Comprehensivelogging Evaluation Technology And Application Research For Marine Shale Gas In Southern Sichuan

Shale gas is an important unconventional gas reservoir,it has a significant difference between conventional reservoir,tight sandstone reservoir,and others in mineral composition,pore types,pore structure and fluid state.Its logging evaluation content includes not only the evaluation of reservoir lithology,physical property and fluid properties,but also that of reservoir geochemical parameters,air content and fracturing.So the logging interpretation methods and evaluation system are not suitable for shale gas reservoir logging evaluation.On the basis of summarizing the logging response characteristics of the shale gas reservoir in the south of sichuan province,this paper establishes the method of effective shale gas reservoir identification,such as curve overlap method and crossplot method.Based on core calibration logging data,a shale gas reservoir well logging interpretation model was set up by series of ways,including a new water saturation logging method based on the multiple effects of shale gas,a new shale gas adsorption dynamic logging method based on LanGeMiao total temperature adsorption model,and a new mineral content and brittleness index method of established imaging logging of spectrum analysis technology.Based on the analysis of the influence factors of typical shale gas wells,the problem of production capacity prediction of shale gas well is solved,by shale gas production capacity and the evaluation method of classification.the main research contents and achievements have the following aspects:(1)A well logging identification method for shale gas in South Sichuan province is established.According to the survey of Weiyuan,Yongchuan and longmaxi group in Jiaoshiba area in southern Sichuan,and the analysis of the typical shale gas reservoir in the qiangzhusi group in Jingyan-QIanwei area,an identification method of the effective reservoir of shale gas is derived,by the techniques such as total gamma-non-uranium gamma,neutron-density,poisson's ratio-volume compression coefficient curve and crossplot.(2)An interpretation model of shale gas logging in south sichuan is established.Based on core calibration logging and mud logging data,the use of multiple perspectives,multiple methods established the basis of shale gas reservoir of Longmaxi group and Qiongzhusi group,well logging interpretation models have been derived,such as clay and brittleness mineral content,organic carbon content,the reservoir parameters,shale gas content and brittle parameters.(3)A new method for calculating the water saturation logging of shale gas with multiple effects is proposed.The change rule of water saturation in the shale gas reservoir in south sichuan is found.With the increase of organic matter content,water saturation decreases.According to experiment and logging data,the innovation from the non-electrical method is established based on the organic matter and clay content,such as multiple influencing factors of shale gas saturation calculation method,which could solve the technical problems of conventional electrical logging calculation of gas saturation susceptible to the influence of conductive minerals such as pyrite,and improve the shale gas water saturation logging calculation accuracy.(4)A new method for calculating the dynamic logging of shale adsorption containing gas is established based on Langmuir temperature adsorption models.According to a lot of shale core of isothermal adsorption experiment,and analysis the Langmuir volume and Langmuir pressure influenced by temperature,pressure and the content of total organic carbon(TOC).With the characteristics of the dynamic change of longitudinal temperature,pressure,and total organic carbon content of Qiongzhusi group in southwest of Sichuan,a new method of shale gas adsorption dynamic logging calculation based on LanGeMiao total temperature adsorption model is derived.(5)A new technique for analyzing the mineral content and brittleness index of shale reservoir was established.Based on the high precision imaging logging and experimental data,the normal distribution theory was used to establish the imaging logging mineral spectrum,and the mineral content and brittleness index were obtained by nonlinear spectral analysis.The innovative technology solves the technical problems of the brittle mineral content in shale reservoir and brittleness index evaluation,it can accurately reflect the changes of brittle factors such as the thin layer of lithology,fracture and bedding.(6)The classification of shale gas reservoir and the evaluation method of production capacity.The main factors affecting the productivity of shale gas horizontal wells have been analyzed from reservoir storage conditions,reservoir parameters,trails,fracturing parameters and production trends.he evaluation methods and standards of capacity classification have been set up,with the typical Wells analyzes,based on effective length of horizontal well section,quality reservoir type of horizontal well and segmental optimization index.(7)The research achievements have been applied in 23 Wells,and It has obtained obvious effects in practical application.Industrial airflow has been gotten in the shale gas reservoirs,such as Yongye 1HF well,Weiye 1HF well,and Weiye 23-1hf well.The research achievements provide strong technical supporting for major exploration breakthrough of the southern Sichuan Marine shale gas.