Transportation and sealing pattern of the temporary plugging ball at the spiral perforation in the horizontal well section

Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However,the transportation and sealing law of temporary plugging balls(TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of perforations.Adjusting the fracturing fluid injection rate from low to high can control the position of the TPBs,improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.

Fracture propagation law of temporary plugging and diversion fracturing in shale reservoirs under completion experiments of horizontal well with multi-cluster sand jetting perforation

This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.

Numerical simulation on the multiple planar fracture propagation with perforation plugging in horizontal wells

Intra-stage multi-cluster temporary plugging and diverting fracturing(ITPF)is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs.However,propagation geometries of multiple fractures during ITPF are not clear due that the existing numerical models cannot capture the effects of perforation plugging.In this paper,a new three-dimensional FEM based on CZM was developed to investigate multiple planar fracture propagation considering perforation plugging during ITPF.Meanwhile,the fluid pipe element and its subroutine were first developed to realize the flux partitioning before or after perforation plugging.The results showed that the perforation plugging changed the original distribution of the number of perforations in each fracture,thus changing the flux partitioning after perforation plugging,which could eliminate the effect of stress interference between multiple fractures and promote a uniform fluid distribution.The standard deviation of fluid distribution in the perforation plugging case was only 8.48%of that in the non-diversion case.Furthermore,critical plugging parameters have been investigated quantitatively.Specifically,injecting more diverters will create a higher fluid pressure rise in the wellbore,which will increase the risk of wellbore integrity.Comprehensively considering pressure rise and fluid distribution,the number of diverters should be 50%of the total number of perforations(N_(pt)),whose standard deviation of fluid distribution of multiple fractures was lower than those in the cases of injecting 10%N_(pt),30%N_(pt)and 70%N_(pt).The diverters should be injected at an appropriate timing,i.e.40%or 50%of the total fracturing time(tft),whose standard deviation of the fluid distribution was only about 20%of standard deviations in the cases of injecting at20%tftor 70%tft.A single injection with all diverters can maintain high bottom-hole pressure for a longer period and promote a more uniform fluid distribution.The standard deviation of the fluid distribution in the case of a single injection was 43.62%-55.41%of the other cases with multiple injection times.This study provides a meaningful perspective and some optimal plugging parameters on the field design during IPTF.

A Comparative Study of Closure of Tympanic Membrane Perforation between Chemical Cauterization and Fat Plug Myringoplasty

The purpose of closure of small dry tympanic membrane perforations is to restore the continuity of the tympanic membrane in order to improve hearing and decrease the incidence of middle ear infections. Small and cost effective procedures like Chemical Cauterization and Fat Plug Myringoplasty have been found to be effective in healing small central perforations with significant hearing improvement. A study was carried out in 69 patients with central perforations in the Department of ENT, Gauhati Medical College & Hospital for the duration of 1 year from August 11 to July 12. Out of 69 patients, 36 underwent Chemical Cauterization and 33 Fat Plug Myringoplasty. Pre-and post-operative hearing assessments of each patient were done and statistically analyzed. The success rate was found to be 83.33% and 90.9% respectively. In both groups, there was statistically significant hearing improvement with a P value 0.01. From our study, it was found that the two procedures are simple, reliable and also lessened the morbidity of the patient. Thus we recommend the use of these two official procedures for the treatment of central perforations of tympanic membrane less than 5 mm.

Oblique perforation of thick metallic plates by rigid projectiles

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.

井筒-射孔-裂缝全耦合双暂堵压裂实验装置研发与应用

为将基于缝间(段内)射孔暂堵球与缝内暂堵剂的“缝间-缝内”暂堵压裂技术转化为实验教学内容,该文设计了井筒-射孔-裂缝全耦合暂堵压裂物理模拟实验装置。装置能够设置泵注压力、排量、射孔参数、裂缝粗糙程度、裂缝宽度等实验条件,开展非常规储层暂堵压裂物理模拟实验,并通过进出口流量监测、多点测压、可视化图像处理等方式对实验结果进行精细化表征,对段内暂堵与缝内暂堵两种压裂辅助工艺进行评价优化。该实验装置占地面积小、操作简便安全、功能丰富,是储层改造技术创新实践平台的重要组成部分。

