Evolutions of Oil Generation and Expulsion of Marine-Terrestrial Transitional Shales: Implications From a Pyrolysis Experiment on Water-Saturated Shale Plunger Samples

Shale reservoirs are characterized by self-generation and self-accumulation, and the oil generation and expulsion evolution model of organic-rich shales is one of important factors that obviously influence the enrichment and accumulation of shale oil and gas resources. At present, however, relevant studies on marine-terrestrial transitional shales are inadequate. In this study, a pyrolysis experiment was performed on water-saturated marine-terrestrial transitional shale plunger samples with type Ⅱb kerogen to simulate the evolutions of oil generation and expulsion. The results indicate that marine-terrestrial transitional shales have wider maturity ranges of oil generation and expulsion than marine and lacustrine shales, and the main stages of oil expulsion are later than those of oil generation, with corresponding Ro values of 0.85%–1.15% and 0.70%–0.95%, respectively. Although the oil generation and expulsion process induced a fractionation in compositions between the expelled and retained oils, both the expelled and retained oils of marine-terrestrial transitional shales are dominated by heavy compositions (resins and asphaltenes), which significantly differs from those of marine and lacustrine shales. The kerogen of marine-terrestrial transitional shales initially depolymerized to transitional asphaltenes, which further cracked into hydrocarbons, and the weak swelling effects of the kerogen promoted oil expulsions. The oil generation and expulsion evolutions of these shales are largely determined by their organic sources of terrigenous higher organisms. This study provides a preliminary theoretical basis to reveal the enrichment mechanism of marine-terrestrial transitional shale oil and gas resources.

Ascertaining Optimum Pyrolysis Conditions for Biochar Production from Maple Sawdust

Sawdust is a bi-product from wood processing industries. In the recent time, pyrolysis of organic waste is an emerging technology where biochar can be produced and used for carbon sequestration. In that respect, the aim of the present work was to ascertaining optimum pyrolysis conditions in producing sawdust biochar (SBC) for the said uses. The raw material was collected from Belad furniture industry because of their specialization in furniture work and large volume availability. The proximate and ultimate analysis of 3.56% moisture, 1.49% ash content, 72.32% carbon and 0.19% surphur confirmed its good candidature for biochar production. The pyrolysis experiment was carried out by using six combination each of temperature (400, 450, 500, 550, 600 and 650°C), nitrogen flow rates (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0L/mins) and residence times (10, 20, 30, 40, 50 and 60mins). Analysis of resulted biochar was done according to IBI standard. Results showed that the three factors decrease the yield of biochar at their increasing values. SBC yield being optimum at temperature of 400°C, 10 min residence time and 1.0L/min nitrogen flow rate.

Inversion Characteristics of Hydrocarbon Gases Carbon Isotopes Varying With Temperature and Implications for Shale Exploration

In order to understand the influence of source rock types and maturity on hydrocarbon gases carbon isotope change more objectively, a closed-system pyrolysis experiment was carried out on six samples from 250 to 550°C. The values of δ13C1, δ13C2, and δ13C3 were ranged from −73.3 to −29.8%, from −36.3 to −9.5%, and from −38.5 to −12.4%, respectively. The range of δ13C1 was the largest, reaching a top value of 43.5%. The results showed that the temperature has an effect on the carbon isotope value of pyrolysis gas. With the increase of the degree of thermal evolution, the carbon isotope value of methane in all samples, except for huangxian gangue, had a change trend from heavy to light firstly, then got heavier. In addition, the carbon isotope values of methane, ethane and propane had the features of δ13C1 < δ13C2 < δ13C3 when the temperatures were under 550°C, which were made up of a series of positive carbon isotopes. However, when the temperature increased above 550°C, there was an inversion of the simulated gas carbon isotope values in Huangxian coal gangue, Minqin oil shale and Huaan carbonaceous shale, i.e., δ13C2 > δ13C3 and δ13C2 > δ13C1. It indicates that the secondary cracking has occurred at high maturity or over maturity stage.

Characterization of bio-Oil produced by Microwave Pyrolysis of Karanja Seed.

Pyrolysis is one technique that produces three products in a short span of time in which both conventional and non-conventional method of heating (microwave irradiation) can be done. Karanja seed powder is taken as the feedstock in this microwave pyrolysis experiment. Proximate and Elemental analysis of karanja seed powder resulting volatile content of about 84.89% and moisture content of 10.11% whereas the Carbon of 52.08%, Hydrogen of 8.26%, Sulphur of 0.21%, Nitrogen of 4.02% and oxygen of 35.04%. Microwave pyrolysis for karanja seed was conducted for two power inputs of 700W and 800W in which bio-oil yield is high of 47% at 700W and noncondensable gases of 39% at 800W. The FT-IR results resembles the presence of aliphatic compounds. The TGA analysis was also taken for the produced bio-oil. The rheological study was made to determine the dynamic viscosity of the produced bio-oil at 50 rpm in room temperature which is averaged to 52 cP. The flash point of 90°C and fire point of 94°C was also determined for the produced bio-oil