Research On Volcanic Rock Reservoir Characteristics Of The Paleocene First And Second Member Of Funing Formation In Minqiao Oilfield, SuBei Basin

Minqiao oilfield is located in the territory of Jiangsu province Jinhu County min Qiao xiang, regional structure is located in the southeastern Jinhu Sag, the South as Ling Tangqiao low raised, northeast for sishui sub-sag, southwest of Longgang times concave, a sandwiched between two concave fracture anticline, structural area of76km2.Minqiao oilfield drilling formation than the whole, from top to bottom with quaternary Dongtai formation (Qd), two section of Neogene Yancheng group (Ny2), the Paleocene Eocene Sanduo formation (three E2S) and Dainan group two (E2d2), the Paleocene Funing formation (E1f) in Taizhou group and the late Cretaceous (K.2t). Fu four top and pile two top two regional unconformity surface, structure of the main parts of a lack of salt and wearing a. Objective layer to Funing group E1f2+1volcano rock.The development of the reservoir with volcanic rocks in the study area, previous studies mainly focused on the formation and evolution of reservoir. From birth to polyethylene as the main line, established the accumulation pattern of maturation. But as for the oil and gas reservoirs in terms of volcanic rock, The most important characteristics such as petrology, reservoir space, reservoir physical have not in-depth study. So the development of this area has been the lack of understanding of volcano rock reservoir characteristics, and inefficient development state for a long time. Therefore, reservoir evaluation on volcano rock reservoir, the vital significance to improve mining efficiency.Volcanic geological characteristics of oil and gas reservoirs, the technical route of this topic is:the guidance of the theory of reservoir sedimentology, geophysics, rock mineralogy, structural geology, rock physics and other disciplines, as a means of computer technology and mathematical geology, outcrops, of drilling coring and core analysis, three-dimensional seismic, logging measurement, testing and production dynamics underlying volcanic rock and reservoir division and contrast, phase distribution characteristics of volcanic reservoir rocks,fracture identification and evaluation, focusing on the characteristics of volcanic reservoirs in the study area.According to a large number of core data, thin section analysis results, and scanning electron microscopy observations, according to the the Volcanic Rocks classification standard, the volcanic rocks of the the Minqiao field naming division. Departure from the structure and the structure of the rock, and based on the causes of different volcanic rock types and characteristics of meticulous research, summed up the rock types and characteristics of the area. Through a large number of thin section analysis results, X-diffraction analysis results, summarizes the main characteristics of the rock-forming minerals and clay minerals, especially for the basalt clay mineral assemblages and evolution of features and rock flow unit clay mineral assemblages and evolution characteristics careful study. Genetic classification of the system of the area’s volcanic reservoir reservoir space, and then analyzes the relationship between the reservoir space and lithology, volcanic reservoir space holes seam classification of causes and combined mode, holes seammorphology and distribution, rilling characteristics and oil characteristics were carefully studied. According to the hole, the hole seam reservoir and flow capacity seam holes for classification, and thus the characteristics of macro pores, cracks Features System classification and evaluation of macro-holes, holes and fractures the degree of development on this basis.Through research, to achieve the following results and recognition.1.The volcanic lava, volcanic rock types in this area are two main types of sedimentary rocks, the former accounting for about91%, the latter accounting for only9%. The basalt lava mainly for the class, including vesicular basalt, the amygdala basalt, dense basalts; Volcanic sedimentary rocks include pyroclastic rock, breccia fragments, debris breccia and tectonic breccia.2.Volcanic reservoirs in this area is divided into two macro-the holes sewn and base block system. The macro holes sewn with varying degrees and differences in the nature of the blocks,lead to a complex combination of macro-the holes sewn and base block microporosity, various types of reservoir space structure.3. Through the observation that there are different types of volcanic rock reservoir and the secondary reservoir space. Primary porosity is developed, but in the isolated state, there are be filled; Subsequent weathering and leaching and tectonism secondary porosity greatly improve the performance of the reservoir, Especially the distribution of the structural joints will be isolated primary pore series into an organic whole, plays the role of a bridge.4. Properties of basalt are closely related to rock types, The whole reservoir are mainly in low porosity, low permeability, there are two kinds of porosity and permeability too. The same rocks occurred secondary role, properties are significantly improved, General almond-vesicular basalt alteration, autoclastic breccia, lithic breccia have a good reservoir property. Under the influence of ancient topography of the former, the latter near the crater region thickness increased.5. Research shows that, cave filling mode has nothing to do with the oiliness, but between filling mineral color, mineral type and oil-bearing corresponding relation exists, and subject to rock flow unit facies and reservoir lithofacies structure types. Hole, hole, slot combination oily to oily water facies in rock flow unit, subordinate to the oil content of oil lithofacies structure types. Holes, holes, seams are not isolated output, but a combination of state output different forms in the different area, the combined increase in hole, hole, crack oil possibility at the same time, also increased the space and channel of oil and gas migration, diffusion, influence the redistribution of oil and gas.6. The matrix permeability volcanic reservoirs in this area is quite low, generally <1×10-3um2. The variation range of permeability is very big, general from several hundred to several thousand×10-3μm2. In the beginning of production, exchange capacity of matrix and fracture is weak, most of the water cannot be exchanged with the oil in the rock matrix, Mainly the oil flow in the fracture system, the base block system without oi due to low permeability. However, the block of high porosity is the main storage space, so the remaining oil mainly in the pores in the matrix. Together with the reservoir of crude oil viscosity is high, further exacerbating the edge and bottom water along the fracture water breakthrough, resulting in production wells near the crack flooded, therefore, the next step tapping should focus on improving the permeability of the matrix rock.