PetroChina Dagang Company Tianjin 300280 China;
Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China;
College of Geosciences China University of Petroleum Beijing 102249 China;
PetroChina Huabei Company Renqiu 062552 China;
CNPC Bohai Drilling Engineering Company Limited Renqiu 062552 China;