Paradigm for Determining the Optimal Ultradeep and Superthick Saline Aquifer for High-TDS Mine Water Geological Storage

Saline aquifers are the most popular waste and CO_(2)injection and storage reservoirs worldwide.This project proposes that several optimal injection positions should be investigated as hydraulic pressure-focused positions,in order to relieve the high demands of pump performance.The comprehensive indices(F_(i))representing the injectivity of different burial depths were obtained by using information entropy,based on the mercury injection experimental data of 13 rock samples.The results demonstrated that the burial depths of No.4,No.1 and No.2 in the Liujiagou Formation were the most suitable positions for hydraulic focused injection,which means the upper 30 m thickness could be regarded as the hydraulic focused range in the saline aquifer with an average thickness of 400 m.In addition,some laboratory experiments and in situ tests were carried out for the purpose of certifying and analyzing results,including SEM,XRD,brittleness index and logging.The results suggested that the rock samples at the No.4,No.1 and No.2 burial depth ranges have loose microstructure,weak cementation,as well as dual pores and fractures.The lithology is mainly quartz and feldspar,but the clay mineral content is high(10%-25%),which is positive for dissolution.The lithology is suitable for hydraulic fracturing to form extended cracks and micro-fissures during high-TDS(total dissolved solids)mine water injection,because of the high brittleness index.Finally,a theoretical and technical framework for high-TDS mine water injection was established,based on operating pilot engineering.Some theoretical defects and drawbacks learned from the field practices were summarized and solutions proposed.The research in this study could provide guidance and a paradigm for the inexpensive treatment of high-TDS mine water by injection and storage.

Three-dimensional physical simulation and optimization of water injection of a multi-well fractured-vuggy unit

With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.

Data-driven optimization for fine water injection in a mature oil field

Based on the traditional numerical simulation and optimization algorithms,in combination with the layered injection and production"hard data"monitored at real time by automatic control technology,a systematic approach for detailed water injection design using data-driven algorithms is proposed.First the data assimilation technology is used to match geological model parameters under the constraint of observed well dynamics;the flow relationships between injectors and producers in the block are calculated based on automatic identification method for layered injection-production flow relationship;multi-layer and multi-direction production splitting technique is used to calculate the liquid and oil production of producers in different layers and directions and obtain quantified indexes of water injection effect.Then,machine learning algorithms are applied to evaluate the effectiveness of water injection in different layers of wells and to perform the water injection direction adjustment.Finally,the particle swarm algorithm is used to optimize the detailed water injection plan and to make production predictions.This method and procedure make full use of the automation and intelligence of data-driven and machine learning algorithms.This method was used to match the data of a complex faulted reservoir in eastern China,achieving a fitting level of 85%.The cumulative oil production in the example block for 12 months after optimization is 8.2%higher than before.This method can help design detailed water injection program for mature oilfields.

Water-cut rising mechanism and optimized water injection technology for deepwater turbidite sandstone oilfield: A case study of AKPO Oilfield in Niger Delta Basin, West Africa

Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the timing and strategy of water injection were put forward. The water-cut rising shapes of producers after water breakthrough can be divided into three types, and their water-cut rising mechanism is mainly controlled by reservoir connectivity. For the producers which directly connect with injectors in the single-phase sand body of the single-phase channel or lobe with good reservoir connectivity, the water-cut rising curve is "sub-convex". For the producers which connect with injectors through sand bodies developed in multi-phases with good inner sand connectivity but poorer physical property and connectivity at the overlapping parts of sands, the response to water injection is slow and the water-cut rising curve is "sub-concave". For the producers which connect with injectors through multi-phase sand bodies with reservoir physical properties, connectivity in between the former two and characteristics of both direct connection and overlapping connection, the response to water injection is slightly slower and the water-cut rising curve is "sub-S". Based on ratio relationship of oil and water relative permeability, a new model of water cut rising was established. Through the fitting analysis of actual production data, the optimal timing and corresponding technology for water injection after water breakthrough were put forward. Composite channel and lobe reservoirs can adopt water injection strategies concentrating on improving the vertical sweep efficiency and areal sweep efficiency respectively. This technology has worked well in the AKPO oilfield and can guide the development of similar oilfields.

Optimization of the Algorithm for Increasing Injection Rate in Water Injection Wells for Pressure Optimization in P Oilfield

In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness.

