Critical weight on bit of double-driven bottomhole assembly during vertical and fast drilling

It is difficult to determine the optimal weight on bit (WOB) of the double-driven bottomhole assembly (DD-BHA, with double stabilizers and a bent housing positive displacement motor (PDM)) which is employed during vertical and fast drilling. High WOB leads to well deviation out of control, and low WOB leads to low rate of penetration (ROP). So considering the rock physical properties, the anisotropy index function of polycrystalline diamond compact (PDC) bit was derived with the structure and cutting performance parameters of the bit, and the effect of natural hole deviation tendencies on the performance of DD-BHA resisting deviation was represented. The concept of elliptic deformation ratio was used to characterize the performance of DD-BHA resisting deviation. Eventually, a model calculating the critical WOB was established. By comparing the model predictions with the measured hole angle changes in the field, the results show that the model predictions are accurate with error less than 5.8%, which can meet the operational requirements in the projects. Furthermore, the model was adopted to justify and guide the operating conditions and parameters during drilling, which shows that the optimum WOB predicted by the model can not only control deviation but also improve ROP effectively. The model is independent on the formation characteristics of blocks, so it can be expanded widely to other oilfields.

Estimating rock properties using sound signal dominant frequencies during diamond core drilling operations

In many engineering applications such as mining,geotechnical and petroleum industries,drilling operation is widely used.The drilling operation produces sound by-product,which could be helpful for preliminary estimation of the rock properties.Nevertheless,determination of rock properties is very difficult by the conventional methods in terms of high accuracy,and thus it is expensive and timeconsuming.In this context,a new technique was developed based on the estimation of rock properties using dominant frequencies from sound pressure level generated during diamond core drilling operations.First,sound pressure level was recorded and sound signals of these sound frequencies were analyzed using fast Fourier transform (FFT).Rock drilling experiments were performed on five different types of rock samples using computer numerical control (CNC) drilling machine BMV 45 T20.Using simple linear regression analysis,mathematical equations were developed for various rock properties,i.e.uniaxial compressive strength,Brazilian tensile strength,density,and dominant frequencies of sound pressure level.The developed models can be utilized at early stage of design to predict rock properties.

Stage identification and process optimization for fast drilling EDM of film cooling holes using KBSI method

Fast drilling electrical discharge machining(EDM)is widely used in the manufacture of film cooling holes of turbine blades.However,due to the various hole orientations and severe electrode wear,it is relatively intricate to accurately and timely identify the critical moments such as breakout,hole completion in the drilling process,and adjust the machining strategy properly.Existing breakout detection and hole completion determination methods are not suitable for the high-efficiency and fully automatic production of film cooling holes,for they almost all depend on preset thresholds or training data and become less appropriate when machining condition changes.As the breakout and hole completion detection problems can be abstracted to an online stage identification problem,in this paper,a kurtosis-based stage identification(KBSI)method,which uses a novel normalized kurtosis to denote the recent changing trends of gap voltage signals,is developed for online stage identification.The identification accuracy and generalization ability of the KBSI method have been verified in various machining conditions.To improve the overall machining efficiency,the influence of servo control parameters on machining efficiency of each machining stage was analyzed experimentally,and a new stage-wise adaptive control strategy was then proposed to dynamically adjust the servo control parameters according to the online identification results.The performance of the new strategy is evaluated by drilling film cooling holes at different hole orientations.Experimental results show that with the new control strategy,machining efficiency and the machining quality can be significantly improved.

Effect of reprocessing on neutrons of a molten chloride salt fast reactor

Due to their unique features,such as the inherent safety,simplified fuel cycle,and continuous on-line reprocessing,molten salt reactors(MSRs)are regarded as one of the six reference reactors in the Generation IV International Forum(GEN-IV).Molten chloride salt fast reactors(MCFRs)are a type of MSR.Compared to molten fluoride salt reactors(MFSRs),MCFRs have a higher solubility of heavy metal atoms,a harder neutron spectrum,lower accumulation of fission products(FPs),and better breeding and transmutation performance.Thus,MCFRs have been recognized as a type of MSR with great prospects for future development.However,as the most important feature for MSRs,the effect of different reprocessing modes on MCFRs must be researched in depth.As such,this study investigated the effect of different isotopes,especially FPs,on the neutronic performance of an MCFR,such as its breeding performance.Furthermore,the characteristics of the different reprocessing modes and MCFR rates were analyzed in terms of safety,radioactivity level,neutron economy,and breeding capacity.In the end,a reprocessing method suitable for MCFRs was determined through calculation and analysis,which provides a reference for the further research of MCFRs.

