Numerical simulation of water intrusion in wet gas reservoirs: A case study of the Changxing gas reservoir in Yuanba

doi:10.13745/j.esf.sf.2023.2.26

Abstract

Abstract:

The intrusion of edge and bottom waters in water drive gas reservoirs can severely impact the production capacity of gas wells; however, the law of water intrusion in wet gas reservoirs is not well understood. To fill this knowledge gap, the production characteristics of vertical and horizontal wells drilled through the Changxing Formation in the Yuanba gas field is investigated in combination with regional geological conditions, water properties and gas-water interfacial relationship to establish a mechanistic model of water intrusion via numerical simulation, and the influencing factors of gas production and water intrusion such as gas production speed, water body size, tight layer connectivity and height of water avoidance are analyzed. The results show that (1) the gas production speed is the main influencing factor of water intrusion as higher production speed leads to faster water intrusion and shorter stable production period, while the horizontal well can effectively inhibit water intrusion to a certain extent. (2) The size of the water body is another important influencing factor, the larger the water body size, the more serious the water intrusion and the shorter the stable production period. (3) The tight interlayer can inhibit water intrusion to a certain extent, and the bottom water cone, corresponding to the permeable interlayer (K_i_z = 100%K_z), has the fastest advance speed and the shortest stable production period. (4) As the avoidance height increases, the water/gas ratio increases slowly and water intrusion is delayed. Therefore, for water drive gas reservoirs, maintaining a reasonable production pressure difference or optimizing production practice is the key to controlling the rapid coning of bottom water. If the natural tight layer in the reservoir is ineffective, the submersible water cone can be inhibited by establishing an artificial compartment (dense interlayer) with low vertical connectivity. At the same time, when designing well drilling or later replenishing holes, it is necessary to take into account the impact of the injection hole size and height of water avoidance on production. The results of this study can be used to guide the development of submersible wet-gas reservoirs.

Key words: water drive gas reservoir, water intrusion, numerical simulation, gas production speed, connectivity of tight layers

CLC Number:

TE37

LI Yudan, YOU Yuchun, ZENG Daqian, SHI Zhiliang, GU Shaohua, ZHANG Rui. Numerical simulation of water intrusion in wet gas reservoirs: A case study of the Changxing gas reservoir in Yuanba[J]. Earth Science Frontiers, 2023, 30(6): 341-350.

Figures/Tables 19

Fig.1 The distribution map of gas well location in Changxing Formation

Fig.2 Analysis of typical wells (YB-1H well)

Fig.3 Analysis of typical wells (Note that the left is YB1 well and the right is YB2 well; the left is the curve of water-gas ratio and daily water production, and the right is the distribution diagram of gas saturation)

Fig.4 The mechanism model of numerical simulation

Fig.5 Profile of the numerical model of water intrusion in the bottom water reservoir (Note: the upper layer is the gas-bearing layer, the middle layer is the tight layer, and the lower layer is the water layer)

Table 1 Main parameters of the numerical simulation mechanism model

储层埋深/m	储层厚度/m	气藏压力/MPa	气藏温度/℃	孔隙度/%	平面渗透率/mD	垂向渗透率/mD	含气饱和度/%	气藏类型	水体倍数	气水界面高度/m	净毛比
6 900~7 000	100	69.5	152	5	2	0.6	90	底水	1	6 960	0.75

Table 2 Simulation scheme of the effect of the gas production speed on water intrusion

井型	采气速度/ (10⁴m³·d^-1)	水体倍数	致密层垂向连通性	射开程度/m	避水高度/m
直井	10,20,30,40,50	1	100%	30	30
水平井	10,20,30,40,50	1	100%	500	15

Fig.6 Influence of gas production speed on water intrusion (vertical well)

Fig.7 Influence of gas production speed on water intrusion (horizontal well)

Table 3 Simulation scheme of the effect of water body size on water intrusion

井型	采气速度/ (10⁴ m³·d^-1)	水体倍数	致密层垂向连通性	避水高度/m
直井	25	1,3,5,8,10	100%	30
水平井	30	1,3,5,8	100%	15

Fig.8 Influence of water body size on water intrusion (vertical well)

Fig.9 Influence of water body size on water intrusion (horizontal well)

Table 4 Simulation scheme of the effect of the tight layer connectivity on water intrusion

井型	采气速度/ (10⁴m³·d^-1)	水体倍数	致密层垂向连通性	避水高度/m
直井	25	1	0.1%,1%,10%,50%,100%	30
水平井	30	1	0.1%,1%,10%,50%,100%	15

Fig.10 Influence of the tight layer connectivity on water intrusion (vertical well)

Fig.11 Influence of the tight layer connectivity on water intrusion (horizontal well)