Effect of water injection on hydrogen generation during severe accident in PWR

Effect of water injection on hydrogen generation during severe accident in a 1000 MWe pressurized water reactor was studied. The analyses were carried out with different water injection rates at different core damage stages. The core can be quenched and accident progression can be terminated by water injection at the time before cohesive core debris is formed at lower core region. Hydrogen generation rate decreases with water injection into the core at the peak core temperature of 1700 K, because the core is quenched and reflooded quickly. The water injection at the peak core temperature of 1900 K, the hydrogen generation rate increases at low injection rates of the water, as the core is quenched slowly and the core remains in uncovered condition at high temperatures for a longer time than the situation of high injection rate. At peak core temperature of 2100–2300 K, the Hydrogen generation rate increases by water injection because of the steam serving to the high temperature steam-starved core. Hydrogen generation rate increases significantly after water injection into the core at peak core temperature of 2500 K because of the steam serving to the relocating Zr-U-O mixture. Almost no hydrogen generation can be seen in base case after formation of the molten pool at the lower core region. However, hydrogen is generated if water is injected into the molten pool, because steam serves to the crust supporting the molten pool. Reactor coolant system (RCS) depressurization by opening power operated relief valves has important effect on hydrogen generation. Special attention should be paid to hydrogen generation enhancement caused by RCS depressurization.

Steam Flooding after Steam Soak in Heavy Oil Reservoirs through Extended-reach Horizontal Wells

This paper presents a new development scheme of simultaneous injection and production in a single horizontal well drilled for developing small block reservoirs or offshore reservoirs. It is possible to set special packers within the long completion horizontal interval to establish an injection zone and a production zone. This method can also be used in steam flooding after steam soak through a horizontal well. Simulation results showed that it was desirable to start steam flooding after six steam soaking cycles and at this time the oil/steam ratio was 0.25 and oil recovery efficiency was 23.48%. Steam flooding performance was affected by separation interval and steam injection rate. Reservoir numerical simulation indicated that maximum oil recovery would be achieved at a separation section of 40-50 m at steam injection rate of 100-180 t/d; and the larger the steam injection rate, the greater the water cut and pressure difference between injection zone and production zone. A steam injection rate of 120 t/d was suitable for steam flooding under practical injection-production conditions. All the results could be useful for the guidance of steam flooding projects.

Stable Production Technology for Horizontal Well Development in Shallow Water Delta Oilfield of Bohai Bay, China

BZ Oilfield is a medium-sized oilfield with shallow delta facies deposits in Bohai Bay of China,compared with fluvial and delta facies oilfields,there is no mature experience for reference of reservoir configuration,well pattern arrangement and development model in offshore oilfields in China.In view of the difficulty in describing the reservoir configuration of shallow water delta,the single distributary sand dam in shallow water delta is characterized by well-seismic combination and multi-attribute constraints.The mathematical mechanism model of pinch-out position of sand body is established,fine characterization of BZ shallow water delta reservoir is put forward.The horizontal well pattern arrangement type for shallow water delta reservoir is proposed and the method of well pattern optimization based on vertical displacement theory is put forward.A method of inversion of reservoir connectivity using production dynamic data by numerical well testing is proposed and a new method for optimizing water injection rate in water injection wells is proposed aiming at the difficulty of recognizing injection-production connectivity of shallow water delta reservoirs.The fine configuration of BZ shallow water delta reservoir based on distributary sand dam is proposed,which guides the recognition of remaining oil distribution law.By deploying adjustment wells,the water flooding coincidence degree of actual drilling is 86% compared with that of pre-drilling prediction,which indicates that the research results of reservoir configuration can effectively guide the understanding of oilfield geology.Through the theoretical well arrangement type of vertical displacement of single sand body in horizontal wells of shallow water delta reservoir,a high water flooding recovery rate of 35% is achieved in primary well pattern.The connectivity coefficients of injection-production boundary of shallow water delta reservoir configuration are calculated,and the water injection distribution coefficients are obtained by normalizing the directional coefficients.This paper presents a configuration method based on multi-attribute fusion under the constraints of sedimentary process.In this paper,a shallow water delta reservoir configuration method based on multi-attribute fusion constrained by sedimentary process is proposed,and the injection-production connectivity coefficient and injection well distribution coefficient of the configuration boundary are calculated.

