The massive amount of dollars owed and the terms they come with could force more oil and gas drillers to restructure their businesses in bankruptcy court instead of pursuing cost-saving combinations with competitors, Occidental Petroleum CEO Stephen Chazen tells the IHS CERAWeek conference. Companies typically can combine to reduce costs in times of struggle, but many oil and gas companies already have made deep cuts to overhead, and a number of loans come with terms that could make mergers difficult, Chazen says.