Primary Breeding Ratio Analysis of an Improved Supercritical Water Cooled Fast Reactor

The purpose of the study is to analyze the breeding ratio of a supercritical water cooled fast reactor (SCFR) and to increase the breeding core of SCFR. The sensitivities of assembly parameters, core arrangements and fuel nuclide components to the breeding ratio are analyzed. In assembly parameters, the seed fuel rod diameter has higher sensitivities to the conversion ratio (CR) than the coolant tube diameter in blanket. Increasing heavy metal fraction is good to CR improvement. The CR of SCFR also increases with a reasonable core arrangement and Pu isotope mass fraction reduction in fuel, which can achieve more negative coolant void reactivity coefficient at the same time. The breeding ratio of SCFR is 1.03128 with a new core arrangement. And the coolant void reactivity coefficient is negative, which achieves a fuel breeding in initial fuel cycle.

超深井工程理论与技术若干研究进展及发展建议

超深井工程受到高温高压、复杂地层、超长井眼和腐蚀介质等多重因素约束,其安全高效作业面临全方位的技术挑战。为此,针对超深井工程的安全高效设计控制问题,介绍了该工程的发展概况与技术特点;选取井眼轨迹预测与防斜打快、钻柱振动特性分析与减振控制、钻井延伸极限预测与设计控制,以及套管失效风险评估与安全控制等几个重要理论与技术问题,介绍了国内外的相关研究进展及笔者团队的最新研究成果;然后,针对超深井工程提出了若干创新发展建议。研究结果表明,超深井工程理论与技术的发展整体呈现出体系化、科学化、多学科交叉、地质与工程一体化等基本特点。建议在基础理论问题、关键核心技术、技术协同关系、技术迭代模式和多学科交叉融合等方面加强创新研究,以持续推进超深井工程基础理论与关键技术创新发展。

复兴地区页岩油优快钻井技术

川东复兴地区侏罗系湖相、河流相砂泥岩储层发育,油气类型为凝析油、页岩气同产,该区陆相页岩油气水平井具有大井眼、井段长、造斜困难、地层压力安全窗口窄、水平段可钻性差、轨迹控制难、水平段易垮塌等难点。通过井身结构、钻井方式、提速工具、轨迹控制、钻井液类型、完井方式等进行技术集成与优化。结果表明:通过二开井身结构、强化参数钻井、PDC钻头+预弯曲钻具组合、强封堵油基钻井液、旋转导向钻井、不承压防漏固井等关键技术,克服井壁失稳、水平段可钻性差、漏溢转换频繁等复杂情况,提高了钻井效率,节约了钻井周期,形成了一套适合复兴地区页岩区块的优快钻井技术,为该区后续水平井勘探开发提供了借鉴。

塔河地区特深井底部钻具组合力学模拟分析研究

特深层油气资源的高效开发对保障国家能源安全、实现能源接替具有重要意义,是当前油气勘探开发的重点领域。塔河地区油气资源丰富、埋藏深,勘探潜力巨大。为解决特深井钻探面临井底高温致使垂钻系统无法使用、常规钻具防斜能力弱、钻速低等难题,基于广义纵横弯曲法、钻头-地层相互作用模型评价了邻井钻具防斜性能,反演了地层倾角、走向、各向异性系数。为特深井TS-X井提供现场支撑,针对寒武系与震旦系地层特性分析不同BHA结构对井斜影响效果,设计了包含螺杆钻具的底部钻具组合,并形成了最优结构方案。现场施工中代入实钻数据实时预测钻具防斜能力,形成了最优钻压参数方案。实钻结果表明,使用设计钻具具有防斜效果好、钻速快等优点,验证了模型的正确性和优化设计的合理性。研究结果对塔河地区其他特深井安全高效钻探、实现防斜打快具有重要指导意义。