大型注水管网最优运行模式判别规则及参数优选方法研究

注水管网的能耗是整个注水系统的能耗中有一个重要因素,体现在管网选用的运行模式以及参数优化2个方面。通过对大量注水数据的计算与评价,发现运行模式的选择与整个注水系统中各单井的压力分布特征有密切关系,据此形成了注水系统最优运行模式的五条判别规则。根据这些规则可以确定注水系统最优运行模式的选择方法和寻优计算步骤,并给出了不同模式的数学模型及运行参数的优选方法。在此基础上开发了注水系统最优运行模式智能判别软件,软件可以根据需要修改其运行参数,变换运行模式,便捷地模拟运行各种模式状态下的能耗情况,以寻找注水管网最优运行方案。最后通过一个计算实例演示如何通过改变运行模式和参数得到了一个能耗较低的方案。此结果表明本方法可以作为大型注水管网选择最优运行模式与参数优化的有效手段。

低渗透油藏微纳米乳液增注技术实验研究

基于纳米材料在低渗透油藏中良好的降压增注前景,对微纳米乳液作为增注剂的性能进行了研究。利用纳米粒度分析仪、接触角测量仪、岩心驱替装置等对微纳米乳液的基本性能进行评价,并对注入参数进行优化。实验结果表明,该微纳米乳液粒径较小,有一定的吸附性和改变润湿性的能力,能将岩石表面润湿性由强水湿变为弱水湿;该微纳米乳液具有良好的耐温性、防膨性、配伍性,当注入含量为0.5%(w)时,油-水表面张力最低降至0.60 mN/m;当优化后的工艺参数为单一段塞焖井、注入含量为0.3%(w)、注入流量为0.1 mL/min时,注水压力降低16.87%。基于实验室研究结果,现场试验6井次,平均注水压力下降1.8 MPa,日增注35 m^(3),有效持续时间达362 d,为低渗透油藏纳米降压增注技术提供了理论依据。

强非均质多层系双高油藏智能分注调控新方法

智能分层注水是现代油田注水调控的重要内容,为解决强非均质多层系双高油藏注水开发效率低的问题,利用油藏地质资料和生产数据,提出了针对此类油藏的智能分层注水调控新方法。该方法与传统分注方法不同的是,不需要建立地质模型,只需要通过拟合历史生产动态计算出纵向及平面劈分来完善油田分注方案,从而大大节省数模计算时间。通过对实际生产数据的历史拟合,计算出了纵向及平面的注水劈分,帮助分析多层系油藏不同层间及同一层中不同油井的注水占比情况,同时结合改进的随机扰动近似梯度(simultaneous perturbation stochastic approximation,SPSA)优化算法对油藏进行注采优化。将该方法应用到新疆L9油藏,经预测,实施典型井组调整措施2年后,较之前注水方案,区块累计产油量增加了4.6%,累计注水量减少了3.3%,井区含水率降低了2.6%,效果显著。研究表明,该方法能够有效提高注水利用率,优化油田开发效果,为强非均质多层系双高油藏的智能分注调控提供了新的思路和方法。

有缆式第四代智能分层注水技术优化及现场应用

青海油田注水开发油藏类型多,非均值性强,开发矛盾突出,在精细注水实施过程中测调工作量和测试力量不足,由于井况条件产生的测试遇阻问题也未能有效解决。为此油田引进第四代分层注水工艺,不需要投捞测试仪器,解决了仪器遇阻、遇卡的问题,优化电缆密封方式、研制电缆直穿式封隔器和远程通信及控制技术,实现了对注水层段在实时在线调控,为油田开发提供了技术支撑,为后续工艺升级提供了基础。有缆式智能分注技术在青海油田实施45口井,最大分注级数为5封5配,最大下深2033.5 m,施工层段密封率达到100%,单井调配时间相比桥式偏心提高了6倍,测试成功率达到100%。

水/蒸汽喷射时刻对汽油机燃烧和排放影响研究

通过由试验验证的型号为LJ465Q汽油发动机热力学模型,研究了缸内水和蒸汽喷射时刻对发动机性能和排放的影响规律。结果表明,在发动机2000r/min及全负荷下,喷射质量为9mg,喷射压力为10bar,喷射时刻为(-110~-60)°CA时,水喷射工况输出功率随着喷射时刻滞后逐渐减小,功率最大可提高0.71%,燃油消耗率可降低0.74%,喷水后减少了局部高温和局部过浓区域,有助于明显降低NOx排放,其最大降低了66.3%,HC排放有所增加;过热蒸汽喷射工况输出功率随着喷射时刻滞后逐渐增大,功率最大可提高1.7%,燃油消耗率可降低1.8%,NOx排放量随喷射时刻增大而减少,最大降低了55.2%,HC排放降低了15.4%。综上,缸内蒸汽喷射相比于水对发动机性能和排放的影响效果具有一定优势。

