Numerical Analysis of Dynamical Effects Associated with a Plugging String in a Horizontal Well

The finite element method has been applied to simulate the dynamics of a water plugging string in a complex horizontal well of a low-permeability oilfield.The force associated with the pipe string and the packer has been determined under the sucking action of the oil well pump.Such analysis has been conducted for a real drilling well,taking into account the process of lifting,lowering,unblocking and water plugging.Comparison between field measured data and simulation data indicates that the model is reliable and accurate.The packer creep effect under different pressure differences has also been investigated in the framework of the same model.

A novel steady-state productivity equation for horizontal wells in bottom water drive gas reservoirs

It is known that there is a discrepancy between field data and the results predicted from the previous equations derived by simplifying three-dimensional（3-D） flow into two-dimensions（2-D）.This paper presents a new steady-state productivity equation for horizontal wells in bottom water drive gas reservoirs.Firstly,the fundamental solution to the 3-D steady-state Laplace equation is derived with the philosophy of source and the Green function for a horizontal well located at the center of the laterally infinite gas reservoir.Then,using the fundamental solution and the Simpson integral formula,the average pseudo-pressure equation and the steady-state productivity equation are achieved for the horizontal section.Two case-studies are given in the paper,the results calculated from the newly-derived formula are very close to the numerical simulation performed with the Canadian software CMG and the real production data,indicating that the new formula can be used to predict the steady-state productivity of such horizontal gas wells.

Remaining Oil Distribution Law and Potential Tapping Strategy of Horizontal Well Pattern in Narrow Oil Rim Reservoir with Gas Cap and Edge Water

For thin oil rim reservoir with gas cap and edge water, it is helpful to improve the development effect to find out the distribution law of remaining oil in this kind of reservoirs. For this reason, taking the narrow oil rim reservoir with gas cap and edge water of Oilfield A in Bohai Sea as a case, the main controlling factors, including reservoir structure, fault, gas cap energy, edge water energy and well pattern, affecting the distribution of residual oil in this kind of reservoir were analyzed by using the data of core, logging, paleogeomorphology and production. Then, the distribution law of remaining oil was summarized. Generally, the remaining oil distribution is mainly potato-shaped or strip-shaped in plane. Vertically, it depends on the energy of gas cap and edge water. For the reservoir with big gas gap and weak edge water, the remaining oil mainly lies in the bottom of oil column. And for the reservoir with small gas gap and strong edge water, the remaining oil mainly locates at the top of oil column. Aiming at different distribution modes of remaining oil, the corresponding potential tapping strategies of horizontal wells are put forward: in the late stage of development, for the reservoir with big gas gap and weak edge water, the remaining oil concentrates at the bottom of the oil column, and the position of horizontal well should be placed at the lower 1/3 to the lower 1/5 of the oil column;for the reservoir with small gas cap and strong edge water, the remaining oil locates at the top of the oil column, and the position of horizontal well should be put at the upper 1/5 to the upper 1/3 of the oil column height, vertically. Based on the study on remaining oil of Oilfield A, a potential tapping strategy of well pattern thickening and vertical position optimization of horizontal well was proposed. This strategy guided the efficient implementation of the comprehensive adjustment plan of the oilfield. Moreover, 18 infill development wells were implemented in Oilfield A, and the average production of the infill wells is 2.1 times that of the surrounding old wells. It is estimated that the ultimate recovery factor of the oilfield will reach 33.9%, which is 2.3% higher than that before infilling wells. This study can be used for reference in the development of similar reservoirs.

Water modeling of molten steel flow in a multi-strand tundish with gas blowing

Fluid flow characteristics in a four-strand tundish with gas blowing were studied by water modeling experiments.It is found that gas blowing can greatly improve the flow characteristics in the tundish with a turbulence inhibitor.It dramatically increases the peak concentration time,and greatly decreases the dead volume,and reduces the minimum residence time.The gas blowing location,gas flow rate,and porous plug area greatly influence the flow characteristics in the tundish; the gas blowing location near the baffle,smaller gas flow rate,and smaller porous plug area are better for improving the fluid flow characteristics.Using gas blowing can reduce the difference of flows at the middle outlets and side outlets for the multi-strand tundish.Bubbles produced by gas blowing can absorb small inclusions and provide the condition for inclusion collision and aggregation.Therefore,introducing gas blowing into a tundish and combining the turbulence inhibitor can improve inclusion floating and removal,and the cleanness of molten steel can be advanced.

