Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydro...Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.展开更多
为实现煤层气井的定量化排采管控,有效提高单井产气量,以沁水盆地南部马必东试验区高阶煤为研究对象,依据裂缝储层饱和水单相渗流机理,分析了压裂返排后各级裂隙对排水效果的影响,结合压裂与排采数据,探讨了压裂改造范围内的压力传播特...为实现煤层气井的定量化排采管控,有效提高单井产气量,以沁水盆地南部马必东试验区高阶煤为研究对象,依据裂缝储层饱和水单相渗流机理,分析了压裂返排后各级裂隙对排水效果的影响,结合压裂与排采数据,探讨了压裂改造范围内的压力传播特征,将排水区域划分为单相流弹性排水区与两相流弹性排水区,通过建立垂直裂缝线性流拟稳态模型,确定了与试验区地质条件相符的排采控制原则。研究表明:在饱和水单相流阶段,压裂裂缝是水相主要渗流通道,为水相强流动区,100μm级(渗透率1×10-15~1.2×10-15 m 2)外生及微型裂隙对煤层应力、压力传播及气体解吸最为敏感,为水相弱流动区,排采过程中应同时考虑低压力梯度造成的非线性渗流效应与应力敏感作用;排采模型显示:在垂直裂缝拟稳态渗流阶段,储层压力分布呈抛物线型,近井区域产水量高于边界区域,表现为更易发生解吸,单相水流期的渗流阻力主要由煤岩渗透率、排采时间、煤岩压缩系数、裂缝尺寸、压裂改造半径、驱替压力梯度、孔隙压力等多种因素影响,为保证解吸气的连续、高效产出,马必东试验区按照“快-慢-缓”的排采原则,存在合理的排采界限(0.05~0.10 MPa/d);针对高阶碎裂煤,在定流压降幅条件下,产水曲线形态可划分为稳定型、上升型与下降型,同时反映了不同煤储层的供水特性,高产能井解吸前通常出现气驱水尖峰。展开更多
高阶煤层气井低产低效区的普遍存在,已成为制约我国煤层气产业发展的主要瓶颈之一。沁水盆地郑庄区块有2/3的矿井属于低效井,区块整体经济效益差,以郑庄区块为例,剖析造成高阶煤煤层气低效开发问题的影响因素,提出了低效区盘活技术策略...高阶煤层气井低产低效区的普遍存在,已成为制约我国煤层气产业发展的主要瓶颈之一。沁水盆地郑庄区块有2/3的矿井属于低效井,区块整体经济效益差,以郑庄区块为例,剖析造成高阶煤煤层气低效开发问题的影响因素,提出了低效区盘活技术策略和模型。建立了井网部署方式、储层改造适应性技术、高效排采管控方式3个方面的优化技术,形成了适用于高阶煤储层煤层气井增产的技术系列:一是基于开发动态分析和数值模拟的开发井型井网优化技术和水平井耦合降压盘活直井技术;二是基于煤储层特征及煤层气开发机理分析的高阶煤储层疏导式储层改造技术;三是基于煤储层气-水赋存机理和微裂隙气-水流动机理的高效排采管控技术。在此基础上,提出了郑庄区块低效产能带耦合盘活的工艺技术思路:以资源有效动用为核心,通过调整井网井型,采取疏导式储层改造技术和高效排采管控模式,实现低效区带整体协同降压,新井高效开发,老井稳定增产,达到区块整体盘活的效果。建立了低效区整体盘活工艺技术模型,并在郑庄区块进行了现场试验。为期3 a的现场试验取得了显著的开发效果:44口直井平均单井日产气量2 400 m 3 ,是周围老井峰值产气量的3.6倍;22口水平井盘活试验井产量是调整前水平井的4.2倍,耦合降压使得周围低产直井平均单井日产气量提高了435 m 3 ,试验区采气速度由调整前的1.8%提高为目前的7.6%,提高了区域煤层气储量动用程度和采气速度,使区块开发经济效益转亏为盈。该项技术的研发成功,为国内类似地质条件煤层气低效区盘活提供了示范和借鉴。展开更多
基金Supported by the PetroChina Key Science and Technology (2021DJ0703)。
文摘Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.
文摘为实现煤层气井的定量化排采管控,有效提高单井产气量,以沁水盆地南部马必东试验区高阶煤为研究对象,依据裂缝储层饱和水单相渗流机理,分析了压裂返排后各级裂隙对排水效果的影响,结合压裂与排采数据,探讨了压裂改造范围内的压力传播特征,将排水区域划分为单相流弹性排水区与两相流弹性排水区,通过建立垂直裂缝线性流拟稳态模型,确定了与试验区地质条件相符的排采控制原则。研究表明:在饱和水单相流阶段,压裂裂缝是水相主要渗流通道,为水相强流动区,100μm级(渗透率1×10-15~1.2×10-15 m 2)外生及微型裂隙对煤层应力、压力传播及气体解吸最为敏感,为水相弱流动区,排采过程中应同时考虑低压力梯度造成的非线性渗流效应与应力敏感作用;排采模型显示:在垂直裂缝拟稳态渗流阶段,储层压力分布呈抛物线型,近井区域产水量高于边界区域,表现为更易发生解吸,单相水流期的渗流阻力主要由煤岩渗透率、排采时间、煤岩压缩系数、裂缝尺寸、压裂改造半径、驱替压力梯度、孔隙压力等多种因素影响,为保证解吸气的连续、高效产出,马必东试验区按照“快-慢-缓”的排采原则,存在合理的排采界限(0.05~0.10 MPa/d);针对高阶碎裂煤,在定流压降幅条件下,产水曲线形态可划分为稳定型、上升型与下降型,同时反映了不同煤储层的供水特性,高产能井解吸前通常出现气驱水尖峰。
文摘高阶煤层气井低产低效区的普遍存在,已成为制约我国煤层气产业发展的主要瓶颈之一。沁水盆地郑庄区块有2/3的矿井属于低效井,区块整体经济效益差,以郑庄区块为例,剖析造成高阶煤煤层气低效开发问题的影响因素,提出了低效区盘活技术策略和模型。建立了井网部署方式、储层改造适应性技术、高效排采管控方式3个方面的优化技术,形成了适用于高阶煤储层煤层气井增产的技术系列:一是基于开发动态分析和数值模拟的开发井型井网优化技术和水平井耦合降压盘活直井技术;二是基于煤储层特征及煤层气开发机理分析的高阶煤储层疏导式储层改造技术;三是基于煤储层气-水赋存机理和微裂隙气-水流动机理的高效排采管控技术。在此基础上,提出了郑庄区块低效产能带耦合盘活的工艺技术思路:以资源有效动用为核心,通过调整井网井型,采取疏导式储层改造技术和高效排采管控模式,实现低效区带整体协同降压,新井高效开发,老井稳定增产,达到区块整体盘活的效果。建立了低效区整体盘活工艺技术模型,并在郑庄区块进行了现场试验。为期3 a的现场试验取得了显著的开发效果:44口直井平均单井日产气量2 400 m 3 ,是周围老井峰值产气量的3.6倍;22口水平井盘活试验井产量是调整前水平井的4.2倍,耦合降压使得周围低产直井平均单井日产气量提高了435 m 3 ,试验区采气速度由调整前的1.8%提高为目前的7.6%,提高了区域煤层气储量动用程度和采气速度,使区块开发经济效益转亏为盈。该项技术的研发成功,为国内类似地质条件煤层气低效区盘活提供了示范和借鉴。
