Advanced Materials Research Vols. 524-527

Abstract: With the conventional oil and gas development and consumption, unconventional oil and gas becomes more and more important. Unconventional oil and gas development in China should consider some opportunities and challenges. These include developed technique and success methods in other countries, the variable price of oil and gas, the quality and quantity of reserves distribution, taxes policies and the increasing quantity of oil and gas consumption and demand.

Abstract: In the oil drilling engineering, the choice of the best bit-type can improve penetration rate, shorten the drilling cycle time and speed up the oil field exploration and development pace. The drill bits type optimal selection has important meaning in oil drilling engineering. Based on the brief introduction of fractal theory, it pointes out that the fractal theory can describe the depositional sequence of formations with self-similar characteristics in this paper. It puts forward a method of calculating correlation dimension with multivariate model according to log information. It has also established statistical relationship between correlation dimension and the working performance standard of bits. At the end of the paper the bit types selection method, adopting the correlation dimension, has given out. This method is practically feasible through the example validation.

Abstract: Finding the breakthrough position of horizontal wells is essential to water plugging and improving oil production in bottom water drive reservoirs. Physical modeling was carried out in this paper to research the law of bottom water’s movement. The experimental results indicated that: pressure drop in wells, well trajectory and area reservoir heterogeneity were all sensitive factors for breakthrough of bottom water, and the entry points of horizontal wells were determined by the combined function of them. In different well trajectory models, the concave down part of the well cooperate with pressure drop influenced the breakthrough position. Bottom water below the heel end reached the well earliest if the concave down part located at the heel end. When the concave part located at the middle of the well, the two factors played role respectively which resulted in breaking through of bottom water at two places with larger swept area. In different heterogeneous models, permeability difference and pressure drop were both favorable factors for bottom water’s non-uniformly rise. In the model that the heel end located at high permeability part, bottom water under the heel end reached the well earliest. If the heel end was set at the low permeability part, the breakthrough of bottom water occurred at the middle of the well.

Abstract: Sulige gas field in Ordos Basin is the largest discovered gas field in China. But tight sandstone reservoirs is becoming the main limitation of natural gas exploration and exploitation in Sulige gas field. Intensively analysis on micro-pore structure of sandstone reservoirs in Shan1 member of Shanxi formation and He8 member of Shihexizi formation in Permian system in the eastern part of Sulige gas field are conducted by means of drill core observation, slice identification, SEM analysis, casting slice and mercury injection etc. analytical methods. Result shows that fracture is well developed in sandstone reservoirs in the northern part of the interest area, by which petrophysical property of tight sandstone reservoir is improved distinctly. Types of fracture are dominated by diaclase and the diagenesis cracks. Main direction of the fractures is NE and NW, and the angle of the two groups fractures is nearly 90°.But one set of the conjugate shear fractures would develop well and the other was rest rained by the influenced of strong anisotropism of sandbodies. Diaclase and the diagenesis cracks developed along the boundery of tectonic divisions. Fracture is one of the important reasons for improvement of permeability in tight sandstone reservoirs. Gas potential of sandstone in fracture-developed section is much better than that of non-fracture section. Consequently, it is signaficant for all of reservoir forecasting, high productivity gas pool seeking, design and construction of natural gas exploitation to grasp distribution laws of fracture.

Abstract: A series of polyimides (PIs) by thermal imidization of polyamic acid (PAA) were prepared in order to investigate the gas separation property. The single gas permeability of He, H2, CO2, O2, N2 and CH4 were measured and compared in order to determine the effect of the reaction content and thermal imidization temperature on the gas separation properties. The results showed that the higher the thermal imidization temperature is, the more beneficial for the gas separation properties of the PI membranes. The optimum polycondensation reaction content on preparing PI was 25 wt%. The highest ideal selectivity of He/CH4, H2/CH4, CO2/CH4 and H2/N2 is 2814.88, 1652.38, 216.63 and 191.58, respectively.

