泡沫分数对泡沫水泥性能的影响规律分析

泡沫水泥的性能主要取决于泡沫体积分数。通过水泥浆发泡实验,制备了具有良好沉降稳定性的泡沫水泥,深入系统分析了泡沫体积分数的变化对泡沫水泥的性能影响。研究结果表明,随着泡沫体积分数的增大,泡沫水泥浆变得黏稠,失水量降低;同时,泡沫水泥石抗压强度基本成线性降低,气测渗透率升高,弹塑性能增强。泡沫体积分数控制在30%左右,泡沫水泥石具有较好的抗压强度和弹塑性能,同时满足气层的有效封固要求,为现场泡沫水泥浆密度确定和施工安全提供指导。     

库车山前井防漏固井方法技术研究

由于塔里木油田库车山前地区目的层深、地质条件复杂,导致该地区的井在固井过程中时常发生漏失事故,严重影响固井质量。基于此问题,对整个固井期间产生激动压力的原因进行分析。通过研究钻井液性能、环空间隙、钻具和套管下放速度、排量以及井浆流变性能对激动压力的影响,得出环空间隙越小激动压力越大,建议不得小于20mm;降低钻井液屈服值能减小破坏胶凝结构产生的激动压力;提出了更为合理的套管下放速度计算模型以及提升循环排量频率的概念和控制方法 ;调整井浆的流变性能可以有效降低施工中产生的摩阻,并依此提出了注替排量的计算模型。现场应用表明,该套防漏固井方法对库车山前地区井的防漏设计有指导意义。     

Mathematical modelling of two-phase flow in a vertical well considering paraffin deposits and external heat exchange

Processes, occurring during exploration of gas-oil wells in frozen rock are simulated. A system of differential equations, describing hydro and thermal dynamics of an ascending two-phase flow of a hydrocarbon system in a vertical channel taking into account phase transitions and structure of a flow is developed. Kinetics of paraffin deposits on internal walls of an elevating column of a well are considered. The effect of the heat exchange of a well within frozen rock is developed using differential equations that describe the evolution of the radius of thermal influence of the well and the radius of the melting zone. We conclude with numerical research of some preventive ways of dealing with paraffin deposits.     

北部湾盆地徐闻X3井抗高温承压堵漏技术

徐闻X3井是中石化在北部湾盆地部署的一口重点预探定向井,该井渐新统涠洲组下部地层裂缝孔隙较为发育、地层承压能力低、钻井液漏失严重且井下温度高达180 ℃,导致部分堵漏材料高温后失效,采用常规桥接堵漏和水泥浆堵漏效果不理想,需研发出抗高温承压堵漏技术。为此,通过实验室试验优选出抗高温架桥材料高强支撑剂GQJ、抗高温纤维材料SW,以SAN-2工程分布理论为指导,加入不同粒径的CaCO₃和云母作为片状填充材料,并配合高失水剂HH-1及无机盐CaO,形成了抗高温承压堵漏配方,室内模拟0.5～4 mm裂缝宽度承压能力高于12 MPa。现场采用分段逐级堵漏法注入配制好的堵漏浆进行承压堵漏作业,在地层复杂情况下将地层承压能力提升至4.5 MPa,徐闻X3井第三次开钻固井期间再未发生漏失。实践证明,所研发的抗高温承压堵漏技术能够满足该井的固井施工要求,取得了较好的应用效果。     

Dynamic growth of water saturation around oil wells by water coning and transverse dispersion

Reported is a study of permeability damage around a well with water coning problem—after water breakthrough, when the stratified inflow of oil (top) and water (bottom) generates a dynamic transition zone. The enlarged transition zone distributes a water saturation barrier that reduces oil inflow to the well.Using high-resolution reservoir simulator with small grid blocks around the well, we qualified the effects of viscous force, gravity and capillary pressure, and postulated an additional effect resulting from high velocity flow around the well—transverse dispersion (i.e. hydrodynamic mixing). The effect contributes additional growth of the transition zone. Normally, in commercial simulators, the extra transition zone due to transverse dispersion would be neglected as it is overshadowed by capillary pressure when the flow velocity is low. However, it becomes progressive in the well's vicinity since the transverse dispersion coefficient is a function of velocity.We postulate in the paper that the transverse dispersion effect should be added to the well inflow model. The proposed analytical mechanistic model employs coefficient of transverse dispersion as a function of fluid and rock properties. It is shown that well productivity could be significantly affected by water invasion due to transition zone enlargement caused by transverse dispersion. It is also shown that by diverting the stream of water with Downhole Water Sink completion the spontaneous growth of transition zone could be controlled.     