鄂西地区二叠系页岩气钻完井难点及对策

鄂西地区二叠系优质页岩发育、有机质丰度高、资源潜力大,但受地表地下双复杂地质条件的制约,十三五期间区内始终未实现页岩气商业开发。为找寻区内有效储层实现鄂西商业突破,进而率先打开湖北页岩气开发阵地,江汉油田相继在石柱复向斜建南构造二叠系吴二段历时3年部署12口勘探评价井。围绕吴二段“一薄三复杂”特征,地质上采用边摸索边研究边实践的精细工作思路,工程上采用边实践边研究边提效的精准优快迭代方法。通过12口井的钻井—压裂—试采一体化研究,逐步认清二叠系吴二段储层地质特征,形成复杂岩相薄层页岩全息储层精细表征技术,完成了页岩气储层全尺度综合评价,稳步优化二叠系井身结构设计技术,研选了高效破岩钻头钻具组合,研发了防漏防塌防储层伤害的钻井液体系,配套了小井眼窄间隙固井技术,形成页岩优快钻完井技术,实现安全成井率100%;揭示了高模量多灰岩夹层页岩的成缝机制,构建了以“降压促缝、动态控滤、控近扩远”为核心的压裂工艺技术,建立了“实施评估—动态调整”的工艺迭代调整技术,形成了页岩精准压裂技术,压后成藏率100%。勘探开发率先实现了国内二叠系新层系页岩气重大突破,获得了薄层复杂岩相页岩稳定工业气流,湖北省页岩气规模超千亿方增储,为中国非常规能源勘探在新层系方面实施勘探开发提供“湖北经验”,技术成果应用于鄂西渝东地区,推广应用效果好。

深层煤层气水平井安全钻井技术

针对吐哈盆地深层煤层气的勘探,前期以直井试采为主,水平井的钻井技术仍处于探索阶段。由于该区块属于高陡斜坡区、煤系地层发育,导致直井段井斜易超标、煤系地层的井眼井壁易失稳、水平井井段的轨迹难以控制及固井质量差等问题,文章通过分析高陡斜坡区提速限制因素,引入自动垂钻系统,形成直井段防斜打快技术,解决了高陡斜坡区防斜和大钻压快速钻进的矛盾;分析煤层井壁失稳机理,开展浸泡实验,优选了胺基有机盐钻井液体系,提高抑制性和封堵固结井壁性能,强化了煤系地层井壁稳定;结合深层煤层三压力剖面预测数据优化井身结构及轨迹控制,设计防卡PDC钻头和钻具组合,配套强抑制、强封堵性胺基有机盐钻井液,实现了煤层水平段安全延伸;强化钻井参数,应用岩屑清洁工具和个性化通井钻具组合,提高了井眼清洁效率;优化套管选型、扶正器配置及水泥浆体系,保障了固井质量。该系列技术为实现吐哈盆地深层煤层气水平井安全高效钻探奠定了基础。

铝土岩水平井快封堵防塌钻井液技术

陇东铝土岩属于长庆油田重要的资源接替储层,近期完试的陇**井、宁**井在太原组铝土岩勘探获得重大突破。针对该类储层溶孔和裂缝发育,井壁垮塌、漏失风险高及井眼清洁能力差的技术难题,通过铝土岩物性参数、理化性能、力学性能和敏感性测试分析等,明确了陇东铝土岩主要坍塌因素,研发出适用于铝土岩安全钻进的快封堵防塌钻井液技术。该体系在170℃高温高压滤失量小于10 mL,钻井液二次回收率大于91%,铝土岩样品在钻井液体系中浸泡15 d后和清水浸泡15 d后的抗压强度相比提升81.8%。快封堵防塌钻井液技术在长庆首口铝土岩水平井陇4**井进行了试验应用,助力该井700 m水平段的安全钻进,该井投产获日产无阻流量3.53×10^(6)m^(3)高产气流,创鄂尔多斯盆地上古生届勘探开发50多年新纪录,为该类储层的勘探开发提供了技术支撑。

A pre-generated matrix-based method for real-time robotic drilling chatter monitoring

Currently, due to the detrimental effects on surface finish and machining system, chatter has been one crucial factor restricting robotic drilling operations, which improve both quality and efficiency of aviation manufacturing. Based on the matrix notch filter and fast wavelet packet decomposition, this paper presents a novel pre-generated matrix-based real-time chatter monitoring method for robotic drilling. Taking vibration characteristics of robotic drilling into account, the matrix notch filter is designed to eliminate the interference of spindle-related components on the measured vibration signal. Then, the fast wavelet packet decomposition is presented to decompose the filtered signal into several equidistant frequency bands, and the energy of each sub-band is obtained. Finally, the energy entropy which characterizes inhomogeneity of energy distribution is utilized as the feature to recognize chatter on-line, and the effectiveness of the presented algorithm is validated by extensive experimental data. The results show that the proposed algorithm can effectively detect chatter before it is fully developed. Moreover, since both filtering and decomposition of signal are implemented by the pre-generated matrices, calculation for an energy entropy of vibration signal with 512 samples takes only about 0.690 ms. Consequently, the proposed method achieves real-time chatter monitoring for robotic drilling, which is essential for subsequent chatter suppression.

