Spatial variations of pore pressure

A system for calculating pore pressure in a reservoir, the system comprising:

• one or more processors configured to perform operations comprising:
• receiving input data comprising:
• (i) a rock density in the reservoir, (ii) seismic data measured in the reservoir, and (iii) pore pressure measurement data from a Modular Formation Dynamic Tester (MDT);
• calculating, based on the rock density, an overburden pressure volume of the reservoir;
• generating, based on the seismic data, an acoustic impedance volume of the reservoir;
• calculating, based on the overburden pressure volume and the pore pressure measurement data, an effective stress volume of the reservoir;
• generating, based on the effective stress volume and the overburden pressure volume, an estimated pore pressure volume of the reservoir;
• selecting a first top reservoir surface on a first depth seismic volume;
• flattening the first depth seismic volume based on a reference top reservoir surface by correcting effects of structural variation in the subsurface beneath the first top reservoir surface aligning with the reference top reservoir surface for unifying top reservoir surfaces into the reference top reservoir surface;
• calculating a first estimated pore pressure volume based on the reference top reservoir surface;
• selecting a second top reservoir surface on a second depth seismic volume;
• flattening the second depth seismic volume and obtain a second estimated pore pressure volume based on the reference top reservoir surface;
• calculating a pore pressure gradient map, by dividing the pore pressure values on the flattened reservoir surface by an average reservoir depth;
• and
• generating instructions for a drilling system to perform a drilling operation determined by one or more actions comprising a determination of a drill location based on the pore pressure gradient map and anticipated drilling hazards.

A non-transitory computer storage medium encoded with instructions that, when executed by one or more computers, cause the one or more computers to perform operations for calculating pore pressure in a reservoir, the operations comprising:

• receiving input data comprising:
• (i) a rock density in the reservoir, (ii) seismic data measured in the reservoir, and (iii) pore pressure measurement data from a Modular Formation Dynamic Tester (MDT);
• calculating, based on the rock density, an overburden pressure volume of the reservoir;
• generating, based on the seismic data, an acoustic impedance volume of the reservoir;
• calculating, based on the overburden pressure volume and the pore pressure measurement data, an effective stress volume of the reservoir;
• generating, based on the effective stress volume and the overburden pressure volume, an estimated pore pressure volume of the reservoir;
• selecting a first top reservoir surface on a first depth seismic volume;
• flattening the first depth seismic volume based on a reference top reservoir surface by correcting effects of structural variation in the subsurface beneath the first top reservoir surface aligning with the reference top reservoir surface for unifying top reservoir surfaces into the reference top reservoir surface;
• calculating a first estimated pore pressure volume based on the reference top reservoir surface;
• selecting a second top reservoir surface on a second depth seismic volume;
• flattening the second depth seismic volume and obtain a second estimated pore pressure volume based on the reference top reservoir surface;
• calculating a pore pressure gradient map, by dividing the pore pressure values on the flattened reservoir surface by an average reservoir depth;
• and
• generating instructions for a drilling system to perform a drilling operation determined by one or more actions comprising a determination of a drill location based on the pore pressure gradient map and anticipated drilling hazards.