Table 5 Simulation scheme of the effect of avoidance height on water intrusion

井型	采气速度/ (10⁴m³·d^-1)	水体倍数	隔夹层垂向渗透率/mD	射开程度/m	避水高度/m
直井	25	1	0.6	10,20,30, 40,50,60	50,40,30, 20,10,0
直井	25	1	0.6	10	0,10,20, 30,40,50
水平井	30	1	0.6	500	10,20,30, 40,50

Fig.12 Influence of the avoidance height on water intrusion (vertical well)

Fig.13 Influence of the avoidance height on water intrusion (horizontal well)

Fig.14 Influence of the degree of perforation and avoidance height on water intrusion (vertical well)

References 22

[1]	胡勇, 梅青燕, 陈颖莉, 等. 裂缝边底水气藏水侵机理及控制水侵技术研究[C]// 第31届全国天然气学术年会(2019)论文集. 合肥: 中国科学院大学地球科学与行星学院, 2019: 170-179.
[2]	谭晓华, 彭港珍, 李晓平, 等. 考虑水封气影响的有水气藏物质平衡法及非均匀水侵模式划分[J]. 天然气工业, 2021, 41(3): 97-103.
[3]	罗柯, 曹建, 陈建, 等. 中坝雷三高含硫气藏高效开采效果分析[C]// 2014年全国天然气学术年会论文集. 贵阳: 中国石油学会, 2014: 356-364.
[4]	孙永亮, 王小鲁, 王玉善, 等. 柴达木盆地台南气田边水水侵影响因素及剩余气分布特征研究[J]. 录井工程, 2020, 31(2): 106-112.
[5]	刘晓旭, 钟兵, 胡勇, 等. 低渗透气藏气体渗流机理实验[J]. 天然气工业, 2008, 28(4): 130-132, 152.
[6]	吴建发, 王兴文, 赵金洲. 判断气举井稳定生产的新方法[J]. 钻采工艺, 2004, 27(6): 32-33, 36.
[7]	卢国助, 冯国庆, 卞小强, 等. 川中充西须四段气藏气井单井开采特征及开采对策研究[J]. 天然气勘探与开发, 2007, 30(4): 33-36, 68.
[8]	樊怀才, 钟兵, 刘义成, 等. 三重介质底水气藏非稳态水侵规律研究[J]. 天然气地球科学, 2015, 26(3): 556-563.
[9]	张烈辉, 刘香禺, 赵玉龙, 等. 孔喉结构对致密气微尺度渗流特征的影响[J]. 天然气工业, 2019, 39(8): 50-57.
[10]	张烈辉, 胡勇, 李小刚, 等. 四川盆地天然气开发历程与关键技术进展[J]. 天然气工业, 2021, 41(12): 60-72.
[11]	李凤颖, 伊向艺, 刘兴国, 等. 河坝飞三有水气藏治水对策研究[J]. 特种油气藏, 2012, 19(4): 92-95, 155.
[12]	汪旭东, 孙天礼. 元坝长兴组气藏水侵评价及开发调整对策[J]. 化学工程与装备, 2020(7): 112-113.
[13]	黄仕林, 杨博文, 张娟, 等. 元坝气田不同类型储层气水两相渗流特征[J]. 油气地质与采收率, 2022, 29(4): 122-127.
[14]	武恒志, 李忠平, 柯光明. 元坝气田长兴组生物礁气藏特征及开发对策[J]. 天然气工业, 2016, 36(9): 11-19.
[15]	胡勇, 陈颖莉, 李滔. 气田开发中 “气藏整体治水” 技术理念的形成、发展及理论内涵[J]. 天然气工业, 2022, 42(9): 10-20.
[16]	吕志凯, 唐海发, 刘群明, 等. 塔里木盆地库车坳陷超深层裂缝性致密气藏水封气动态评价方法[J]. 天然气地球科学, 2022(11): 1874-1882.
[17]	张鹏, 徐耀东, 杨志伟. Y21区块含水层储气库边底水侵入数值模拟[J]. 断块油气田, 2021, 28(6): 781-785.
[18]	周旻昊, 乐平, 郭春秋, 等. 裂缝型气藏水侵动态模拟研究[J]. 实验室研究与探索, 2020, 39(12): 104-109.
[19]	杨敏, 陈东, 杨凤来, 等. 巨厚气藏非均匀水侵的主要影响因素分析[C]// 第32届全国天然气学术年会(2020)论文集. 重庆: 中国石油塔里木油田分公司勘探开发研究院, 2020: 647-652.
[20]	张厚青, 刘冰, 徐兴平, 等. 底水油藏水平井最优避水高度及合理长度的研究[J]. 科学技术与工程, 2012, 64(4): 774-778.
[21]	石婷. 裂缝性底水气藏水侵物理模拟及数值模拟研究[D]. 成都: 西南石油大学, 2016.
[22]	于清艳, 刘鹏程, 李勇, 等. 缝洞型底水气藏水平井水侵动态数学模型与影响因素研究[J]. 现代地质, 2017, 31(3): 614-622.