 ------------------------
                 Charles E. Edwards 


                                      -12-

<PAGE>

April 30, 1999   /s/ C. Eugene Ennis            Chairman of the Board
                 ------------------------
                 C. Eugene Ennis


April 30, 1999   /s/ C.D. Gray                  Director
                 ------------------------
                 C.D. Gray


April 27, 1999   /s/ Douglas C. Williamson      Director
                 -------------------------
                 Douglas C. Williamson 


                                      -13-