B油田开发中后期储层特征及渗流规律研究
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摘要
通过钻井资料、测井资料、岩心分析测试数据并结合室内模拟试验,研究了B油田长期注水开发条件下储层岩性、物性、微观孔隙结构、润湿性等储层特征的变化,以及储层特征变化前后的渗流特征。同时还研究了由于注入水的不配伍储层结垢状况,及其对水驱油特征的影响。该研究得到初步认识如下:
1.储层物性变化
根据不同时期的测井资料和室内岩心模拟注水开发实验前后所测的物性对比分析可知,长期注水开发后储层孔隙度整体呈增大趋势,但变化不大;渗透率变化以降低为主,但相对高渗样品渗透率升高明显,长期注水冲刷后储层非均质性增强。
2.储层孔隙类型及孔隙结构变化
注水冲刷后储层孔隙组合类型未发生改变,以溶蚀孔—粒间孔为主。浊沸石、晶间溶蚀孔隙有所增加,面孔率略有增大。根据压汞数据分析可知,排驱压力(P_d)增大与减小比例基本相当,中值压力(Pc_(50))主体呈增大趋势,孔隙结构变化复杂。
3.填隙物含量及粒度的变化
测井解释和薄片测试都表明,长期注水冲刷后储层绿泥石和浊沸石含量减少。薄片观察发现,实验后绿泥石晶须明显减少;浊沸石溶蚀强度有所增大,通过粒度分析也可看出,粒径Φ＞4的极细微粒及粘土质微粒明显减少。
4.润湿性变化
研究区储层由于长期注入水冲刷,水的自吸速度增加,等渗点含水饱和度增大,储层润湿性向更加亲水方向发展。
5.水驱油渗流特征
实验后岩心的相渗曲线发生变化,主要体现在注水实验后部分样品的水相相对渗透率呈增大趋势,油相相对渗透率呈减低趋势,驱油效率有所降低,含水率升高较快。
水洗后模型水驱油启动压力普遍增大,相同压力条件下驱油效率降低,水驱波及面积减少,主要水驱大通道未发生改变,但出口见水加快,出现了更多的簇状未动用油。
长期冲刷使储层孔隙结构非均质性增强、水湿加强,是造成上述结果的主要原因。
6.储层结垢特征及对渗流特征的影响
由于注入水和地层水的不配伍造成明显的储层结垢,以硫酸钡和碳酸钙垢为主。地层水和注入水多次混合实验表明,70PV注入量下结垢使渗透率平均降低30%左右;采用矿化度稍高的模拟水进行实验,发现垢晶体首先在大孔道生成,随着混合注入量的增加,渗透率下降明显。储层结垢使储层驱油效率明显降低,平均驱油效率降低7.7%。
Through a great deal of data of oil field, the core analysis test data and combining indoor model experiment, changes of reservoir characterization such as lithology, physical property, pore structure, and wettability are studied in B oil-field after long-term flood development and displacement of oil by water in a scale deposit injury condition. Then, variety regulation of reservoir characterization is obtained in long-term flood development. At the same time, also studied the injection of water as a result of the non-compatibility of scale reservoir conditions, and its impact on the water characteristics of flooding. Preliminary conclusions of the study are as follows:
1. Changes in reservoir physical property
Accordance with the logging data and core simulation of indoor water-flooding development measured in different periods of time before and after the experiment were analyzed, we can see that after the development of long-term water, reservoirs was increased total porosity, but the degree is little, a majority of permeability declined, but the relative higher permeability of samples increased significantly, so after long-term water erosion enhanced reservoir heterogeneity.
2. Changes of reservoir porosity and pore structure
The type of the combination of pores did not change-mainly emposieu-intergranular space. Laumontite, intergranular corrosion porosity increased, the rate of face porosity slightly increased. Data analysis based on mercury penetration, we can see the proportion of increase and fall of displacement pressure is equal, median pressure is mainly increased, pore structure becomes more complexity after washing.
3. Changes of interstitial material content and the grain size
Log interpretation, slice and scanning electron microscopy test shows that after long-term water erosion, the content of chlorite and laumontite decreased. Slice shows that after the experiment significantly whisker chlorite reduced, laumontite dissolution have increased , the particle size analysis shows that particle sizeΦ> 4 of the very fine particles and clay particles decreased significantly.
