EXHIBIT 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation of our report included in this Form 10-K into the Company's previously filed Registration Statements on Form S-8 (File Nos. 333-80505, 333-10813 and 33-60926). /s/ ARTHUR ANDERSEN LLP Tulsa, Oklahoma February 28, 2002