| Liaohe depression is a major production area of liaohe oil field, it has the same construction with the southern Bohai bay in Jiyang and Huanghua depression which are belong to the Bohai bay basin. It consists of two parts, onshore and offshore. The discovery of oil reservoir of metamorphic rock in Archean Eonothem in liaohe depression is the breakthrough of bedrock exploration. It changes the fact that only metamorphic rock can formate hydrocarbon accumulation in the past, enrich the theory of hydrocarbon accumulation in Liaohe depression, the Archean Eonothem rock reservoir is the important exploration targets in the future. After years of exploration, there are still many key problems unsolved, the understood of Archean Eonothem metamorphic rock reservoir accumulation characteristics is more and more important.This work mainly studies the characteristics of archaean group metamorphic buried hill reservoir in the Liaohe depression. This is mainly through the analysis of core and logging curve, the buried hill reservoir geological characteristics and identification of reservoir lithology、 fracture, etc. It established a set of metamorphic buried hill reservoir evaluation methods. Then analysised the buried hill reservoir characteristics from two aspects of reservoir geological characteristics and logging response characteristics. At the same time, by using this method Liaohe depression archaean group metamorphic buried hill reservoir of reservoiring condition and oil reservoir distribution laws can be analyzed. Through the study, it has made the main achievements and cognition.(1) Through the comprehensive analysis of archaean group metamorphic buried hill reservoir geologic characteristic in Liaohe depression, reservoir rock lithology is given priority to with dark clouds plagioclase gneiss, also including the acidic magmatic rock reservoir, mixed granite reservoir. The oldest rock types in Liaohe depression are basal type formed by regional metamorphism regional metamorphic rocks. Through intense transformation and migmatization, alteration and retrograde metamorphism, only part of the rocks have been leaved. The rocks mainly include grain of rocks, amphibolite rocks, gneissic rocks.(2) Different lithology rocks response different mechanisms. High density curve amplitude of diabase show high range block and hydrogen index curve is massive, uniform single-layer values. Natural gamma ray value is low and low potassium to pledge. Significantly the density value of diorite lower than diabase density value, and hydrogen index slightly higher than diabase, low potassium, uranium and thorium, natural gamma ray significantly higher than diabase, Pe lower than diabase, the time curve is bigger than diabase. Alkaline in the dike rock of syenite, monzonite mineral combination, some to make the transition to granite and pegmatite rock mass, has rich alkaline for its characteristics of rock mass is a few meters to tens of meters thick. Rich potassium feldspar as its characteristics, the highest k value, the massive density curve, hydrogen index tends to 0, potassium, uranium and thorium logging curve shows high range block, especially larger amplitude of potassium, thorium. Natural gamma ray (SGR) curve shows high amplitude, block, and Pe value is low. Quartz vein is the mixed stage or later, most along the fault zone and fracture zone site penetration and hydrogen index tends to 0, natural gamma (SGR) much smaller than alkaline rock body, Pe curve in low, caliper rules, expanding phenomenon is not obvious. Low density of andesite and unstable, is in the archean strata rock density minimum a rock.(3) By both core and cuttings observation and identification of structure analysis, the study area is in good condition for the development of reservoir. Buried hill in Liaohe depression archaean group is the combination of metamorphic rocks and magmatic rocks, reservoir space development, in metamorphic recrystallization, denudation leaching, weathering erosion, etc. It has experienced a long geological time. Reservoir pore has the characteristics of double medium. Through a lot of core observation, casting thin sections identification and characteristics of capillary pressure curve data, it has been found that structural fracture and broken intergranular pore is the main reservoir space types, and the least development is the root cause of the corrosion holes, seams and the porosity of the crystal formation. Metamorphic rock reservoir fracture reservoir heterogeneity. Among them, the light color reservoir rock crack development, is the ideal of metamorphic rock reservoir. In the metamorphic reservoir, a variety of causes of pore combination is the main reservoir space for oil and gas, fracture aperture for the oil and gas important reservoir space. Under the gravity effect on the tensile fracture structural activity was significant. It is carried on by the fracture of vertical and horizontal cutting and sag in north east direction distribution as a result, then it makes structural types, causes and the spatial distribution has certain regularity. Cover structures are controlled by basement and good compliance.(4) Through the acoustoelectric imaging logging data, it can identify fracture and reservoir. The characteristics of archaean group metamorphic buried hill reservoir in liaohe basin are the material basis of log interpretation method research. Proterozoic lithology is given priority to carbonate rock, but Archaean lithology are regional metamorphic rocks. Buried hill formation most has the characteristics of high resistivity, various lithology resistivity. Therefore, lithology identifications are mainly by natural gamma ray, density and compensated neutron and reflective logging series such as jet lag. Applicable condition of deep and shallow dual lateral logging is to use water-based mud. It can reflect the open fracture. Under the condition of the same fracture porosity, fracture angle is larger, the resistivity is higher. Under the same fracture angle, the fracture porosity is bigger, the dual lateral resistivity value is smaller. Fracture porosity and fracture angle phase at the same time, the greater the basement rock resistivity reservoir, the higher the double side. The bigger the mud resistivity is, the bigger dual laterolog numerical is. Acoustic time is usually used in pure, caliper logging lithology with little change. Neutron logging can reflect formation porosity, through the formation of hydrogen index measurement. Density logging can reflect the total porosity of the rock, by measuring the volume density of the rock. Pe log value reflect the formation elements of atomic number. Reservoir space heterogeneity of Xing buried hill is strong, and it is difficult to use quantitative data description, and it has the dual medium of porosity and fracture characteristics through the resistivity, acoustic time, density, neutron logging data and logging, core data, such as reservoir identification.(5) It points out the favorable zones for hydrocarbon accumulation in the study area. In liaohe depression before Mesozoic basement in Liaodong lung and Yanshan fold belt with two big rock block, it is in such a weak tectonic belt, the type, cenozoic evolution into a continental rift basin. Basement structure and lithologic control the concave shape, source sub-sag, cover structure and the formation and distribution of buried hill reservoir. Bedrock lithology structure which control the oil and gas reservoirs including former tertiary, and basement lithology structure control the formation of buried hill reservoirs, and former tertiary basement structure control the tectonic pattern of the sag. Cenozoic tectonic evolution, sedimentary characteristics and reservoir configuration are ways to control the reservoir formation. Xinglong station buried hill zone, large wasteland, Cao buried hill zone are the main buried hill zone. Oil and gas shows commonly and very long interval. The oil and gas showing in the 230 m above in Cao buried hill, it shows in more than 35 m in large wasteland buried hill. Properties of crude oil are mainly high pour-point oil. |
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