| Liangjia-Wuxing belt of Yitong Basin exits an effective source rock, qualified reservoir, good cap, favorable traps and storage conditions, and thus has excellent conditions for hydrocarbon accumulation. The core analysis and log facies analysis of the phase as a means to carry out phase analysis of single well and sedimentary facies characteristics, determine the quality of the reservoir (Wanchang group, Yongjie group, Sheling group) favorable sedimentary facies distribution. Using of property of reservoir, thin section, mercury penetration and other analysis data on the microstructure analysis of reservoir, divides the level of reservoir, researches to the vertical and horizontal distribution of reservoir,evaluates the reservoir. Using the stripping technique of the formation recover the history of hydrocarbon source rock, we can see Shuangyang group,Sheling group andYongjie group has different the hydrocarbon expulsion threshold and times, so the nature of fluid is different. Using the homogenization temperature of brine inclusions, burial history and thermal history to comprehensive researches the area, which shows oil and gas in the aera has experienced two charging and accumulation process, establishes the oil and gas accumulation model, sums up the oil and gas accumulation law. The main results and understanding obtained papers summarize as follows:(1)Wanchang group sedimentary system of Liangjia-Wuxing belt is the fan-delta front-shallow lake, including fan delta front and the shallow lake two kinds of sedimentary facies, Yongjie group is Island-half-shallow lacustrine system ,Sheling group is deep lake sedimentary system.Study area mainly developed fan delta front distributary channel, mouth bar, distal bar and other high quality reservoir sand microfacies types. Established sedimentary facies patterns in the purpose layer of Liangjia-Wuxing belt. (2)The reservoir porosity of Sheling group varys between 2.3 to 15.2%, with an average of 10.5%, the reservoir permeability is 0.02～28.58×10-3um2, an average of 3.96×10-3um2; the reservoir porosity of Yongjie group varys between 2 to 22.1%, average 13.96%, permeability is 0.01～188.54×10-3um2, an average of 17.61×10-3um2; the reservoir porosity of Wanchang group varys between 6 to 29.9%, with an average of 15.4%, permeability is 0.15～148.53×10-3um2, an average of 7.85×10-3um2. In general, with the depth of the reservoir properties is getting worse, Wanchang group is better than Yongjie group, the Yongjie group is better than Sheling group.(3)The distribution of sand shows that: various types of sandstone and mudstone overlayed,The ratio of sand and mud from southeast to northwest of Wanchang Group–Sheling group in Liangjia structural belt gradually becomes smaller; horizontal, along the main river channel sand body in the direction of connectivity within the well, sand and sand overlay each other to form a broader distribution of sand, the direction perpendicular to the river sand on the connectivity is poor, and heterogeneity is strong; plane, sand thickness of Liangjia structural belt gradually becomes thinning from southeast to northwest, sand thickness of Wuxing structural belt from southwest to northeast gradually becomes thinning.(4)The correlation of Oil and Oil source shows that the oil spot samples of first chart of Yongjie group in Chang 30 well should be mainly from the oil shale Yongjie group; oil-bearing sandstone in the thrid chart of Wan chang group of Chang 30 well has Shuangyang source rocks and Yongjie source rocks features ,mainly from Shuangyang group and source rocks;oil–bearing sandstone in first chart of Shuang yang group of Chang 11 well is mainly from shale source rocks of Shuangyang group ;the second chart of Yongjie group of chang 29 wells contain oil sandstone samples mainly from the oil shale source rock of Shuangyang group.(5) Build oil and gas accumulation model of Liangjia and wuxing structural belt, sum up the law of oil and gas accumulation area as follows:①cut oil and gas source fault controls transporting;②quality of reservoir controls petroleum filling;③structure and sand physical controls oil and gas distribution;④the maturity of source rock decide types of oil and gas field. Comprehensive study and comparison with the known domestic petroleum basins shows: the fundamental reason that constraints the gas field's scale of Liangjia-Wuxing is the relative lack of gas resource, oil and gas inefficient migration in the area or different dirction migration of hydrocarbon are closely related. |
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