Calculating single layer production contribution of heavy oil commingled wells by analysis of aromatic parameters in whole-oil GC-MS

Traditional fluid production profile logging is not usually suitable for heavy-viscous crude oil wells.Biodegradation of heavy oil can lead to the loss of n-alkanes,and the use of chromatogram fingerprint techniques in studying the production contributions of single layers in heavy oil commingled wells has limitations.However,aromatic compounds are relatively well preserved.We took the heavy oil commingled wells of small layers NG55 and NG61 in the ninth area of the Gudong oil field as examples.Based on the principle of chromatography,the whole-oil GC-MS was used,and the aromatic parameters which have a strongly linear relationship with the ratio of mixed two end member oils were verified and selected in laboratory.Studies showed that the ratio of （1,4,6-＋ 2,3,6-trimethylnaphthalene） to 1,2,5-trimethylnaphthalene has a strongly linear relationship with the ratio of the mixed two end member oils （R2=0.992）.The oil contributions from single layers NG55 and NG61 in six commingled heavy oil wells were calculated using established charts and this relationship.The calculated results are consistent with the results of long period dynamic monitoring and logging interpretation in the study area and can provide a scientific basis for monitoring production performance and hierarchical management of reservoirs.The study provides a new geochemical method for calculation of the contributions of single layers in heavy oil commingled wells when conventional fluid production profile logging is not suitable.

Calculation of the contribution of single-zone production by ultraviolet spectrum technique:A case study in well QHD32-6-3 field

Based on the established mathematic model and graphic interpretation, a new method, which is used to calculate the contribution of single-zone production in a commingled producing well by the ultraviolet spectrum technique, has been established. The standard plate was drawn using the extinction coefficient E of sample oils formulated artificially as y-axis and the wavelength as x-axis. The curve resulting from the UV analysis of sample oils in the commingled well was inserted into the standard plate and compared. The proportion of each single zone in the commingled producing well was identical with the proportion of the curve which is closest to the curve of sample oils formulated artificially. In the well QHD32-6-3 field, taking well A22 for example and using this method, the production contribution of a single zone was calculated. The result showed that the Nm4 zone is a major "contributor", the proportion of the Nm4 zone is 70%, and that of the Nm1 zone is 30%. The ultraviolet spectrum technique provided a new reservoir geochemical technique of monitoring production contribution, especially for biodegraded heavy oil, but it has some limitation, just depending on the GC fingerprint technique.

Practice and understanding of sidetracking horizontal drilling in old wells in Sulige Gas Field, NW China

To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problems such as leakage, collapse and sticking in slim-hole sidetracking, and difficult evaluation of remaining gas were gradually overcome, and a set of drilling and completion technology, well deployment optimization technology and geo-steering technology suitable for sidetracking horizontal wells in tight sandstone gas reservoirs have been worked out. By making full use of the old well, sidetracking horizontal wells can greatly reduce development costs, enhance the producing degree of inter-well remaining reserves, and get production 3-5 times of that of adjacent vertical wells.Its production effect is influenced by encountered sandstone length, the position of the horizontal segment in the reservoir, produced effective reservoir thickness, gas saturation, controlled reserves and fracturing effect, etc. Up to now, in Block Su10 and Su53, 12 sidetracking horizontal wells have been drilled, which have an average drilling cycle of 49 days, average horizontal section length of 689 m,average effective drilling ratio of 61.5%, average well-head pressure of 16.2 MPa, and daily output of 4.7×10~4 m^3 at the initial stage after production. By the end of 2017, the average yield increment was more than 1 000×10~4 m^3 with good effect. With the increase of low yield old wells, wells in the enrichment regions tend to be saturated and the rest gas-bearing areas are lower in grade, therefore, sidetracking horizontal well can be used for optimization of well pattern, well deployment mode and exploitation of remaining oil areas.

Variability in Quantity and Salinity of Produced Water from an Oil Production in South Kuwait

Produced water (PW) is the largest waste stream in the oil and gas industry. Water remains trapped for millions of years in the reservoir with oil and gas. When a hydrocarbon reservoir is infiltrated by a production well, the produced fluids commonly contain water. The understanding of this water’s constituents and volumes is vital for the sustainable continuity of production operations, as PW has a number of negative impacts on the infrastructure integrity of the operation. On the other hand, PW can be an alternative source of irrigation water as well as of industrial salt. Interestingly, both the quantity as well as the quality of PW do not remain constant but can vary, both progressively and erratically, even over short periods of time. This paper discusses such a situation of variable PW in an oil and gas operation in the State of Kuwait.

