Whose address of operation was the Echirax Concession? 
{'header': ['Client', 'Years of Operation', 'Area of Operation', 'Country', 'Services'], 'page_title': 'Challenger LTD', 'section_title': 'Challenger Limited: Selected Clients', 'caption': 'Challenger Limited: Selected Clients', 'rows': [['Agoco', '1991-current', 'Sarir field', 'Libya', 'Drilling, workover'], ['Lasmo', '1993-94', 'Wadi Borjuj', 'Libya', 'Drilling, workover'], ['Waha', '1994', 'El Zahra', 'Libya', 'Drilling, workover'], ['IPC-Dublin', '1997-97', 'Kilwa', 'Tanzania', 'Drilling'], ['OMV', '1997', 'Field 103', 'Libya', 'Drilling, workover'], ['Fina', '1997', 'El Hamada', 'Libya', 'Drilling, workover'], ['Marathon', '1998', 'Manzala field', 'Egypt', 'Drilling'], ['Khalda/ Repsol', '1998-99', 'West Desert', 'Egypt', 'Drilling'], ['Total', '1999-current', 'El Mabrouk', 'Libya', 'Drilling'], ['Agiba-Agip', '1999', 'West Desert', 'Egypt', 'Drilling'], ['IPLL', '1999-current', 'El Naka field', 'Libya', 'Drilling'], ['SOC', '2000-current', 'SOC fields', 'Libya', 'Drilling'], ['Veba', '2000', 'Different fields', 'Libya', 'Drilling, workover'], ['Perenco Oil Co.', '2000-01', 'EchiraX Concession', 'Gabon', 'Drilling']]}