This problem will occur when running in 64 bit mode with the 32 bit Oracle client components installed.

Attempt to load Oracle client libraries threw BadImageFormatException. This problem will occur when running in 64 bit mode with the 32 bit Oracle client components installed. ---> System.BadImageFormatException: 试图加载格式不正确的程序。 (Exception from HRESULT: 0x8007000B)
at System.Data.Common.UnsafeNativeMethods.OCILobCopy2(IntPtr svchp, IntPtr errhp, IntPtr dst_locp, IntPtr src_locp, UInt64 amount, UInt64 dst_offset, UInt64 src_offset)
at System.Data.OracleClient.OCI.DetermineClientVersion()

解决方案：

应用程序池 --》选择对应程序池 右键 高级--设置启用32位应用程序为True