Application and development of numerical simulation for under- ground horizontal directional drilling

In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.

Stress Analysis of Buried Pipeline Installed by Horizontal Directional Drilling Using ANSYS Finite Element Software

In designing a horizontal directional drilling (HDD) pipeline project, designers face the challenge of determining the regions of maximum and minimum stresses on pipelines, ensuring the stability of the bore-hole from collapse and minimizing the stresses induced on the pipeline due to the bore-profile. This study analyses the stress induced on an HDD pipeline system using the ANSYS Version 18, mechanical APDL finite element (FE) software. The pipeline used as the case study was a gas transmission pipeline installed in south-west Nigeria. A macro-file for ANSYS Version 18, mechanical APDL used to model the pipeline was developed. The results showed that the maximum and minimum stresses induced on the HDD pipeline were at the top and bottom of the pipe, respectively;while the stresses on the sides were uniform (≈888 kg/cm2) all through the pipeline, irrespective of element number. The maximum stress occurred at the curvature point with the highest entry angle (10°), resulting in a maximum deflection at this point. The model stress validation performed by comparing results with theoretical solutions, both with respect to radius of curvature and internal pressure, showed percentage difference (errors) less than 10%. The cross sectional area validation showed a percentage difference of 0.059%.

Combined stochastic and discrete simulation to optimise the economics of mixed single-horizontal and multilateral well offshore oil developments

Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,drilling a multilateral well does not always increase the flow rate when compared to two single-horizontal wells due to competition in production inside the mother-bore.Here,a holistic approach is proposed to find the optimum balance between single and multilateral wells in an offshore oil development.In so doing,the integrated approach finds the highest Net Present Value(NPV)configuration of the field considering drilling,subsurface,production and financial analysis.The model employs stochastic perturbation and Markov Chain Monte-Carlo methods to solve the global maximising-NPV problem.In addition,a combination of Mixed-Integer Linear Programming(MILP),an improved Dijkstra algorithm and a Levenberg-Marquardt optimiser is proposed to solve the rate allocation problem.With the outcome from this analysis,the model suggests the optimum development including number of multilateral and single horizontal wells that would result in the highest NPV.The results demonstrate the potential for modelling to find the optimal use of petroleum facilities and to assist with planning and decision making.

Surface settlement induced by horizontal directional drilling

Horizontal directional drilling(HDD)is a widely used trenchless method for underground utility connections.The associated ground settlement triggered by HDD depends on the size,types,and surface texture of pipe,diameter of borehole,and soil conditions.The pre-sent study investigates the surface settlement due to the construction of a 1067 mm diameter HDD,which will replace an existing sewer siphon under the SR-60 highway in Chino,California using empirical,and numerical methods.Based on the results obtained from the subsurface investigation,an empirical analysis was conducted first.followed by numerical modeling of the HDD using PLAXIS 2D soft-ware.A careful comparison between two different methods indicated closer values of surface settlement between the empirical method(7.3 mm)and the numerical modeling(4.6 mm).In addition,the shape of surface settlement and horizontal settlement curves for the empirical and numerical methods was found to be similar.The minor discrepancy between the two methods resulted as the numerical model can host several soil layers whereas the empirical equation can use only one type of soil.Finally,a parametric study was conducted to evaluate the effect of borehole cover depth,size,and soil parameters on surface settlement.It was observed that soil strength param-eters yielded a greater effect on surface movement,whereas modulus of elasticity has a relatively smaller influence with zero contribution from Poisson’s ratio.

Laboratory study of fluid properties owing to cutting intrusions during horizontal directional drilling

During horizontal directional drilling installations,a primary function of drilling fluids is to yield drill cuttings and lubricate the product pipe.This paper presents the results of a research study of drilling fluid parameters,and the filter cake properties associated with drill cutting intrusions.Different sand meshes and field cutting sizes were added to the drilling fluids.Based on the laboratory experiments of eighteen samples including testing drilling fluid rheology and filter cake properties,the influence of drill cuttings on low solid-phase drilling fluid systems were obtained.The results reveal that drilling fluid plastic viscosity values increase with sand content and particle size.The 100-mesh sand exhibits a larger plastic viscosity compared to the 200-mesh sand.This suggests that the coarser the sand,the greater is the plastic viscosity.By contrast,drilling fluids with 200-mesh sand exhibit greater shear forces than the 100-mesh sand.When the sand content is4%,the shear dilution ability of the drilling fluid begins to weaken.The thinnest filter cake is formed after 6 h with a 100-mesh cutting size and 4%sand content.However,when the cutting size changed to 150-mesh and 2%content,the largest filter cake toughness and strength after rolling for 12 h were obtained.Simultaneously,the combination of 200-mesh and 150-mesh with 2%–4%content rolling for 12–24 h indicate different results.For the filter cake thickness,cutting content is the primary influencing factor followed by particle size and gradation.The factor with the least influence is rolling time.We found that rolling time and gradation were the most significant factors affecting the toughness of the filter cake,followed by cutting content.Conversely,particle size exhibits the least influence on filter cake toughness.These results are important to better understand the solid-phase control of drilling fluids in the field.

