强纵向非均质性油藏油水层识别及油水界面精细刻画

doi:10.13809/j.cnki.cn32-1825/te.2021.03.019

摘要/Abstract

摘要：

伊拉克A油田K油藏为中东地区典型的孔隙型碳酸盐岩油藏,其孔隙结构复杂,电阻率纵向变化范围大,油水关系也极为复杂。为了建立该油藏可靠的油水层测井判别标准并进一步落实油水界面,以孔隙结构研究为切入点,首先理论分析了不同孔隙结构储层的电阻率随海拔高度变化的趋势线特征;同时结合测试和生产动态,分小层建立了K油藏油水层判别标准及油水界面;最后结合构造演化及成藏史分析了油水界面横向变化特征及成因。结果表明：①K油藏孔隙结构具有明显的纵向分层特征,从下向上整体呈渐变趋势,藻模孔及粒间孔含量向上增多,有效喉道半径向上增大;②孔隙结构在纵向上的差异是导致各小层油水层判别标准及油水界面差异的主控因素：以微孔为主的小层喉道半径小,排驱压力高,油水界面高,油层电阻率下限标准低;以粒间孔或藻模孔为主的小层喉道半径大,排驱压力低,油水界面低,油层电阻率下限高;③油水界面在横向上呈弯曲特征,同一小层的油水界面沿构造长轴向东倾斜;沿构造短轴呈拱形,即南北两翼低,构造高部位高,且北翼较南翼更低;④85口直井油水层解释及260余口水平井生产动态验证了弯曲油水界面的确定性。研究结果为油藏稳油控水措施的制定提供了依据,也为进一步优化开发方案及水平井轨迹调整奠定了基础。

关键词: 碳酸盐岩储层, 孔隙结构, 非均质性, 油水层识别, 油水界面

Abstract:

K oil reservoir, in Oilfield-A, Iraq, is a typical porous carbonate reservoir. It is characterized by complex pore structure, wide range of resistivity and complex oil-water contact（OWC）. In order to establish the reliable criteria for fluid typing and ascertain the OWC, firstly, the study of pore structure has been taken as a starting point, and the relationship between resistivity and elevation has been taken an insight into. Then a new criteria for fluid typing and OWC for each sub zone have been established by incorporating well testing and production dynamics. Lastly, the lateral variation of OWC and its genesis is analyzed based on structural evolution and hydrocarbon accumulation history. The results are as follows. ①Pore structure of the K oil reservoir shows strong longitudinal stratification characteristics, and the amount of mold pores and interparticle pores as well as effective pore-throat radius increases upwards. ②Vertical variation in pore structure is the main controlling factor of the identification criteria for oil and water layers and OWC variations for each sub layer. The layers dominated by micropores have small pore-throats radius, high displacement pressure, high OWC and low reservoir resistivity threshold, while the layers dominated by interparticle pores and mold pores are the opposite. ③The OWC is curved laterally, and slopes eastward along the long axis of the structure in the same small layer. Along the short axis of the structure, the contact is arched, that is the north and south margin is lower than the structure crest, and the lowest contact is in the northeast margin. ④The determination of the curved OWC has been verified by the reservoir interpretation of 85 vertical wells and the production dynamics of more than 260 horizontal wells. This study provides not only an effective solution for water control and stabilizing oil production but also a guideline for further optimization of field development plan and trajectory adjustment of horizontal wells.

Key words: carbonate reservoir, pore structure, heterogeneity, identification of fluid typing, oil-water contact（OWC）

中图分类号:

TE122.2

陈明江,刘俊海,程亮. 强纵向非均质性油藏油水层识别及油水界面精细刻画[J]. 油气藏评价与开发, 2021, 11(3): 428-436.

Mingjiang CHEN,Junhai LIU,Liang CHENG. Identification of fluid type and fine characterization of oil-water contact for an oil reservoir with strong vertical heterogeneity[J]. Petroleum Reservoir Evaluation and Development, 2021, 11(3): 428-436.

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小层	岩相	主要孔隙类型	有效喉道半径（μm）	岩心孔隙度（%）			岩心渗透率（10^-3μm²）
小层	岩相	主要孔隙类型	有效喉道半径（μm）	最小	最大	平均	最小	最大	平均
Kh^2-1-1	砂屑生屑泥粒灰岩	微孔、粒间孔	0.75	12.7	25.4	20.1	0.27	537	3.4
Kh^2-1-2U	砂屑泥粒灰岩	粒间孔、微孔	2.86	8.8	25.9	19.7	2.22	522	19.4
Kh^2-1-2L	砂屑颗粒灰岩	粒间孔	7.16	12.7	27.8	19.5	0.40	1 042	172.8
Kh^2-2	生屑砂屑藻屑泥粒灰岩	藻模孔、粒间孔	1.10	6.0	30.2	24.8	0.76	475.9	9.8
Kh^2-3	生屑藻屑泥粒灰岩	藻模孔	1.92	2.1	30.0	24.5	0.026	476	17.5
Kh^2-4	生屑粒泥灰岩	微孔、藻模孔	0.445	19.6	30.0	25.1	0.18	19.4	3.2
Kh^2-5	浮游有孔虫粒泥灰岩	微孔	0.25	9.5	27.7	23.1	0.092	18.3	1.1

小层		电阻率（Ω·m）				油水界面（m）
小层		油层	油水层	水层		油层底界海拔	水层顶界海拔
Kh^2-1-1		≥1.3	1.3~0.9	≤0.9		-2 614	-2 627
Kh^2-1-2U		≥3.0	3.0~1.8	≤1.8		-2 629	-2 632
Kh^2-1-2L		≥3.5	3.5~2.0	≤2.0		-2 629	-2 633
Kh^2-2		≥1.1	1.1~0.7	≤0.7		-2 626	-2 635
Kh^2-3		≥2.5	2.5~1.0	≤1.0		-2 635.5	-2 642
Kh^2-4	上部	≥1.1	1.1~0.7	≤0.7		-2 614	-2 627
Kh^2-4	下部	≥0.6	0.6~0.5	≤0.5	-2 611.5		-2 622
Kh^2-5		干层