Removal of oil-based filter cake is a complex task especially in horizontal and multilateral wells.Thepresence of oil makes the removal process more challenging because the oil surrounds the weightingmaterials and prevents acid-filter cake interaction.Therefore,different additives are required to change thewettability of the filter cake to enhance the removal efficiency.This paper introduces a new biodegradableacid system (NBAS) that can efficiently remove oil-based filter cake in horizontal and multilateral wellswhere calcium carbonate is used as weighting agent.The new biodegradable acid system (NBAS) consists of 50 vol.% biodegradable acid and 5 vol.% mutualsolvent.HPHT filtration experiments were performed to evaluate the filter cake removal efficiency and theretained permeability.The filtration and removal experiments were conducted on real core samples (Indianalimestone and Berea sandstone) at a temperature of 212°F and 300 psi differential pressure.Afterwards,the NBAS was evaluated by measuring physical properties and conducting corrosion,compatibility andthermal stability studies.The obtained results showed that the NBAS was compatible and thermally stable for more than 48 hrsat 212°F and 300 psi.The NBAS has a density of 1.05 g/cm3,viscosity of 1.47 cP,and surface tensionof 32 dynes/cm at room temperature.The corrosion rate of the developed system was 0.03 lb/ft2 which isacceptable according to oil and gas industry practices.Removal experiments showed that filter cake wascompletely removed from the core samples.For Berea sandstone,100% of the permeability was regainedwhile the retained permeability for Indiana limestone was 122.5% confirming the complete removal ofexternal and internal filter cake as well as core samples stimulation.The new acid system can be considered as an efficiant solution for oil-based filter cake removal that isbiodegradable and cost effective where the reservoir permeability can be regained in one stage only.
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机译：除去油基滤饼是一个复杂的任务，特别是在水平和多边孔中。石油的阶下使得去除过程更具挑战性，因为该油包围着加权材料并防止酸滤饼相互作用。因此，需要不同的添加剂来改变接受性滤饼中提高去除效率。本文介绍了一种新的生物生物霉菌系统（NBAS），可以有效地除去水平的碱性井晶碳酸钙的油基滤饼，用作加权剂。新的可生物降解酸系统（NBA）由50体积％的可生物降解酸和5体积％。％mutualsolvent.hpht过滤实验进行评估滤饼去除效率和其渗透性。过滤和去除实验在真正的核心样品（印第安纳州Mestone和Berea砂岩）上进行温度为212°F和300 psi差压。在NBAS时，NBAS是Evalua通过测量物理性质和传导腐蚀，兼容性和热稳定性研究。得到的结果表明，NBAs与48小时212°F和300psi相容并热稳定。NBA的密度为1.05g / cm 3，粘度在1.47cp，室温下32达因/ cm的表面张力。发达系统的腐蚀速率为0.03磅/英尺，根据石油和天然气工业实践是可见的。避免实验表明，滤饼从核心样品中替换。对于贝雷砂岩，100％的渗透率被恢复为印第安纳州石灰石的保留渗透率为122.5％，确认完全去除了外部和内部滤饼以及核心样品刺激。新的酸系统可以被认为是油的功效溶液 - 基于滤饼的滤饼即可，可以在储层渗透率仅在一个阶段重新获得储层渗透性和成本效果。
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