According to the principle of thermodynamics, thermodynamic phase diagrams are calculated and drawn, the possibility, direction and physicochemical conditions of the two chemical reaction processes of TSR reaction and dissolution of carbonate rocks by H₂S are determined, and the direct reduction of CaSO₄ (or SO₄²⁻) to H₂S at different temperatures is obtained. It shows that when CaCO₃ is at the boundary between precipitation and dissolution in geological system, a small amount of acidic fluid will make the precipitated CaCO₃ dissolved, and when the concentration of Ca²⁺ and CO₃²⁻ increases, a new equilibrium of precipitation and dissolution will be achieved. When the depth of dissolution of CaCO₃ is about 1000 m, H₂S achieves the best effect. Only long-term and repeated TSR reactions can produce sufficient acidic fluid (H₂S), which is the necessary condition for dissolution modification of carbonate reservoirs to achieve obvious results.

Through systematic organic geochemistry analysis, the main hydrocarbon source rocks of terrestrial formation in northeastern Sichuan are systematically evaluated, sources of oil are determined by carefully comparison of geochemical characteristics between source rocks and oil, and accumulation characteristics are identified. Analysis results indicate that terrestrial formations, such as Group Xujiahe, Ziliujing and Qianfoya, develop vast effective, even rich source rocks with high organic matter abundance, and the average TOC values of different districts and groups range from 0.41% to 2.99%. Type Ⅱ and type Ⅲ are widely distributed, and source rocks are high mature to over mature with Ro ranging from 1.3% to 2.0%. Generally, hydrocarbon source rock of terrestrial formation in northeastern Sichuan has high hydrocarbon generation potential, which could be favorable main source rocks of middle and lower Jurassic terrestrial unconventional oil and gas in research area. Comparison of geochemical characteristics between source rocks and oil and accumulation characteristics analysis demonstrate that middle and lower Jurassic terrestrial unconventi onal oil and gas are generated from terrestrial sources with few marine sources, which proves that oil and gas migration difficulty caused by the extremely tight terrestrial reservoirs leads to in-source or near-source accumulation. Oil and gas in group Qianfoya are from Ziliujing source rocks and that in group Ziliujing are from both Ziliujing and Xujiahe source rocks in Yuanba-langzhong. Oil and gas are all from Xujiahe source rocks in Xuanhan-daxian. Lower Jurassic shale can fill the requirements for shale gas, while middle and lower Jurassic tight sandstone can fill the requirements for tight sandstone oil.

Characteristic and origin of “spherical particle” are studied based on contrast analysis of petrography and carbon and oxygen isotope of “spherical particles” in basite drawn from well and typical amygdules in basalt sampled in the field. Results show that “spherical particles” and amygdules are significantly different in microscopic and carbon and oxygen isotopic characteristics although they are similar in macroscopic feature. “Spherical particles” are characterized by non-oscillatory zoning, obvious recrystallization in the rim, and different carbon and oxygen isotopic values in different “spherical particle” of the same sample. Amygdules are characterized by oscillatory zoning, big crystalline particle, and similar carbon and oxygen isotopic values in different amygdule of the same sample. It can be concluded that “spherical particle” stems from magma capturing pieces of sedimentary carbonate, rather than secondary minerals filling vent. As a result, the basite drilled from the Cambrian and Carboniferous strata is intrusive rock, and volcanism may not occur in related strata.

Petrology, mineralogy and geochemistry method such as thin section, cast thin section, scanning electron microscope observation, cathodoluminescence, energy spectrum and major element experiment were used to analyze the genesis of Permian volcanic reservoir in Yuenan Region, Tarim Basin. It is found that Permian volcanic reservoir, dominated by secondary pore space can be regarded as favorable reservoir because the porosity of the primary pore space can reach 14% and 13.1×10^?3 μm² respectively. Genesis of the secondary pore and cracks is the weathering, whose intensity increases with the depth decreasing. The porosity and the permeability is positively correlated to weathering. The thickness of weathering effect can reach at least 220 m. The weathering dissolution and leaching process take priority of weak plane, such as large number of primary pores, cooling contracted crack, cryptoexplosion fracture which generate in the cooling of volcanic and cleavage crack, twin stitch of primary mineral. Weathering sequence of feldspar phenocryst and matrix is found in rhyolite, weathering products are mainly illite, with small amounts of montmorillonite, and the entire sequence of clay minerals growth process is preserved. Weathering can modify substantially pore structure on the basis of primary porosity, and improve the porosity and permeability greatly, which is the main controlling factor of Permian volcanic reservoir of Yuenan Region, Tarim Basin.

Seismological interpretation revealed that basalts are overlain by rhyolite in the Halahatang area, Northern Tarim, Northwest China. The overlying rhyolite is dated by SIMS zircon U-Pb method, yielding a precise concordia age of 287.3 ±2.0 Ma, which limits the latest eruption age of the underlying basalt and reveals that the eruption age of the main pulse of the Tarim flood basalt is before 287 Ma, not ~275 Ma.

