Promissory Note

EXHIBIT 10.15

PROMISSORY NOTE

PROMISE TO PAY. MITCHAM INDUSTRIES, INC., (“Borrower”) promises to pay to First Victoria Bank (“Lender”), or order, in lawful money of the United States of America, the principal amount of Eight Million Five Hundred Eighteen Thousand Nine Hundred Nineteen & 00/100 Dollars ($8,518,919.00), together with interest on the unpaid principal balance from February 11, 2002, until maturity. The interest rate will not increase above 18.000%.

PAYMENT. Subject to any payment changes resulting from changes in the Index, Borrower will pay this loan in 48 payments of $197,125.14 each payment. Borrower’s first payment is due March 11, 2002, and all subsequent payments are due on the same day of each month after that. Borrower’s final payment will be due on February 11, 2006, and will be for all principal and all accrued interest not yet paid. Payments include principal and interest. Unless otherwise agreed or required by applicable law, payments will be applied first to accrued unpaid interest, then to principal, and any remaining amount to any unpaid collection costs. Interest on this Note is computed on a 365/365 simple interest basis; that is, by applying the ration of the annual interest rate over the number of days in a year, multiplied by the outstanding principal balance, multiplied by the actual number of days the principal balance is outstanding. Borrower will pay Lender at Lender’s address shown above or at such other place as Lender may designate in writing.

VARIABLE INTEREST RATE. The interest rate on this Note is subject to change from time to time based on changes in an independent index which is the WALL STREET JOURNAL PRIME AS ANNOUNCED IN THE WALL STREET JOURNAL (the “Index”). The Index is not necessarily the lowest rate charged by Lender on its loans. If the Index becomes unavailable during the term of this loan, Lender may designate a substitute index after notice to Borrower. Lender will tell Borrower the current Index rate upon Borrower’s request. The interest rate change will not occur more often than each DAY. Borrower understands that Lender may make loans based on other rates as well. The Index currently is 4.750% per annum. The interest rate to be applied prior to maturity to the unpaid principal balance of this Note will be at a rate of 0.500 percentage points over the Index, resulting in an initial rate of 5.250% per annum. Notwithstanding the foregoing, the variable interest rate or rates provided for in this Note will be subject to the following maximum rate. NOTICE: Under no circumstances will the interest rate on this Note be more than (except for any higher default rate or Post Maturity Rate shown below) the lesser of 18.000% per annum or the maximum rate allowed by applicable law. For purposes of this Note, the “maximum rate allowed by applicable law” means the greater of (A) the maximum rate of interest permitted under federal or other law applicable to the indebtedness evidenced by this note, or (B) the “Weekly Ceiling” as referred to in Sections 303.002 and 303.003 of the Texas Finance Code. Whenever increases occur in the interest rate, Lender, at its option, may do one of the following: (A) increase Borrower’s payments to ensure Borrower’s loan will pay off by its original final maturity date, (B) increase Borrower’s payments to cover accruing interest, (C) increase the number of Borrower’s payments, and (D) continue Borrower’s payments at the same amount and increase Borrower’s final payment.

PREPAYMENT. Borrower may pay without penalty all or a portion of the amount owed earlier than it is due. Any partial payment shall be in an amount equal to one or more full installments. Prepayment in full shall consist of payment of the remaining unpaid principal balance together with all accrued and unpaid interest and all other amounts, costs and expenses for which Borrower is responsible under this Note or any other agreement with Lender pertaining to this loan, and in no event will Borrower ever be required to pay any unearned interest. Early payments will not, unless agreed to by Lender in writing, relieve Borrower of Borrower’s obligation to continue to make payments under the payment schedule. Rather, early payments will reduce the principal balance due and may result in Borrower’s making fewer payments. Borrower agrees not to send Lender payments marked “paid in full”, “without recourse”, or similar language.

If Borrower sends such a payment, Lender may accept it without losing any of Lender’s rights under this Note, and Borrower will remain obligated to pay any further amount owed to lender. All written communications concerning disputed amounts, including any check or other payment instrument that indicates that the payment constitutes “payment in full” of the amount owed or that is tendered with other conditions or limitations or as full satisfaction of a disputed amount must be mailed or delivered to: First Victoria National Bank, Loan Operations, P.O. Box 1338, Victoria, TX 77902.