Research into magnetic guidance technology for directional drilling in SAGD horizontal wells

SAGD horizontal wells are used to enhance oil recovery from heavy oil reservoirs.This technology requires precise separation between the production well and the injection well to ensure the efficient drainage of the reservoir.By studying the attitude of the downhole probe tube and the production well trajectory,an algorithm is proposed for eliminating ferromagnetic interference while drilling injection wells.A high accuracy filter circuit has been designed to correct the detected magnetic signals,which are ultra-weak,frequency-instable,and narrow-band.The directional drilling magnetic guidance system（DD-MGS） has been developed by integrating these advanced techniques.It contains a sub-system for the ranging calculation software,a magnetic source,a downhole probe tube and a sub-system for collecting ＆ processing the detected signals.The DD-MGS has succeeded in oilfield applications.It can guide the directional drilling trajectory not only in the horizontal section but also in the build section of horizontal injection wells.This new technology has broad potential applications.

Research on Horizontal Vibration of Heavy-Weight Drill Pipes in Directional Drilling

The mode of load and deformation of directional drilling string and the expression of trigonometric series of deflection equation are established by means of elastic deformation energy and of the vertical and horizontal bending. A calculation formula for natural frequency of horizontal resonance and rotational speed is derived based on the calculation method by Ritz, with which analysis is made for the cause and affecting factors of the excessive abrasion of heavy-weight drill pipe in high-angle holes so as to provide reference and basis for rational selection of drilling parameters and drilling tools in the future high-angle directional drilling.

Formation and Control of Drilling Burrs

In this paper, a new forming model of the feed direction burr for drilling process is presented. The feed direction burr formation is experimented and studied. The related theories are analyzed, and the influential factors of the feed direction burrs are pointed out. Furthermore, a certain number of new measures to prevent and decrease the burr in drilling process are advanced.

水平定向钻进技术在青海钾盐矿开采中的应用研究

为了提高青海某钾盐矿的开采效率和产量,提出了贯通井的开采方案,首次利用水平定向钻进技术和对接井技术施工了多组贯通井,从水平井注水后从竖井抽取卤水,极大地提高了钾盐的开采量。工程施工初期出现了卡钻事故,通过优化泥浆配方、钻头合理选择、防卡钻钻具的设计使用,避免了卡钻事故的再次发生。该工程完成40条水平井和竖井的对接后,该区域内的钾盐年产量提高3.5万t,证明利用水平定向钻进技术提高钾盐矿开采效率和产量的方案是可行的。相关研究成果可为后续利用水平定向钻进技术进行可溶性矿产开采提供理论依据和实践指导。

水平定向钻进坚硬地层孕镶金刚石钻头的研究与应用

针对水平定向钻进坚硬地层效率低的问题,通过利用FeCoCu预合金胎体的硬脆性以及硬质颗粒碳化硅弱化胎体的特点,提高钻头的自锐性。采用分层结构设计,将高、低耐磨性胎体层沿钻头径向方向交替排布,其中高、低耐磨性胎体层厚度分别为2.5~3.5 mm和1.0~1.5 mm,可实现高、低耐磨性胎体层同步磨损,提高钻进效率。将FeCoCu预合金胎体和分层式胎体结构相结合,研制的孕镶金刚石钻头成功应用于水平定向钻进勘察工程坚硬钾长花岗岩地层,平均机械钻速0.8~1.5 m/h,钻头使用寿命为30~40 m。与普通同心圆尖齿钻头相比,机械钻速提高约1倍,寿命提高30%以上。