Study on the Critical Production Calculation Method of the Water-Flooding Reservoir with Gas Cap

The aim of this paper is to solve the problems that the existing method of critical production of gas cap reservoir is only suitable for single-phase flow, and the method of critical production of gas cap reservoir under water-flooding is still blank. In this paper, the relationships between dynamic and static equilibrium, plane radial flow theory, oil-water infiltration method and three-dimensional seepage field decomposition theory, were applied to study a calculation method for critical production of directional wells and horizontal wells. Furthermore, the effects of different factors on critical output were studied, such as horizontal permeability, ratio of horizontal permeability to vertical permeability, length of horizontal section, effective thickness, viscosity of crude oil and water content etc. Results show that the critical production increases with the increment of the horizontal permeability, the ratio of the vertical permeability to the horizontal permeability, the reservoir thickness and the horizontal well length;when the viscosity of crude oil is small, the critical production decreases first and then increases with the increase of water content;when the viscosity of crude oil is high, the critical production increases continuously with the increase of water content. This study could provide theoretical and technical guidance for changing of the working system of oil wells. It can avoid gas channeling and improve the development effect.

Investigation of low water recovery based on gas-water two-phase low-velocity Non-Darcy flow model for hydraulically fractured horizontal wells in shale

Various mechanisms are employed to interpret the low water recovery during the shale-gas production period,such as extra-trapped water in the fracture network,water imbibition due to osmotic pressure and capillary pressure.These lead to the difficulty of water flow,which could be described by lowvelocity non-Darcy's law known as threshold pressure gradient(TPG).In this paper we firstly employ the low-velocity non-Darcy's law to describe the water flow and use Darcy flow accounting for slip flow and free molecular flow mechanisms to model gas flow in the shale formation.The sensitive study using numerical simulation shows that the proposed flow model could model the low fracturing liquid recovery and that large pseudo TPG leads to lower fracturing liquid recovery.Thus,the proposed model would give new insight to model the low water recovery in shale formations.

用于稠油热采井的耐温凝胶堵剂研制与评价——以春光油田为例

针对河南春光油田稠油热采水平井水窜严重的问题,通过耐高温凝胶堵剂配方研究及性能评价,配套双封定位封堵工艺,实现了水平井不同水窜位置的有效封堵。所研制的耐高温凝胶堵剂,具有耐温耐盐性能好和封堵强度高的特点,耐盐1.00×10^(5)mg/L,耐温达到350℃,高温60 h后突破真空度仍保持在0.065 MPa以上,现场实施后有效延缓了稠油水平井水窜速度,改善了稠油热采水平井开发效果。

峰峰矿区突水特点及定向水平井封堵技术研究

煤矿底板突水常采用注浆封堵治理方法,而受开采历史技术条件的限制,遗留了很多传统方法无法封堵的突水点,时刻威胁矿井的安全生产。基于峰峰矿区的水文地质特征,对各突水点进行分类,分析突水的主要影响因素。通过数值分析和现场实践,研究了灰岩含水层浆液扩散规律,确定了适合峰峰矿区的堵水材料参数。研究表明,峰峰矿区突水事故由多种因素耦合作用引起,主要突水水源为大青灰岩水和奥陶系灰岩水,大型及特大型突水占比接近50%;突水通道以底板采动裂隙和正断层断裂带为主,采用定向水平井封堵时,水平段应距断层面小于30 m,充填骨料粒径范围宜为1~40 mm。提出的水平井“查—钻—注—检”快速封堵突水点方法应用于牛儿庄矿特大型突水点残余水量治理中,彻底有效封堵了突水通道,为我国大水矿区老突水点的高效封堵治理提供了技术手段。

水平井找水方法及堵水技术综述

水平井在提高油气井产能方面具有明显优势,但受油藏非均质性影响,在边底水油藏或水驱油藏的开发过程中水平井出水情况较为常见,给油田高效开发带来巨大挑战。因此,有效的找水和堵水技术是改善水平井开发效果的重要手段之一。针对水平井出水识别难的问题,全面总结了动态验证、机械找水、测井找水和示踪剂找水等水平井找水方法的特点和现场应用情况,并对水平井找水、堵水方法存在的问题及发展方向进行了分析。该研究可为高含水低效水平井找水和堵水工作提供借鉴。

