海拉尔南屯组储层酸化技术
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摘要
海拉尔油田普遍存在着地质条件差异大、储层粘土矿物分布不均、分布规律不明显等特点,并且存在着注水压力上升快,吸水能力下降严重的情况。其中苏仁诺尔油田开发目的层主要为下白垩统南屯组二段,呼和诺仁油田主要开发贝301区块,开发目的层为南二段上部和中部。南屯组储层以往酸化措施有效率低,有效期短,效果很不理想。本文通过对储层物性、敏感性的深入分析,对南屯组储层特征有了清楚的认识,该储层物性变化大,泥质含量较高,粘土矿物中伊利石、高岭石等占主要成份,属于敏感性储层。在此基础上,进行酸液配方筛选以及酸液性能评价,确定了溶蚀率高、破碎率低,并且破乳、助排、抑制二次沉淀等性能良好的酸液配方体系。此外根据该油田的地质特征,确定了适宜的施工工艺,并开展现场试验12口井、13井次,有效率100%,平均有效期12个月,最长有效期达18个月。施工初期平均降压2.8MPa,单井注水量增加7.3m3,保证了南屯组储层注水开发效果。
Hailar Basin is the biggest petroliferous basin which is outside Songliao Basin and belongs to Daqing region. With the proceeding of oil exploration and development, it has become one of the most important suppliers for Daqing Oilfield’s sustainable 40 million tons output. Nantun Group is a main pay horizon in this oilfield, such as for Su131 Block in Surenur Oilfield and Bei301 Block in Huhenuren Oilfield. These oilfields generally have features of different geological condition and uneven clay mineral distribution, and have problems of rapid water injection pressure increase and great water adsorbing capacity decrease. The former acidification got unsatisfactory stimulation result of low efficiency, short valid period due to poor targeted formula and unreasonable operational process. In this paper, geological characteristics, physical characteristics and formation sensitivity of this oilfield are analyzed, and clear understanding for formation characteristics has been got. Nantun Group has great physical characteristics difference, and it is strongly sensitive due to its high content of clay, in which, illite and kaolinite are the major components. Based on the above analysis, research on acid formula and performance evaluation are conducted, and the new acid system has features of high corrosion rate, low crush ratio, quick demulsification, easy flow back and prohibiting secondary precipitation, etc, which will improve matrix permeability significantly. Additionally, more appropriate operational process is determined according to the reservoir geological characteristics. Up to now, field test has been performed on 12 wells, and satisfactory stimulation results are achieved. This technology ensures waterflooding proceeding smoothly in Nantun Group.
Combined with previous acidification situation conducted in Nantun Group, and analysis on formation geological feature, physical feature and sensitivity, targeted acid formula and operational process are researched. Following results are achieved.
1. Research by X-Ray diffraction, polarizing microscope and scanning electron microscopy (SEM) indicates, clay mineral of Su131 Block are mainly kaolinite and illite, and followed by montmorillonite-illite mixed layer, and montmorillonite- chlorite mixed layer. It is medium sensitive to water, with water sensitivity index 0.3~0.7. But two target intervals, layer No.16 above and No.18 below, have different characteristic on acid sensitivity, the former is strongly sensitive to chlorhydric acid, and the latter is strongly sensitive to mud acid.
2. According to sensitivity characteristic of Su131 Block, two acid systems are determined, organic acid system for the upper layer can improve the permeability of natural core by 147%, and compound acid and organic acid system for the lower layer can improve the permeability of natural core by 148%. For operational process, multi-stage diverting technique and reasonable operation scheme are adopted to realize separate layer diverting acidification by one treatment, which resolves the problem of no packer operation on water injection wells with two different layers.
3. Research by X-Ray diffraction, polarizing microscope and scanning electron microscopy (SEM) indicates, clay mineral of Bei301 Block has great difference in different wells, which is mainly strongly water sensitive mineral montmorillonite, and velocity sensitive mineral, such as kaolinite and illite; some wells has acid sensitive mineral chlorite. Basically, this formation is strongly sensitive to water and medium sensitive to velocity.
4. According to strongly water sensitivity of Su131 Block, alcohol-based retarded acid system is determined, which has features of high dissolution rate (14.7%), low crush ratio (2.4%) ,low corrosion rate, and no precipitation under pH 7.1. For operational process, operation parameters are determined according to acid software calculation. Additionally, over-displacing and after-protection technique is applied to guarantee the treatment results.
Up to now, field test has been performed on 12 wells with effective rate of 100% and average 12 months valid period, at most 18 months. Injection pressure is decreased by 2.8MPa on average at the initial stage, and water injection volume for single well is increased by 7.3m3.
With the proceeding of Hailar Oilfield waterflood development, more and more injection wells with difficulty of water injection and low yield production wells is emerging. This technology provides a set of well stimulation method, which not only ensures the development of Hailar Oilfield, but also instructs acidification operation on similar strongly sensitive formations.