分时电价下油田分压周期注水优化研究

为降低由各注水井需求压力不一致导致的阀组节流损失,以泵站总能耗成本最低为目标函数,以站内泵机组及站外注水井服务要求为约束条件,借助数学规划和优化高级建模系统(GAMS)建模编程,调用内嵌分枝减小最优化导航(BARON)求解器求解,建立了一种分时电价下分压周期注水的数学模型。针对实际注水情况,考虑各压力范围注水井组交叉注水与顺次注水2种运行方案,通过对比分析确定了最佳注水方案。研究结果表明,优化后低压注水井组节流损失平均降低约7 MPa,中压注水井组节流损失平均降低约3 MPa,分时分压周期注水方式一周期内能耗成本可降低约13000元,极大降低了现场因节流损失带来的能耗成本,具有良好的经济效益。同时,顺次注水相较交叉注水具有更好的实用价值与可操作性,可为现场实际运行生产提供一定参考。

S油田注水站站场改造和工艺优化整合效果研究

随着油田的进一步开发,注水系统水、聚驱注水站的界限将逐步被打破,单座注水站运行负荷率低,深度水和普通水注水站合建效益越发明显。通过对结合产能工程已完成改造的南十和新南十注水站进行效果评价,提出在满足改造对所辖注水管网的压力损耗影响较小的前提下,对S油田两站之间距离近、建成时间长、设备腐蚀和老化严重的8座注水站的站场采取改造和工艺优化整合措施,改造及优化后,整体核减站场4座、优化岗位用工40人,达到减员增效、降低注水单耗的目的。该项研究对其他采油厂完成注水站站场改造和工艺优化整合工作具有重要的借鉴意义。

TVC-MED海水淡化系统运行优化试验研究

文章针对低温多效海水淡化(MED)与蒸汽抽射压缩器(TVC)耦合系统的工作特征,建立TVC-MED影响方式模型,分析TVC不同抽气运行模式对于MED造水比(GOR)的影响,通过优化设置TVC位置及调节蒸发器二次蒸汽量,对TVC-MED系统进行了优化改造,并通过现场运行试验,综合评价了改造后TVC-MED系统性能的提升效果。结果显示,TVC-MED系统优化改造后,海淡造水比平均提升1.06,产品水产量增加147 t/h,可累计增产淡水产值1545.24万元/a。

XB油田注水系统形势及优化调整措施

针对XB油田注水系统处理规模大、区域站库负荷低、系统间负荷不均衡的问题,提出了有针对性的优化措施。通过站库能力转换,实施系统间注水能力优化调整,合理分配注水站库能力,满足区域注水需求,实施后区域平均负荷率提高20%;对规模大、负荷低的站库,打破站库水质界限,实施布局优化调整,利用规模大站库对零散站库进行功能整合,实施后两区域平均负荷率分别提高41%和13.3%,共减少用工64人。措施后可有效实现注水系统的降本增效,为油田高质量发展助力。

基于大数据的汽轮机系统中变频技术与循环水泵优化研究

随着工业领域的发展和汽轮机系统的广泛应用,提高系统运行效率和降低能耗成为重要课题。本研究基于大数据技术,针对汽轮机循环水泵进行改造与优化。通过分析变频技术的原理和优势,以及大数据技术在汽轮机系统中的应用,设计了基于大数据的汽轮机循环水泵变频改造方案。通过实施该方案,可充分利用大数据分析和变频技术,提高汽轮机系统的运行效率,提高系统的稳定性和可靠性。

非插入式液压智能分控技术研究与应用

注水调配是油田实现注水井有效注水的重要手段。目前,涠洲海域多采用裸眼射孔完井,注水管柱为桥式偏心管柱或同心集成管柱,注水层位平均4~6层。井眼轨迹复杂,狗腿度大,需要依靠钢丝作业投捞水嘴完成调配,作业难度大、时间长、成功率偏低,且占用井口影响高产井作业。为提高智能化和精细化,设计了非插入式液压分控注水管柱以及配套的液压控制智能注水工具,可依靠地面控制系统完成地面智能在线测调。建立配水器水嘴模型,通过实验确定摩擦系数,精确描述流量压力关系,提高分注精度。通过管柱设计和管柱摩阻计算,在涠洲6-13油田A6井进行了非插入式液压智能分控技术应用,实现了液压精细分控,突破了温度高、井眼轨迹复杂、井深大的应用难题,测调效率提高了90%,分注精度达到油藏指标的95%。

薄互层砂岩油藏分层调配效果提升方法

C油田目前处于中高含水期,开发矛盾突出,表现在纵向超、亏压差异大、平面注采不均、单层水窜、稳控水难度大,迫切需要进行优化注水以改善油田开发效果。通过结合开发规律、生产阶段及井况进行产液量预测,考虑地层压力、水淹、地质因素进行分层配注实践,提出了优化注水建议及方法,在实践中进一步改善分层配注水平,最终提高水驱储量动用、改善注水开发效果。