POST MATURITY RATE. The Post Maturity Rate on this Note is the lesser of the maximum rate allowed by applicable law or 18.000% per annum. Borrower will pay interest on all sums due after final maturity, whether by acceleration or otherwise, at that rate.

DEFAULT. Each of the following shall constitute an event of default (“Event of Default”) under this Note:

Payment Default. Borrower fails to make any payment when due under this Note.

Other Defaults. Borrower fails to comply with or to perform any other term, obligation, covenant or condition contained in this Note or in any of the related documents or to comply with or to perform any term, obligation, covenant or condition contained in any other agreement between lender and Borrower.

False Statements. Any warranty, representation or statement made or furnished to Lender by Borrower or on Borrower’s behalf under this Note or the related documents is false or misleading in any material respect, either now or at the time made or furnished or becomes false or misleading at any time thereafter.

Insolvency. The dissolution or termination of Borrower’s existence as a going business, the insolvency of Borrower, the appointment of a receiver for any part of Borrower’s property, any assignment for the benefit of creditors, any type of creditor workout, or the commencement of any proceeding under any bankruptcy or insolvency laws by or against Borrower.

Creditor or Forfeiture Proceedings. Commencement of foreclosure or forfeiture proceedings, whether by judicial proceeding, self-help, repossession or any other method, by any creditor of Borrower or by any governmental agency against any collateral securing the loan. This includes a garnishment of any of Borrower’s accounts, including deposit accounts, with Lender. However, this Event of Default shall not apply if there is a good faith dispute by Borrower as to the validity or reasonableness of the claim which is the basis of the creditor or forfeiture proceeding and if Borrower gives Lender written notice of the creditor or forfeiture proceeding and deposits with Lender monies or a surety bond for the creditor or forfeiture proceeding, in an amount determined by Lender, in its sole discretion, as being an adequate reserve or bond for the dispute.

Events Affecting Guarantor. Any of the preceding events occurs with respect to any guarantor, endorser, surety, or accommodation party of any of the indebtedness or any guarantor, endorser, surety, or accommodation party dies or becomes incompetent, or revokes or disputes the validity of, or liability under, any guaranty of the indebtedness evidenced by this Note. In the event of a death, Lender, at its option, may, but shall not be required to, permit the guarantor’s estate to assume unconditionally the obligations arising under the guaranty in a manner satisfactory to Lender, and, in doing so, cure any Event of Default.

Change in Ownership. Any change in ownership of twenty-five percent (25%) or more of the common stock of Borrower.

Adverse Change. A material adverse change occurs in Borrower’s financial condition, or Lender believes the prospect of payment or performance of this Note is impaired.

Insecurity. Lender in good faith believes itself insecure.

Cure Provisions. If any default, other than a default in payment is curable, it may be cured (and no event of default will have occurred) if Borrower, after receiving written notice from Lender demanding cure of such default: (1) cures the default within fifteen (15) days; or (2) if the cure requires more than fifteen (15) days, immediately

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initiates steps which Lender deems in Lender’s sole discretion to be sufficient to cure the default and thereafter continues and completes all reasonable and necessary steps sufficient to produce compliance as soon as reasonably practical.

LENDER’S RIGHTS. Upon default, Lender may declare the entire indebtedness, including the unpaid principal balance on this Note, all accrued unpaid interest, and all other amounts, costs and expenses for which Borrower is responsible under this Note or any other agreement with Lender pertaining to this loan, immediately due, without notice, and then Borrower will pay that amount.

ATTORNEYS’ FEES; EXPENSES. Lender may hire an attorney to help collect this Note if Borrower does not pay, and Borrower will pay Lender’s reasonable attorneys’ fees. Borrower also will pay Lender all other amounts Lender actually incurs as court costs, lawful fees for filing, recording, releasing to any public office any instrument securing this Note; the reasonable cost actually expended for repossessing, storing, preparing for sale, and selling any security; and fees for noting a lien on or transferring a certificate of title to any motor vehicle offered as security for this Note, or premiums or identifiable charges received in connection with the sale of authorized insurance.

