SAN FRANCISCO — The Heller Ehrman estate appears to have collected only $8 million of the $77 million owed to it by clients since its bankruptcy filing nearly three months ago, a monthly operating report shows.

Most of the firm’s receivables, the largest portion of Heller’s potential assets, are older than 90 days, which make them pretty stale. With no one to pound down the doors of debtors, bankruptcy lawyers said, there’s a diminishing chance of collecting on those accounts.