塔里木盆地奥陶系碳酸盐岩古岩溶类型识别
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摘要
在塔里木盆地奥陶系海相碳酸盐岩中识别出准同生岩溶、风化壳岩溶、埋藏岩溶3种不同类型的古岩溶作用。根据地质、录井、钻井、地球物理等响应特征,分别总结了它们各自的主要识别标志。粒内溶孔、铸模孔和粒间溶孔等组构选择型溶孔的发育,非组构选择型溶孔、小型溶洞、溶沟和溶缝及其渗流粉砂充填物的出现,大气淡水胶结物的产出等是准同生岩溶的主要识别标志;风化壳岩溶作用主要的识别标志包括:风化剥蚀及其伴生的风化残积层,高角度的溶沟、溶缝及落水洞,大小不等的各种溶蚀孔洞及其相应的充填物,充填物具有大气水参与的地球化学特征,钻井过程中的钻具放空以及泥浆的大量漏失,高自然伽马和低电阻的测井响应特征,相对低速的地震反射特征;埋藏岩溶作用一般可以根据地层水对原有孔洞缝的增溶并被油气充注的特征加以识别。指出准同生岩溶作用控制了早期碳酸盐岩储层的形成与分布,风化壳岩溶作用是储层形成的关键作用,埋藏岩溶作用则是储层优化改造的关键因素之一。
Three types of palaeokarst can be recognized in Ordovician non-marine carbonate in Tarim Basin,which are syndepositional rock-dissolution,weathering karstification and buried rock-dissolution.Their main recognizable indicators are summed up by analyzing the responsive characteristics in the aspects of the geology,well logging,drilling and geophysics.The recognizable indicators of syndepositional rock-dissolution include abundant texture-optimal dissolved-pores,such as the intra-grain,mold and inter-grain dissolved-pores,and non-texture-optimized dissolved-pores,small-scale dissolved-caves,dissolved channels,dissolved-fissures,as well as vadose silts and meteoric freshwater cements.The recognizable indicators of weathering karstification include the Ordovician carbonate weathering out and residue on a regional unconformity,high-angle dissolved channels,dissolved fissures,sinkhole,dissolved pores and caves with different scale and the fillings,the carbonate fillings in the dissolved pores and caves are of the geochemical characteristics that meteoric freshwater is of,the drilling break leakage occures,the well logging response is characteried by high combination gamma ray neutron value and low electrical resistivity value,as well as the low-velocity seismic response characteristics are dominant.The buried rock-dissolution can be recognized by further original pore and cave dissolution and infilling by oil and gas.It is indicated that early development and distribution of carbonate reservoir are controlled by the syndepositional rock-dissolution,the weathering karstification is the key to the formation of carbonate reservoir,the buried rock-dissolution is one of key factors of optimal reworking of carbonate reservoir.
Three types of palaeokarst can be recognized in Ordovician non-marine carbonate in Tarim Basin,which are syndepositional rock-dissolution,weathering karstification and buried rock-dissolution.Their main recognizable indicators are summed up by analyzing the responsive characteristics in the aspects of the geology,well logging,drilling and geophysics.The recognizable indicators of syndepositional rock-dissolution include abundant texture-optimal dissolved-pores,such as the intra-grain,mold and inter-grain dissolved-pores,and non-texture-optimized dissolved-pores,small-scale dissolved-caves,dissolved channels,dissolved-fissures,as well as vadose silts and meteoric freshwater cements.The recognizable indicators of weathering karstification include the Ordovician carbonate weathering out and residue on a regional unconformity,high-angle dissolved channels,dissolved fissures,sinkhole,dissolved pores and caves with different scale and the fillings,the carbonate fillings in the dissolved pores and caves are of the geochemical characteristics that meteoric freshwater is of,the drilling break leakage occures,the well logging response is characteried by high combination gamma ray neutron value and low electrical resistivity value,as well as the low-velocity seismic response characteristics are dominant.The buried rock-dissolution can be recognized by further original pore and cave dissolution and infilling by oil and gas.It is indicated that early development and distribution of carbonate reservoir are controlled by the syndepositional rock-dissolution,the weathering karstification is the key to the formation of carbonate reservoir,the buried rock-dissolution is one of key factors of optimal reworking of carbonate reservoir.
引文
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[12]钱一雄,邹远荣,陈强路,等.塔里木盆地塔中西北部多期多成因岩溶作用地质-地球化学表征[J].沉积学报,2005,23(4):596-603.
[13]吴胜和,欧阳健.塔里木盆地轮南地区奥陶系岩溶体系的测井分析[J].石油大学学报(自然科学版),1994,18(2):123-127.
[14]王嗣敏,金之钧,解启来.塔里木盆地塔中45井区碳酸盐岩储层的深部流体改造作用[J].地质论评,2004,50(5):543-547.
[2]顾家裕,朱筱敏,贾进华,等.塔里木盆地沉积与储层[M].北京:石油工业出版社,2003.
[3]陈景山,王振宇,代宗仰,等.塔中地区上奥陶统碳酸盐岩台地镶边体系分析[J].古地理学报,1999,1(2):8-17.
[4]王大纯,张人权.水文地质学基础[M].北京:地质出版社,1986.
[5]Longman M W.Carbonate diagenetic texture from near-surface diagenetic environments[J].AAPG Bull.,1980,63:401-487.
[6]闫相宾,李铁军,张涛,等.塔中与塔河地区奥陶系岩溶储层形成条件的差异[J].石油与天然气地质,2005,26(2):202-207.
[7]鲁新便,高博禹,陈姝媚.塔河油田下奥陶统碳酸盐岩古岩溶储层研究[J].矿物岩石,2003,23(1):87-91.
[8]顾家裕,周兴熙.塔里木盆地轮南潜山岩溶及油气分布规律[M].北京:石油工业出版社,2001.
[9]张达景,吕海涛,张涛,等.塔河油田加里东期岩溶储层特征及分布预测[J].沉积学报,2007,25(2):214-223.
[10]James N P,Choquette P W.Paleokarst[M].Springer-Verlag New York,1988.
[11]钱一雄,蔡立国,李国蓉,等.碳酸盐岩岩溶作用的元素地球化学表征[J].沉积学报,2002,20(1):70-74.
[12]钱一雄,邹远荣,陈强路,等.塔里木盆地塔中西北部多期多成因岩溶作用地质-地球化学表征[J].沉积学报,2005,23(4):596-603.
[13]吴胜和,欧阳健.塔里木盆地轮南地区奥陶系岩溶体系的测井分析[J].石油大学学报(自然科学版),1994,18(2):123-127.
[14]王嗣敏,金之钧,解启来.塔里木盆地塔中45井区碳酸盐岩储层的深部流体改造作用[J].地质论评,2004,50(5):543-547.
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