Study on the Scale Composition and Scaling Mechanism of Wellbore in Mahu Oilfield

doi:10.12422/j.issn.1006-396X.2024.04.003

Abstract

Abstract:

In recent years, many oil wells in Mahu oil fields have experienced scaling on the pipe wall, which leads to wellbore blockage and seriously affects the production effect. In this paper, the structure and composition of scale in Mahu oilfield were studied, and the mechanism of scale formation was investigated by using OLI?ScaleChem simulation method and the interaction experiments between fluid and rock matrix. The results show that the main fouling is CaCO₃, and the deeper the well is, the larger the amount of scale is. In addition, the wellbore temperature, pressure and pH of the fluid all have certain influence on scaling. According to the results of fluid rock reaction, it is inferred that CaCO₃ scale is the reaction product of highly mineralized fluid and calcium?rich minerals under the condition of acidic well fluid, and forms into balls under the action of polymer, resulting in hole and wellbore plugging. The results of the study are of great significance in guiding the proposal of subsequent scaling prevention and treatment measures in the oilfield.

Key words: Mahu oilfield, CaCO₃ scale, Scaling mechanism

摘要：

近年来，玛湖油田多口油井在生产过程中均出现管壁结垢现象，导致井筒堵塞，严重影响了生产效果。研究了玛湖油田垢物的结构与组成；采用OLI?ScaleChem模拟方法，研究流体与岩石基质的作用，探究了垢物的形成机理。结果表明，油井的垢物主要为CaCO₃，且井深越大，其结垢量越大；井筒的温度、压力以及流体的pH对结垢均有一定的影响；CaCO₃垢物是酸性入井流体条件下高矿化度流体与富钙岩石矿物的反应产物，其在聚合物作用下成球，进而堵塞孔缝和井筒。研究结果对油田后续结垢预防措施和处理措施的提出具有重要的指导意义。

关键词: 玛湖油田, CaCO₃垢物, 结垢机理

CLC Number:

TE358.5

Hao ZHOU, Xigang GONG, Hongjiao TANG, Huan LIU, Feng SHI, Juan ZHANG, Leilei YANG. Study on the Scale Composition and Scaling Mechanism of Wellbore in Mahu Oilfield[J]. Journal of Petrochemical Universities, 2024, 37(4): 18-24.

周浩, 龚喜刚, 唐红娇, 刘欢, 时凤, 张娟, 杨磊磊. 玛湖油田井筒垢物的组成及结垢机理研究[J]. 石油化工高等学校学报, 2024, 37(4): 18-24.

Figures/Tables 15

Table 1 The constitute of simulation water in Mahu oilfield

无机盐	质量浓度/（mg·L^－1）
Na₂CO₃	3 823.80
NaHCO₃	4 975.60
CaCl₂	4.90
MgCl₂	1.20
K₂SO₄	2 048.80
KCl	15 615.60
NaCl	9 135.00

Fig.1 Appearance of the scale sample

Fig.2 EDS spectra of the scale sample

Table 2 Elemental composition of the scale sample

元素	质量分数/%
C	20.07
Na	0.59
Ca	17.36
Sr	1.16
O	60.82

Fig.3 SEM image of the scale sample

Table 3 Analysis results of ion composition in produced water of Mahu oilfield

离子	质量浓度/（mg·L^－1）
矿化度	57 129.74
CO $3 2 -$	4 679.00
HCO $3 -$	7 276.00
OH^-	0
Cl^-	15 036.00
SO $4 2 -$	2 365.50
Ca²⁺	10.85
Mg²⁺	2.39
K⁺	19 784.00
Na⁺	7 976.00

Table 3 Analysis results of ion composition in produced water of Mahu oilfield

离子	质量浓度/（mg·L^－1）
矿化度	57 129.74
CO $3 2 -$	4 679.00
HCO $3 -$	7 276.00
OH^-	0
Cl^-	15 036.00
SO $4 2 -$	2 365.50
Ca²⁺	10.85
Mg²⁺	2.39
K⁺	19 784.00
Na⁺	7 976.00

Fig.4 The effect of temperature and pressure on CaCO3 scaling amount in Mahu oilfield

Fig.5 Well depth and pH effects on the CaCO3 scaling trend in Mahu oilfield

Table 4 Mineral component content of rocks in Mahu oilfield

组分	质量分数/%
石英	48.2
钾长石	5.0
斜长石	6.5
白云石	18.2
黄铁矿	5.5
普通辉石	6.8
黏土矿物	9.8

Table 5 Elemental composition of rocks in Mahu oilfield

元素	质量分数/%
O	47.89
Na	2.89
Mg	7.80
Al	4.97
Si	18.28
K	2.07
Ca	12.48
Fe	3.61

Fig.6 SEM images of rock surface crystals

Table 6 Results of elemental analysis of rock surface crystals

元素	质量分数/%
C	13.56
O	47.59
Al	3.11
Si	6.51
Ca	22.61
Mg	6.62

Fig.7 SEM images of rock surface before and after interaction with simulated water

Fig. 8 EDS images of rock surface before and after interaction with simulated water

Table 7 Element mass fraction of the rock before and after reaction with simulated water

元素	质量分数/%
元素	作用前	作用后（8 d）
O	47.89	41.81
Na	2.89	1.88
Mg	7.80	7.78
Al	4.97	5.16
Si	18.28	15.64
K	2.07	1.21
Ca	12.48	3.08
Fe	3.61	2.72

