【作者】 陈广坡；

【导师】 徐国盛；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 碳酸盐岩岩溶型储集层分布广泛,正成为国内增储上产的主要勘探目标。但由于这种储集层在纵向和横向上非均质性强,储层发育受多种因素的控制,储层地质模型难以建立,储层预测也成为世界性难题。研究表明轮古西地区奥陶系碳酸盐岩油气的分布与碳酸盐岩顶部的风化壳和内幕的溶蚀缝洞有关。奥陶系碳酸盐岩岩溶型储层的地质模型建立、岩溶型储层的地震识别与预测,以及影响储层发育的构造裂缝的预测,是制约高效勘探和开发碳酸盐岩油藏的主要问题。本文通过对轮古西地区奥陶系岩溶型储集层地质特征的描述,认为岩溶型储层的储集空间主要由溶蚀孔洞、溶蚀扩大缝、大型溶蚀洞穴和构造裂缝等组成;岩溶型储层的类型主要有裂缝型、裂缝孔洞型、孔洞型、洞穴型四大类。在对岩溶型储层特征分析的基础上,认为岩溶作用程度、古地貌的控制、断裂和构造裂缝的发育程度、岩性以及沉积成岩、充填作用是控制岩溶发育的主要控制因素。其中岩溶作用以及构造运动引发的破裂作用,是储集空间得以改善的主要因素,而胶结充填作用、压实作用是导致储集岩致密化程度增加、孔隙减小的主要因素。古地貌则是影响岩溶型储集层发育规模、储层好坏的主要影响因素。通过对这些主要控制因素的分析,首次建立了轮古西地区岩溶型储层发育的地质模型,并在其它地区研究的基础上,对岩溶型储层的发育规律进行了总结。认为潜山岩溶型储集层在纵向上可以分为表层岩溶带、渗流岩溶带和潜流岩溶带,这三个岩溶带呈准层状分布。其中表层岩溶带位于潜山顶部,厚度小于50m,裂缝、溶蚀孔洞是最主要的储集空间,横向连通性较好,储集性能最好。渗流岩溶带厚度约30-120m左右,溶蚀裂缝、溶蚀孔洞及洞穴是主要的储集空间,沉积充填作用较弱,有效储集空间发育,断裂、裂缝是控制这个带储层发育的主要因素。潜流岩溶带位于渗流岩溶带下部,厚度约50-80m左右。溶蚀裂缝、溶蚀孔洞及大型洞穴是主要的储集空间,但容易被砂泥质所充填,造成有效储集空间的减少,溶蚀和充填作用是控制这个带储层发育的主要因素。岩溶型储集层的发育主要受古地貌的控制,在古地貌上可以分为岩溶高地、岩溶斜坡和岩溶洼地三个古地貌单元。其中岩溶高地主要遭受大气降水、风化和剥蚀等作用,岩溶型储集层欠发育;岩溶斜坡是岩溶型储层最发育的古地貌单元,它主要遭受大气降水、风化剥蚀、地表径流的侵蚀、溶蚀等作用,易于形成溶蚀裂缝、孔洞、大型洞穴等储集体;岩溶洼地位于古地貌的缓坡或洼地,是水流汇集的地方,岩溶型储层欠发育,也易于被砂泥所充填。根据控制岩溶发育的主要控制因素,以及岩溶型储层的发育特征,通过正演的方法对各种岩溶型储集层进行了正演分析,并根据钻井资料,对岩溶型储层在地震上进行了精细的标定,证实了利用地震资料对岩溶型储集层的可预测性,并对敏感的地震属性参数进行了筛选和分析,认为地震的振幅属性、能量属性和频率属性对岩溶型储集层较为敏感。表层岩溶带的岩溶型储层在地震上表现为弱振幅、高相干(低相关)、低阻抗、低频率等特征,内幕岩溶则表现为强振幅、高能量、低频率、低阻抗等特征。内幕岩溶储层的发育,是引起地震绕射波振幅变化的主要原因。碳酸盐岩岩溶洞穴型油气藏具有强振幅、调谐性和低速度的特点。其中洞穴宽度是影响地震波振幅的主要因素,洞穴高度是影响调谐性的主要因素。“串珠状”现象的出现一是需要溶洞散射波有一定的能量,二是需要有形成强烈多次波的条件。一般情况下,有一定宽度且上、下分布的多个洞容易形成“串珠状”现象,单个大洞难以产生“串珠状”现象。通过对轮古西地区岩溶型储层的研究,总结出了一套针对岩溶型储集层的储层预测的技术系列:地震属性分析(振幅、能量、频率、相干等)、波阻抗反演、三维可视化、古地貌恢复与分析、构造裂缝预测以及多资料融合的储层综合评价技术。并对各个单项技术的优缺点和适用性进行了论述和评价,指出利用某一个单一的技术很难对岩溶储集层进行很好的预测,必须利用多种技术进行综合才能对岩溶型储集层进行较为精确的预测,多种技术的融合才能对岩溶型储集层进行客观合理的评价。利用在轮古西地区总结出的岩溶型储层的地质模型和多种资料相结合的储层预测技术系列,在湛江涠西南、二连的赛汉塔拉凹陷等区块进行了实际应用,均取得了良好的应用效果,证实了岩溶型储层的地质模型和多种技术相结合的储层预测技术系列具有较好的适用性、可行性和有效性,能够在其它地区推广和应用。更多还原

【Abstract】 Carbonate karstic reservoir was distributed very widely and was becoming the main exploration target for increasing products in our nation. But the reservoir had the features of high heterogeneity in longitudinal and lateral, multiple reservoir controlling factors and hard geological model to build, so the reservoir prediction was the difficulty problem in worldwide. The research showed that the Ordovician carbonate prolific zone of the western LunGu area had relation to the weathered crust on the top of carbonate and dissolution cave inside carbonate. The geological model building of Ordovician carbonate karstic reservoir, reservoir identification from seismic and prediction, and the prediction of tectonic fracture controlling reservoir, were the key problems of efficient exploration and development of carbonate oil pool.In the paper, by the geological characteristics description of Ordovician karstic reservoir in the western LunGu area, the storage spaces of karstic reservoir were considered as solution pore, dissolution enlarged fracture, large solution cave and structural fracture. The karstic reservoir mainly contains four types, which were fracture, fracture-pore, pore, and cave. By the analysis of karstic reservoir development, the extent of karstification, palaeogeomorphology, the developing extent of faults and tectonic fracture, lithology, sedimentary and diagenesis, and packing action were considered as the main controlling factors of the reservoir. The karstification and regmagenesis due to tectonic movements were the main controlling factors to improve the storage space. The cementation, packing action and compaction were the main factors to increase the reservoir tightness and decrease the porosity. The palaeogeomorphology mainly had influence on the reservoir development scale and quality. The geological model was build for the first time by the analysis of these factors, and the rules of karstic reservoir development were summarized according to the study on other areas. The results showed that the reservoir can be divided into superficial karst zone, vadose karst zone, and