基于损伤力学的矿用定向钻机金属结构寿命评估

针对ZYL-15000D型煤矿用履带式全液压定向钻机底座寿命评估,首先通过Q345B钢的脉动循环加载拉伸疲劳试验数据,拟合得到应力幅值和寿命的关系式,经由应力修正和安全系数的选取,转换得到对称循环下的应力幅值和寿命的关系式。结合基于损伤力学推导出的损伤退化模型,根据Q345B钢试验数据拟合确定损伤退化模型中的待定参数,将Q345B钢对称循环下应力幅值和寿命的关系式代入,得到Q345B钢的疲劳损伤退化模型。然后借助ABAQUS对钻机整机进行结构分析,得到钻机底座的危险点位置(即应力最大处),在该型号样机试验台上通过应变片测得钻机底座危险点处的应力—时间历程。最后采用雨流计数和应力修正,对测得的随机载荷谱进行处理得到雨流计数直方图(应力均值-幅值-循环次数),再转换为对称循环载荷的形式,代入确定的疲劳损伤退化模型中,评估钻机底座的疲劳寿命。

四川盆地致密气水平井钻井关键技术

为搞清四川盆地致密水平井钻井工程技术难点,针对致密气水平井井眼轨迹设计复杂、地层易坍塌掉块、卡钻风险高、下套管困难以及钻井周期慢等技术难点,开展了地层压力预测及应力分析、井眼轨迹设计优化、钻井参数及钻井设备优选、优化钻井液体系及参数、下套管模拟预测和套管强度校核等多方面工作。研究结果表明:1)西南致密气水平井地层坍塌压力为1.55~1.60 g/cm^(3),当水平段钻井方位约为105°及15°时井壁稳定性较好,有益后期储层压裂改造;2)采用“双二维”轨迹设计,钻具组合扭矩降低15%以上,摩阻降低20%以上,定向钻井速度可提高45%以上;3)钻机配套DQ50DBS型顶部驱动装置,配置2~3台1600HP钻井泵和NC52非标钻杆,钻井排量控制在35 l/s以上,可保证井眼清洁度及携岩效率;4)使用白油基钻井液体系的同时加入“刚性粒子+树脂纤维+沥青胶粒”措施进行封堵,可保证井壁稳定;5)优选P110钢级、10.54 mm壁厚完井套管并采用旋转方式下入,在满足后期压裂施工的同时,降低套管下入摩阻12%以上。上述成果认识对加快四川盆地致密气勘探开发进程具有指导意义。

基于事故树的N-K模型施工事故风险耦合分析

为了研究水平定向钻施工事故风险,考虑事故树定性分析与N-K模型(N为系统的组件数量,K为每个组件与其他组件的交互数量)定量分析方法的缺点,从人为、设备、环境及管理4类风险因素构建一种基于事故树的N-K施工事故风险分析综合模型。通过建立事故树施工底层事件与N-K模型耦合风险因素集合映射关系,分别计算单因素、双因素以及多因素耦合风险概率,求解风险耦合值。结果表明:水平定向钻施工事故风险概率随着风险耦合因素的增加而增大;三因素耦合作用时,设备-环境-管理耦合作用值最大为0.2608,人为-设备-管理次之为0.2034;双因素耦合作用时,环境-管理耦合作用值最大为0.1554;水平定向钻施工事故共有50种引发事故的可能途径,可以按照准备阶段、导向孔钻进阶段、扩孔阶段、管道回拖阶段与规划管理阶段对整体事故风险进行分阶段预防。研究成果一方面可为风险研究提供新的综合模型,另一方面也可为水平定向钻安全施工提供重要的参考依据。

水平定向钻孔水压致裂地应力测量数值模拟分析

为解决水平钻孔水压致裂法在地应力测量中计算原理不明确的问题,以天山胜利隧道水平定向钻勘察项目为依托,首先构建基于原生裂隙法与多孔交汇法的水平孔围岩三维应力状态理论模型,并探讨其控制边界条件及计算方法;然后,通过与室内物理模型试验数据进行对比分析,验证理论模型的合理性;最后,构建水平孔水压致裂法地应力测量有限元模型,通过对比数值模拟、理论计算和室内试验结果,验证该有限元模型建模方法的可行性。结果表明:1)理论模型计算结果与室内物理模型试验记录数据接近,最大误差为6.8%,说明结合原生裂隙法与多孔交汇法构建的水平孔围岩应力状态理论模型可以适用于基于水平定向钻勘察的水压致裂法地应力计算;2)数值模拟结果与试验记录数据接近,最大误差为9.51%,说明采用Abaqus扩展有限元法(XFEM)结合嵌入式Cohesive单元的方法能够合理模拟真实水平孔水压致裂测量地应力的过程;3)理论模型计算结果与数值模拟结果的一致性较好,最大误差在允许范围内,验证了理论模型与有限元模拟方法的正确性、准确性和可靠性。