Abstract: Artificial barrier morphology distribution mechanism and the EOR factors of he heavy oil reservoir with bottom water is be researched, Through numerical calculation and numerical simulation method. The model for calculating the height of the artificial-interlayer with curvilinear side surface is established. This model quantitatively describes the relationship between the artificial-interlayer height and oil yield, reservoir thickness, radial distance from well axis, reservoir permeability and crude oil viscosity. Maximum artificial-interlayer height and radius, the artificial-interlayer heights at different radial distances can be obtained according to this model. Through the case, the characteristics of artificial-interlayer form are analyzed, and rules of artificial-interlayer conformation are obtained when artificial-interlayer liquid with different volume, viscosity and race are injected. The further research are carried out through numerical simulation method, and the theoretical results are be Compared and verified which deepen the study of artificial-interlayer shape influence factor . Results show that: the volume and position of injected gel have more influence on development effect is obviously, the interlayer is designed 3M over the oil-water interface and thickness perforated is 6m is better, which provides a reference for the development of bottom-water reservoir.

Abstract: Guided by the theory of petroleum system, we analyzed the Lower Palaeozoic hydrocarbon accumulation elements and conditions of the Middle uplift of Southern Yellow Sea Basin and concluded the hydrocarbon accumulation pattern. The results showed that: the source rock of lower Palaeozoic in the Middle uplift of Southern Yellow Sea Basin consists of the dark mudstone and carbonate rock; carbonate rock is the main favorable reservoir followed by clastic rock; there are three source-reservoir-cap assemblages; the source rock of Lower Palaeozoic has experienced two hydrocarbon generation stages which are late Silurian and late Middle Triassic; hydrocarbon generated by Lower Palaeozoic source rock can only migrate to the traps near the center of hydrocarbon generation by sandbody and cracks in a short distance; lithologic trap and broad anticlinal trap are the main types in the study area. Through the above analysis, we conclude two accumulation patterns of Lower Palaeozoic in the Middle uplift of Southern Yellow Sea Basin.

Abstract: The tight oil reservoir is abundance in shengli oilfield and has a good exploration prospects, and overall "deep", "small", "thin" , "poor" , "scattered" geological features, It main performance in the development was conventionally low or no productivity, the initial production decline, late decreasing slowed and original watercut is 35%, to deepen the study of the percolation mechanism, the use of numerical reservoir simulation technology, the long horizontal segment of the multi-stage fractured horizontal well geological parameters (fracture spacing, fracture half-length, horizontal length, fracture conductivity, etc.)optimized design, the successful implementation of the long horizontal segment multi-stage fractured horizontal wells( Fan 154 - P1), initial production is five times higher than the same period in straight well, to achieve the highly efficient development of such oilfields.

Abstract: Based on the actual production data, this paper selected some evaluation parameters and established reasonable evaluation criterion for the horizontal well development effect in the ultra low-abundance and thin zone reservoir by using statistical analysis method，reservoir engineering analysis process and reservoir numerical simulation technology .In addition, a development effect evaluation system specially for the horizontal well development effect in the ultra low-abundance and thin layer reservoir was build up with the fuzzy comprehensive evaluation approach. Finally, the evaluation system were applied in several low-abundance and thin reservoir blocks. It was shown that the evaluation system can scientifically estimate the development effect of this kind of reservoir and has a practical application value.

Abstract: There are two important features on microstructure of shale.Firstly, Shale rocks are composed of rather fine grained particles, and their pores are very small, at the scale of nanometers.Gas slippage is complicate because its pore diameter is typically less than 10 nm. Secondly, a large amount of shale gas are absorbed in shale the same as coal-bed methane. Adsorbed gas desorption changes the structure. Permeability of shale is dynamic because of Nano-pore structure and desorption of absorbed gas during production. Shale gas slippage dynamic characteristics is researched in Nano-scale pores,based on capillary bundle medle and solid deformation theory. Mathematical model results show that pore diameter and pressure have important effect on permeability. Permeability increases firstly then reduces because of pressure drawdown when pore diameter is less than 10 nm. The lager pore diameter is, the lower pressure point of permeability Inflection and the faster permeability decline rate is. Gas molecular diffusion has less influence on flow when pore diameter is lager than 20 nm and when pressure is lager than 10 MPa. This model can be used for shale gas evaluation and production optimization.