Schlumberger Ltd., New York, said Tuesday that it has signed a pact with purchase software and network services company Commerce One Inc., Mountain View, Calif., to develop e-commerce services across its oil and gas businesses. The move is significant because Schlumberger has a growing business in the area of smart cards, which are the size of a credit card with a microprocessor embedded inside. The microprocessor is used to identify individuals within a company making purchases, and for securing the transactions those employees complete. It is widely thought that payments for Internet purchasing, for basic supplies as well as parts that go into products, might bring smart cards into wider use. The technology could use a boost. Though the cards have been available for several years, educational institutions are among only a handful of entities that use them widely today. And more often than not, they are used for access to buildings and plant facilities rather than transactions.