Calculating minimum perforating depth with consideration of plastic deformation around well-hole

In order to obtain the perforation depth, the three zones with different permeability because of plastic deformation and fluid invasion were studied based on related theories. The study shows that the calculation of perforation depth should take account of not only damaged zone, but also plastic zone, because the plastic zone has much lower permeability. The required minimum perforation depth was obtained by making the solution of elastic/plastic equations, and the factors affecting perforation depth were analyzed accordingly.

海上低渗储层精细分层压裂技术及应用

海上低渗、特低渗储层具有埋藏深、跨度大、薄互层发育、井斜大、射孔段长等特点,常规笼统压裂方式对厚储层纵向改造不充分,产能释放不彻底。提出了以“机械封隔硬分层+暂堵转向软分层”为核心的精细分层压裂技术,将钻井工程参数与录井全烃分析相结合,形成了一套海上低渗储层地质工程甜点预测方法,实现储层纵向甜点识别及压裂层位划分;通过管柱优化设计,形成了多封隔器投球滑套、封隔器+桥塞分层为主的机械硬分层技术;通过优选暂堵球及暂堵优化设计,形成了低、中、高温系列暂堵球为主的暂堵转向软分层技术。该技术现场应用17口井,实现了纵向储层有效改造,增产效果显著,为海上低渗、特低渗储层有效开发提供了技术支撑。

沁水盆地煤层气水平井缝网体积压裂工艺优化研究

从煤层气的解吸机理开展剖析,明确气井的增产是要构建立体的人工缝网,以增加更多的裂缝参与流动。为此首先分析实现人工缝网所需的压裂液体系,认为低粘度压裂液是形成大面积缝网的首要因素;其次,从施工排量、成本控制、安全风险等多方面综合考虑,选取主体压裂工艺为桥射联作;再次就所选压裂工艺进行不断优化,根据现场实际情况设计出沁水盆地南部压裂所使用的施工参数。通过现场试验应用结果表明,该工艺能够满足构建体积缝网的需要,达到了增产的目的,为沁水盆地南部高阶煤煤层气井的压裂增产提供了新思路,为高效开发煤层气提供了新方法。

页岩水平井多簇喷砂射孔暂堵转向压裂裂缝扩展规律

采用真三轴压裂模拟系统开展了页岩水平井多簇喷砂射孔暂堵转向压裂模拟实验,研究了暂堵剂粒径、暂堵剂浓度、单簇射孔数和簇数对封堵提压、多裂缝转向规律及暂堵剂分布的影响。结果表明:缝内小粒径组合+段内大粒径组合暂堵剂有利于提高封堵压力并促进裂缝多期性转向,添加纤维的组合可快速憋压至超高,但易产生沿着井筒扩展的纵向缝;暂堵峰值压力随暂堵剂浓度的增加而提升,但暂堵剂浓度达到一定值后,进一步增加暂堵剂浓度并不能显著提高暂堵峰值压力;岩样破裂压力和暂堵峰值压力随单簇射孔数增加呈下降趋势,较少的单簇射孔数有利于提高破裂压力及暂堵峰值压力,对多簇裂缝扩展的控制作用更显著;较少的簇数不利于人工裂缝总数及复杂程度的提升,较多的簇数难以实现有效封堵。缝内暂堵时暂堵剂主要分布在复杂裂缝区域,特别是多裂缝相交处,而段内暂堵时暂堵剂优先分布于形成复杂缝的射孔簇孔眼附近。

储气库救援井磨料水射流管外开窗试验研究

针对井筒不完整和存在落鱼的废弃事故老井出现井下封堵困难和气窜问题,如何实现有效封堵已成为老井改造储气库的关键。为此开展了储气库救援井磨料水射流钻杆成孔试验。试验结果表明:随着喷射距离的增大,单位时间内钻杆成孔深度显著减小;随着喷射压力的增大,钻杆成孔所需的时间缩短;钻杆成孔所需的最佳磨料质量分数为6%~8%,磨料粒径分布在40~60目范围内,可实现较好的破坏效果。通过正交试验分析认为,钻杆成孔的极限喷距随着喷射压力的增大而增大,随着喷射距离增大而减小;为缩短作业时间,应调整参数为高喷射压力(>25 MPa)和短喷射距离(<20 cm)。所得结论可为现场作业提供技术借鉴。