放顶煤工作面以孔代巷合理布孔参数

为了解决刘家梁矿2号煤层低含量赋存高强度开采引发工作上隅角瓦斯问题,缓解矿井因岩巷掘进造成采掘接替紧张的局面,提出了采用大直径高位走向长钻孔代替工作面低位岩石抽采巷的瓦斯治理技术,结合矿井2号煤层顶板煤岩物理力学参数,通过理论分析、UDEC、FLUENT数值模拟的方法,分别从工作面裂隙带发育、工作面采空区流场分布等不同的专业角度,分析、研究了瓦斯流通通道及赋存规律,为定向高位钻孔合理布孔层位选择提供理论支撑;结合1号钻场瓦斯抽采效果,修正工作面煤岩赋存资料,优化2号钻场抽采设计,调整钻孔布置参数,以工作面瓦斯抽采纯量、上隅角瓦斯浓度为指标,对不同条件下瓦斯治理效果进行对比,实践证明:走向高位长钻孔能够取代低位岩石抽采巷,用于低含量赋存、高强度开采的放顶煤工作上隅角瓦斯治理,治理效果显著,上隅角瓦斯浓度维持在0.6%以下。

水平定向钻穿越水敏性地层冒浆预测及防控

非开挖水平定向钻穿越施工中,孔内压力过高会造成地表隆起冒浆事故,严重污染周围环境,造成重大经济损失。以福州市塘坂引水工程供水管道水平定向钻穿越项目为例,考虑工程水敏性软化造浆地层,基于Mohr-Coulomb准则构建了针对水敏弱膨胀地层的孔内最大允许泥浆压力计算模型,并通过现场位移监测数据验证了模型的正确性;随后通过现场应用校验了非开挖水平定向钻穿越水敏弱膨胀地层的冒浆防控技术可靠性。研究结果表明:所推导的计算模型比现有其他孔内允许泥浆压力预测模型更加适用于水敏性软化造浆地层;水平定向钻穿越冒浆防控技术应以孔内泥浆压力控制为主,结合泥浆技术、工艺优化防止憋压,最后辅以局部薄弱点加强、定向控制冒浆等手段进一步加强冒浆预防措施,保障施工安全。

特深科学钻探装备技术现状与发展建议

特深科学钻探是直接获取地球深部信息的唯一技术手段,对于深入理解地球内部结构、探索地下资源具有重要意义,已上升为国家战略科技问题。为响应党中央“向地球深部进军”的号召,需大力推进对特深科学钻探装备技术的研发。本文简要回顾了国内外特深科学钻探装备技术发展历程,结合我国发展需求,梳理总结了特深科学钻探中顶驱、绞车、钻井泵等关键装备面临的技术难题,并在此基础上提出了发展方向及展望,为我国特深科学钻探工程发展提供参考。

近距离薄煤层群首采层卸压瓦斯协同抽采技术研究

为有效解决近距离薄煤层群开采首采层上、下邻近层大量卸压瓦斯涌入的治理问题,以某煤矿为研究对象,采用理论分析和数值模拟的方法,研究近距离薄煤层群开采条件下卸压瓦斯运移规律,并根据富集特征确定卸压瓦斯抽采钻孔的空间位置。研究结果表明:首采层开采覆岩导气裂隙带最大发育高为10.3~23.2 m。设计超大直径顺层预抽钻孔高0.8 m,宽2.08 m;顶板定向长钻孔终孔最优抽采位置为垂直距离开采层顶板15.0~23.0 m,水平距离回风侧20.5~27.5 m;2条埋管抽采最佳错距为距底板高1.1,1.7 m,深入采空区11.3,20.8 m。优化后的布置参数应用于现场实践,试验工作面回采期间上隅角瓦斯体积分数保持在0.7%以下。研究结果能够实现近距离薄煤层群开采条件下卸压瓦斯高效抽采,保证矿井安全高效生产。

非开挖拖拉管在市政污水处理中的施工与应用

基于市政污水管道的特点采用非开挖法,并对非开挖技术进行深入分析后选用非开挖拖拉管的方式进行污水管道施工,根据对拖拉管线定位探测方法分析最终选择了水平定向钻技术,最后对非开挖拖拉管在施工过程中容易出现的问题进行技术分析,并提出相应的控制措施。

非开挖水平定向钻拉管施工技术的应用

非开挖水平定向钻拉管施工技术相较于开槽埋管主要优势在于穿越障碍物,且施工周期更短,随着信息化时代发展,该项技术愈演愈烈。主要针对拉管施工中各工序以及要点作了分析总结,就导向轨迹作了重点分析并推导了“斜直线-曲线-直线-曲线-斜直线”钻孔轨迹入土点距障碍物的长度以及入土角角度的关系,为施工现场提供了丰富的参考资源。