Theoretical Progress and Key Technologies of Onshore Ultra-Deep Oil/Gas Exploration

Oil/gas exploration around the world has extended into deep and ultra-deep strata because it is increasingly difficult to find new large-scale oil/gas reservoirs in shallow–middle buried strata. In recent years, China has made remarkable achievements in oil/gas exploration in ultra-deep areas including carbonate and clastic reservoirs. Some (ultra) large-scale oil and gas fields have been discovered. The oil/gas accumulation mechanisms and key technologies of oil/gas reservoir exploration and development are summarized in this study in order to share China’s experiences. Ultra-deep oil/gas originates from numerous sources of hydrocarbons and multiphase charging. Liquid hydrocarbons can form in ultradeep layers due to low geothermal gradients or overpressures, and the natural gas composition in ultra-deep areas is complicated by the reactions between deep hydrocarbons, water, and rock or by the addition of mantle- or crust-sourced gases. These oils/gases are mainly stored in the original highenergy reef/shoal complexes or in sand body sediments. They usually have high original porosity. Secondary pores are often developed by dissolution, dolomitization, and fracturing in the late stage. The early pores have been preserved by retentive diageneses such as the early charging of hydrocarbons. Oil/gas accumulation in ultra-deep areas generally has the characteristics of near-source accumulation and sustained preservation. The effective exploration and development of ultra-deep oil/gas reservoirs depend on the support of key technologies. Use of the latest technologies such as seismic signal acquisition and processing, low porosity and permeability zone prediction, and gas–water identification has enabled the discovery of ultra-deep oil/gas resources. In addition, advanced technologies for drilling, completion, and oil/gas testing have ensured the effective development of these fields.

Side-polished SMS based RI sensor employing macro-bending perfluorinated POF

A refractive index(RI)sensor based on perfluorinated plastic optical fiber(PF-POF)is introduced in this paper.The PF-POF as multi-mode fiber was side-polished(SP)to form a macro-bending single-mode-multimode-single-mode(SMS)structure.Both ends of the sensor were closely connected to single-mode quartz optical fiber(SMF).The spectral char-acteristics of the sensor are measured,analyzed and discussed.The results show that when the length of PF-POF is 8 cm,the macro-bending radius is 3 cm,and the SP-depth is 20μm.The intensity sensitivity reaches−219.504 dBm/RIU in the range of RI=1.330~1.356.A reference is provided for the application of PF-POF in RI sensor in the future.The sensor is featured with low-cost,good flexibility and high efficiency.

Analysis of Soil Remediation Technology for Heavy Metalcontaminated Sites in Electroplating Enterprises

The advantages and disadvantages of chemical leaching,phytoremediation,in-situ/ex-situ solidification and stabilization,cement kiln co-disposal and safe landfill remediation are analyzed.In addition,the application of chemical leaching and in-situ/ex-situ solidification and stabilization technology in the treatment of heavy metal-contaminated soil in electroplating enterprises in China is introduced in detail to provide reference for the remediation of heavy metal-contaminated soil around electroplating enterprises in China.

Carbon isotope reversal of desorbed gas in Longmaxi shale of Jiaoshiba area,Sicuhan Basin

Through analysis of components and carbon isotope compositions of gas desorbed from shale cores,the carbon isotope reversal phenomenon in the shale gas from the Silurian Longmaxi Formation of Jiaoshiba area in Sichuan Basin were well studied.Results showed that compared with the wellhead gas,the desorbed gas from Longmaxi shale had significantly more wet components and more heavy carbon isotope values;carbon isotope values of each component became heavier with the desorption time,δ^(13)C_(1)values of different samples had maximum positive variations of 12.3-23.9‰,butδ^(13)C_(2)values only had maximum positive variations of 0.8e2.3‰,indicating carbon isotope values of methane changed more obviously than that of heavy hydrocarbon.The above results were consistent with previous results of shale core desorption experiments carried out by other researchers.Shale gas in strata might have no carbon isotope reversal,and the phenomenon thatδ^(13)C_(1)values changed more significantly thanδ^(13)C_(2)values during the core desorption was not caused by diffusion rate differences among different components,but mainly due to different desorption stages of methane and ethane,i.e.,the ethane was in its early desorption stage while the methane was in its later desorption stage;during the production process,phase differences among different components of alkane gas and differences in the desorption stages induced by adsorption,could be the major cause for total reversal of carbon isotopes of shale gas in Longmaxi Formation,but it also could not excluded that mixture of kerogen cracking gas and crude oil cracking gas probably had a partial or more major contribution to the carbon isotope reversal.

Investigation on temperature characteristics of weak fiber Bragg gratings in a wide range

A weak fiber Bragg grating(WFBG)is an ideal quasi-distributed optical fiber sensor.Special attention should be paid to the spectrum and sensing performance of the WFBG at extreme temperatures due to its poor reflection intensity.In this Letter,the temperature characteristics of the WFBG from-252.75℃ to 200.94℃ are experimentally investigated.Five WFBGs with reflectivity from^0.25% to^10% are used in the experiments.The reflectivity variations and wavelength shifts at different temperatures are studied.Experimental results show that the WFBG can survive and work at extreme temperatures,but the performance is affected significantly.The reflectivity is affected significantly by both cryogenic temperature and high temperature.The temperature responses of Bragg wavelengths in the wide temperature range are also obtained.