石油实验地质

COMPOSITION OF LIGHT HYDROCARBON PYROLYSATES AND ITS GEOCHEMICAL SIGNIFICANCE

Li Zhi, Mao Hongyi, Zhu Meiqian

1991, 13(1): 1-21. doi: 10.11781/sysydz199101001

Abstract(665) PDF-CN(282)

Abstract:
Under anoxytropic conditions, source rock samples were heated tosim-ulate their thermal evolution. The light hydrocarbon compounds (C₅-C₁₀) extracted from the pyrolysis products using low boiling point solvent are defined as light hydrocarbon pyrolysates.Gas chromatography shows that there are more than 100 compounds in light hydrocarbon pyrolysates. With the view of chemical thermodynamics, the generation, disappearance and intertransformation of light hydrocarbons are closely related to the source materials, the conditions and thermal environments of organic matter. By the determinations on source rock samples with five organic types, we draw some conclusions that the compositions of light hydrocarbon pyrolysates will vary with the sedimentary enviroments of mudstone, organic types and the degree of thermal evolution. Several trial parameters are also proposed in the paper.

CHARACTERISTICS OF PETROLOGICAL ASSEMBLAGE IN THE DANFENG GROUP AND ITS TECTONIC SIGNIFICANCE

Yin Yong, Gao Changlin

1991, 13(1): 22-32. doi: 10.11781/sysydz199101022

Abstract(867) PDF-CN(363)

Abstract:
On the basis of the characteristics of petrological assemblage and pe-trogeochemistry, the tectonic environment of volcanic recks in the Danfeng Group, east Qinling is studied. The Danfeng Group consists of volcanic lavas, pyroclastic rocks and metamorphic sandstones. Volcanic lava dominated by basalt and andesite is composed of basalt-andesite-dacite-rhyolite assemblage, which is classified as calc-alkalic volcanic rock series according to Peacok index, and has a hightotal amount of rare earth elements enriched in light rare earth. The loss of Ce is obvious.This assemblage should belong to the volcanic rocks of island arc type. It is distributed in an envircnment of volcanic island-arc tectonism over the area of the Danfeng Group which is the source area of immuture apogrites in the Liuling Group.

PROBE INTO A KIND OF HYDROCARBON POOLS UNCONVENTIONALLY TRAPPED IN DEEP DEPRESSION OF SEDIMENTARY BASIN

Gao Jianmin

1991, 13(1): 33-40. doi: 10.11781/sysydz199101033

Abstract(906) PDF-CN(337)

Abstract:
The author thinks that there exists a kind of hydrocarbon pools unconventionally trapped in the deep depression of a sedimentary basin different from any conventional structural traps. Generally, good source rocks are developed in the deep depression of a sedimentary basin, while reservoirs are concentrated in the front of various sand bodies. Because of their low porosity and poor permeability, the sand bodies have quite high expulsive pressure. Large quantity of hydrocarbons entered reservoirs after primary migration when the deeply depressed part in the sedimentary basin had reached the mature threshold, which would expel the original pore water in the reservoirs upward until hydrocarbon pools formed. Because there is no water in the lower part of the pools, or if there is, it would not connect with that on the top, the pools will not be affected by buoyant force. At this time, the sum of static pressure of formation water and expulsive pressure of porosity cappillary in the reservoir itself is the major confining pressure, the trapping results are comparable with those from conventional capping traps.

DIAGENESIS OF UPPER PALAEOZOIC SANDSTONE IN THE WULANGAR REGION, INNER MONGOLIA

Lu Huanyong, Chen Jingwei, Di Shixiang, Wang Xiren

1991, 13(1): 41-52. doi: 10.11781/sysydz199101041

Abstract(757) PDF-CN(327)

Abstract:
The Upper Paleozoic in the Wulangar Region, Inner Mongolia is more than 400m thick. Most of sandstones belongs to the reservoir of compact type with low porosity and poor permeability. This paper deals with the diagenesis of sandstones and their influence on porosity and permeability. Four stages of diagenesis are generalized as follows: 1. Mechanical compaction of grains and early cementation; 2. Cementation and metasomasis by carbonate minerals. 3. Corrosion of Minerals (mostly carbonate cement or feldspars). 4. Formation of late authigenic clay minerals and recrystallization of early clay minerals. The analysis of diagenetic evolution indicate that intense mechanical compaction led to the decrease in the pores in the sandstones, especially cementation of the carbonate minerals obviously reduced the porosity and permeability. Hcwever, late corrosion of the cements and partial grains is a favourable factor, which improved the reservoir property of several segments.

SIMPLIFIED METHOD TO ESTIMATE DENUDATION AMOUNT IN PALAEOSTRATA WITH THE EVOLUTIONARY TREND OF POROSITY IN SANDSTONE

Ma Lixing, Wan Jingping

1991, 13(1): 53-56. doi: 10.11781/sysydz199101053

Abstract(854) PDF-CN(384)

Abstract:
The expcnential decrease trend of porosity with deepness in sandstone of subsurface hydrccarbon-bearing reservoir may be regarded as a function of the burial history of the strata. The amount of denudation in palaeos-trata can be estimated by the evolutionary trend mentioned above.

