The Research And Evaluation Of Titanate Plugging Technology

Waterflood development has a long history in most oilfields of our country. In waterflooding process, the main development horizons is hypertonic layer of oil fields. During long-term waterflood,it forms seepage channel in high permeability layer. After decades of injected water erosion, the permeability of hypertonic channel increased,the level of Interlayer heterogeneity and in layer heterogeneity enhanced.It is one of the main factors affecting the efficiency of water flooding process that injected water loss from hypertonic channel.To improve this situation, after years of practice and research, people developed a set of EOR techniques led by polymer gel.However, because when the long-chain organic polymer is in the face of high temperature and high salt environment,molecular chains curl and aging dehydration is prone to happen,so polymer gel is poor adaptability with high temperature and high salinity reservoirs.Against to the short term of validity of polymer flooding in the high temperature and high salinity reservoir,this paper introduced titanate whiskers profile agent to profile control and water shutoff.Titanate system used in this paper consisted with two solutions named AandB, agent A and the B contact with each other in the formation and react to product a complex, this complex recrystallize and formation the titanate seed crystals,then seed crystals grow in the pores in the ground, and formation of whiskersunder the high temperature and pressure of the formation.Eventually forming a network structure in the formation. To improve thepermeability of hypertonic layer of the the formation, to achieve the purpose of Profile control and water shutoff.Firstly,this paper has studied the formation of titanate whisker and growth mechanism under the formation conditionsunder an electron microscope.During the experiment, it can be observed the formation of a large number of crystal particles in the microscopic model and measured obtaining the diameter range between0～10μm, that can meet the requirements of Profile control and water shutoff.Then, displacement experiments were carried out with cores and tubes filled with sands as porous mediums at formation temperature and salinity conditions. It is founded in the core experiments that:when the volume injected in is1PV, the concentration of titanate plugging system is20%, during the injection process, the pressure gradually increased; if higher permeability the core has, the lower magnitude of the injection pressure increases. When we inject the same amount of effective substance but at different concentrations into the cores, the lower the concentration we injected in,the worse effect we get.after the injection is completed, the higher the core permeability, the lower stemming ratio.Sand filling tube experiments is to study the injection volume, concentration and slug size influence on plugging effect.The more injected in, the better profile effect.When the rate of injection is constant, the lower effective concentration of the titanate plugging agent will spread farther distance, but the effect is worse; when injecting a certain amount, the smaller the alternating slugs is,the effect of profile control is better.Twin-tube flooding experiments has studied the oil displacement efficiency and fractional flow between High and Low permeable pipe in different treatments radius (10m,20m,30m).It was found that:When the treatment radius is larger, fractional flow between High and Low permeable pipe get closer;the more titanate plugging agent injected in, the more titanate plugging agent get into the hypertonic tube, titanate plugging agent sweep farther, oil recovery of hypertonic tube increases more.