Research On Ultra-Deep And Complex Reef Reservoir Prediction Technology

Organic reef is the most important oil and gas reservoir of carbonate rock and the main object of the oil and gas exploration and development.Many scholars home and abroad have made researches on organic reef and gained great achievements.But there is still argument on forming mechanism,controlling factors and distribution prediction of organic reef reservoirs.Meanwhile there is lack of theoretical guidance for spatial and temporal distribution of reef forecasting.Effective technical ideas and methods have not been found.With progressing of exploration and development,reef depth increasing,scales decreasing,degree of concealment increasing,difficulty of description increasing,strengthening basic theoretical research on reef reservoir growth,distribution and forecasting,to propose the prediction method and the prediction model which can be applied on other reservoirs is absolutely needed.This paper takes the Changxing formation reef reservoir of Yuanba gas field in northeastern Sichuan for example,on the basis of existing research results,it makes use of multi-discipline research method to describe reef reservoir,and then identifies the chief controlling factors and the growth model of reef reservoir.By analyzing the seismic response characteristics,launching the research on reef recognition,high quality reservoir characterization and classified quantification prediction for reservoir,this paper creatively proposes a series of methods for reef fine characterization and reservoir prediction,and establishes a related technologies system of reef fine characterization and reservoir prediction for the ultra-deep complex reef reservoirs.The main work is as follows:1)Making research on chief controlling factors of reef reservoir,the formation mechanism of different microfacies reef dolostone reservoir has been revealed,and Yuanba Changxing reef reservoir formation and evolution models have been established.2)Aimed at the gentle slope platform marginal reef which is small,scattered,multi-stage,and deeper than 6000 meters,based on research results of reef reservoir formation and evolution models,the research on reef groups development and reservoir distribution patterns has been made.The single reef model has been established,the distribution regularities of reef reservoir have been defined.In conclusion,five patterns of reef development and reservoir distribution have been established.3)Under the guidance of pattern of reef development and reservoir distribution,using multi-attribute information fusion technology,the research on reef boundary and connectivity has been carried out,and the technology of recognition and meticulous depiction to ultra-deep small reef group has been developed.4)Based on reef development,reservoir distribution pattern and reef meticulous depiction,using a variety of inversion methods,the reef reservoir quantification prediction has been carried out.The technology of reservoir classified quantification prediction,whose core theory is prestack geostatistics,has been development,which can perform classified quantification prediction for reef reservoirs.5)The research result has guided Yuanba gas field development,and achieved good effects.Arranging development evaluation wells and development wells totaling 27 wells,26 wells of these have been successfully drilled yet.The relative error of the vertical section reservoir thickness of 9 wells among them is only 4.7%.The average AOF of the wells tested is 367x104m3/d.The research results will play a guidance role for the development of the similar reservoirs.