Tahe Area 12 Super Deep, Super Heavy Oil Reservoir Evaluation And Development Technology Research,

The Ordovician reservoir in Tahe field 12^th block is supper-deep karst aperture-cave reservoir. This reservoir is of great burying depth, intensity heterogeneity, which is filled with heavy crude with high viscosity. It is extremely difficult to develop this kind of reservoir, and there is no successful experience to follow. In 2007, wells in the 12^th block like AD4, AD7, and S94CH in the 12^th block have successively obtained high commercial production, especially the highest daily output of S94CH ever reached to 1000 ton. Such block has been the key district to increase reserve and production for northwest branch of Sinopec during the eleventh five-year plan.In this paper, starting from finding the geological factors which control productivity and distribution of gas and oil, we have studied geological characteristics for exploration and development in the 12^th block Ordovician reservoir through synthetically applying many kinds of methods and technologies to make clear the geological characteristics, development law and controlling factors of fracture-cavity reservoirs. Reservoir productivity and distribution of gas and oil have been studied. Meanwhile, we studied development performance characteristics and property characteristics of supper-heavy oil reservoir, quested the reasonable development mode and efficient development process technology of supper-heavy oil reservoir. Based on these work, theoretical basis and technology support for reasonable development have been provided.Based on the study in this thesis, we achieved following conclusions and recognition:1. The 12th region was rich with faults, which is not only the channel of gas and oil but also the essential condition of sealing gas and oil.The three faults in the study region, F2, F3 and F4, dominate the structural framework in the 12th region: the low laying structure in west, the structure slop and structure high dominant the distribution direction of karst aperture-cave reservoir and the migration of gas and oil.2. The Ordovician reservoir in 12th region undergo karst process of the three stages of the middle Caledonian, the early and late stage of early hercynian, while karst process is of great intensity and large scale cavities are developed in this stage, which are mainly controlled by ancient landform and faults.3. Karst aperture-cave reservoir in east of the 12th region is easy to be filled, while the middle is of good property and the west worse.On the whole, the 12th region is in highland and slope of karst region, which are relatively in east and middle-west. It is obviously that the east is higher than the west, since the east is karst highland and the west is karst basin with karst slope between them. On the slope region, karstification is obviously and it is more probable to be remained of this effect, especially on the slight slope or secondary karst hammock on the slope. These regions are the best choice to find karst reservoir, and secondly the karst highland and regions of karst valley near the karst slope.4. Gas and oil are enriched in east fracture-cavity zones like S99-TK1207, AD4-AD7, TK1231-AD15 and in west fracture-cavity zones like TK1243-TK1210, TK1204-TK1229.5. The relationship of gas and oil in the 12th region are controlled by faults, which results that it is rich in water in the east, rich in gas and oil in west, rich in water in partial areas of the west.6. Energy complement development mode of supper-deep and supper-heavy oil reservoir has been formed.Comprehensively study reservoir geology research, development characteristics research, reservoir property characteristics and reference the field development mode and technical status of main region in Tahe field and other fields in abroad, according to the aim of chasing largest economic efficiency and improving the final recovery, it is suggested that natural energy plays the role in the early development stage and it is of good effect to apply the development mode of single-well water injection substituting oil after ceasing flush in the early stage for closed constant-volume system, also it is of good effect for muti-well unit with certain natural energy to apply the development mode of complement energy by injection water at the early and middle development stage.7. Efficient well net deployment technique for the supper-deep and supper-heavy reservoir in the 12th region has been achieved.In view of the characteristics of the supper-deep and supper-heavy reservoir in the 12th region of Tahe field, according to integral deployment, hierarchy development and dynamic adjustment, we has formed a set of efficient well deployment techniques. For the denudation area of upper Ordovician, we should evaluate new fracture-cavity zone, deploy wells on high part of structure and karst zone as well as sites with preferential characteristic of seismic reflection. For coverage area, we should search high production fracture-cavity zone, deploy wells on sites with the most preferential characteristic of seismic reflection, deploy wells in a line along fracture zone, expend and infill those fracture-cavities with sufficient energy, evaluate new fracture-cavity zone.8. Through studying sensibility of wellbore temperature and pressure in the 12th region, it is suggested that temperature is the main factor affecting the oil viscosity in this region while pressure is insignificant factor to viscosity of heavy oil.9. Through systematic study on those viscosity reduction process technology such as blending light dropping viscosity, chemical methods, heated by electricity, heated by closed heat flux in recycling and so on, it is concluded that blending light and chemical viscosity reduction process satisfy the needs of heavy oil development in the 12^th region, especially process of blending light dropping viscosity holds a dominant position. However, those like heated by electricity, heated by closed heat flux in recycling are of worse feasibility at present.10. Lifting process technology in supper-deep supper-heavy oil wells has been formed.①large diameter pipe process technology for oil production②blending light dropping viscosity process technology③electric submersible pump process technology④flow modification process technology⑤oil-soluble chemical viscosity reduction process technology...