Research On Mechanism And Development Mode Of Abnormally High Pressure Tight Sandy Conglomerate Reservoir

Abnormally high pressure dense glutenite reservoir has its unique characteristics.It has high initial production,but it’s production decreases rapidly and stable production time is short.The reservoir has a serious heterogeneity,the pressure sensitive effects,and water sensitivity effects,etc.When the fluid flow,it has nonlinear flow,starting pressure gradient,etc.So these reservoir development is very difficult.Therefore,a correct understanding of the development of features and characteristics of seepage of such reservoirs,determine a reasonable development mode to guide cost-effective development of such reservoirs is significant.Firstly,this paper research development mechanism and characteristics,then study on the pressure gradient,nonlinear seepage,stress sensitivity,water sensitivity effects.For the existence of serious heterogeneity,this paper study on the reservoir classification.Secondly,for specific target area well,we classified each of its block for different types of reservoirs,then study on its reasonable development.Abnormally high pressure reservoir usually full use of natural elastic energy for development at first,then followed by waterflooding for the prevention of stress sensitivity.Therefore,step by step steady state replacement is applied to determine the performance variation of production,the formula that can predict the natural depletion oil recovery is built,which considers the start-up pressure gradient and pressure ensitivity.Due to the elastic recovery efficiency is very low,injection water is needed.So,this paper launch water injection technology research using of reservoir engineering and simulation technology.In this paper,the final selection of classification parameters are the mainstream throat radius,movable fluid saturation,clay content,pressure gradient,oil viscosity,pressure-sensitive factor,permeability and porosity.The parameter’s classification boundaries are given,and a comprehensive taxonomy are established.The results show that:Ai 1 well block and 604 wells block are the second type reservoir;18 well block,Ai 013 block,6 wells block are the third type reservoir.The recovery is only 6%by using natural elastic energy and T₁b₁ layer recovery is 21.58%,T₁b₂ layer recovery is 17.88%by using water injection development.Water injection can effectively improve recovery.The second type of reservoir optimal well spacing is 300m×520m,the third type reservoirs is 200m×340m.Ai 1 well block for representative,the optimal timing of water injection pressure coefficient is 1.3;the optimal fracture half-length is 150m;the best conductivity is 50×10^-3μm³·m;optimal production rates of 10t/d;the optimal timing of the return for the first 12 years.