鄂尔多斯盆地上古生界气藏产能差异探讨

鄂尔多斯盆地上古生界苏里格气田和榆林气田储层均为低压、低孔和低渗储层，然而榆林气田气井生产状况却明显优于苏里格气田。为此，利用铸体薄片、压汞、物性和动态测试资料，探讨了不同低压、低孔和低渗储层气井产能差异的主要因素，指出了形成较高产能储层的条件。通过对榆林气田和苏里格气田气藏特征进行对比，结合控制气井产能的地质和工程因素的分析，认为造成两个气田气井产能差异的主要地质因素是储层的孔喉结构和储层规模。榆林气田储层以粒间孔+中、粗喉道为主，延伸宽度160~420 m，优于苏里格气田储层；苏里格气田砂体属于辫状河沉积，矿物成熟度较低（岩屑石英砂岩），且仅粗粒沉积构成储层，而榆林气田砂体属于三角洲沉积，砂体连续性好，矿物成熟度高（石英砂岩），因而后者具有更高的产能。这表明在鄂尔多斯盆地寻找较高产能储层的目标是：具有横向更连续的砂体和更易形成好的孔喉结构的三角洲沉积。

A STUDY ON DELIVERABILITY VARIATIONS IN LOW-PRESSURE, LOW-PERMEABILITY RESERVOIRS: PALEOZOIC RESERVOIR IN ORDOS BASIN

Although Sulige and Yulin gas fields are both in low pressure, low porosity and low permeability Paleozoic formation of the Ordos Basin, gas wells in Yulin gas field are much more productive than those in Sulige. Therefore, this paper carried out a study on the dominating factors causing deliverability variations of gas wells in such kind of formation by cast flakes, mercury intrusion method, physical and dynamic test data. After comparing characteristics of both gas fields and combining geologic and engineering factors controlling well deliverability, it was pointed out that pore throat structure and reservoir scale were the dominating features resulting in different production performance in gas wells. On one hand, Yulin gas field has better petro physical properties than Sulige with less developed intergranular pores and middle/coarse throats; on the other hand, Sulige gas field belongs to braided river sedimentary environment, where minerals are less matured (quartzarenite) and only coarse particles construct the reservoir formation, while Yulin belongs to delta sedimentation, having better sand continuity and higher mineral maturity (quartz sandstone). From those observations, exploration targets of highly productive reservoirs should focus on delta sedimentation with aerial continuous sand bodies and more favorable pore throat structure.