SAGD开发中突破夹层技术对策研究

摘要/Abstract

摘要：

开发实践表明,稠油油藏内部发育的夹层影响蒸汽辅助重力泄油(SAGD)开发效果。实际SAGD开发应当充分考虑夹层对SAGD生产效果的影响,寻找突破夹层的有效对策,以期提高SAGD产量。以国内某超稠油油藏地质特征为基础,结合夹层岩石力学参数测试结果,利用耦合岩石力学数值模拟技术确定了不同参数(岩石力学参数、物性参数、操作参数)对岩石变形量、SAGD产量的敏感性。研究结果表明,夹层的渗透率和SAGD注汽压力是影响SAGD产量的主要因素。进一步地,针对夹层特征,结合实际操作可行性,提出了提高注汽压力和直井辅助两种突破夹层技术对策,并给出了相应的技术界限及突破效果,该研究结果可用于指导稠油油藏双水平井SAGD经济高效开发。

关键词: SAGD, 夹层, 变形, 耦合, 突破对策

Abstract:

Inter-bedded barriers sandwiched in heavy oil reservoirs have impacts on steam assisted gravity drainage (SAGD) performance. In the real SAGD operation, the impacts must be taken into full consideration and effective countermeasures against barriers must be studied to improve the SAGD oil production rate. In this paper, features of deformation of barrier rock under high temperature and high pressure conditions in the SAGD process were studied by coupled geomechanical numerical simulations with parameters gained from geomechanical tests of barrier rocks. The permeability of the barrier and the injection pressure of SAGD were determined to be main factors affecting the oil production rate of SAGD. Furthermore, two types of countermeasures against inter-bedded barriers, namely increasing injection pressure and vertical well assisted, were proposed, with characteristics of barriers and operational feasibility being taken into account together. And technical limitation and corresponding operation effect of each countermeasure were also provided. The results have an important guiding significance to the realization of economic and efficient development in SAGD process.

Key words: steam assisted gravity drainage (SAGD), inter-bedded barrier, deformation, coupling, countermeasure

中图分类号:

TE345

石兰香, 李秀峦, 马德胜, 刘鹏程. SAGD开发中突破夹层技术对策研究[J]. 现代地质, 2017, 31(05): 1079-1087.

SHI Lanxiang, LI Xiuluan, MA Desheng, LIU Pengcheng. Countermeasures Against Inter-bedded Barriers in SAGD Process[J]. Geoscience, 2017, 31(05): 1079-1087.

图/表 16

表1 夹层岩石力学参数

Table 1 Geomechanical parameters of interbeded barriers

岩石类型	弹性模量/GPa	泊松比	内摩擦角/(°)	内聚力/MPa	热膨胀系数/(10^-5/℃)
泥质夹层	1.11~4.67	0.02~0.46	8.04~16.6	1.74~3.29	0.8~3
钙质夹层	7.82~43.68	0.02~0.2	49.8~53.89	12.06~16.64	1.1~6
砂岩	0.1~2.0	0.3~0.425	40~50.4	0.062~1	1.4~4

图1 三维精细网格单井组SAGD模型示意图

Fig.1 Three dimensional SAGD model of fine grid blocks

表2 油藏数值模拟参数

Table 2 Parameters in reservoir simulation model

油层顶深/m	油层厚度/m	油藏压力/MPa	油藏温度/℃	50℃原油黏度/ (mPa·s)	渗透率/ 10^-3um²	孔隙度/%	含油饱和度/%
450	24	4.5	22	20×10⁴	1 056	28.9	65

表3 SAGD 2 500 d内各参数对产量的敏感性

Table 3 Sensibility of each parameter on production after 2,500 days of SAGD process

敏感性参数	参数值	最大渗透率/ 10^-3 μm²	相对于未耦合情况下的累积产量提高比例/%	敏感性参数	参数值	最大渗透率/ 10^-3 μm²	相对于未耦合情况下的累积产量提高比例/%
弹性模量/ GPa	0.21	26	16.1	初始渗透率/ 10^-3 μm²	1	3.1	10.8
	2.1	39	17.4		10	31	17.4
	21	31	15.5		100	295	28.3
泊松比	0.2	29	16.7	C_n值	25	21	17.4
	0.3	31	17.4		50	96	34.9
	0.4	36	18.8		100	728	71.6
内摩擦角/(°)	10	29	16.2	热膨胀系数/ (10^-5/℃)	2	14	10.4
	20	31	17.4		4	20	12.1
	30	35	18.7		6	31	17.4
内聚力/MPa	0.5	24	17.4	注汽压力/ MPa	5	26	10.9
	5	29	16.4		6	29	17.7
	15	31	14.8		7	31	17.4

图2 耦合与未耦合情况下SAGD 2 500 d时蒸汽腔发育情况对比

Fig.2 Comparison of steam chamber shapes after 2,500 days of SAGD operation

图3 不同参数下的注汽量曲线

Fig.3 Steam injection rate curves with different parameters

图4 不同参数下的产量曲线

Fig.4 Oil production rate curves with different parameters

图5 注采井间发育不同厚度夹层时SAGD生产效果曲线

Fig.5 Production performance curves of SAGD with different thickness barriers

图6 SAGD开发2 500 d后注采井中间发育不同渗透率夹层时蒸汽腔发育情况对比

Fig.6 Comparison of steam chambers shapes with different barrier permeabilities after the 2,500 days of SAGD

图7 直井辅助井网模式

Fig.7 Well pattern of vertical well assisted

图8 有、无直井辅助时SAGD开发 2 500 d蒸汽腔发育情况对比

Fig.8 Comparison of steam chamber shapes with and without vertical well assisted after 2,500 days of SAGD operation

图9 有、无直井辅助SAGD生产效果曲线对比

Fig.9 Comparison of production performance with and without vertical well assisted

图10 有、无直井辅助SAGD蒸汽腔体积变化曲线对比

Fig.10 Comparison of steam chamber volumes with and without vertical well assisted

表4 直井辅助方法突破不同夹层可行性

Table 4 The feasibility of vertical well assisted SAGD to break through different barriers

夹层渗透率/ 10^-3 μm²	夹层位置/m	夹层厚度/m	2 500 d SAGD累积产油提高比例/%	是否突破夹层
0.001	注汽井上方3	1	0	否
1	注汽井上方3	1	5.8	是
10	注汽井上方3	1	10.8	是
1	注汽井上方3	2	2.8	否
1	注汽井上方3	3	1.7	否
1	注采井中间	1	0	否
10	注采井中间	1	0	否
100	注采井中间	1	0	否

表5 不同夹层突破对策的技术界限及其效果

Table 5 Technical limits and performances of different breakthrough strategies

突破夹层技术对策	夹层位置/m	夹层渗透率/ 10^-3 μm²	夹层厚度/m	2 500 d内提高产量/%
提高注汽压力	注汽井上方≥3	≥10	≤1	>30.5
直井辅助	注汽井上方≥3	≥1	≤1	>5.8

图11 不同时间温度观察井bt5温度剖面

Fig.11 Vertical temperature profile of bt5 at various dates

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