Hailar Basin is the biggest petroliferous basin which is outside Songliao Basin and belongs to Daqing region. With the proceeding of oil exploration and development, it has become one of the most important suppliers for Daqing Oilfield’s sustainable 40 million tons output. Nantun Group is a main pay horizon in this oilfield, such as for Su131 Block in Surenur Oilfield and Bei301 Block in Huhenuren Oilfield. These oilfields generally have features of different geological condition and uneven clay mineral distribution, and have problems of rapid water injection pressure increase and great water adsorbing capacity decrease. The former acidification got unsatisfactory stimulation result of low efficiency, short valid period due to poor targeted formula and unreasonable operational process. In this paper, geological characteristics, physical characteristics and formation sensitivity of this oilfield are analyzed, and clear understanding for formation characteristics has been got. Nantun Group has great physical characteristics difference, and it is strongly sensitive due to its high content of clay, in which, illite and kaolinite are the major components. Based on the above analysis, research on acid formula and performance evaluation are conducted, and the new acid system has features of high corrosion rate, low crush ratio, quick demulsification, easy flow back and prohibiting secondary precipitation, etc, which will improve matrix permeability significantly. Additionally, more appropriate operational process is determined according to the reservoir geological characteristics. Up to now, field test has been performed on 12 wells, and satisfactory stimulation results are achieved. This technology ensures waterflooding proceeding smoothly in Nantun Group.
Combined with previous acidification situation conducted in Nantun Group, and analysis on formation geological feature, physical feature and sensitivity, targeted acid formula and operational process are researched. Following results are achieved.
1. Research by X-Ray diffraction, polarizing microscope and scanning electron microscopy (SEM) indicates, clay mineral of Su131 Block are mainly kaolinite and illite, and followed by montmorillonite-illite mixed layer, and montmorillonite- chlorite mixed layer. It is medium sensitive to water, with water sensitivity index 0.3~0.7. But two target intervals, layer No.16 above and No.18 below, have different characteristic on acid sensitivity, the former is strongly sensitive to chlorhydric acid, and the latter is strongly sensitive to mud acid.
2. According to sensitivity characteristic of Su131 Block, two acid systems are determined, organic acid system for the upper layer can improve the permeability of natural core by 147%, and compound acid and organic acid system for the lower layer can improve the permeability of natural core by 148%. For operational process, multi-stage diverting technique and reasonable operation scheme are adopted to realize separate layer diverting acidification by one treatment, which resolves the problem of no packer operation on water injection wells with two different layers.
3. Research by X-Ray diffraction, polarizing microscope and scanning electron microscopy (SEM) indicates, clay mineral of Bei301 Block has great difference in different wells, which is mainly strongly water sensitive mineral montmorillonite, and velocity sensitive mineral, such as kaolinite and illite; some wells has acid sensitive mineral chlorite. Basically, this formation is strongly sensitive to water and medium sensitive to velocity.
4. According to strongly water sensitivity of Su131 Block, alcohol-based retarded acid system is determined, which has features of high dissolution rate (14.7%), low crush ratio (2.4%) ,low corrosion rate, and no precipitation under pH 7.1. For operational process, operation parameters are determined according to acid software calculation. Additionally, over-displacing and after-protection technique is applied to guarantee the treatment results.
Up to now, field test has been performed on 12 wells with effective rate of 100% and average 12 months valid period, at most 18 months. Injection pressure is decreased by 2.8MPa on average at the initial stage, and water injection volume for single well is increased by 7.3m3.
With the proceeding of Hailar Oilfield waterflood development, more and more injection wells with difficulty of water injection and low yield production wells is emerging. This technology provides a set of well stimulation method, which not only ensures the development of Hailar Oilfield, but also instructs acidification operation on similar strongly sensitive formations.
引文
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12.范旭,庞彦明,松辽盆地宋芳屯油田葡萄花油层储层敏感性评价及油层保护对策,大庆石油学院学报,1999,23(3)。
13.张吉光等,海拉尔盆地苏仁诺尔成藏系统,石油勘探与开发,1998,25(1)
14.王昌军,罗觉生等,油田储层敏感性评价实验研究,化学与生物工程,2006,23(6)
15.马中振,庞雄奇等,海拉尔盆地乌尔逊凹陷石油地质特征,新疆石油地质,2007,28(3)
2.〔美〕B.B.威廉斯,J.L.吉德里,R.S.谢克特.油井酸化原理.(罗景琪译,罗悌夫校).北京:石油工业出版社,1984-10
3.石京平等,储层岩石速敏伤害机理研究,成都理工大学学报(自然科学版), 2003,10
4.佟曼丽,油田化学.山东东营:石油大学出版社,1997.10
5.曹维政等,海拉尔盆地贝301区块注水开采室内研究,大庆石油地质与开发,2004.2
6.王宝峰,国内外酸化产品及添加剂介绍,钻井液与完井液,1997,14(6)
7.张军闯,酸化的现状及前景,世界石油工业,1998,5(12)
8.陶德伦,汤井会,系列酸化解堵技术研究及应用,大庆石油地质与开发,1998,17(4)
9.蒋卫东,王振铎,有机缓速土酸的性能研究和现场应用,钻采工艺,1998,21(5)
10.付正等,海拉尔盆地贝尔凹陷兴安岭群储层粘土矿物组成及特征研究,地球学报,2008,4
11.王宝峰,蒋卫东,砂岩基质酸化中的短岩心和长岩心流动模拟试验研究,钻采工艺,2000,23(4)。
12.范旭,庞彦明,松辽盆地宋芳屯油田葡萄花油层储层敏感性评价及油层保护对策,大庆石油学院学报,1999,23(3)。
13.张吉光等,海拉尔盆地苏仁诺尔成藏系统,石油勘探与开发,1998,25(1)
14.王昌军,罗觉生等,油田储层敏感性评价实验研究,化学与生物工程,2006,23(6)
15.马中振,庞雄奇等,海拉尔盆地乌尔逊凹陷石油地质特征,新疆石油地质,2007,28(3)