旋挤钻法在软土及砂土地层施工灌注桩的研究

研究目的:采用常规旋挖钻法在地下水丰富的黏土地层和软土及砂土地层施工的灌注桩,部分灌注桩因坍孔出现扩径和缩径,扩径浪费混凝土,缩径使灌注桩不合格,由此提出把旋挖钻法改进为旋挤钻法,达到灌注桩轻微扩径不缩径不浪费混凝土的完整合格桩,本文对其展开研究。研究结论:(1)把旋挖钻法钻斗的慢速重钻改进为旋挤钻法钻斗的快速轻钻可行,可减小振动,挤密孔壁土,预防孔壁坍孔;(2)旋挤钻法成孔对于地表浅部极易坍孔地层用长护筒护壁,且护筒长度要大于极易坍孔地层厚度,对于易坍孔和不易坍孔地层用比重1.25和1.15等指标的泥浆护壁,且泥浆护壁是以垂直式的可控泥浆和离心力水平式的扰动土混合泥浆共同作用于护壁,迫使孔内部分扰动土与泥浆粘黏旋挤进入孔壁内,孔壁得到加固稳定不坍孔;(3)采用旋挤钻法在地下水丰富的黏土地层和软土及砂土地层施工的灌注桩,灌注混凝土充盈系数为1.02~1.03和1.04~1.05,均达到轻微扩径不缩径不浪费混凝土的完整合格桩;且成孔效率高,可减少污染、节约成本;(4)本研究成果可为铁路、公路等领域提高混凝土灌注桩施工质量提供参考。

柯柯亚深层煤岩气水平井钻井实践

吐哈盆地侏罗系煤岩天然气区块位于山前高陡构造,地层倾角大,地质条件复杂,为国内陆地埋藏最深的煤岩气气藏,煤层水平井钻探技术在该领域尚属空白,钻井过程中“斜、慢、阻、卡”矛盾突出,亟须开展煤岩气水平井钻完井技术研究。为此,针对井身结构优化、井眼轨道优化、防斜打快技术、煤层坍塌机理、水平段安全钻完井开展了深入分析研究,柯新1H先导试验结果表明:①大三层井身结构可以满足水平井安全钻进,但具有较大的优化潜力;②垂直钻井技术在2500 m以浅的煤上地层应用效果佳,为中上部地层防斜打快提供了技术手段;③技术套管下深的确定是关键,是保障水平段能否成功实施的基本条件;④水平段通过多靶点轨道设计、随钻岩性追踪、无扶单弯螺杆+缩小底部钻具外径、双向通井工具、强抑制强封堵钻井液等手段降低卡钻风险,在煤层起伏变化大的情况下,确保了千米长水平段钻进与下套管作业顺利实施。

适用于航天控制系统零件精密内孔加工的高效电火花铣削技术

高效电火花铣削技术着眼于提升航天控制系统精密零件内孔加工的效率与精度,通过将高速电火花加工方法与传统铣削工艺相融合,突破传统电火花加工内孔需制备对应形状电极、加工效率低、几何精度差、再铸层厚度难以控制的限制,从电极损耗补偿和自适应过程控制、实时速度控制及轨迹规划、再铸层与表面质量控制方法等三方面出发,探索高效电火花铣削加工在复杂孔系壳体类、精密轴套类以及功能微孔类零件加工中的应用。该方法与传统电火花成形加工精密内孔相比,可将加工效率提升65%,同时最高可降低87.17%的再铸层厚度值,实现了精密内孔加工效率、质量与成本的多重提升。随着高效电火花铣削技术在精密加工中的广泛应用,将大幅提高航天控制系统关键零部件的制造能力,同时能够为日益增多的零件种类以及日益复杂的零件结构,提供更加全面的工艺解决方案。

