低渗透砂岩气藏产能递减规律

DECLINE LAWS OF THE PRODUCTIVITY OF LOW-PERMEABILITY SANDSTONE GAS RESERVOIRS

低渗砂岩气藏的单井产量低、稳产能力差。气田的产能稳产接替方式一般采用新钻井来弥补递减产能，所以研究气田的产能递减规律，可以为产能部署提供一定的参考。为此，建立了一套气田产能递减规律分析的思路：首先分析单井的递减规律，然后结合每年的投产钻井数，计算出气田每年的产能总递减率：即可计算出气田每年递减的产能。利用该研究思路分析了中国典型低渗透砂岩气田——苏里格气田的单井递减规律和产能总递减率。苏里格气田的气井初期递减率较大，中后期逐步减小，递减率的变化幅度越来越小；气田产能总递减率不是逐渐减小或逐渐增大的，而是围绕某一定的区间范围跳跃变化。该递减特征为苏里格气田的产能部署提供了依据。

The single well in low-permeability sandstone gas reservoirs is characterized by low-production and poor sustainable production capability. The compensating method to the above problem is to drill new wells to makeup the declined productivity. So the study of the laws of declining gas productivity can provide a certain references for the deployment of the productivity. A set of the law analyzing thoughts are established in the paper： first, analyzes the diminishing laws of the single well ; and then combining with the annual numbers of drilled wells, calculates the annual total decline rate of the gas-field productivity, that is the productivity which can be computed for the annual decline of the gas field. With the help of the above study thought, the decline laws of individual well and total gas- field productivity decline rate are analyzed for Sulige Gasfield, the typical low-permeability sandstone gasfield in China. In Sulige Gasfield, the initial decline rates of the gas wells are rather serious, but in the medium and end, they are gradually decreased, and furthermore the change rate are more and more less. The total decline rate of the gasfield productivity does not decrease or increase gradually, but jumps in a certain interval. The decline character- istics have provided the basis for the productivity deployment in Sulige Gasfield.