Properties,combustion behavior,and kinetic triplets of coke produced by low-temperature oxidation and pyrolysis:Implications for heavy oil in-situ combustion

This work aimed at investigating the crucial factor in building and maintaining the combustion front during in-situ combustion(ISC),oxidized coke and pyrolyzed coke.The surface morphologies,elemental contents,and non-isothermal mass losses of the oxidized and pyrolyzed cokes were thoroughly examined.The results indicated that the oxidized coke could be combusted at a lower temperature compared to the pyrolyzed coke due primarily to their differences in the molecular polarity and microstructure.Kinetic triplets of coke combustion were determined using iso-conversional models and one advanced integral master plots method.The activation energy values of the oxidized and pyrolyzed cokes varied in the range of 130-153 k J/mol and 95-120 kJ/mol,respectively.The most appropriate reaction model of combustion of the oxidized and pyrolyzed cokes followed three-dimensional diffusion model(D_(3)) and random nucleation and subsequent growth model(F_(1)),respectively.These observations assisted in building the numerical model of these two types of cokes to simulate the ISC process.

Shale Oil Occurrence and Reservoir Characteristics of the Qijia-Gulong Depression in Songliao Basin

1 Introduction The technology breakthrough in the exploration of shale gas and tight oil has greatly extended the global fossil fuel resources （Jia et al., 2012; Zou et al., 2012; Qiu et al., 2013）. Although shale oil has been the global hot topic in the study of unconventional resources, there are varied definitions with respect to shale oil by different researchers.

An Investigation into the Effects of Oil-Well Cement Expansion Agent on the Integrity of Cement Sheath

Generally,the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation.However,this approach can detrimentally affect the sealing ability of cement sheath if the expansion agent is used in an unreasonable way.For these reasons,in the present work,numerical simulations have been conducted to analyze the effect of elasticity modulus of cement sheath,the elasticity modulus of formation,the expansion rate of cement,the geo-stress on the micro-annulus caused by cement expansion,and the cement sheath expansion on the integrity of cement sheath and formation.The micro-annulus between the casing and the cement sheath has been found to decrease according to the ratio between the elasticity modulus of formation and the elasticity modulus of cement sheath.A positive correlation has been observed between the micro-annulus and the cement expansion ratio.The microannulus decreases as the geo-stress increases,but the effect of the geo-stress on the micro-annulus is much smaller.In conclusion,the expansion agent is suitable for the formation in which the elasticity modulus is higher than the cement sheath.

A New Method for Converting T_(2) Spectrum into Pore Radius

In this paper,a new method for converting the T_(2)(relaxation time) of NMR(nuclear magnetic resonance) into the pore radius is proposed.Combined with NMR and centrifugation experiments,the relationship between pore radius and T_(2) of the sample was established.The results show that the new method is more reasonable than the traditional method.When the sample was denser and the mercury saturation was lower,the pore distribution curve was obtained by traditional method had a worse agreement with mercury injection experiment,while pore distribution curve of the new method had a better agreement with the mercury injection curve,which reflected the greater advantage of the new method as the reservoir becomes denser.The new method can obtain all the pore information in the sample.The results show that the pores in tight sandstone are mainly consisted with mesopore and macropore,and the connectivity of macropore is better than that of mesopore.The new method can effectively characterize the full pore distribution and the seepage characteristics in different pores interval of tight reservoirs,which had a great significance to evaluate the recoverable resources of tight reservoir.