Greenhouse gas emission (GHG) is the main contributor to global warming, so the industry players need to take a huge step to reduce GHG. Furthermore, the implementation of carbon tax has eroded oil project values and drives teams to think about ways to reduce the carbon tax.
This paper highlights the subsurface studies, gas balancing method, and surface modification effort to reduce the gas emission in Field B while reaping the benefits not just of reduced carbon tax but increased oil production and revenue.
Gas injection is not just increasing reservoir pressure but also reduces emission. Several reservoirs in the field have been depleted by 66% to 500 psi. The team converted the existing oil wells to gas injection wells instead of spending high CAPEX to drill new gas injection well. This way the team can confirm the benefit of gas injection with a low-risk cash injection.
The field has a high amount of unproduced Non-Associated Gas (NAG), but this NAG cannot be produced without a gas evacuation plan. Producing the NAG will cause the field to vent higher with existing facilities installations. So, the team came out with a plan to monetize the gas by installing a new gas pipeline and new gas processing platform. Furthermore, the Associated Gas (AG) which was vented previously can be channeled to the new compression system to further reduce the emission.
Currently, the gas from the surge tank is lined up straight to the vent stack. A Vapour Recovery Unit (VRU) was proposed to install upstream of the surge vessels. The VRU will pump the gas back to an AG gas compressor and straight to the gas sales line.
The gas injection project has increased the reservoir pressure from 500 psi to 700 psi. As a result, one idle well reactivated to produce oil, two wells were drilled from the same reservoir, and gas venting was reduced by up to 7 MMscf/d. Because of this success, several other wells were identified for gas injection candidates in other reservoirs.
NAG gas project is expected to provide 100 MMscf/d revenue. In addition to that, the NAG project also helps to reduce AG venting because of AG compressor limitations. The additional AG volumes are around 5 MMscf/d.
VRU installation is still undergoing doability and commerciality study because the gas from the surge vessel is minimal. However, the team's dream towards zero gas emission is a step closer if VRU installation is brought forward.
Because the field is not well equipped with a gas meter for each piece of equipment. An accurate and understanding of gas balance estimation is important to drive zero gas emission.