The process of organic matter transformation into oil and gas is also a balance process of hydrocarbon transformation. This
article probes to distinguish the oil expulsion history from gas expulsion history based on the hydrocarbon generation, hydrocarbon
residual, and hydrocarbon expulsion processes of the source rocks. In this method, the first step is to study the hydrocarbon
expulsion rate by means of hydrocarbon generation potential method; the second step is to study the oil generation rate by
means of the heating–pressuring experiment method; the third step is to study the oil residual rate by means of the mathematical
method. The difference between the values of oil generation rate and oil residual rate is defined as the oil expulsion rate,
while that between the values of hydrocarbon expulsion rate and the gas expulsion rate is defined as the gas expulsion rate.
Then, combined with the geological parameters of source rocks, the oil and gas expulsion history can be obtained. This study
on Es1 Source rocks, Nanpu Sag, Bohai Bay Basin, China shows that the primary expulsion period of Es1 source rocks is Guantao–Minghuazhen period. 相似文献
This paper utilizes multi-methods,such as core observation,slice identification,isotope analysis,trace element analysis,fluid inclusion technique and so on,to study the causes of the dolomite in the Nanpu Sag and the origins of the dolomite reservoir.The study results show that the forming environment of dolomite in the Nanpu Sag is a fresh-water lake environment,and the dolomite is the product of dolomitization which is caused by volcanic thermal fluids in the Early Dongying period.With the development of intergranular pores in the dolomitization process,a lot of dissolved pores/vugs and fractures were formed by denudation in the later periods because of the influence of thermal fluids including the associated fluids of volcanic activities and the expelled hydrocarbon fluids of the source rocks.On the whole,these secondary dissolution spaces greatly enhance the reservoir ability of the dolomite,and there are enough reservoir spaces in the dolomite in the Nanpu Sag. 相似文献
The Chang-7 shale of the Upper Triassic Yanchang Formation was deposited in a deep-lacustrine environment in the southwest part of the Ordos Basin. It is characterized by a strong lithological heterogeneity, consisting primarily of pure shale and sandy laminated shale. This study explored the impact of sandy laminae in the thick pure shale on hydrocarbon generation, retention, and expulsion, which were rarely considered in previous studies. Based on core observation, thin section, and geochemical analysis, the hydrocarbon generation, retention, and expulsion characteristics were obtained for both pure shale and sandy laminated shale. In general, the Chang-7 shale stays at low mature to mature thermal evolution stage and has good hydrocarbon generation potential. It contains mainly Type II kerogen with an average total organic carbon (TOC) of 2.9% and average (S1?+?S2) of 8.2 mg/g. Compared with sandy laminated shale, pure shale contains more retained liquid hydrocarbon and has a higher amount of asphaltene and nitrogen–sulfur–oxygen (NSO) polarized components, indicating a relatively weak hydrocarbon expulsion process. The middle part of a thick pure shale retains more liquid hydrocarbon and has higher percentages of asphaltene and NSO polarized components than that of the top and basal part of the shale where sandy laminae occur. The difference in hydrocarbon retention capacity is interpreted to have been primarily caused by the comparatively higher reservoir quality of the sandy laminated shale, having higher amount of brittle minerals and larger pores than the pure shale. Polymer dissolution and nanopore adsorption are also key factors in hydrocarbon retention and component partition. Based on this study, we suggest that sandy laminated shale, which receives most of the hydrocarbon from adjacent pure shale, should be the current favorable shale oil exploration targets. Even though pure shale contains high hydrocarbon potential, its development is still pending improved technologies, which could solve the challenges caused by complicated geological conditions.
This paper provides a new method to estimate recovery factors of oil resources. The China National Petroleum Assessment (2003–2007)
(CNPA 2007) evaluates in-place oil resources and applies the recovery factor (RF) to estimate recoverable oil resources. The
RF of oil resources plays an important role in the CNPA 2007. Based on the geological features, 24 types of oil assessment
units are defined, such as the Mesozoic rift unit, the Mesozoic and Cenozoic foreland unit, etc. Through the recovery factor
statistics of oil reserves (discovered) in different accumulations, as well as the potential analyses of enhanced petroleum
recovery, appropriate RF valuing standards of oil resources (discovered and undiscovered) in different assessment units are
developed. Calculation methods of oil resource RFs are established, including the appraisal standards, scoring, and calculation
steps of oil resource RFs. Through the case studies, the valuing and appraisal standards of oil resource RFs are verified.
Robust appraisal standards allow the RF method to be a valuable tool to effective assessment of China’s recoverable oil resources. 相似文献