王坡煤矿碎软煤层气动定向高效成孔工艺研究

针对王坡煤矿碎软煤层区域瓦斯治理的需求,对现有气动定向钻进工艺及装备进行优化升级。通过对气动螺杆钻具升级改造,将额定扭矩提升至450 N·m以上;研制的89 mm低风阻螺旋通缆钻杆配套有线通缆测量系统,施工孔深提升至300 m以上;基于“波浪式”精准探测煤层顶底板钻孔轨迹工艺,从侧钻开分支原理出发,改进钻具造斜强度实现快速开分支;系统性分析气动定向工艺在不同地层钻进时轨迹变化特点,形成精准轨迹控制技术,大幅提升施工效率。现场试验期间,共计完成34个主孔,49个分支孔,总进尺17 287 m,平均成孔深度350 m,平均日进尺103 m/d,最高154 m/d,钻孔平均瓦斯抽采体积分数60%以上,百米钻孔抽采纯量是邻近区域普通钻孔2.7倍。

巴彦油田深层欠压实地层定向井优快钻井技术

巴彦油田地层沉降快速、欠压实,且岩性复杂,储层埋深超4000 m,平均井深超5000 m,钻井施工过程中易发生井壁失稳、定向井机械钻速慢、轨迹不易控制等问题,建井周期长达54.96 d。为此,开展了井眼轨道优化、个性化钻头优化设计、降摩减阻提速工具应用、钻井参数和钻井液性能优化。研究结果表明:1.2(°)/30 m降斜率利于研究区钻井施工;五刀翼PDC钻头浅内锥、异型齿和后排减震齿设计,可提升抗冲击能力,提高机械钻速;“水力振荡器+钻柱扭转控制系统”及“旋转导向+低速大扭矩螺杆”可以提高定向段机械钻速50%以上;“低钻压、高转速、大排量”的工程参数可使上部乌兰图克组地层提速9%以上,“高钻压、高转速、低排量”的工程参数使深部五原组、临河组地层提速14%以上;聚合物钻井液体系配合微纳米封堵剂,解决了井壁失稳复杂情况。现场应用11个平台90口井,平均机械钻速提高了8.89%,建井周期缩短23.94%。优快钻井技术推动了巴彦油田兴华1区块钻井大幅度提速,为同类油气藏快速建井、加快产能建设提供了借鉴。

预弯曲动力学防斜打快技术在塔里木盆地台前区应用研究

塔里木盆地直井段井斜不易控制,严重影响油气资源的经济高效开发。通过分析塔里木盆地台盆区井斜不易控制的地质原因,建立数学和数值计算模型优化设计预弯曲动力学防斜打快底部钻具组合和配套钻头,结合现场实际制定防斜打快施工方案。结果显示:志留系下部-桑塔木组等大倾角地层及裂缝广泛发育是直井易斜的主要地质原因;钻具组合弯角、弯角到下扶正器距离、弯角到上扶正器距离逐渐增大,降斜力先增大后减小最后趋于平稳,分别在0.9°~1.25°,0.5~0.7 m和4~6 m取得极值。PDC钻头造斜能力随保径长度和宽度的增加减弱,随保径倾角、内锥角、冠部旋转半径和高度的增大而增强。研究成果在塔里木盆地TK4-3X等井现场应用9口井,井斜控制良好,平均机械钻速较邻井同开次提高45.68%,实际钻井周期较设计周期累计节约周期105.64天,平均周期节约率21.43%。

曲9区块水平井钻井液优快钻井技术

曲9区块明化镇组和馆陶组地层沉积较厚,地层发育大段易水化软泥岩。水平井钻进过程中钻井液井壁稳定、井眼净化、润滑防卡和储层保护技术难度大。通过优选聚合醇润滑防塌钻井液体系,辅助现场钻井液维护处理工艺,保证了该区块3口水平井的顺利施工,钻完井时效较前期施工井有明显提高,达到了优快钻井的良好效果。

川西新场构造带须二段致密气藏定向井优快钻井关键技术

川西新场构造带须家河组二段致密砂岩储层受限于钻井成本与开发收益的不匹配,长期未能形成规模化商业开发。本文根据工区地质特征,通过以必封点、井眼尺寸和井眼轨道优化为核心进行井身结构设计优化,以旋锤钻具、低成本旋转导向工具、预弯曲钻具组合钻井、基于最小机械比能的实时钻井参数优化为核心进行系列提速关键工艺研究,形成了川西新场构造带须二段致密气藏定向井优快钻井关键技术。该技术在区块全面应用,最短钻井周期由231.1 d缩短到95.7 d,取得了良好的运用效果,实现了区块的效益开发。