4. The change of wettability
The rate of water imbibition increased after long-term washing, and the hydrophilicity enhanced. In the point where water and oil have the same permeability, the water saturation increased.
5. characteristics of water/oil displacement
In the core before and after the experiment relative permeability curve did not change significantly, mainly in a few of the experimental model of water injection the water permeability with increasing efficiency, displacement efficiency with a little fall ,and the water content increased faster.
Trigger pressure of water/oil displacement was generally increased after eroding, displacement efficiency was declined and swept area was decreased under the same pressure condition of water-oil displacement, the major paths of water/oil displacement had not been changed ,but water breakthrough time accelerated and more cluster type residual oil appeared.
6. crustation characteristics of the reservior
The research discovers that crustation of the reservior were mainly barium sulphide and calcium carbonate, as a result of the non-compatibility of injection water and formation water. The permeability had decreased by 30% after 70PV crustation. Deposition was firstly generated in high capacity channels by using water of higher degree of mineralization, permeability was obviously decreased with the increasing of injection. Displacement efficiency was obviously decreased with a average index of 7.7% as a result of crustation of the reservoir.
1.储层物性变化
根据不同时期的测井资料和室内岩心模拟注水开发实验前后所测的物性对比分析可知,长期注水开发后储层孔隙度整体呈增大趋势,但变化不大;渗透率变化以降低为主,但相对高渗样品渗透率升高明显,长期注水冲刷后储层非均质性增强。
2.储层孔隙类型及孔隙结构变化
注水冲刷后储层孔隙组合类型未发生改变,以溶蚀孔—粒间孔为主。浊沸石、晶间溶蚀孔隙有所增加,面孔率略有增大。根据压汞数据分析可知,排驱压力(P_d)增大与减小比例基本相当,中值压力(Pc_(50))主体呈增大趋势,孔隙结构变化复杂。
3.填隙物含量及粒度的变化
测井解释和薄片测试都表明,长期注水冲刷后储层绿泥石和浊沸石含量减少。薄片观察发现,实验后绿泥石晶须明显减少;浊沸石溶蚀强度有所增大,通过粒度分析也可看出,粒径Φ＞4的极细微粒及粘土质微粒明显减少。
4.润湿性变化
研究区储层由于长期注入水冲刷,水的自吸速度增加,等渗点含水饱和度增大,储层润湿性向更加亲水方向发展。
5.水驱油渗流特征
实验后岩心的相渗曲线发生变化,主要体现在注水实验后部分样品的水相相对渗透率呈增大趋势,油相相对渗透率呈减低趋势,驱油效率有所降低,含水率升高较快。
水洗后模型水驱油启动压力普遍增大,相同压力条件下驱油效率降低,水驱波及面积减少,主要水驱大通道未发生改变,但出口见水加快,出现了更多的簇状未动用油。
长期冲刷使储层孔隙结构非均质性增强、水湿加强,是造成上述结果的主要原因。
6.储层结垢特征及对渗流特征的影响
由于注入水和地层水的不配伍造成明显的储层结垢,以硫酸钡和碳酸钙垢为主。地层水和注入水多次混合实验表明,70PV注入量下结垢使渗透率平均降低30%左右;采用矿化度稍高的模拟水进行实验,发现垢晶体首先在大孔道生成,随着混合注入量的增加,渗透率下降明显。储层结垢使储层驱油效率明显降低,平均驱油效率降低7.7%。
Through a great deal of data of oil field, the core analysis test data and combining indoor model experiment, changes of reservoir characterization such as lithology, physical property, pore structure, and wettability are studied in B oil-field after long-term flood development and displacement of oil by water in a scale deposit injury condition. Then, variety regulation of reservoir characterization is obtained in long-term flood development. At the same time, also studied the injection of water as a result of the non-compatibility of scale reservoir conditions, and its impact on the water characteristics of flooding. Preliminary conclusions of the study are as follows:
1. Changes in reservoir physical property
Accordance with the logging data and core simulation of indoor water-flooding development measured in different periods of time before and after the experiment were analyzed, we can see that after the development of long-term water, reservoirs was increased total porosity, but the degree is little, a majority of permeability declined, but the relative higher permeability of samples increased significantly, so after long-term water erosion enhanced reservoir heterogeneity.
