油藏降压过程中套管受力与安全排液速率研究  

Study on the Casing Stresses and Allowable Unloading Rate during the Reservoir Depressurization

作　　者：王志坚 孙立柱 高志卫 Wang Zhijian;Sun Lizhu;Gao Zhiwei(Sinopec Xinjiang Xinchun Petroleum Exploitation Co.,Ltd.)

机构地区：[1]中石化新疆新春石油开发有限责任公司

出　　处：《石油机械》2020年第1期110-116,共7页China Petroleum Machinery

基　　金：中石化科技攻关项目“胜利油田稠油油藏高速高效开发关键技术”(2016JT01)。

摘　　要：利用蒸汽驱对水驱稠油油藏进行开采是提高油气采收率和保持单井稳产的重要技术措施,能否将油藏压力降低到5 MPa以下是决定蒸汽驱成功实施的关键。鉴于此,建立了油藏压力降低过程中压力分布计算模型,结合胜利油田某水驱稠油区块实际地质力学参数研究了油藏压力变化规律。以获得的油藏压力、井底流压和油藏基岩应力作为边界条件,建立了油藏降压过程中套管受力计算的三维地质力学模型,对降压过程中套管受力进行了分析,研究了排液速率、排液时间和油藏渗透率对套管安全的影响规律。计算结果表明:在油藏压力降低过程中,套管应力不断增加;排液速率越大、地层渗透率越小,井底流压越低,套管应力越大。给出了胜利油田某试验区块排液降压施工参数,成功指导了该区块的排液降压施工。该区块成功将油藏压力从9.7 MPa降低到5.0 MPa,未出现任何套管损坏事故。这表明建立的模型具有较好的计算精度和可靠性,可以为胜利油田水驱稠油油藏转热采时的排液降压提供参考和借鉴。Steam flooding is an important technical measure to improve oil and gas recovery efficiency and maintain a stable single-well production rate for water flooding heavy oil reservoirs.However,the key to the success of applying steam flooding is whether the reservoir pressure could be reduced below 5 MPa.By establishing the calculation model of pressure distribution in the reduction of reservoir pressure,the change rule of the reservoir pressure was studied based on the actual geomechanical parameters of a water flooding heavy oil block in Shengli Oilfield.Using the oil reservoir pressure,bottom hole flowing pressure and matrix pressure of the oil reservoir as the boundary conditions,the 3D geomechanical model for computing the casing stresses during the dropping of reservoir pressure was built,and the casing stresses during the pressure drop were analyzed to study the rule of influence of unloading rate,unloading time and reservoir permeability on casing safety.Calculation results showed that:in the reduction of reservoir pressure,the casing stress is increasing;the higher the unloading rate and the lower the formation permeability,the lower the bottom hole flowing pressure and the higher the casing stress.In this paper,the operation parameters for liquid unloading and pressure reduction of a test block in Shengli Oilfield were given,which are successfully used for guiding the pressure reduction operation through liquid unloading in the block.Field monitoring data indicated that:the reservoir pressure of the block was successfully reduced from 9.7 MPa to 5.0 MPa,without any casing damage.This showed the model established has a good calculation accuracy and reliability,and it could be used as an example and reference for pressure reduction through liquid unloading of the heavy oil reservoirs in Shengli Oilfield.

关 键 词：稠油油藏 油藏压力 渗透率 排液速率 套管损坏 

分 类 号：TE355[石油与天然气工程—油气田开发工程]