基于倾角检测仪的水平井定向桥射联作技术

在定向桥射联作施工中,当射孔枪泵送至井下水平段射孔位置后,利用现有技术手段无法检测射孔弹发射口的朝向。通过研制倾角检测仪和全集成定向射孔装置,将选发控制芯片和三轴加速度传感器集成于一体,设计控制电路实现分簇射孔的起爆控制,实时测量射孔弹的方向并上传至地面选发控制系统;当检测到射孔弹方向不正确时,拖动枪串重新泵送使弹架旋转并重新定向,如果射孔弹方向仍不正确,则起出工具串整改后再施工。该技术使得接头与弹架触点连接无需接线,缩短了施工时间,方向测量角度偏差≤2.00°。在F196-XP34井现场应用11段,成功率100%。该技术可应用于所有水平井定向桥射联作,尤其适用于套管外避光纤的射孔工艺,具有较大的推广应用价值。

多簇压裂井射孔技术研究现状及其发展方向

分簇射孔技术是提高非常规油气藏压裂改造效果的关键技术之一。本文介绍了分簇射孔技术的研究现状,并探讨了其发展方向。以主流页岩气储层为例,分析了分簇射孔限流参数应用案例和效果。分簇射孔研究未来发展方向应更多的考虑地质工程一体化,结合人工智能展开精细化分段分簇及限流优化,关注分簇射孔井套变因素及暂堵压裂井射孔优化,研发新型定向和射孔工具。多簇压裂井射孔技术提升可进一步助力压裂改造效果的最大化。

泵送桥塞射孔联作工艺在新疆准南煤田煤层气开发中的应用

随着新疆煤层气井开发的行业发展,煤层气从钻井到排采各个施工工艺都在转变,常规压裂工艺在煤层气井压裂施工中已出现技术限制。泵送桥塞射孔联作工艺具有施工排量大、压裂级数不受限制、施工周期短的优点,在煤层气井体积压裂方面开始广泛应用。采用射孔与桥塞带压联作工艺,通过压裂泵车将工具串送入预定位置坐封,桥塞先行坐封,然后射孔,能够提高施工的效率和压裂改造效果。本文将对此技术采用的主要设备、工艺流程、工艺特点、工艺优化及在新疆准南煤层气开发现场的实际应用情况作出阐述。

平头弹穿透金属靶板的模式分析

对平头弹穿透金属靶的剪切冲塞和绝热剪切冲塞两种可能穿甲模式进行分析.对作者先前提出的绝热剪切冲塞失效模型进一步发展,给出在绝热剪切冲塞条件下修正的终点弹道极限和剩余速度.对相关的平头弹穿甲Weldox E系列钢靶的试验数据进行分析比较,讨论靶板厚度、靶材强度对终点弹道性能的影响.更多实验数据证实:在一定靶厚时由于靶板的结构响应导致弹道极限附近存在剩余速度跳跃;随靶厚和靶材强度增加,穿甲模式由剪切冲塞向绝热剪切冲塞转换.

易钻桥塞射孔联作技术在水平井分段压裂中的实践

四川盆地侏罗系沙溪庙组储层低孔低渗,使用常规改造手段很难获得工业油气流。为此,在G16H井首次开展了电缆带易钻式桥塞分段射孔加砂压裂联作试验,桥塞通过8 mm电缆下入,在水平段通过压裂车进行泵送,到达预定位置后地面给电信号进行坐封,同时桥塞与射孔枪丢手,上提射孔枪依次进行多簇射孔作业,每段分3～4簇射孔,坐封桥塞、射孔、加砂压裂作业最快可在12 h内完成。G16H井共分10段施工,压后利用Ф50.8 mm连续油管成功钻磨Ф114.3 mm套管用桥塞9只,钻磨完单只桥塞平均用时仅60 min左右。该井放喷测试获得了24.7 t/d的高产工业油气流。易钻桥塞射孔联作加砂压裂技术的成功实施,初步探索出针对该低孔低渗区块的一套有效储层改造技术手段,为下一步侏罗系沙溪庙组储层高效开发积累了宝贵的现场经验。

