| Xinchang gas field lied in the western sichuan depression is sure to be in the middle of a large north east to uplift belt, from filial piety springs anticline eastward a flat nose structure. Is made up of more than shallow, middle and deep reservoir of vertically superimposed on large dense clastic rock gas field, its production is located in the national forefront, shaxi Js2temple group is the absolute main force of the gas field gas reservoir, gas reservoir on the longitudinal consists of four gas. The stable situation is very severe in gas reservoir, in addition to its dense gas reservoir, low abundance of objective reasons, a more deep-seated reason is that the sedimentary facies, reservoir evaluation and reservoir control factors such as relative lack of research; And sequence stratigraphy research as a foundation work can provide the basis for adjustment of gas reservoir development scheme.Since1995, high-resolution sequence stratigraphy research has been introduced into China, brought an upsurge of study of it. Many scholars apply the theory which plays an increasingly important role in the oil and gas exploration and development to the continental basin with Chinese characteristics and achieved fruitful results. Sichuan basin is an ancient large-scale petroliferous superimposed basin, through six-time tectonic cycle and its tectonic activity is sometimes strong and sometimes weak. Longmen mountain nappe tectonic belt and uplift has formed Micang mountains and provided a rich source for the basin, its depocenter and subsidence center shifted constantly.This thesis applied sedimentlogy, basin analysis and the theory of high-resolution sequence stratigraphy, based on the drilling, logging and seismic data, carried out a systematic and in-depth study of the high resolution sequence stratigraphy research of JS2’’3gas layer of Shaxi temple group in Xinchang gas field. The results and understandings are as follows:(1) According to the drilling and logging data of the study area, the top and bottom interface of Js2K3layer of Shaxi temple group in Xinchang area has been identified. Sequence boundary forms a scour surface, intermittent exposure surface, lithology and lithofacies transition surface and maximum flooding surface. Established the stratigraphic division of the objective interval markers by drilling data, logging data which are JS21the top shale, JS21the bottom mudstone, JS22-2～JS23-1and JS23-1～JS23-2the demarcation of mudstone, JS23-2the bottom of high resistivity sandstone. All of the objective interval markers have obvious characteristics and with the core characteristics and logging identification sign of good, can be used to compare in the whole range.(2) Combining the genetic types and characteristics of sequence boundary on the basis of the stratigraphic classification, proposed the research area sequence classification scheme. The study area was divided into a long-term cycle, two mid-cycles and four short-term cycles, each term cycles are divided into two short-term cycles, and the SSCl has been divided into two short-term cycles, they were SSSCl and SSSC2. In two time unit demarcation line as the preferred isochronous comparison sign of base-level cycles of different levels are high accuracy isochronous correlation, established the Xinchang area, Shaxi Temple group of high resolution sequence stratigraphy. By contrast, the highest precision genetic stratigraphic unit can reach (grade one hundred thousand) short-term base-level cycles.(3) Analysis of sedimentary facies in the high-resolution sequence stratigraphic framework found that the sediment source of the study area are rich enough and mainly from northern part of Micang mountains, also has the secondary material sources from the west longmen mountain. According to the factors of rock association, sedimentary structure, sedimentary sequence and sedimentary mechanism, the reservoir is mainly composed of grayish green lithic arkose and its sedimentary microfacies are mainly subaqueous distributary channel of delta front, also has a channel flank sedimentary, interaction cutting shall superimposed, sand body thickness is big, is a good reservoir.(4)Petrophysical analysis data in the study area is rich, especially the chip data. Using triangle clastic rock components for the first time and by applying feldspar and quartz (F/Q) says climate index, using L/Q analyse the index structure, by controlling factors of sequence development through the analysis of the index changes. For example, Js23period L/Q>F/Q, suggests that climate is dominant; while F/Q value increases over time, suggests that climate become dry; JS21period, L/Q value is small and stable, show where MiCangShan and longmenshan tectonic activities smoothly, and F/Q decreases over time, and change from L/Q>F/Q to L/Q<F/Q shows the climate has dominant structural advantage at first and then become more dry climate.(5)Has carried on the classification to sequence structure development, and further studied the basin within different facies belt short-term cyclic sequence development characteristics, summed up the short-term cycle mode of distribution of the basin and analyzing the characteristic of the sequence development of stratigraphic accumulation style. Under the condition of A<S shows that the reservoir has abundant sediment supply and less accommodation space. When superposition of base level cycle are mainly composed of type" A ", the base level of sediments in the decline period denudation could not be saved. Summed up the layer sequence development mode in the study area, the dual factors of climate and tectonic mechanism can let a space change caused by datum spin recovery control process. So it can control the sand body structure, genetic type and scale of development in shaxi Js21temple group. |
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