Quantifying Corrosion Rate in Oil and Gas Wells by Measuring Alloying Constituents in Produced Water

Most oil and gas wells worldwide are completed with low alloy carbon steel due to cost-effectiveness, despite its high susceptibility to corrosion. Corrosion in alloy steels occurs through galvanic or electrolytic reactions, resulting in the release of metallic ions. This release adversely affects the strength and integrity of production tubing. The current study focused on quantifying the amount of alloying constituents present in the produced waters of oil and gas wells using inductively coupled plasma-optical emission spectroscopy (ICP-OES) to calculate the corrosion rate on the production tubing. Two types of alloy steel tubing, API 5CT T-95 and API 5CT J55, were selected. The wells were chosen based on sweet and sour production. The levels of ions present in the produced water—Nickel, Chromium, Manganese, Molybdenum, and Iron—were measured. Ion dissolution was converted to corrosion rate using the exposed area of the tubing and the water flow rate. The study concluded that a very high corrosion rate occurs in sweet wells completed with T-95 metallurgy, whereas the corrosion rate in sour gas producers is significantly less compared to sweet producers. For the oil wells, although they are sour producers, a very low corrosion rate was observed with API 5CT J55 metallurgy. Furthermore, the study revealed that quantifying the alloying constituents in produced water is key to developing suitable corrosion projection approaches, predicting the service life of production tubing in gas and oil wells and metallic structures, and guiding production engineers to make informed decisions and timely responses to corrosion threats before failure.

含气油井采出液低温集输工艺界限研究

老油田因开发时间较长,存在产液量低、含水率高、能耗大等问题。为降低老油田高含水区块的运行能耗,针对低含气油井和高含气油井开展了降温实验,根据井口回压和进站温度随时间的变化规律,获取了含气油井采出液的低温集输工艺界限。结果显示:低含气油井在降温过程中出现了两个压力突变点,高含气油井在降温过程中压力呈不规则变化,但也出现压力突变区域;产液量越大、含水率越高、气液比越大,越有利于油井进行低温集输。推广区块内有55口油井从双管掺水工艺转为低温集输工艺,实施后全年可节约运行费用235.9万元,减少CO_(2)排放量为2650 t,节能减排效果明显。

基于效益复产的控水采气技术——以磨溪气田嘉陵江组二段气藏为例

高产水气井因低效或无效益关停后,井口压力恢复较高,井控安全风险大。按照原有常规开发模式复产将面临地层水处理成本高、无人值守生产管理难度大等问题。为实现磨溪气田下三叠统嘉陵江组二段气藏安全效益复产,综合考虑气藏生产管理、安全环保和经济效益等因素,提出新型控水采气技术作为高压、高产水、低负效气井复产的工艺措施。通过开展控水采气生产现场试验,分析不同产水量、产气量、生产时长和间开周期条件下油压、产量等动态数据之间的关系,确定合理生产压差、产水规模和间开周期;同时结合气藏生产组织、生产管理等综合因素确定开关井制度,通过安装智能间开系统等配套工艺,进一步提升控水采气技术措施效果。研究结果表明:(1)该技术确保气藏关停井整体成功复产,有效降低了井控风险;(2)通过现场试验和推广应用,验证了选井标准和工艺参数计算方法的科学性;(3)“智能间开系统”等配套工艺进一步提升了现场运用效果。该技术为关停井复产、高压井管控、精细生产管理及提高气藏采收率提供了有力的技术支撑,在同类气藏中具有较强的推广应用价值。