2. Changes of reservoir porosity and pore structure
The type of the combination of pores did not change-mainly emposieu-intergranular space. Laumontite, intergranular corrosion porosity increased, the rate of face porosity slightly increased. Data analysis based on mercury penetration, we can see the proportion of increase and fall of displacement pressure is equal, median pressure is mainly increased, pore structure becomes more complexity after washing.
3. Changes of interstitial material content and the grain size
Log interpretation, slice and scanning electron microscopy test shows that after long-term water erosion, the content of chlorite and laumontite decreased. Slice shows that after the experiment significantly whisker chlorite reduced, laumontite dissolution have increased , the particle size analysis shows that particle sizeΦ> 4 of the very fine particles and clay particles decreased significantly.
4. The change of wettability
The rate of water imbibition increased after long-term washing, and the hydrophilicity enhanced. In the point where water and oil have the same permeability, the water saturation increased.
5. characteristics of water/oil displacement
In the core before and after the experiment relative permeability curve did not change significantly, mainly in a few of the experimental model of water injection the water permeability with increasing efficiency, displacement efficiency with a little fall ,and the water content increased faster.
Trigger pressure of water/oil displacement was generally increased after eroding, displacement efficiency was declined and swept area was decreased under the same pressure condition of water-oil displacement, the major paths of water/oil displacement had not been changed ,but water breakthrough time accelerated and more cluster type residual oil appeared.
6. crustation characteristics of the reservior
The research discovers that crustation of the reservior were mainly barium sulphide and calcium carbonate, as a result of the non-compatibility of injection water and formation water. The permeability had decreased by 30% after 70PV crustation. Deposition was firstly generated in high capacity channels by using water of higher degree of mineralization, permeability was obviously decreased with the increasing of injection. Displacement efficiency was obviously decreased with a average index of 7.7% as a result of crustation of the reservoir.
引文
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[2]梅志超,沉积相与古地理重建[M],西安:西北大学出版社,1994
[3]何自新等.鄂尔多斯盆地演化与油气[M],北京:石油工出版社,2003
[4]彭仕宓,尹旭,张继春等.注水开发中粘土矿物及其岩石敏感性的演化模式[J],石油学报,2006,27(4):71-75
[5]黄思静,杨永林,单钮铭等.注水开发对砂岩储层孔隙结构的影响[J],中国海上油气(地质),2000,14(2):122-128
[6]李继红,曲志浩,陈清华等.注水开发对孤岛油田储层微观结构的影响[J],石油实验地质,2001,23(4):424-428
[7]杨永林,黄思静,单钮铭等.注水开发对储层砂岩粒度分布的影响[J],成都理工学院学报,2002,29(1):56-60
[8]单华生,姚光庆,周锋德.储层水洗后结构变化规律研究[J],海洋石油,2002,3(1):62-66
[9]李军,蔡毅,崔云海.长期水洗后储层孔隙结构夺化特征[J],油气地质与采收率,2002,9(2):68-70
[10]徐守余.渤海湾盆地胜沱油田二区储层微观渗流场演化研究[J],石油实验地质,2003,25(4):381-384
[11]张幸福.陆相复杂断块油田精细油藏描述技术[M],北京:石油工业出版社,200t
[12]杨正明,低渗透油藏渗流机理及其应用,中国科学院研究生院博士学位论文:1-20
[13]吕成远,王建.低渗透砂岩油藏渗流启动压力梯度实验研究[J].石油勘探与开发,29(1),2002,2:86-89
[14]王凤琴.乳状液在多孔介质中渗流规率研究.西北大学博士学位论文:50-55
[15]孙卫.B油田长6油层微观模型化学堵水实验[J].石油与天然气地质,1997,9,18(3):199-203
[16]杨正明.裂缝性低渗透油藏中弱凝胶驱油研究[J].第七届全国一般力学学术会议论文集,2002:162-165
[17]李东霞,苏玉亮.低渗透储层驱替特征[J].油气地质与采收率,2006,13:64-67
[18]林玉保.特低渗透储层油水渗流特征研究[J].大庆石油地质与开发,2005,24,(6): 42-44
[19]刘中春.低渗透油藏岩石物性对渗流的影响分析[J].油气地质与采收率,2006,11(6):39-41
[20]王志伟.低渗透油藏非达西渗流视渗透率及其对开发的影响[J].钻采工艺,2006,29(3):48-52
[21]曲志浩,孔令荣.低渗透油层微观水驱油渗流特征[J].西北大学学报,2002,32(4):329-334
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