A method for producing hydrocarbons from an oil and/or gas field using a physical property model representative of a physical property of the oil and/or gas field, the method comprising: defining an initial well path within user defined drilling parameter constraints; defining a proxy constraint volume as a three-dimensional cellular volume, defining acceptable constraint parameters to be applied to values derived from an intersection of the initial well path and the proxy constraint volume, said acceptable constraint parameters comprising maintaining a minimum safe distance from at least one object type; and if the intersection of the initial well path and the proxy constraint volume is not within the acceptable constraint parameters, iteratively adjusting the initial well path to create successive well paths until at least one of the successive well paths is within the acceptable constraint parameters for the values derived from the intersection of the well path and proxy constraint volume; drilling a well according to the initial well path if the intersection of the initial well path and the proxy constraint volume is within the acceptable constraint parameters, or drilling a well according to one of the successive well paths that is within the acceptable constraint parameters; and extracting hydrocarbons from the oil and/or gas field from the well, CHARACTERIZED IN THAT: each cell of the proxy constraint volume comprises a distance value derived from data from a 3D earth model representing the oil and/or gas field, wherein said distance value is set to zero for cells along or within the at least one object type, and wherein the distance value, for each cell not along or within said at least one object, is calculated and set as the distance from said each cell to the closest zero value cell. defining an initial well path within user defined drilling parameter constraints; defining a proxy constraint volume as a three-dimensional cellular volume, defining acceptable constraint parameters to be applied to values derived from an intersection of the initial well path and the proxy constraint volume, said acceptable constraint parameters comprising maintaining a minimum safe distance from at least one object type; and if the intersection of the initial well path and the proxy constraint volume is not within the acceptable constraint parameters, iteratively adjusting the initial well path to create successive well paths until at least one of the successive well paths is within the acceptable constraint parameters for the values derived from the intersection of the well path and proxy constraint volume; drilling a well according to the initial well path if the intersection of the initial well path and the proxy constraint volume is within the acceptable constraint parameters, or drilling a well according to one of the successive well paths that is within the acceptable constraint parameters; and extracting hydrocarbons from the oil and/or gas field from the well, each cell of the proxy constraint volume comprises a distance value derived from data from a 3D earth model representing the oil and/or gas field, wherein said distance value is set to zero for cells along or within the at least one object type, and wherein the distance value, for each cell not along or within said at least one object, is calculated and set as the distance from said each cell to the closest zero value cell.