松辽盆地北部非均质致密油水平井增产改造设计优化技术

Optimization Techniques for Stimulation Design of Horizontal Wells of Heterogeneous Tight Oil in Northern Songliao Basin

松辽盆地北部致密油储层为半深湖—深湖相夹三角洲前缘亚相和河流相沉积,具有纵向不集中、横向不稳定、甜点单体规模小、连片程度差、物性变化大、含油性差异大等非均质特征;非均质性强导致的力学差异易导致裂缝延伸不均衡、压裂段数多、规模大,对支撑剂、原材料及施工设施都要求高,等裂缝间距压裂设计不适应该地区。为此展开攻关,形成了增产改造设计优化技术,其中裂缝间距优化、压裂井段划分、射孔优化、裂缝长度与高度优化、裂缝导流能力优化等方法,解决了非均质储层体积压裂改造裂缝系统优化问题;同时压裂液、支撑剂、地面设施的优化与配置,满足了松辽盆地北部致密油大规模体积改造的需求。现场试验10口井97段,单井压后产量平均达40m3/d,是周围同物性条件直井的17倍,实现了陆相非均质致密油的有效改造,对大庆油田致密油增储上产具有重要意义。

The tight oil reservoir in the northern part of Songliao Basin is the sedimentation of semi-deep to deep lacustrine facies mingled with delta frontal subfaices and fluvial facies. It is characterized as decentralized longitudinally, instable horizontally, small in sweet-point scale, poor flat connectivity, changeable in physical properties, and different in oil bearing properties. The mechanical difference, caused by strong heterogeneity, makes fractures extend non-uniformly and leads to more fracturing sections and a larger fracturing scale so that high requirements are set on the proppant, raw materials and operational facilities. Equal fractural spacing fracturing design is not suitable in this region. To solve this problem, the techniques for stimulation design have been developed for optimization of fractural spacing, division of fracturing sections, optimization of perforation, optimization of fi＇actural length and height and optimization of fractural conductivity so that optimization of fractural system can be achieved in volumetric fracturing of heterogeneous reservoirs. Meanwhile, optimization arrangement of fracturing fluid, proppant and surface facilities met the requirements for a large-scale volumetric renovation of tight oil reservoir in northern part of Songliao Basin. A total of 10 wells with 97 sections were tested on the field. The single-well production reached 40 m3/d on average, 17 times as high as that from the neighboring straight wells with the same conditions of physical properties. Continental heterogeneous tight oil reservoirs were brought under effective renovation. The techniques are of a great significance to Daqing to increase tight oil reserves and production.