ANALYSING METHOD OF PYROLYSIS CHROMATOGRAPHY ON ASPHALTINE

Zhou Mingyi, Cao Yulan

1991, 13(1): 57-64. doi: 10.11781/sysydz199101057

Abstract(542) PDF-CN(369)

Abstract:
Organic matter(kerogen,asphaltine)is quickly heated in inert gas flow to a higher temperature (550-660℃). The pyrolysis products (gasifiable) are separated into monosomy compounds through capillary column of gas chromatography. Thereafter, dependingon the distributions and relative quantities of different compounds on the chromatogram, the structural characteristics of various original polymers can be infered and compared, so as to carry out geochemical study.

SIMULATION EXPERIMENTS ON BIOGAS GENERATION AND ESTIMATION OF GENERATION AMOUNT OF BIOGAS IN STRATA

Lu Weiwen, Hai Xiuzhen

1991, 13(1): 65-76. doi: 10.11781/sysydz199101065

Abstract(627) PDF-CN(423)

Abstract:
Recent plant (dry grass) and mud, Quaternary mudstone and turf, Pre-Quaternary brown coal are used to study the various aspects of gas generation by anaerobic microorganism decomposition, including the asumption, method, device and results of composition analysis. It is considered that the gas generation of organism is the result of continuous unbalance over a long period of time. The quantitative relation between the amount of generated gas and buried age of organic matter is also discussed, which provides evidence for the estimation of the amount of generated biogas. Based on the fast lightening of methane δ¹³C in the gas sample series, the contradiction between the lighter isotopic index and the heavier surface methane δ¹³C in biogas exploration can be solved.

IMPROVEMENT ON DETERMINATION OF PORPHYRIN FROM CRUDE OIL AND SOURCE ROCKS

Ruan Jinshui, Fan Zhaoan, Xiao Guiying

1991, 13(1): 77-81. doi: 10.11781/sysydz199101077

Abstract(497) PDF-CN(286)

Abstract:
In order to raise the separating efficiency and determination precision, as well as to simplify the analysing process, the authors made some improvements on the procedure of porphyrin analysis and determination, based on thecharact eristics of porphryin melocular and saturated hydrocarbons. The method is economical of manpower and material resources.

AN EXPERT SYSTEM TO PREDICT OIL AND GAS TRAPS

Chen Jinhua, Xiong Weigang, Zhang Shuangxi

1991, 13(1): 82-92. doi: 10.11781/sysydz199101082

Abstract(656) PDF-CN(289)

Abstract:
The expert system enables the optimization and full application of multiple-informations such as thecretic and practical knowledges, geophysical, geolcgical and geochemical informations. The model of knowledge acquirement in the system is set up with the resolvent and generalization used during the process of practical prediction. Five parts are involed in the knowledge expression model, i.e: graded knowledge expression, data processing, method expression and descriptions of controlling knowledge and uncertainty. The expert system based on the model inclueds knowledge base, data base, reasoning and learning parts,which is capable of theoretic and practical computations. It is applied to check computations of Chacshe structure in Qingtong depression, north Jiangsu.

ANALYSIS OF SEVERAL ALGORITHMS IN ZONATION USING SOFTWARE PACKAGE OF ORDERED CLUSTER

Xing Xue, Tong Guobang, Lin Jinxuan

1991, 13(1): 93-98. doi: 10.11781/sysydz199101093

Abstract(773) PDF-CN(320)

Abstract:
The three algorithms (two algorithms contain two measuring indexes) in the zcnation using software package of ordered clustering are introduced and analysed. The method is tested, taking the analysis of sporc-pcllen from Tianjin hole 124 as an example.

AIRBORNE MUTIPLE SPECTRA SCANNING IMAGES APPLIED IN LAND INVESTIGATION IN DONAUESCHINGEN AREA, WEST GERMANY

Tan Haiqiao

1991, 13(1): 99-106. doi: 10.11781/sysydz199101099

Abstract(648) PDF-CN(242)

Abstract:
The feasibility and limitations of air-borne mutiple spectra scanning images applied in land-use investigation are approached. The establishment of classification system for land-use,the correlation of images of different bands to different targets, the process of monitoring classification, statis tical evaluation of classifying presision for the study area are discussed respectively. According to the pratical needs of land-use classification in the study area, two bands are chosen from original 11-band images, and applied in automatic classification with the desired results come about. The results show that airborne multiple spectra scanning images have both advantages of aerophotos and salellite images, which will give higher resolution as well as make digit image processing with the aid of computer. It can be also regarded as an effective measure of remote sensing in land-use investigation. But due to the unstability of image forming platform, the reliability of image formation and results of investigation are often affected, which limited its wide use in land-use investigation.

1991 Vol. 13, No. 1

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