帅页3-7HF页岩油小井眼水平井水基钻井液技术

帅页3-7HF井是部署于苏北溱潼区块的一口页岩油Φ118 mm小井眼侧钻水平井。在施工过程中面临着页岩地层井壁失稳、小井眼环空压耗大,易于漏失、水平井降摩减阻要求高、CO_(2)污染等诸多难题。通过研究,构建了页岩水基钻井液体系SM-ShaleMud-Ⅱ。室内评价表明,该体系具有优异的抑制能力、封堵性能和润滑性能,能够满足苏北页岩油长水平井对钻井液性能的要求。现场试验表明,页岩水基钻井液体系高温高压滤失量小于7 mL,体系黏附系数小于0.07,完钻起钻摩阻小于16 t,有效保持了阜二段页岩储层井壁稳定达110 h,改变水基钻井液对阜二段浸泡时间的认知。该井创页岩地层Φ118 mm小井眼裸眼段1948.66 m最长,水平段1361.66 m最长等多项记录,其施工经验可为后续超小井眼长水平井施工提供参考,也为页岩水基钻井液SM-ShaleMud-Ⅱ在苏北页岩油大规模应用奠定了基础。

基于自乳化保护的水平井选择性堵水方法及其在南海东部P油田的应用

针对海上油田水平井控水成本高,化学堵水成功率低,部分油井堵水作业后产液量大幅降低等问题,提出了一种基于自乳化保护的水平井化学堵水方法。通过自乳化保护液的注入对含油储层进行保护,避免后续堵剂污染含油储层,实现选择性堵水。提出现场注入工艺参数及堵水药剂性能设计原则,实现水平井不找水堵水。与传统化学堵水技术相比,该技术无需找水作业、现场施工工艺简单,通过药剂性能及施工参数控制,堵水体系可定向封堵出水层位,有效提高化学堵水的成功率并降低作业成本。研究表明,基于自乳化保护的堵水技术体系性能与施工工艺参数设计可实现选择性不找水堵水,保护液体系可对水平井含油储层形成有效保护,避免堵剂对含油储层的污染。室内实验表明堵水后水驱采收率提高29.58个百分点。研究结果应用于南海P油田,控水稳油效果良好。

新沟致密油水平井水基钻井液性能优化评价

新沟油区水平井的水平段短,且目前现场所用混油硅酸盐体系会出现井径扩大率偏大现象,对于水平井施工具有较大潜在风险,为此,研制出一种多功能抑制封堵剂,以优化混油硅酸盐体系的抑制性、润滑性和封堵性,优化后的混油硅酸盐体系的各项性能均达到了新沟油区致密油1500米以上水平井钻井作业需求对钻井液的性能要求。同时,为提高后续致密油长水平井开发的高润滑、强抑制、优良经济性等,研制出了低油水比油基钻井液体系。针对该油区优化和研制的两种钻井液体系,有效保持井壁稳定和井下安全,为该区块致密油藏后续的低成本、高效开发提供了技术支持。

海上油田水平井底水脊进控制技术

对南海涠洲11-4油田C4水平井底水脊进的原因进行了分析,提出利用选择性堵剂和选择性注入及过顶替的方法来控制底水脊进。根据涠洲11-4油田的地层条件,选择性堵剂可选用廉价的具有不同成冻时间及不同强度的冻胶型堵剂并利用地层渗透率的差异和相渗透率的差异进行选择性注入,即堵剂优先进入高渗透层,水基堵剂优先进入出水层;过顶替是用粘度与堵剂粘度相当的流体将堵剂顶替至水平井的油水界面,从而为原油留下更好的产出通道。现场试验证实,该方法应用效果很好,C4井有效期超过一年;该平台其他3口井也相继投产,平台最高产油量达到147.1m3/d。截止到2004年8月,累计产油12913m3,投入产出比为1∶16。

割缝衬管水平井堵水技术现状及发展趋势

割缝衬管是目前国内外水平井完井的主要方式,该类复杂结构井的堵水工作对于其整体开发效果的提高具有重要意义。对相关堵水技术现状进行了分析,指出环空封隔(ACP)定位注入技术可有效克服堵剂笼统注入的局限及风险,是适合割缝衬管水平井结构特点的堵水新思路。但目前环空封隔材料的性能尤其是触变性制约了该技术的进一步发展。在总结探讨存在问题的基础上,提出应结合国内水平井结构及施工工艺特点,建立相应技术标准,开发高性能环空封隔材料,进而为割缝衬管水平井堵水技术的发展、突破奠定基础。另外,应结合国内水平井所处油藏条件苛刻的实际,进一步开展抗温抗盐、选择性堵剂的研究。

