| Taking Yi Can 1 well drilling, fracturing test engineering as an opportunity, with help of the southeastern Yichuan- Huanglong area of Ordos wells core,measured, logging data, through the experimental test analysis means combined with sedimentary microfacies, diagenesis, tectonic evolution of the reservoir feature of Yichuan area Ma five 1 + 2 and the main controlling factors for analysis and prediction of favorable reservoir distribution area.According to coring and logging data, up to now,the Yi Can 1 well was one of the most developed well in the weathering crust reservoir of the ancient submerged platform in Yichuan area southeast of the basin.The performance of hole gap composite,dissolved pore aperture and high density, the low of filling degree, and the best of top property,the highest measured core porosity is 10.8%, the permeability is 15.45 mD.The drilled well gas logging abnormal display in the five 1 sub section of Majiagou Formation, the best gas bearing of the top weathering crust reservoir.The gas display section is 2634.08 to 2636.68 m, thick 2.6m in Ma five 12, and the gas logging total hydrocarbon peak is 1.5248%,the base value 0.2822%.The three consecutive point gas measuring peak value was more than 1.0% in2635,2536,2537 m of Ma five 12,the box type of gas logging abnormal morphology which indicates that the gas reservoir is better.The Ma 5 13 also drilled in case of weak gas logging abnormal display, thick 1.9m, the gas logging total hydrocarbon peak is 0.1190% and the base value is 0.0408%.However, the success of Yi Can 1 well does not illustration the whole development weathering crust reservoir and better gas bearing property of Ma 1+2 in Yichuan area, the Ma six segment thickness is larger inYichuan area which 13 wells in 10 wells drilled six Ma large thickness, usually 3.8 36.8m, the average thickness of 20.3m, the underlying Ma1+2 formation of five MA in the wind of shell formation dissolution pore type reservoirs have hindered. Secondly most coring wells show that Ma five1+2 reservoir lithology with mud dolomite, crystal dolomite, part of micritic dolomite secondary limestone dolomite and fine dolomite, indicating that the Ma five1+2 deposition is still in the period containing anhydrite nodule dolomite flat microfacies belt. Combined with sedimentary microfacies and diagenesis analysis in Eastern Yichuan area in latent karst palaeogeomorphology low reservoir site, due to the late diagenetic secondary limestone dissolution pores and cracks more easily lead to the reservoir caused by calcite filling and then made the reservoir Dense.By comparing the connecting wells in the study area showed that ancient landforms in the higher parts of the region West of the Yi chuan area overlying limestone layers thickness reduction of six paragraphs, Ma five1+2 cream containing dolomite secondary low levels of ash and weathering crust of meteoric water leached transformation to the cream containing dolomite, is favourable to the development of karst vug reservoir place. Yichuan ancient hidden platform on the West side is weathered crust gas reservoirs of favorable exploration targets. |
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