The progress of geological theory and technology for unconventional oil and gas

Current development of oil and gas extends from conventional to unconventional that is more difficult and more expensive.In the near future,a situation will be achieved that both conventional and unconventional oil and gas will develop simultaneously.According to the cause of formation,unconventional oil and gas may be divided into three categories.The first category is the heavy oil and oil sands,which are the normal crude oil damaged by biodegradation and water washing;heavy oil and oil sands are widely distributed and highly potential;there is a lot of exploitation of them.The second category is the tight oil and gas,shale oil and gas,and coalbed methane;the main feature is the reservoir porosity and permeability in very poor conditions;they are continuous-massive accumulation reservoir;this category develops very rapid and the production grows very fast.The third category is the oil shale,which is immature kerogen mixed with clay and fine-grained inorganic minerals.Oil shale is rich in organic matter,and can generate oil by heating.Oil shale was found early and widely distributed;the highest proportion of them is in the United States.The unconventional oil and gas exploration and development led the innovation of petroleum geology theory and technology.Meanwhile,unconventional resources are very huge,equivalent to 2-3times of the conventional oil and gas resources;the exploration and development technologies are maturing,which greatly extends the life cycle of the oil industry,leading the petroleum industry to a great-leap-forward development.