东胜气田致密高含水气藏合采气井效果评价及产出影响因素分析

为了确定鄂尔多斯盆地北缘致密高含水气藏合采气井开发效果,指导同类型气藏合采气井高效开发。以东胜气田致密高含水气藏为研究对象,分析了单采井与合采井不同开发阶段、不同井区及纵向上的产出效果,以及合采井层间含气性差异对合采井产出的影响,明确了东胜气田致密高含水气藏合采井的开发效果及层间产出的影响因素。研究结果表明:①东胜气田致密高含水气藏合采井具有初期压力高、产量高的特征,但整体开发效果与气藏含气性或产水情况有相关性;②通过参数对比分析,合采井生产层产出效果与产层物性、含气性具有明显的正相关性,产层之间的含气性差异也会影响合采开发效果;③合采井稳定生产临界携液(携泡)流量与气井水气比也具有一定的相关性。结论认为:①东胜气田致密高含水气藏合采井初期压力、产量较高,但在低含气饱和度(高水气比)区域合采井整体开发效果较差,同时气田合采井随着开发时间的推移纵向上层间的产出状况也不断发生变化;②合采气井生产层物性、含气性越好,生产层的产出效果越好,且以物性条件为主导,但在较大的层间含气性差异下,合采井层间易发生严重的气液倒灌使得整体开发效果变差;③合采气井水气比越高,稳定生产临界携液(携泡)流量越大。

东胜气田致密高含水气藏合采气井层间干扰影响因素

为了明确鄂尔多斯盆地北缘致密高含水气藏合采气井层间干扰及其影响因素,指导同类型气藏合采气井高效开发,以该盆地北缘东胜气田致密高含水气藏为研究对象,分析了储集层地质条件、储集层改造对合采井产层段贡献的影响,指出了该类合采气井层间干扰的主控因素。研究结果表明:(1)合采井各产层段贡献率主要受各产层段的孔隙度、渗透率及含气饱和度控制,其产层段孔隙度占主导地位;(2)储层压裂改造对于提高气井产量具有较大的作用,但对合采井各产层段的贡献率却很小;(3)对于致密高含水气藏而言,含气饱和度是合采井产层段贡献率及层间干扰的一个重要影响因子;(4)合采井各产层段之间的孔隙度级差、渗透率级差及含气饱和度级差直接影响着合采井层间干扰程度。结论认为:(1)合采井产层段的孔隙度越大、渗透性越好、含气饱和度越高,则产层段的产量贡献率越大;(2)合采井孔隙度、渗透率及含气饱和度3个参数的级差越大,层间干扰程度越大,当孔隙度级差大于1.248或渗透率级差大于2.69或含气饱和度级差大于1.22时,合采井层间干扰已经非常严重,亟需开展治理。

埕岛东区水淹油藏加密水平井合理生产压差研究

埕岛油田东区馆上段Ng4^(2)层油藏历经多年注水开发,已形成较强水淹,在井区调整加密水平井大幅提高产能的开发需求下,既要保证油井较高的产能和采油速度,又要在平台寿命期内合理控制含水上升达到较高的采收率,需要优化合理的生产压差。通过建立埕岛东区的油藏物理模型,设立六种不同生产压差分别模拟评价含水率变化特征、产液量变化特征、采出程度变化特征,并开展综合开发效果评价。结果显示,在埕岛海上平台开发寿命周期内最优生产压差为1.2 MPa,并在251GB-P1、251GB-P2等井的矿场实践中取得了较好的开发效果。研究认为,在水淹油藏通过优化生产压差实现提升产油量、提高采油速度和最终采出程度的目的是可行的。

高压含水气井两相流态节流判断与控制方法

井筒气水两相管流节流前后动态特性分析与控制,对保障致密气等高压含水气井高效稳定安全开采和水合物防治具有重要意义。考虑等熵绝热、等压热容、等容热容、不同井深节流能量等因素,推导气水两相流体流经喷嘴的能量、动能和温度动态变化等热力学微分方程组,建立高压含水气井两相节流能量、节流系统热量、节流物质平衡和流体质量流量变化等井下节流场数学模型,提出一种气水两相井筒节流前后动态特性分析与控制方法,为优化井下节流器及其节流喷嘴的结构参数和保障气井流动安全提供理论依据。最后依据数值模拟手段及其判断结果,以鄂尔多斯盆地东缘大宁-吉县区块为例进行验证,以揭示高压含水气井喷嘴尺寸和深度、含水率、节流前压力和温度对节流前后动态特性的影响规律。结果表明:高压含水气井气水两相流体质量流量先是随节流压力比减小而呈指数级增大,并在压力比降至0.55阈值附近时达到最大值,增大喷嘴下入深度和含水率、同时降低节流前压力和温度,可提高节流后温度,有利于抑制水合物生成;且节流过程临界质量流量受喷嘴内径的影响最大,含水率和节流前压力次之,而节流前温度和喷嘴深度的影响最小,且增加含水率会提高临界质量流量,但产气量也随之下降;大宁–吉县区块现场工程实例分析表明,井下节流喷嘴内径由3.0 mm扩至5.0 mm和节流前压力由14 MPa增至18 MPa时,气水两相流体的临界质量流量提升幅度分别为179.3%和27.8%,而利用地层温度等将节流前温度由313 K升至333 K时,节流过程临界质量流量反而小幅下降且下降幅度仅为5.15%,为此,增大喷嘴内径及其下入深度和节流前压力同时降低节流前温度,有利于提高气水两相流体节流过程中临界质量流量,并提升高压含水气井的产气量。

