TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Process: The hydrocarbon charge is oligomerized using two reactors, where the reaction conditions of the first reactor is selected to convert a portion of olefinic compounds having lower number of 2-5C in C6+ intermediaries olefin. The second reactor operates at temperatures and pressures chosen to promote the oligomerization of heavy olefins in to distillate. The first reactor operates at a lower pressure, temperature and higher hourly space velocity compared to second reactor. The pressure difference between the two reactors is sufficient to achieve a flash separation of the effluent exiting the first reactor to remove the light gases, and optionally excess water before its introduction into the second reactor.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The hydrocarbon charge is oligomerized in the presence of at most 70 (preferably 1-30) wt.% of oxygenated compound. The process comprises, before oligomerization, a step of synthesis of oxygenated compound, where the total products obtained during the synthesis is optionally mixed with the charge for the oligomerization. The oxygenated compound is obtained by conversion of biomass. The weight ratio of the effluent from the condensation of ethanol and the charge containing 2-10C olefin is 0.005-1000, preferably 0.01-100. The hourly space velocity of the charge is 0.1-20 h-1, preferably 1-8 h-1. The inlet temperature or reactor is 150-400 degrees C, preferably 220-350 degrees C. The pressure within the reactor is 8-500 bars, preferably 14-49 bars. The effluent from the step of oligomerization of the charge is fed into a separation zone to separate at least 1-4C olefins and 5-9C olefins, which are recycled in a step of oligomerization of the charge, optionally after undergoing oligomerization. The hydrocarbon charge is oligomerized in two reactors in oligomerization series, the effluent leaving the second reactor being resulted in a separation zone to separate 1-4C olefins and 5-9C olefin, which are recycled in charge of the first reactor of the oligomerization step of the hydrocarbon charge, and least part of the 5-9C or 1-4C olefins is recycled in charge of the second reactor of the oligomerization step of the hydrocarbon charge. Preferred Components: The organic compound is: alcohols, ethers (exception of dimethyl ether), carbonyl compounds, including 2-20C, preferably 2-8C, and the corresponding ethers; alcohols or ethers, preferably ethanol, propanol, isopropanol, butanol, isobutanol, glycerol, ethylene glycol, and the corresponding ethers.