GOVERNING LAW. This Note will be governed by, construed and enforced in accordance with federal law and the laws of the State of Texas. This Note has been accepted by Lender in the State of Texas.

RIGHT OF SETOFF. To the extent permitted by applicable law, Lender reserves a right of setoff in all Borrower’s accounts with Lender (whether checking, savings, or some other account). This includes all accounts Borrower holds jointly with someone else and all accounts Borrower may open in the future. However, this does not include any IRA or Keogh accounts, or any trust accounts for which setoff would be prohibited by law. Borrower authorized Lender, to the extent permitted by applicable law, to charge or setoff all sums owing on the indebtedness against any and all such accounts.

THIS NOTE IS BASED ON FINANCIAL STATEMENT DATED, 10-31-2001.

COLLATERAL. Borrower acknowledges this Note is secured by SECURITY AGREEMENT DATED 02-11-2002 COVERING PURCHASE MONEY SECURITY INTEREST ON ALL EQUIPMENT AND INVENTORY PURCHASED FROM SERCEL, LTD., GEOSPACE CORP., AND MARK PRODUCTS, INPUT OUTPUT; AND ASSIGNMENT OF ALL LEASES AND REVENUES GENERATED FROM SAID EQUIPMENT AND INVENTORY.

SUCCESSOR INTERESTS. The terms of this Note shall be binding upon Borrower, and upon Borrower’s heirs, personal representatives, successors and assigns, and shall inure to the benefit of Lender and its successors and assigns.

GENERAL PROVISIONS. If any part of this Note cannot be enforced, this fact will not affect the rest of the Note. Borrower does not agree or intend to pay, and Lender does not agree or intend to contract for, charge, collect, take, reserve or receive (collectively referred to herein as “charge or collect”), any amount in the nature of interest or in the nature of a fee for this loan, which would in any way or event (including demand, prepayment, or acceleration) cause Lender to charge or collect more for this loan than the maximum Lender would be permitted to charge or collect by federal law or the law of the State of Texas (as applicable). Any such excess interest or unauthorized fee shall, instead of anything stated to the contrary, be applied first to reduce the principal balance of this loan, and when the principal has been paid in full, be refunded to Borrower. The right to accelerate maturity of sums due under this Note does not include the right to accelerate any interest which has not otherwise accrued on the date of such acceleration, and Lender does not intend to charge or collect any unearned interest in the event of acceleration. All sums paid or agreed to be paid to Lender for the use, forbearance or detention of sums due hereunder shall, to the extent permitted by applicable law, be amortized, prorated, allocated and spread throughout the full term of the loan evidenced by this Note until payment in full so that the rate or amount of interest on account of the loan evidenced hereby does not exceed the applicable usury ceiling. Lender may delay or forgo enforcing any of its rights or remedies under this Note without losing them. Borrower and any other person who signs, guarantees or endorses this Note, to the extent allowed by law, waive presentment, demand for payment, notice of dishonor, notice of intent to accelerate the maturity of this Note, and notice of acceleration of the maturity of this Note. Upon any change in the terms of this Note, and unless otherwise expressly stated in writing, no party who signs this Note, whether as maker, guarantor, accommodation maker or endorser, shall be released from liability. All such parties agree that Lender may renew or extend (repeatedly and for any length of time)

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this loan or release any party or guarantor or collateral; or impair, fail to realize upon or perfect Lender’s security interest in the collateral without the consent of or notice to anyone. All such parties also agree that Lender may modify this loan without the consent of or notice to anyone other than the party with whom the modification is made. The obligations under this Note are joint and several.

PRIOR TO SIGNING THIS NOTE, BORROWER READ AND UNDERSTOOD ALL THE PROVISIONS OF THIS NOTE, INCLUDING THE VARIABLE INTEREST RATE PROVISIONS. BORROWER AGREES TO THE TERMS OF THE NOTE.

BORROWER ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THIS PROMISSORY NOTE.

BORROWER:

MITCHAM INDUSTRIES, INC.

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