Advanced Materials Research Vol. 868

Abstract: Taking displacing pressure gradient and threshold pressure gradient into account, we have carried on a research of effective displacement theory in low permeability formation. Based on displacing pressure gradient expression of different production diverging/converging, we get displacing pressure gradient engraving when formational pressure, injection pressure, bottom hole producing pressure, and inter well distance is changing. And analyze its regular as well. On the basis of experimental result, establishing the relationship between threshold pressure gradient and displacing pressure gradient, and analyze the critical value of different pay zones for effective displacement. Study has shown that if we want to drive low permeability formation it is necessary that the displacing pressure gradient is larger than the threshold pressure gradient. It is the optimal choice for low permeability formations effective displacement that the well spacing should be smaller. It can achieve a goal that effective driving low permeability reservoir by the adjustment of taking measures and the injection-production pressure systems modulation. The study has important guiding significance for the development of low permeability formation, and it has got effective verification in oil field test.

Abstract: Reorientation fracturing of post-phase development of conventional low productive formations and pro-phase development of unconventional reservoirs such as shale gas plays and coalbed methane formations has been and will always be of considerable significance for oil/gas development. Conventional reorientation trajectory prediction results cannot exactly match the field actual fracture mapping propagation ones. Based on the discrepancy, this research focuses on the dominant factors influencing re-fracture propagation path and re-recognizes the disturbed stress field. Taking advantage of the proposed Principle of Maximum Circumferential Tensile Stress, the fracture propagation path is numerically modeled, which is more in conformity with the fracture mapping compared with the conventional one. Finally, the importance of proper estimation of reorientation fracturing propagation trajectory is analyzed.

Abstract: Several geological factors can have a potential effect on dissociation of natural gas hydrate (NGH). It is important to understand their roles in safe exploitation of NGH deposits. This paper accordingly reviews experimental and numerical-modeling researches on impact factors of NGHs dissociation by depressurization. NGHs dissociation usually increases with increasing temperature, permeability, water saturation, thermal conductivity of sediments and depressurization rate of production well, whereas it is reverse for pressure, hydrate saturation, production wells pressure, gas saturation and particle size. Comparably, the effect of porosity and the heat conduction of production well can be reasonably ignored at different spatial scales. The heterogeneity of NGH deposits, chemical components of pore fluids, relative permeability and capillary pressure can also play a role in NGHs dissociation. However, their influencing mechanisms still need further studies in future.

Abstract: With the change of topology structure of gas pipeline network, dynamic characteristics of gas in the pipeline will change in a very complicated way. A dynamic simulation experimental system of gas pipeline will be introduced in this paper to indicate gas flow dynamic characteristic. Numerous of experiments of several kinds of typical gas topology network structure will be conducts under different working conditions. Experimental results will be analyzed as well to achieve the main influence factors of gas flow dynamic characteristic.

Abstract: As a compound modifying and flooding agent, the organic-inorganic crosslinked plugging system which is mixed by gel and silicide according our experimental study, formed integral crosslinked system at high temperature and varied in a broad range gelling time by regulate concentration of organic-inorganic crosslinked plugging system. It exhibits excellent thermostability, shear properties, plugging performance and washable characteristic. In this visual experiment, the organic-inorganic crosslinked plugging systems injection, waterflooding effect and sealing capacity on homogeneous reservoir and heterogeneous reservoir are all exhibited clearly. The results of experiment show that organic-inorganic crosslinked plugging system has a good injectivity and water plugging performance. Depth of injection has an important effect on water-flooding situation, further influencing the increasement of recovery factor. Before the injection of Organic-Inorganic Crosslinked Plugging System, we inject some viscosity reducer, such as foam solution which reducing the deep oil viscosity, keeping the high recovery efficiency and preventing the mistaken plugging.

Abstract: ASP Flooding has a better displacement efficiency, but there is still a serious problem of wells scaling. Researched on formation mechanism and influence factors of silica scale in ASP flooding with alkali, the formation of silica scale is mainly due to the alkali dissolution reaction of reservoir rock to produce the soluble silicon ions and form silica scale in formation conditions. Laboratory experiments simulated formation mineralization aqueous solution, analyzed the morphology of silica scale by scanning electron microscopy, and studied the role played by calcium, magnesium, aluminum ion, polyacrylamide, surfactant. The experimental results show that: calcium, magnesium, aluminum ions, polyacrylamide, and surfactant can promote the formation of silica scale, and the morphology characteristics of silica scale are different.

Abstract: East Xing Six District of Daqing oilfield development has 50 years of history, the block has entered high well density, high water cut stage. The apricot East Xing Six District demonstration zone development belongs to the continental sedimentary system, it has reservoir types and physical properties have large differences, It was long-term effected by injected water, after water flooding, water degree condition becomes very complex and unpredictable, so the washing condition analysis is an important guarantee for Daqing oilfield stable production. Using the oil field sealed coring well data, various types of reservoirs washing degree thickness change and growth are analyzed, We can know that with the further water flooding development and well pattern infilling, all kinds of oil reservoir production status; and then analyzes the potential distribution of the oilfields, and provides a basis for the development of the block and the adjustment of the next step of work, has an important guiding significance.

Abstract: Coalbed methane is one of the important unconventional energy, due to its characteristics determined there must be taken effective fracturing modification measure to get industrial gas flow, this paper analyzes the damage mechanism of fracturing fluid, the selection of additives in fracturing fluid and the methods of enhancing coalbed methane, and puts forward some corresponding suggestions to improve the recovery of CBM wells supporting a certain practical significance.

Abstract: The sedimentary facies is the combination of the sediment which has some rules of lithological and construction characters and paleontological evidence. It characterizes the source direction and the strength degree of water dynamics. As the developmental situation of the reservoir of different sedimentary facies is different, the permeability, porosity and oil saturation is distinctive. The production is related to the sedimentary facies, this lead to the different production capacity of different sedimentary facies. The oil-producing capacity varies with the sedimentary facies of the reservoir. Therefore, different kinds of data of the reservoir must be analyzed with proper methods. This passage, using the single layers data and the well history data of 244 wells in M block of Daqing Oil Field, through the method of grey relation analysis theory, analyzes the influence of the sedimentary facies to the productivity of the production well. And the weight of different sedimentary facies to the oil productivity of the production well is confirmed. Also, the oil productivity of the production well is quantified.

Abstract: As a cat well in Mahudang of Burma on anticline structure zone, YH-1 encountered narrow formation pressure window stratum in the process of drilling with the problem that loss of filtration is serious and the speed of air cutting rises rapidly. Application of drilling liner hanger into cementation, combined with expansive slurry system in well YH-1 has met cementing requirements. Well sections are qualified and sealing sections of high quality amount to 49.4 percent. The field application results display that the usage of drilling liner hanger in narrow formation pressure window well section, associated with appropriate slurry system are able to satisfy well cementation requirements.