Seismic reflection characteristics of Permian volcanic rocks in the Tarim Basin were summarized and illustrated by using large number of exploration data from Tarim oil field, and then logging-seismic integrated recognition model was established. Meticulous characterization of Permian volcanic rocks?spatial distribution was achieved through comprehensive study of outcrop, drilling, logging and 2D seismic data. The Remnants of the Permian basalt in the Tarim basin cover an area of about 2. 46 ×10⁵ km², and the remnants of the Permian rhyolite cover an area of about 4.04×10⁴ km². As Permian stratas are missed in most area of north and east Tarim Basin, original Pemian volcanic eruption area may be much larger than residual area. This study lays foundation for further understanding of Permian volcanism in Tarim basin.

Nearly all the literatures about Palaeoproterozoic positive δ¹³C excursion in the carbonate sequences on the earth during 2.20-2.06 Ga, which is called as Lomagundi Event, are reviewed. Hypotheses including biology evolvement, the rise of atmospheric oxygen, the Palaeoproterozoic ice age, super-continent break-up and evaporation, are proposed to interpret the Lomagundi Event in those literatures. Based on statistics of relations between the positive δ¹³C excursion and each geological phenomenon according to the data from those literatures , the authors conclude that those hypotheses are all reasonable, but different importance. The carbon isotope fractionation theory shows that the developing magnitude of buried organic matter will increase carbon isotope ratio of carbonate carbon reservoir. Biology evolvement can raise oxygen amount in atmosphere. Warm environment after the Palaeoproterozoic ice age and Kenorland super-continent break-up can both offer good conditions for biology developing. Thus, these evolutions can increase amount of buried organic matter and then cause positive carbon isotope excursion in carbonate carbon reservoir. Meanwhile, evaporation distributed over the world during the time may also cause positive δ¹³C excursion in local restricted environment, so the authors should research depositional environment case by case when considering the positive δ¹³C excursion. The authors analyzed original data of Mn/Sr, δ¹³Cand δ¹⁸O from North America and Fennoscandian Shield to judge effect of weathering, diagenesis and metamorphismon carbon isotope data of the samples. The result shows δ¹³C and δ¹⁸O data of samples are reduced by weathering in some case.

The data of n-alkane of lacustrine sediments in west of Sichuan prove the connection between the value of δ(¹³C) of C17-C22 n-alkane and the altitudes. The δ(¹³C) values of C17-C22 n-alkane increase along with the elevated altitude. According to the δ(¹³C) data, The relationship results from three key associated factors: partial pressure mospheric carbon dioxide p(CO₂), temperature and precipitation. The results also support the opinion that the δ(¹³C) value of C26-C33 n-alkane decrease along with the elevated altitude. Thus, comparing two aspects (n-alkane of longer and shorter train) mentioned above, it could be better to estimate the change of the altitude and the environment during the past time.

Hydrocarbon migration is a very important research aspect in petroleum geology and exploration. It is also a complicated problem influenced by lots of controlling factors and involves many scientific and engineering aspects. Development of hydrocarbon migration researches in China is summarized. A variety of methods such as geological, geochemical, physical, geophysical, experimental modeling, and numerical modeling areused to study the mechanisms of hydrocarbon migration in recent years. Particularly, numerical modeling has drawn extensive attention in researches. Some scholars consider other new factors which effect hydrocarbon migration, e.g. ground stress, channel and block on the pathway, phase-state of fluids, etc. Three-dimensional numerical models are developed by many researchers, including some new modeling methods such as artificial neural net work simulation, alternating-direction implicit interactive scheme, and second order splitting-up implicit interactive scheme. The authors also point out the development trends in the future.

Hydrocarbon migration is a very important research aspect in petroleum geology and exploration. It is also a complicated problem influenced by lots of controlling factors and involves many scientific and engineering aspects. Development of hydrocarbon migration researches in China is summarized. A variety of methods such as geological, geochemical, physical, geophysical, experimental modeling, and numerical modeling areused to study the mechanisms of hydrocarbon migration in recent years. Particularly, numerical modeling has drawn extensive attention in researches. Some scholars consider other new factors which effect hydrocarbon migration, e.g. ground stress, channel and block on the pathway, phase-state of fluids, etc. Three-dimensional numerical models are developed by many researchers, including some new modeling methods such as artificial neural net work simulation, alternating-direction implicit interactive scheme, and second order splitting-up implicit interactive scheme. The authors also point out the development trends in the future.

With numerous observations of thin sections and casting sections of the rocks, and the application of various analytical techniques including X ray diffraction, the main diagenesis, pore evolution and the characteristics of diagenetic sequence in the Jurassic reservoir sandstone in Tula Basin, southern Altyn Tagh, Xinjiang, are carefully studied. It is concluded that the pore evolution is both controlled by depositional conditions and affected by burial diagenesis. Compaction is the major factors turning the pore texture of the sandstone worse. Cementation of the carbonate is very weak in the early diagenesis period, and this make the dissolution weak too. The strong compaction and weak cementation are of importance that form the result of the worse reservoir space. Modified by tectonics, the clastic rocks became the better reservoir of oil and gas with its high porosity and permeability in the Tula Basin.