碳酸盐岩早期差异成储路径及...KT-Ⅰ与KT-Ⅱ层系为例_卢家希.pdf

书书书第 25 卷第 1 期2023 年2 月古地理学报JOUNAL OF PALAEOGEOGAPHY(Chinese Edition)Vol.25No.1Feb 2023文章编号:16711505(2023)01022619DOI:107605/gdlxb202301015碳酸盐岩早期差异成储路径及其对储集性能的影响:以滨里海盆地 N 油田石炭系 KT-与 KT-层系为例*卢家希1，2，3谭秀成1，2，3金值民1，2，3陈烨菲4王淑琴4赵文琪4李长海4，51 中国石油碳酸盐岩储层重点实验室西南石油大学研究分室，四川成都 6105002 西南石油大学油气藏地质及开发工程国家重点实验室，四川成都 6105003 西南石油大学天然气地质四川省重点实验室，四川成都 6105004 中国石油勘探开发研究院，北京 1000835 北京大学地球与空间科学学院，北京 100871摘要以滨里海盆地 N 油田石炭系 KT-与 KT-层系碳酸盐岩储集层为例，综合岩心、薄片、扫描电镜、高压压汞、常规物性分析以及各类测试资料，对碳酸盐岩储集层特征以及早期成储路径展开系统研究，并进一步探讨成储路径与储集层孔喉结构和质量的关系。结果表明，KT-层系以云岩类储集层为主，颗粒灰岩次之，其中云岩类储集层以晶间(溶)孔、小型溶洞为主，孔喉连通性好，为高孔高渗的孔洞型储集层，而颗粒灰岩类储集层以粒内溶孔、铸模孔及生物体腔孔发育为特征，孔喉连通性差，属中孔低渗的孔隙型储集层。KT-层系以粒间(溶)孔和生物体腔孔发育的颗粒灰岩为特征，为中高孔高渗的孔隙型储集层。进一步分析表明，KT-层系云岩与灰岩储集层单旋回厚度小，皆受高频海平面升降变化驱动的早成岩期岩溶的控制，而KT-层系单旋回厚度大，颗粒滩未经历早期岩溶的改造。3 类储集层的成储路径分别为:(1)KT-云岩类储集层，准同生期白云石化作用导致矿物相转变并使得部分矿物更易遭受溶蚀早成岩期岩溶作用控制储集层的形成云岩抗压溶岩石骨架有利于储集层的保护;(2)KT-颗粒灰岩储集层，早成岩期岩溶作用优化储集层初期压实控制胶结流体通道进而控制胶结作用粒间孔与粒内孔差异胶结控制储集层的保护;(3)KT-颗粒灰岩储集层，原始沉积环境控制储集层的形成初期压实与早期胶结作用控制储集层的保护。成储路径差异控制了不同的孔渗特征与孔喉结构，而孔喉结构进一步控制了早期岩溶型云岩、早期岩溶型颗粒灰岩、原生孔保存型颗粒灰岩 3 种储集层的质量。研究结果将为具类似特征的碳酸盐岩储集层成因分析提供参考，也因发现了云岩较灰岩更易早期溶蚀的现象而具有较为重要的岩溶地质学意义。关键词碳酸盐岩储集性能成储路径早成岩期岩溶石炭系滨里海盆地第一作者简介卢家希，男，1998 年生，硕士研究生，研究方向为储层地质学。E-mail:。通讯作者简介谭秀成，男，1970 年生，教授、博士生导师，研究方向为碳酸盐岩沉积与储层。E-mail:。中图分类号:TE122.2文献标志码:A*中国石油集团公司十四五前瞻性基础性科技项目(编号:2022DJ3209)资助。Financially supported by the Fourteenth Five-Year PlanForward-looking Basic Science and Technology Project of CNPC(No.2022DJ3209)收稿日期:20220718改回日期:20220805Differential reservoir formation paths of carbonate rocks in early stageand impacts on reservoir properties:a case study of KT-and KT-layers in N Oilfield，Pre-Caspian Basin第 25 卷第 1 期卢家希等:碳酸盐岩早期差异成储路径及其对储集性能的影响:以滨里海盆地 N 油田石炭系 KT-与 KT-层系为例LU Jiaxi1，2，3TAN Xiucheng1，2，3JIN Zhimin1，2，3CHEN Yefei4WANG Shuqin4ZHAO Wenqi4LI Changhai4，51 esearch Branch of Southwest Petroleum University，Key Laboratory of Carbonate eservoirs，CNPC，Chengdu 610500，China2 State Key Laboratory of Oil and Gas eservoir Geology and Exploitation，Southwest Petroleum University，Chengdu 610500，China3 Sichuan Natural Gas Geology Key Laboratory，Southwest Petroleum University，Chengdu 610500，China4 PetroChina esearch Institute of Petroleum Exploration and Development，Beijing 100083，China5 School of Earth and Space Sciences，Peking University，Beijing 100871，ChinaAbstractTaking Carboniferous KT-I and KT-II carbonate reservoirs in N oilfield in Pre-Caspian Ba-sin as an example，the characteristics of carbonate reservoirs and evolution of reservoir properties at theearly stage are systematically studied based on the core analysis，thin section，scanning electron microsco-py，high-pressure mercury invasion，conventional physical property analysis and various tests In addi-tion，the relationship among the evolution of reservoir properties，pore throat structure and quality is fur-ther discussed The results show that KT-I reservoir is dominated by dolomite with intergranular dissolvedpores and small karst caves with good pore-throat connectivity，which belongs to high porosity-highpermeability pore-cavity reservoir，followed by grainstone with intragranular dissolved pores，mold poresand biologic cavity pores that have the poor pore-throat connectivity，which belongs to the pore-type reser-voir with the medium porosity and low permeability KT-II reservoir is characterized as grainstone with in-tergranular dissolved pores and biologic cavities，belonging to the porous reservoir with medium-high po-rosity and high permeability Further analysis shows that the thickness of single cycle layer of KT-I dolomiteand limestone reservoirs is small，which is controlled by the early diagenetic karst driven by high frequen-cy sea-level fluctuation The thickness of KT-II layer is large，and there is no early karstification of thegrain beach There are mainly three types of reservoirs:(1)Penecontemporaneous dolomitization with sta-ble transformation of minerals results in the dissolution of some minerals，followed by the formation of reser-voirs controlled by the karstification at early diagenetic stage，and the pressure dissolution-resistance rockskeleton helps the protection of reservoir;(2)The early diagenesis karstification promoted the reservoirpropertythe early compaction controls the chemical fluid migration that can induce the cementationdif-ferential cementation controls the preservation of intergranular pore and intragranular pore;(3)Primarysedimentary environment controls the formation of reservoirearly compaction and cementation control pres-ervation of reservoir Different reservoir formation mechanisms lead to different porosity，permeability andpore throat structure，which controls the quality of reservoirs including the dolomite and grainstone after ear-ly karstification，and the limestone that owns the primary pores The results will provide a reference for thegenetic analysis of carbonate reservoirs with similar characteristics It also has significant karst geology mean-ing based on the discovery that dolomite is much easier to dissolve than limestone during the early