Research On Reservoir Sensitivity Damage And Protection Technology Of Dabei Kelasu Tectonic Belt Reservoir In Kuqa Depression

With the development of China's petroleum resources,exploration and development of low permeability oil and gas fields gets more and more attention from people.Dabei-Kelasu tectonic belt reservoir in Kuche depression belongs to the low porosity and low permeability reservoir,with small pore throat radius,strong heterogeneity,rich clay mineral content and micro fracture,which makes the area more vulnerable to sensitive damage in a series of the development and production process.The author aims Dabei Kelasu tectonic belt reservoir in Kuche depression as the research object,understands the geological characteristics of the reservoir by scanning electron microscopy,X diffraction technology etc.,and conducts the indoor sensitivity evaluation experiment.On this basis,reservoir sensitivity damage experimental study has been carried out for artificial fractured tight sandstone reservoir cores in the study area,the sensitivity protection and stimulation measures are put forward.The main research contents and The results are as follows:The main rock type of the Dabei Kelasu tectonic belt reservoir in Kuche depression is lithic sandstone,some are feldspar lithic sandstone.In whole,the rock particles are coarse,mainly consist of conglomerate,pebbly coarse sandstone,inequigranular sandstone.The rock structure maturity is medium.Reservoir pellets take line,bump-line contact primarily.The cementaed type is mainly contact-pore and block-pore.In the overall,type of throat is mainly leptothroat and even microthroat,common throat type in research layer is mainly: the necking throat,the laminated throat and fractured throat.Clay minerals that are developed in the reservoir can be divided into two kinds of clay mineral assemblages: illite + chlorite?illite + chlorite + illite smectite mixed layer.In this paper,taking the reservoir in 4 areas as an example,through the indoor sensitivity evaluation experiment,it is found that the Dabei Kelasu tectonic belt reservoir generally shows a strong stress sensitivity and Jamin damage in Kuche depression;moderate to strong velocity sensitivity,water salt sensitivity,alkali sensitivity;weak to strong acid sensitivity damage;weak water lock damage.Through the contrast analysis experiment,it is found that the main sensitization factor in the tight sandstone region is the poor connectivity,complex pore structure,easy to plug,which is different from the conventional reservoir damage mechanism(due to the sensitivity of clay mineral content).As the development of micro pores and micro cracks in matrix quantitatively,under external static pressure conditions it can easily be cause permeability decrease by the extrusion,resulting in strong stress sensitivity reservoir.In order to evaluate the velocity sensitivity of the artificialfractued cores,the simulation of the velocity sensitivity damage test was carried out.At the same time,for the tight reservoir,this paper includes sensitivity damage research in the the process of EOR is studied through artificial fracturing,and makes a contrastive study on the reservoir sensitivity differences between normal condition and artificial fracturing,provide the basis for the subsequent development of reservoir production.Taking into account the common phenomenon in the process of oil production and development,production declines due to the reservoir damage,which is often irreversible,aiming at all kinds of sensitive damage in research area the corresponding protective measures are studied.For example,it is advised to add particle stabilizer and clay stabilizer in the liquid into the well to alleviate the damage;for the damage caused by acid sensitivity,additives should be selected for acid system.