VTK垂直钻井系统在阿北1井钻井中的应用

阿北1井四开井段地层倾角大、构造角度和倾向变化较大,采用大钟摆钻具组合和轻压吊打等措施,纠斜控斜效果不明显。为严格控制井身质量,在四开井段采用171.5 mm VTK垂直钻井系统控制井斜钻进,共计入井11次,总进尺504.92 m,平均机械钻速1.23 m/h,最大井斜2.09°,最小井斜0.11°,不仅达到了纠斜和控斜钻进的目的,同时还提高了机械钻速。     

川东地区高陡构造VTK垂直钻井配套钻井液技术

针对川东地区高陡构造高地层倾角井井眼轨迹控制难度大,并且上部自流井群泥页岩极易发生垮塌等特点,提出应用VTK(VertiTrak)垂直钻井技术防斜打快,并配合使用活度平衡防塌钻井液,以确保井眼稳定和VTK设备安全.介绍了钻井液体系的选择思路和配方的优选.天东004-X3和板东006-H1两口试验井通过应用该技术,平均机械钻速比邻井相同层位提高了57.1％以上,钻井周期缩短了6.1 d,表明VTK垂直钻井技术在高陡构造高倾角井和易斜地层能有效控制井斜,实现直井段的防斜打快、提高机械钻速,配套的活度平衡防塌钻井液具有“强抑制、平衡滤液活度、超低渗透”特性,能有效解决易塌泥页岩地层的井眼稳定问题,并成功实现化学防塌,较大幅度地降低了钻井液密度.     

System performance of a deep borehole heat exchanger

Deep borehole heat exchanger (BHE) systems, installed in abandoned boreholes, have been operative in Switzerland for several years now. The operational conditions of the 2302 m deep BHE plant at Weggis have been monitored continuously since 1994. In the first operational phase, lasting from October 1994 to May 1996, the plant was severely underused, as shown by the high production temperatures (40 °C). This behaviour was investigated by a numerical model accounting for the heat transport in the rock matrix and along the different tubing systems, with special emphasis on the heat transfer in a multi-layer insulated central pipe. Lacking detailed logging data or undisturbed temperature profiles, an axis-symmetrical model had to be used, assuming uniform rock parameters. Sensitivity studies highlighted the effect of varying flow rate or operation/recovery cycle lengths and helped to develop a strategy that allowed us to make an accurate calculation of the long-term Weggis production history. The initial model assumptions, based on this detailed treatment of the tubing system, could explain the operational data. By means of slight model variations that account only for the minor effects of metallic sleeves, the long-term production temperature history of the Weggis plant could be accurately fitted. These findings were confirmed by a detailed analysis of the May 1996 data. Due to the low degree of utilization, only numerical sensitivity analyses were able to highlight the potential of the deep BHE plant at Weggis. The results indicate that the low utilisation of 40 kW during the first operational phase could be increased to over 200 kW. The specific yield of deep systems is much higher than in conventional shallow BHE systems. Our simulation procedure proves that the heat transfer in a deep BHE system is well understood.     

车排子地区车47井石炭系划分及对比

车排子地区车47井3 370.0—3 456.5 m井段为灰黑色含砾粗中粒岩屑砂岩、深灰—灰黑色含砾岩屑砂岩与砂岩互层,夹含碳粉砂岩,岩石组合与建组剖面及白板地等哈拉阿拉特组第六岩性段顶部可对比;在含碳粉砂岩中获得Protohaploxypinus clarus,P. verrucosus,P. junggarensis,P. jimsarensis,Noeggerathiopsidozonotriletes multirugulatus等晚石炭世孢粉化石,时代大致为Moscovian期。上部（井深2 551.2—3 370.0 m）为玄武质—安山质火山角砾岩、火山集块岩等,火山熔岩极少,岩石组合既不同于以火山熔岩为主的哈拉阿拉特组1—4段,又与阿腊德依克赛组下段显著有别,且位于第六岩性段顶部岩屑砂岩之上,可与建组剖面上获得锆石U-Pb年龄为306.9 Ma和304.5 Ma的哈拉阿拉特组第七岩性段对比,可确定其时代为晚石炭世Kasimovian期。     

呼探1井井口压力波动特征及成因机理

呼探1井是准噶尔盆地南缘中段首口获得天然气勘探重大发现的超深层异常高压气井,该井在试采时井口压力出现大幅波动,无法有效确定储集层参数及开展合理产能评价。因此,基于颗粒架桥堵塞原理,利用气藏动态分析法,表征了裂缝中颗粒循环堵塞—解堵变化趋势;同时,建立呼探1井双重介质渗流机理模型,开展压力波动特征分析及成因机理研究。研究表明,裂缝中颗粒循环堵塞—解堵是造成压力大幅波动的主要原因,一方面,随着裂缝中颗粒不断运移解堵,压力波动幅度逐渐减小,表皮系数逐渐减小,采气能力趋于稳定;另一方面,在裂缝循环堵塞—解堵的过程中,裂缝开度越大,压力波动幅度越大,同一裂缝开度下,近端裂缝堵塞—解堵,导致压力波动幅度较大,远端则相反。不仅为准噶尔盆地南缘中段储集层特征研究、井位部署、产能评价提供依据,而且为超深层异常高压气井压力分析提供借鉴。