References 19

1	ZHANG N，WANG X C，ZHANG J M，et al.Experimental and statistical study on wellbore scaling mechanisms and characteristics for huanjiang oilfield［J］.Geofluids，2022，2022：9068440.
2	王琪，刘江红，韩露，等.油田主要结垢机理及结垢预测模型研究进展［J］.长春理工大学学报（自然科学版），2016，39（1）：129⁃133.
	WANG Q，LIU J H，HAN L，et al.Research progress of the main fouling mechanism and fouling prediction model in oilfield［J］.Journal of Changchun University of Science and Technology（Natural Science Edition），2016，39（1）：129⁃133.
3	穆凯，梁利平，张富畋，等.白豹油田结垢机理与阻垢剂应用效果研究［J］.石化技术，2016，23（11）：236⁃237.
	MU K，LIANG L P，ZHANG F T，et al.Research on scaling mechanism and application effect of scale inhibitors in Baibao oilfield［J］.Petrochemical Industry Technology，2016，23（11）：236⁃237.
4	胡志杰，王小琳，杨娟，等.姬塬油田结垢机理与趋势分析［J］.精细石油化工进展，2013，14（6）：24⁃27.
	HU Z J，WANG X L，YANG J，et al.Analysis on scaling mechanism and tendency in Jiyuan oilfield［J］.Advances in Fine Petrochemicals，2013，14（6）：24⁃27.
5	贾永刚，梁惠萍，李华，等.陇东油田结垢现状及对策研究［J］.石油知识，2019（2）：56⁃57.
	JIA Y G，LIANG H P，LI H，et al.Current status and countermeasures of scaling in Longdong oilfield［J］.Petroleum Knowledge，2019（2）：56⁃57.
6	丁小.压力和温度对三元复合驱中成垢的影响［J］.内蒙古石油化工，2012，38（17）：74⁃75.
	DING X.The influence of pressure and temperature on scaling in ternary composite flooding［J］.Inner Mongolia Petrochemical Industry，2012，38（17）：74⁃75.
7	陈峰，赵春辉，陈朝林.油田注水系统结垢机理研究［J］.油气田地面工程，2006，25（7）：7⁃8.
	CHEN F，ZHAO C H，CHEN Z L.Research on scaling mechanism of oilfield water injection system［J］.Oil⁃Gasfield Surface Engineering，2006，25（7）：7⁃8.
8	KUMAR S，NAIYA T K，KUMAR T.Developments in oilfield scale handling towards green technology-A review［J］. Journal of Petroleum Science and Engineering，2018，169：428⁃444.
9	姜欣欣.碳酸钙结晶动力学研究［J］.西安石油大学学报（自然科学版），2015，30（6）：89⁃92.
	JIANG X X.Study on crystallization kinetics of calcium carbonate［J］.Journal of Xi'an Shiyou University（Natural Science Edition），2015，30（6）：89⁃92.
10	袁野.油田采出水离子对CaCO₃微晶成垢行为的影响［D］.北京：中国石油大学（北京），2018.
11	NIU S W.Research and application of geology and engineering integration for lowpermeability tight oil reservoirs in Shengli oilfield［J］.China Petroleum Exploration，2023，28（1）：14⁃25.
12	JIANG H Y，SUN N N，JU Y Y，et al.Study on the effect of surface properties of non⁃metallic materials on the growth mechanism of crystallization fouling［J］.Processes，2023，11（8）：2232.
13	邓菁玉，韩丰泽，罗晓静，等.面向油田结垢治理的绿色阻垢剂研究进展［J］.当代化工，2022，51（12）：2935⁃2940.
	DENG J Y，HAN F Z，LUO X J，et al.Research progress of green antiscalants for oilfield scaling inhibition［J］. Contemporary Chemical Industry，2022，51（12）：2935⁃2940.
14	王育袭.油田注水开发过程中结垢现象的防治［J］.当代化工研究，2022（14）：85⁃87.
	WANG Y X.Prevention and control of scaling in oilfield waterflooding development［J］.Modern Chemical Research，2022（14）：85⁃87.
15	王永强.南堡油田注水井结垢及治理对策研究［D］.成都：西南石油大学，2016.
16	何举涛，刘伟，程占全，等.环江油田井筒结垢机理研究［J］.石化技术，2022，29（1）：91⁃92.
	HE J T，LIU W，CHENG Z Q，et al.Study on wellbore scaling mechanism in Huanjiang oilfield［J］.Petrochemical Industry Technology，2022，29（1）：91⁃92.
17	凌革，李张洁，李宁博，等.油田开发用绿色阻垢剂的研究进展［J］.油田化学，2022，39（3）：564⁃570.
	LING G，LI Z J，LI N B，et al.Research progress of green scale inhibitor in oilfield development［J］.Oilfield Chemistry， 2022，39（3）：564⁃570.
18	潘岩，吴嫡，薛光亭，等.SZ36⁃1原油加工预处理过程结垢分析［J］.石油炼制与化工，2020，51（11）：99⁃102.
	PAN Y，WU D，XUE G T，et al.Analysis of scaling during the pretreatment process of SZ36⁃1 crude oil［J］.Petroleum Processing and Petrochemicals，2020，51（11）：99⁃102.
19	张学刚.海上油田注水水质分析及结垢腐蚀规律研究［J］.当代化工，2023，52（9）：2119⁃2122.
	ZHANG X G.Study on water quality analysis and scaling corrosion law for offshore oilfield［J］.Contemporary Chemical Industry，2023，52（9）：2119⁃2122.