A geomechanical study of the Champion Southeast (CPSE) field, Brunei was undertaken as part of the planning of a waterflood in the field. The key geomechanical issue addressed determining the change in reservoir pressure that could be sustained without reactivating faults in the reservoir or fracturing intact rock. Differential depletion of reservoirs and fault blocks has resulted in pressure compartmentalisation and variable pore pressure-stress conditions in the CPSE field. Pore pressure and minimum horizontal stress (äh) data recorded during depletion of the two most significantly depleted fault blocks were used to determine the stress path between undepleted and depleted reservoirs. The minimum horizontal stress (óh) is 15.5 MPa/km in hydrostatically pressured reservoirs. In the most depleted reservoirs, pore pressure is currently 6 MPa/km and óh is 12.5 MPa/km. The pore pressure-stress (Pp/óh) coupling ratio with depletion in the two fault blocks is 0.84. Other reservoirs and fault blocks at various stages of depletion in the CPSE field are assumed to lie on the same stress path. The vertical stress magnitude (óv) has been constrained to approximately 22 MPa/km in CPSE and the maximum horizontal stress (óH) has been loosely constrained to ~17 MPa/km. There is no clear evidence for the variation in óH with depletion. The present day stress regime is one of normal faulting where óH is the intermediate stress hence accurate knowledge of óH is less significant to failure analysis than óh and óv.