| With the rapid development of modern petroleum industry,The focus of the petroleum exploration and development have to turn to some rather low permeability reservoirs and unconventional reservoirs which have difficulty in developing,and the proportion of the reservoirs have a growing trend.In a long time during the future,Unconventional oil and gas exploration will occupy the main petroleum exploration and development in our country.In this paper,the Silurian kepingtage group low permeability reservoir of TZ 16 wellblock is the object of this study,on the basis of system analysis,deepen the understanding of reservoir geological characteristics of the region,study the potential damage factors of this reservoir,and carries out many dynamic adaptability evaluation experiments between different working fluid(i.e.acidizing fluid,fracturing fluid),comprehensive analysis the reservoir damage degree during the acidification,fracturing operations and work-over.making the critical value of inflowing fluid salinity of this wellblock clear,optimizing the most appropriate formula of acid and fracturing fluid for this wellblock area,which is due to the results of the dynamic adaptability evaluation experiments.Combined with the whole rock diffraction(XRD),scanning electron microscopy(SEM),the casting thin sections,nuclear magnetic resonance(NMR),and other means of microscopic analysis,the type and mechanism of reservoir damage are obtained,and puts forward specific protection measures,it provides fundamental parameters for the scientific and efficient exploitation of the wellblock,it have reference significance for other wellblocks.The research result shows that:(1)The Kepingtage group is the main reservoir of TZ16 Silurian low permeability oilfield,and the main oil group is the SI group of 1 sub segment.Its sedimentary facies belongs to tidal flat sedimentary system,the reservoir lithology is medium to fine grained sandstone and its interstitial material include clay mineral and carbonate cement,The pore types mainly include residual inter-granular pores and inter-granular dissolved pores,it belongs to low permeability reservoir.(2)Sensitivity tests evaluation shows that the reservoir has high speed sensitivity and the critical speed of the fluid is 0.75 ml/min,and medium weak salt sensitivity and the critical salinity is 33000 mg/L in this wellblock.(3)Take acidification as a common measure to increase production,comparative evaluate the adaptability for target area reservoir of the single mud acid and mud acid system and friction-reducing acid system.the reservoir core permeability could be increased by 40%-75%after the mud acid system dynamic adaptability evaluation experiment,and the reservoir core permeability also could be increased by 35%-50%after the friction-reducing acid system dynamic adaptability evaluation experiment,however,it will lead to secondary damage for the reservoir which includes secondary sediment and the particle migration and so on if improper controlling the flow-back speed ratio and time.(4)Fracturing as a common measure to increase production can greatly improve the flow capacity of reservoir,polymer and residue in fracturing fluid as new blockages for fracture and matrix,the permeability is reduced by 36.30%after evaluation experiments between 0.45%guanidine gum fracturing fluid system and cracks,however the permeability is reduced by 51.48%after 0.55%Xanthan gum fracturing fluid evaluation experiments.The damages from the fracturing fluid system contain the adsorption and retention of fracturing fluid polymers,the pores and throats blocked by fracturing fluid residue,the particle migration and oil water emulsion and so on.(5)By comprehensive comparison,we recommend the use of mud acid system and 0.45%guar gum fracturing fluid for reservoir reconstruction work;using the classification acidification process;controlling the time and speed of residual acid can further improve the effective period of the measures. |
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