巴西盐下碳酸盐岩油藏裸眼智能完井技术分析

巴西盐下碳酸盐岩油藏主要位于Campos和Santos盆地,所处海域水深1 900～2 400 m,属于超深水海域; 油藏位于巨厚盐层下,部分区域盐层厚度达2 000 m,钻完井作业难度大,费用高。套管内射孔并下入智能完井管柱成为该区域主要的完井方式。然而,套管射孔作业对储层伤害严重,作业时间长,超深水作业综合日费昂贵,使得油田开发成本进一步增加。为提高油田开发经济效益,分析巴西盐下碳酸盐岩储层岩石特征,提出适用于该区块的裸眼智能完井技术,并利用ANAYS有限元软件对裸眼井在不同生产压差下井壁稳定性进行模拟。结果表明:巴西盐下碳酸盐岩储层岩石力学强度较高,生产压差15 MPa时,井眼极限扩大率1.5%,发生塑形屈服区域小,井壁稳定性好,适合裸眼完井。优化后的裸眼智能完井技术方案经济、可行,能较大幅度降低钻完井成本。

Application of Open Hole Intelligent Completion Technology inBrazilian Pre-salt Carbonate Reservoir

The subsalt carbonate reservoirs in Brazil are mainly located in the Campos and Santos basins. The water depth is 1 900 m～2 400 m, which belongs to the ultra-deep waters. The reservoir is under the huge thick salt layer, and the thickness of salt layer in some areas is 2 000 meters. The drilling and completion operations are difficult and costly in this area, the casing and perforation completion with smart well is the main method in this area however casing and perforating operation has serious damage to the reservoir with long completion duration. Due to the high daily cost of ultra-deepwater operations, this has led to further increases in oilfield development costs. In order to improve the economic benefits of oilfield, the open hole intelligent completion technology applicable to the block by analyzing the rock characteristics of the subsalt carbonate reservoirs in Brazil was introduced. ANAYS software was used to simulate the stability of the borehole wall under different production pressure differentials in open hole completion. The result shows that the rock mechanical strength of the subsalt carbonate reservoir in Brazil is high. At the production pressure difference of 15 MPa, the limit expansion ratio of the wellbore is 1.5%, with a small plastic deformation area. It indicates that the wellbore wall in this area has good stability, which is suitable for open hole completion. The optimized open hole intelligent completion technology is economical and feasible, it can bring a large drop in the cost of drilling and completion.