新场气田沙二气藏致密砂岩气层再评价研究

Re-evaluation Research on Sha2 Tight Sandstone Gas Reservoir in Xinchang Gasfield

新场气田沙二气藏为多层叠置气藏,自上而下主要由4套含气砂体组成,共分为JS21、JS22、JS23、JS24四个气层,埋深为2200～2500m,平均孔隙度为10.2%,属低-中孔储层,试井解释有效渗透率低于0.1×10^-3μm^2,属典型的致密砂岩储层。新场沙二气藏累计提交探明地质储量534.35×10^8m^3,动用地质储量445.08×10^8m^3,累计采气量120.35×10^8m^3,优质储量已全部动用,解释级别较低的致密砂岩气层动用程度较低。随着压裂改造工艺技术的进步,在以前难动用的储层上建产,将成为该气藏稳产的重要手段。根据各地质参数对油气的不同响应特征,建立了超平衡钻井条件下气测值的校正与恢复方法、地质指标权重评价等录井解释评价新技术,并利用该技术,对原来解释级别较低的致密砂岩气层潜力进行了再评价,筛选出了该类气层的潜力级别,为老井挖潜和气藏后期开发部署提供技术支撑。

Sha2 gas reservoir of Xinchang gasfield is a multi-layer superimposed one with 2200-2500 m of buried depth.It is composed of four sets of gas-bearing sandbody from up to down,and it can be divided into JS21,JS22,JS23 and JS24four gas pays.It belongs to the typical tight sandstone reservoir of low-middle porosity with10.2% of the average porosity and lower than 0.1 ×10^-3μm^2of the effective permeability interpreted by well test.It has been submitted 534.35 ×10^8m^3of the proven geological reserves totally and 445.08 ×10^8m^3of the producing geological reserves and 120.35 ×10^8m^3of the cumulative gas production in Sha2 gas reservoir of Xinchang gas field.In this reservoir,high quality reserves have all been produced,and the tight sandstone gas-bearing formations with lower rank of logging interpretation are at less producing degree.Along with the progress of fracturing technology,to produce the previously hardly-producing reservoirs will become an important means of stable production of the gas reservoir.According to the different response characteristics of the geological parameters to oil and gas,we set up new technologies of logging interpretation and evaluation,such as gas logging value correction and recovery method under overbalance drilling conditions and the geological index weight evaluation and so on.This technology is applied to re-evaluation of the potential of the tight sandstone gas-bearing formations with lower rank of logging interpretation,and the potential level of this type of gas reservoir is known,which provides technical support for tapping potential of the old wells and development of the gas reservoir in the later period.