underflow karst zone in longitudinal, and these three zones showed para-laminar distribution. The superficial karst zone was on the top of buried hill, with the thickness less than 50m. The main storage spaces were fracture and dissolution cave, and had good connectedness in lateral and storage capability. The vadose karst zone had the thickness about 30-120m. The main storage spaces were dissolution fracture, dissolution cave and hole. The sedimentary packing action was weak, and the effective storage spaces developed. The faults and fractures were the main controlling factors of reservoir in the zone. Below the vadose karst zone was the underflow karst zone, with the thickness about 50-80m. The dissolution fracture, dissolution cave and large hole were the main storage spaces. But the spaces were filled with arenaceous-pelitic matter frequently, which decreased the effective storage spaces. The main controlling factors of reservoir were dissolution and packing action. The development of karstic reservoir was mainly controlled by palaeogeomorphology, which can be divided into karstic highland, slope and depression. The karstic highland were suffered from atmospheric water, weathering and denudation, and lack of karstic reservoir. The karstic slope was the most developing unit of karstic reservoir, which suffered from the erosion and dissolution of atmospheric water, weathering and denudation, and surface runoff, and was easy to form storage spaces of dissolution fracture, cave and large holes. The karstic depression was on the gentle slope or depression of palaeogeomorphology, and was the location of current converging. The karstic reservoir were lack and also easy to be filled with arenaceous-pelitic matter.The different kinds of karstic reservoir were analyzed by forward method according to controlling factors and features. The reservoir was demarcated in seismic by well data, which proved the reservoir predictability by seismic data. The sensitive seismic attributes were filtered and analyzed, which showed that seismic amplitude, energy and frequency attributes were the sensitive to karstic reservoir.The reservoir of superficial karstic zone showed weak amplitude, high coherency (low correlation), low impedance and low frequency. The insider karstic reservoir showed strong amplitude, high energy, low frequency, and low impedance. The development of insider karstic reservoir caused amplitude change of seismic diffraction wave. The karstic cave reservoir had the characteristics of high amplitude, low tune and low velocity. The cave width mainly affected the seismic amplitude, and its height mainly affected the tune. The appearance of string beads depended on two factors: one was the scattered wave of cave had certain energy, and the other was the condition to form intense multiple. On general condition, multiple caves with certain width and distribution upper and lower were easy to form string beads, but the single large cave was hard.According to the study on the karstic reservoir of the western LunGu area, a set of reservoir comprehensive prediction and assessment techniques was summarized, which contained seismic attributes analysis (amplitude, energy, frequency and coherence), impedance inversion, palaeogeomorphology and tectonic fractures prediction, and multiple data combination. The relative merits and applicability of each single technique was summarized and evaluated, which showed using the single technique was hard to predict the reservoir precisely. So the combination of multiple techniques should be used to predict the reservoir more accurately and evaluate it more reasonably.Applying the geological model and the comprehensive prediction techniques for karstic reservoir summarized by the western LunGu area to the block of Weixinan in Zhanjiang and Saihantala depression in Erlian showed good application effect, which proved its good applicability, feasibility and validity, and can be spread and applied in other area.更多还原