XAN-SP筛管水平井环空化学封隔器研究

为提高水平井开发效益,解决筛管水平井找水、控水和堵水的技术难题,研制了筛管水平井环空化学封隔器(ACP)。针对ACP材料的触变性、管外填充形状稳定性和封隔强度等3大技术难点,研制了新型XAN-SP环空化学封隔器材料。通过持压强度、流动性和剪切强度试验,评价了XAN-SP浆体的触变性能、胶凝强度和填充形态稳定性;在XAN-RC封堵模拟试验流程中测定了XAN-SP胶塞的封隔强度和膨胀性能;模拟ACP在现场实施的实际工况,设计了三种模拟试验流程,研究了XAN-SP环空化学封隔器技术在现场实施的工艺参数。试验结果表明,XAN-SP是一种触变性强、填充形状稳定性好、封隔强度高的新型ACP材料。现场试验表明,通过模拟试验流程确定的ACP施工参数能够保证现场施工的安全顺利进行。

挤注封堵管柱在塔河油田水平井的应用

针对水平井生产过程中,因层间窜通、管外窜、边底水锥进等原因造成高含水的问题,在已有成熟的直井段挤注、封堵管柱工艺的基础上,对挤注桥塞、可钻桥塞、坐封工具及管柱工艺进行了改进,研发了以挤注桥塞及防中途坐封桥塞为核心工具的水平井挤注、封堵管柱工艺。2口井的挤注试验和8井次封堵试验表明,水平井挤注、封堵管柱工艺是解决层间窜通、固井质量不好等问题行之有效的手段。该技术为适应水平井井况而特殊设计,减少了管柱施工的时间、成本和风险,可视情况单独或组合使用,可对高含水层及管外窜进行有效挤注、封堵作业。

水平井预置速凝堵剂管外封窜技术

针对水平井管外窜漏产生的高产液、高含水、低产油现象,为解决常规封窜堵水措施施工工艺复杂、风险高、周期长、效果差等问题,研制了一种水平井预置速凝堵剂管外封窜技术。该技术利用预置速凝堵剂对水平井管外进行分段封隔,且挤注完成后通道自动关闭,无过顶替或顶替不到位等问题,具有施工简单快速,预置速凝堵剂剂量准确、用量少,封隔强度高,安全可靠等特点。该技术在冀东油田浅层水平井成功应用3井次,综合含水降低10个百分点,达到了控水稳油的目的。该技术可用于水平井及大斜度井管外封窜,具有广泛的应用前景。

塔河砂岩油藏水平井出水分析及配套堵水工艺

随着油田的规模注水和深入开发,塔河油田砂岩油藏整体已经进入中、高含水开发阶段,堵水逐渐成为水平井开发后期稳产增产的主要措施之一。找水是堵水的前提,但受成本和井筒条件复杂等因素的影响,不可能对所有井进行仪器找水作业;因此,有必要基于出水分类特征开展综合分析,为堵水和含水分析提供理论依据。文中在分析物性因素出水的基础上提出饱和度因素出水类型,通过典型井例分析,将其分为油水过渡带抬升出水和局部物性饱和度因素出水,并初步配套形成乳状液堵剂、相渗调节剂和有机冻胶饱和度出水堵剂系列,以及降压增注和暂堵保护2种堵水工艺。水平井堵水的堵剂优选和工艺优化,对解决水平井低产低效问题,实现有效控水、提高整体注水利用率具有重要的现实意义。

筛管水平井堵水材料的研制与评价

环空化学封隔器(ACP)技术是有效分隔筛管完井水平井水平段环空的工艺手段,但是其核心ACP材料的性能仍有待于进一步完善。针对常规堵水材料强度低、环空充填不完全和降解难的问题,研制了一种筛管水平井堵水用高强度可降解ACP材料,其采用瓜胶和甘露聚糖酶等作为封隔材料组分,突破了HPAM基凝胶材料的局限。实验研究了其胶凝、环空充填和降解等特性,并借助全尺寸筛管水平井模型和现场试验,验证了其应用于水平井堵水环空封隔的可行性。

低产液量水平井找堵水管柱的设计与应用

针对长庆油田致密油藏低产液量水平井利用现有测试方法无法准确找到出水层的情况,设计了适用于不同地层压力的低产液量水平井找水测试管柱,同时针对不同出水位置设计了桥塞卡堵水管柱和封隔器卡堵水管柱。低产液量水平井找水测试管柱在长庆油田应用21井次,找水有效率96.7%;两种卡堵水管柱堵水在长庆油田应用22井次,堵水成功率达到81.8%。这表明,利用所设计的低产液量水平井找水测试管柱,能准确找出低产液量水平井的出水层段,所设计的卡堵水管柱能对不同位置的出水层段进行机械封堵。