多相计量撬现场参数整定及单井计量测试

单井多相计量一直是油田迫切需要突破的问题,科氏力流量计以其较高的质量流量精度,实时提供含水率而广受欢迎。但受限于现场条件,作为含水率及体积流量换算的密度参数并不准确或无法提供。基于此阐述一种在油田现场对单井采出液就地进行油水分离及密度检测的方法。以现场实验获取的单井采出液原油,地层水水密度值作为基于科氏力多相计量撬的参数,进行所采样单井的计量测试实验,与平台现有高精度流量计及取样化验含水率数据比对,相对误差在±5%以内。

低产液井系统效率影响因素分析及对策

油田开发进入高含水后期,低产液井数增多,抽油机作为举升工艺的主要手段,效率的高低对能耗具有直接的影响。针对目前低产液井系统效率偏低的问题,对抽油机系统效率影响因素进行分析,确定影响低产液井系统效率的主要因素为沉没度、抽汲参数和抽油设备。统计、对比低沉没度井系统效率,沉没度在200~300 m时系统效率最高;生产参数方面,冲次对系统效率影响较大,冲程、泵径次之;设备方面,非节能、匹配不合理对系统效率的影响较大。依据分析结果,明确潜力和对策方向,通过采取参数优化通过采取参数优化、间抽、设备更新调换等措施1576井次,节电728.74×10^(4)kWh,系统效率提高了4.96%,供采关系得到改善,抽油机系统的整体工作效率提升,经济效益显著提高。

产水气井冲缝套动态冲蚀机理研究

在产水气井中,冲缝筛管同时受到腐蚀和冲蚀磨损,服役寿命远远低于预期。为了解冲缝筛管在产水气井中快速失效的原因,模拟含水气井的腐蚀环境,进行了室内腐蚀试验,并建立了冲缝套的2种缺陷分布模型,模拟计算不同缺陷分布模型,以腐蚀速率为动网格速率,探究了不同缺陷深度和含水体积分数下冲缝套的冲蚀机理。研究结果表明:含水体积分数从0增加到100%,腐蚀速率从0.0115 mm/a增加到0.0399 mm/a,腐蚀坑的截面为圆形;缺陷在边缘中间区域时,最大冲蚀磨损量分布在缺陷处;缺陷在其他区域时,最大冲蚀磨损量分布在边缘四角区域的非缺陷区域;最大冲蚀磨损速率与缺陷深度、含水体积分数成正比,这种腐蚀与冲蚀的共同作用是冲缝筛管在产水气井中服役寿命大幅缩减的原因。所得结论可为延长冲缝筛管服役寿命研究提供理论参考。

产水气井排采工艺进展

排水采气工艺技术作为治理气井出水的关键措施,对气田的持续稳产、增加产气量和延长生命周期具有关键作用。造成气井井底积液的原因包括完井液返排不足、气藏的开发特点以及气井间开不连续生产等因素。当前治理气井积液的技术有泡沫排水、柱塞气举、速度管柱、电潜泵、堵水等常规工艺以及高压气举、井间互联、连续油管等停产井复产工艺,研究的重点主要集中在提高气井携液能力、完善配套设备、降低实施成本、研发适应不同气藏条件的工艺技术等方面。需要根据储层地质特征、测井数据、产水规模、产气量、井筒压力损失情况等关键因素,综合考虑工艺原理、适用性、投资成本、优势与局限性,科学地选择排水采气工艺。将复产工艺与常规工艺相结合,可高效地应对实际生产问题。未来,排水采气工艺将向智能化、多学科融合、长效性与可持续性方向发展。

