Online Journal for E&P Geoscientists

Yang, Yunlai ^*1; Mahmoud, Khalid A.²
(1) Advanced Research Center, Saudi Aramco, Dhahran, Saudi Arabia. (2) Area Exploration Department, Saudi Aramco, Dhahran, Saudi Arabia.

Provided hydraulic heads in the ground water surrounding a hydrocarbon accumulation are the same, the only force acting on the hydrocarbon body is buoyancy, which is vertical. This force results in the horizontal contact between oil and water. If hydraulic heads are different, the hydrocarbon body is also subjected to a lateral hydraulic force. The direction of the resultant force of buoyancy and hydraulic force is not vertical. As a result, the oil water contact is tilted. Obviously, for a given trapping structure, the boundary of hydrocarbon accumulation for tilted oil water contact is different from the one of the horizontal oil water contact. This hydrodynamically influenced trapping phenomenon has been observed worldwide. Hubbert (1953) developed an approach to map such hydrodynamic traps based on lengthy and complicated mathematical manipulations. It is important to correctly map the tilted oil water contact in order to delineate the accumulation and evaluate the reserves.

Based on explicit hydraulic principles we derived an equation to locate oil water contact from simple mathematical manipulations. We then developed a clear approach to delineate hydrodynamic traps using our constructed equation. We applied our approach to exploration prospects and the results explained the observed findings from the drilled wells.