低渗透储层水淹油井堵水压裂技术研究与试验

为了提高水淹油井的单井产量,根据油井不同见水类型,研究形成了不同水淹类型油井堵水压裂技术。针对孔隙性见水油井,研究形成了选择性堵水压裂技术,选择性堵水剂的堵水率是其堵油率的3.3倍,具有较高的选择性封堵能力。针对裂缝性见水油井,研究形成了封堵老缝定向射孔压新缝技术:其裂缝固化剂固化后体积变化小于5%,突破压力高达9.8MPa;定向射孔根据老井剩余油分布情况,选择射孔方位,以控制压裂裂缝延伸方向。现场2口井试验表明,堵水压裂后平均日增油分别为0.81和0.76t,具有较好的增产效果,为长庆低渗透储层水淹油井提高单井产量提供了有效的技术手段。

马58H致密油藏水平井分段多簇射孔压裂技术

马58H井是位于三塘湖盆地马朗凹陷马中地层岩性圈闭的水平探井,属致密凝灰岩油藏,具有高孔低渗、小孔喉、非均质性强的特点,水平井段长804 m。为解决该井压裂作业存在的难题,开展了致密油藏水平井分段压裂技术研究。针对低温井压裂液快速破胶难及施工后对致密油储层的伤害问题,研制出配套的超低浓度、低伤害复合压裂液体系,并通过对裂缝条数、裂缝长度、裂缝导流能力的优化、铺砂浓度与导流能力关系优化、簇间距及孔数优化,采用速钻桥塞分段多簇射孔压裂工艺,顺利完成了该井压裂施工。马58H井分段压裂施工总液量7 755.9 m3,总砂量566.3 m3,最高排量11.2 m3/min,压裂后获得日产131 m3的高产油流,为吐哈油田三塘湖致密油高效开发动用探索了一条新途径。

迪那2气田测射联作完井工艺评价与优化

测射联作工艺具有减少起下管柱作业、降低储层污染、提高油气井完井效率等优点,因此在迪那2气田产能建设早期,普遍采用测射联作并且不丢枪的完井工艺,但投产后逐渐暴露出井筒堵塞、井下动态监测受限等问题,因此有必要对该工艺进行评价及优化。调研统计,产建早期测射联作完井的生产井75%出现油压急剧波动下降的异常现象;结合气藏工程理论及修井实践分析,油压异常的根本原因在于,堵漏剂返排、地层出砂等堵塞了测射联作管柱末端的生产筛管(即打孔油管)孔眼。对此,产能建设中后期采用射孔、测试分步实施的完井工艺,显著减少了井筒堵塞的现象,并为生产动态监测的开展创造了有利条件。迪那2气田的完井工艺实践对于类似气田具有较好的借鉴意义,在选用测射联作完井工艺之前,应进行充分的适用性评价或针对性的改造优化。

水力泵送桥塞压裂技术在长庆油田的应用

长庆油田水平井体积压裂工艺技术迅速发展,但常规的分段压裂技术已不能完全满足体积压裂工艺的需要。水力泵送桥塞分段压裂技术采用射孔和座桥塞带压联作,通过压裂泵车送入水平段预定位置进行座桥塞射孔,提高了体积压裂的效率。在长庆陇东区域开展了5口井的试验,试验表明,水力泵送桥塞压裂技术具有封隔可靠、分段压裂级数不受限制、压裂周期短的特点。水力泵送桥塞压裂技术的成功实施,初步探索出针对该区块的一套有效储层改造技术手段,为下一步陇东区域大规模、高效体积压裂开发积累了宝贵的现场经验。