低孔裂缝性气藏非酸解堵工艺研究

发布时间：2018-03-27 21:13

本文选题：裂缝性储层　切入点：钻井液伤害　出处：《西南石油大学》2017年硕士论文

【摘要】：目标区块储层埋藏深度大,温度、压力高,基质渗透率和孔隙度低,天然裂缝发育且被方解石、泥质充填或半充填,是典型的低孔裂缝性储层。为保证钻井安全性,常在钻井液中添加大量重晶石作为加重剂以平衡地层压力,由于井底压差和起下钻造成的压力激动,钻井液极易大量漏失入天然裂缝,重晶石等固相颗粒在裂缝中长期沉积老化形成严重堵塞,导致气井自然产能极低,需对储层进行增产改造。该区前期采取的增产措施改造效果差异大,采取酸化和酸压,无法对重晶石等非酸溶性物质形成有效溶蚀,而且导致井下管柱严重腐蚀;而采取加砂压裂则出现压裂液滤失严重,加砂难度大,施工压力高等问题。针对低孔裂缝性储层的改造难点,本文提出一种新的非酸解堵改造思路,完成的主要工作如下:(1)通过对目标储层地质特征和前期改造工艺分析,明确了储层特点和改造工艺要求,确立了非酸解堵的基本思路。(2)利用室内实验和CFD数值模拟等手段,系统分析了裂缝性储层钻井液伤害程度的主控因素,明确了伤害特征和伤害程度、范围,为后续解堵方案的制定提供依据。(3)通过理论分析和室内实验选取了一种具有浸润、分散与螯合作用的高效非酸解堵剂,并从pH值、辅剂浓度、主剂浓度、反应时间、反应温度和钙镁垢对解堵性能的影响等方面,揭示了不同条件下解堵剂的作用机理;结合目标储层特点,筛选了多种添加剂,形成一套非酸解堵液体系,并采取室内动态实验评价了该体系的解堵效果。结果表明,该非酸解堵液体系对硫酸钡溶蚀能力达到15g/L以上,对硫酸钡伤害岩心最终渗透率恢复了 240%和500%,具有很好的解堵能力,满足现场施工要求。(4)根据前期模拟和实验结果,设计了一套适合目标储层的非酸解堵工艺方案,并选取B84井进行现场验证,结果表明,非酸解堵液体系能够有效解除重晶石堵塞,日产气量由15×104m3增至70×104m3～80×104m3,验证了配方体系和工艺的可靠性。本论文完成的研究内容以及取得的研究成果,对解除目标储层重晶石堵塞、恢复提高单井产能及保证井筒完整性具有一定指导意义,为类似储层的高效开发提供了可借鉴的研究方法和技术思路。
[Abstract]:The reservoir in the target block is characterized by high burial depth, high temperature, high pressure, low matrix permeability and porosity, and natural fractures developed and filled with calcite, muddy or semi-filled. It is a typical low-porosity fractured reservoir. A large number of barites are often added to the drilling fluid to balance the formation pressure. Because of the pressure excited by the bottom hole pressure difference and the downhole drilling, the drilling fluid is easy to leak into the natural fracture. Barite and other solid particles formed serious blockage during the long-term deposition aging of fractures, which resulted in extremely low natural productivity of gas wells, and the reservoir should be increased and reformed. The effect of stimulation measures adopted in the early stage of this area is very different, and acidification and acid pressure are adopted. It can not effectively dissolve barite and other non-acid soluble substances, and lead to serious corrosion of downhole pipe string, while sand fracturing may cause serious filtration loss of fracturing fluid, and it is difficult to add sand. In view of the difficulties in reconstruction of low porosity fractured reservoirs, this paper puts forward a new idea of non-acid plugging removal and reconstruction. The main work accomplished is as follows: 1) by analyzing the geological characteristics of the target reservoir and the previous retrofit process, The basic idea of non-acid plugging removal is established. By means of laboratory experiments and CFD numerical simulation, the main controlling factors of damage degree of fractured reservoir drilling fluid are analyzed systematically. Through theoretical analysis and laboratory experiments, a kind of high efficiency non-acid plugging removal agent with infiltration, dispersion and chelating effect was selected, and pH value was used. The effects of concentration of adjuvant, concentration of main agent, reaction time, reaction temperature and scale of calcium and magnesium on the performance of plugging removal are discussed, the mechanism of action of plugging agent under different conditions is revealed, and a variety of additives are screened according to the characteristics of the target reservoir. A set of non-acid plugging removal liquid system was formed, and the effect of the system was evaluated by dynamic experiments in laboratory. The results showed that the solution ability of the non-acid plugging system to barium sulfate solution was more than 15g/L. The final permeability of the core damaged by barium sulfate is recovered by 240% and 500%, which has a good plugging removal ability and meets the requirements of field construction. (4) according to the previous simulation and experimental results, a set of non-acid plugging removal technology scheme suitable for the target reservoir is designed. Well B84 is selected for field verification. The results show that the non-acid plugging liquid system can effectively remove barite plugging. The daily gas production increased from 15 脳 104m3 to 70 脳 104m3~80 脳 104 m3, which verified the reliability of the formula system and process. It is of certain guiding significance to restore and improve the productivity of single well and to ensure the integrity of wellbore, which can be used for reference research methods and technical ideas for the efficient development of similar reservoirs.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE37

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