Study On Remaining Oil Of C21-2and C21-3Section Of Yanchang Formation And Waterflood Development Adjustment Based On Reservoir Quality Types In Wangjiawan Oilfield, Ordos Basin

After the arrival of the development period of the reservoir, the primary developing direction of oilfield turns to the research of remaining oil and adjusting the exploration, in order to further enhance the recovery degree and recovery factor. Before the conduction of the remaining oil, it is necessary to find out reservoir and remaining oil types, and to promote correspond exploration and development plans aiming at different types.In2005, Wang Guwan oilfield of xingzichuan oil production had ended its beginning period of waterflood development, now is in its mid-term period, so that making the comprehensive water cut reach to77%. Although the conventional way of injection-production and injection-production well pattern are not able to meet the needs, there are still some remaining conventional mining reserves. Therefore, the next step of the exploration should consider from two factors which are original reservoir quality and the control of remaining oil reservoir, in order to make the proper water injection scheme of next time of the exploration.Since June2012, the author, accompanied by Yan Chang group has started to research the21reservoir waterflood development adjustment scheme of Wang Jiawan oilfield. And the bellowing part is a four-point summary of what he acquires from the experience:1. According to the actual development situation of Wang Jiauwan oilfield, reservoir quality types in the studying area are divided into A, B, C, D four types based on effective reservoir thickness, flow coefficient (permeabilityxeffective reservoir thickness), storage coefficient (porosity×effective reservoir thickness). And respectively researching the plane distribution rule and vertical distribution rule of reservoir quality type of C21-2, C21-3two main oil-producing formation.2. In the light of geological and technological factors, three kinds of remaining oil occurrence are studied that are still remaining oil, plane remaining oil and remaining oil in vertical direction. Furthermore, according to different control factors, to analyze its mechanism and provide basis for adjustment exploration.3. This paper studies the relationship between reservoir quality type and the control factors of remaining oil occurrence. After analyzing the relationship, important theoretical basis can be provided for the adjusting the water flooding development plan.4. Basing on the corresponding relationship between reservoir quality type and the control factors of remaining oil occurrence, from the view of plane and vertical it put forward the exploration and injection-production development adjustment scheme on account of different control factors of remaining oil. On the plane the adjustment scheme is that:For class A reservoir, it needs to adjust the well pattern and increase water injection; For class B reservoir, it mainly needs to adjust the well pattern; For class C and D reservoirs, it needs to improve and perfect the well pattern and adjust the water injection way. On the vertical the adjustment scheme is that:for class A reservoir, it needs segmentation and pressuring that combined with plugging; For class B reservoir, it needs selective fracturing, for multilayer commingled producing well group, it needs layered water injection, cyclic waterflooding and the adjustment of the depth profile control.