SJ油田低产低效油井间开生产模型优化研究

SJ油田属于典型的低渗、特低渗油藏,该油田低产低效井(液量≤3 m^(3)/d,泵效≤30%)占开井数32.1%。低产低效井在连续抽吸过程中,由于地层供液不足,会造成油井处于干抽状态,抽油泵故障率增加等问题。建立了考虑油相渗透率、原油黏度随地层压力变化、同时考虑地层启动压力梯度的油井流入量计算模型。在此基础上,结合井筒的流出动态,建立了低渗透油藏低液量井生产模型。利用Visual Studio语言编写了低产低效油井间开制度优化系统软件,实现了低产低效油井间开工作时间的计算。实例验证表明,油井按照“该模型所确定的间歇开采时间”进行生产,产量均能达到原先连续生产时产量的95%以上,由此节约的电能所产生的经济效益巨大。

产水气井最小携液配产确定方法

产水气井通常采用“高产低配,低产高配”的思路,采用无阻流量的经验配产比例来确定气井生产制度。为提高产水气井携液能力和减少排水采气成本,建立定量化确定气井最小携液配产的方法,论证不同配产制度下产气量和井筒临界携液产量变化规律,在神府气田取得较好应用效果。研究结果表明:可以根据区块的地层压力、经验系数α以及管柱尺寸建立区块最小携液配产方程,通过数值求解,得到不同管柱下携液配产或配产比例图版;在较低无阻时最小携液配产比例较高,且变化较快,而非单一的经验配产比例;最小携液配产受到管柱尺寸、试气无阻和地层压力的影响较大,而受到区块α值的影响较小。建立的最小携液配产方法可以有效减少气井投产初期井筒积液的发生,对产水气井合理配产、管柱优化和生产动态分析具有一定指导作用。

磺基水杨酸显色法测定气井腐蚀水样中的铁含量

针对气井中CO_(2)腐蚀以及缓蚀剂的投加效果,利用磺基水杨酸显色法测定气井产出液中的铁离子浓度,通过铁离子浓度长期变化情况及同一裂缝系统气井铁离子浓度对比,考察腐蚀情况。分别研究溶液pH值、显色时间及溶液放置时间等对测定结果影响,结果表明,在pH值2~4时、显示时间20 min,可得到较准确的监测结果。同时监测气井加注缓蚀前后产出液铁离子浓度变化,表面缓蚀剂加注具有一定防护效果,将水样铁离子监测结果与现场腐蚀挂片实验结果相比较,结果吻合度较高。

高产水气井同井采注技术研究及应用

高产水气井因产水量大而存在井筒连续排液难、地面气水混输难及产出水处理成本高等问题。为此,基于“潜油电泵深抽+采出水不出地面处理”研究思路,研制了一种井下气液流道转化关键装置,实现井下气水流道空间转换及产层与回注层有效封隔;创新形成高产水气井潜油电泵同井采注工艺技术,确保气井油管稳定采气、油套环空产出水不出地面直接井下回注。潜油电泵同井采注工艺技术在42口高产水关停气井中推广应用,累计增产3350万m3,产出水全部实现井下回注,节省污水处理成本926万元,实现高产水气井经济有效排采。

气井精细排采智能管理系统的研发与应用

中国石油西南油气田公司重庆气矿所辖气田多处于开发生产后期,产水气井占比大,尤其是在“大中心站”管理模式和“油公司”改革模式下,依靠单一常规泡排(泡沫排水采气)和人工间歇开关井的生产方式,已无法满足气井精细排采的需求,老井精细管理面临巨大挑战。为此,通过开展井筒压力损失最小化及智能管理相关研究,依托现有物联网基础,研发了一套智能管理系统,集成“智能泡排+智能针阀+泡排大数据分析”的功能,实现低压低产泡排井稳定带液生产,间歇生产井采气时率最大化,充分发挥气井产能。研究及应用结果表明:(1)该系统能够根据气井实时生产数据进行智能分析和决策,合理确定开井、关井时机。(2)结合井筒压力损失和井筒积液量计算,该系统能够智能推送起泡剂加注量与加注时机,并自主调整针阀开度及优化井筒流态,提升低压产水气井的携液能力,实现气井“三稳定”(井口压力、日产气量和水气比三项指标的相对稳定)生产。(3)该系统在五百梯气田天东11井现场获得成功应用,降本增效显著。气井精细排采智能管理系统的研发与应用,为老井挖潜增产开辟了新的技术途径。