海拉尔油田南屯组小型测试压裂地质特征分析

Analysis on the geological characteristics of Nantun Formation in Hailaer Oilfield based on mini-frac test

蒋建方 何琛 宋清新 金玲 冯章语 刘秋均 初振钰 张甜

JIANG Jianfang HE Chen SONG Qingxin JIN Ling FENG Zhangyu LIU Qiujun CHU Zhenyu ZHANG Tian

中国石油大学非常规油气科学技术研究院 中国石油大学石油工程教育部重点实验室 胜利油田分公司滨南采油厂

Unconventional Oil & Gas Science and Technology Institute, China University of Petroleum (Beijing), Beijing 102249, China Key Laboratory of Petroleum Engineering Education Ministry, China University of Petroleum (Beijing), Beijing 102249, China Binnan Oil Production Plant, SINOPEC Shengli Oilfield Company, Binzhou 256600, Shandong, China

小型测试压裂分析是认识储层特征、优化主压裂设计、提高施工效率的有效举措。采用FracproPT2011压裂软件，对大庆海拉尔油田南屯组20口井的小型测试压裂效果进行了分析；结合地层断层发育特点和三轴岩石力学测定结果，研究了现场压裂施工困难的客观原因。结果显示：南屯组储层压裂井底停泵压力梯度和闭合应力梯度区间分别为0.018 0~0.026 9 MPa/m、0.015 4~0.023 2 MPa/m，平均达到0.021 6 MPa/m、0.019 4 MPa/m；气测渗透率主要集中在(0.1~0.3)×10⁻³ μm²之间，占比65%，存在天然裂缝和压裂多裂缝；压裂过程中的射孔孔眼摩阻和近井弯曲摩阻区间分别为0.85~2.86 MPa、1.42~14.36 MPa。发育断层引起的构造应力主体区间为5.0~10 MPa，最小水平主应力梯度为0.016 4 MPa/m，岩石杨氏模量和泊松比分别为36 090~38 400 MPa、0.24~0.39。附加构造应力、较高的最小主应力、杨氏模量大和泊松比大是南屯组储层压裂施工压力和停泵压力异常高以及低砂比、易砂堵的四大主因。

Mini-frac test analysis is one effective measure to clarify reservoir characteristics, optimize main fracturing design and improve construction efficiency. In this paper, the mini-frac test results of 20 wells in the Nantun Formation of Hailaer Oilfield were analyzed using FracproPT2011 fracturing software. Then, combined with the development characteristics of reservoir faults and the triaxial test results of rock mechanics, the objective causes of the difficult fracturing operation in field were researched. It is indicated that the bottom hole pump-off pressure gradient and closure stress gradient for fracturing the reservoir of Nantun Formation are 0.018 0−0.026 9 MPa/m and 0.015 4−0.023 2 MPa/m, respectively, averaging 0.021 6 MPa/m and 0.019 4 MPa/m. The gas test permeability is mainly in the range of (0.1−0.3)×10 μm, accounting for 65%, and there are natural fractures and hydraulic multi-fractures. The perforation friction and near-well tortuosity friction in the process of fracturing are in the range of 0.85−2.86 MPa and 1.42−14.36 MPa, respectively. The principal tectonic stress induced by developed faults is in the range of 5.0−10 MPa, the minimum horizontal principal stress gradient is 0.016 4 MPa/m, and the Young’s modulus and Poisson’s ration of rocks are 36 090−38 400 MPa and 0.24−0.39, respectively. And additional tectonic stress, higher minimum principal stress, high Young’s modulus and high Poisson’s ratio are four main reasons for the abnormally high construction pressure and pump-off pressure, low proppant concentration and easy sand blockage during the fracturing of the reservoir of Nantun Formation.

10.13639/j.odpt.2019.05.014