Injection of Gas and Improved Oil Recovery - the Norwegian Experience By Steinar Njå, Norwegian Petroleum Directorate

The first oil production in Norway was done by Philips Petroleum Company Norway using the revamped drilling rig Gulftide from the summer 1971 until spring 1974, i.e. during development of the Ekofisk field. This is the only time flaring of associated gas has been approved in Norway for other reason than safety. I.e. for regular production. Flaring of Associated Gas

Historical view of the flaring on the NCS Gas export started CO 2 tax introduced NPD Task force

Petr. Act § 4-1 “ Production of petroleum shall take place in such manner that as much as possible of the petroleum in place in each individual petroleum deposit, or in several deposits in combination, will be produced. The production shall take place in accordance with prudent technical and sound economic principles and in such a manner that waste of petroleum or reservoir energy is avoided. The licensee shall carry out continuous evaluation of production strategy and technical solutions and shall take the necessary measures in order to achieve this.” Petr. Act § 4-4 “Flaring in excess of the quantities needed for normal operational safety shall not be allowed unless approved by the Ministry” Prudent Extraction and Utilization GGFR, Paris

 Petroleum Act requires licensees to address associated gas utilization (Plan for Development and Operation (PDO) and Plan for Installation and Operation (PIO)  EIA is part of the PDO/PIO approval process  Often PDO/PIOs only approved after significant investments to avoid flaring (eg. temporary re- injection)  Regulatory authority: Norwegian Petroleum Directorate (NPD)  Measurements, reporting and monitoring  Metering systems with accuracy of +/- 5%  Audited by NPD and reported volumes basis for taxation  Assessment of policies and regulations  Building of gas infrastructure of vital importance  Regulation of grid access State owns infrastructure through Gassled, non-discriminatory access with Ministry of Petroleum and energy setting transport tariffs  Tax on flaring is part of a general CO 2 tax on energy combustion Little/no impact on routine flaring but has help improve technologies and operational procedures for non-routine flaring CO 2 tax of importance for continued compliance Overview of policies and regulations – Norway

Total gas production on the NCS, GGFR, Paris

Focused Norwegian R&D Programs on IOR EOR Field Pilots ! EOR Field Pilots ! Financed by oil companies Authorities + oil companies Authorities + oil companies Experience transfer FORUM Experience transfer FORUM Follow up R&D programs Follow up R&D programs R&D Programs by NRC R&D Programs by NRC To be continued Financed by group of oil companies State R&D Program for IOR and Reservoir Technology GGFR, Paris

Background for decisions on gas injection  Lack of gas export opportunity and flaring not permitted and /or  Gas injection gave higher oil recovery and higher economic value than water injection  Injected gas to be sold to the market at an later stage Historical gas injection per field on the Norwegian Continental Shelf GGFR, Paris

Norwegian experience with gas injection  Successful IOR projects !!!  Lower residual oil with gas injection. Reported to NPD:  Average S org = 0,10 (fields with gas injection)  Average S orw = 0,22 (fields with water injection) Challenge  The timing of the production of the injected gas GGFR, Paris

Effect of gas injection Conclusions from NPD review:  28 % of the gross gas production has been reinjected  Additional million scm oil, including approved future plans for gas injection  Total efficiency; additional oil : 0,43-0,48 million scm oil/ billlion scm gas Historical gas injection and future approved plans for gas injection GGFR, Paris

The economics of gas re-injection  Gas re-injection has to compete with other alternatives for utilization  For IOR purposes there are always great uncertainties regarding efficiency and added recovery of oil  For storage purposes better utilization of transportation systems and improved delivery efficency is the main economical driver  Some gas will be used as fuel(2-3%) to reinject and 15-25% of gas reinjected will be left in the reservoir GGFR, Paris

Conclusions (I) 1.The combination of  prohibition against flaring of gas  IOR research efforts  authorities initiatives  prudent technical work and sounds decisions by oil companies has led to several successful gas injection projects 2.Several large Norwegian fields with gas-injection have recovery factors for oil in the range %. 3.Gas injection in Norwegian fields yields an extra oil recovery in the range 320 to 360 million scm. GGFR, Paris

Conclusions (II) 4.An important question is how long it is profitable to keep the injected gas in the reservoir. The timing of the massive production of the injected gas should not be fixed at an early stage, but needs to be updated late in the field life. 5.Re-injection of gas for IOR purpose represents a great potential for value creation. If the gas cannot be exported to the market or utilized on site, the reinjection is also an alternative that contributes to reducing a global environmental problem GGFR, Paris

Thank you for your attention!