Modeling of the Bohai oilfield engineering geology demonstration information system based on digital seabed technology

In this paper, the framework and technologic process of engineering geology demonstration information system （EGDIS） of the Bohai oilfield are presented, and the key technologies for system modeling, such as storage and processing technology of multi-source and heterogeneous data, integrated display technology of multi-source information and multiple safeguard system design are studied. EGDIS of the Bohai oilfield is an integrated application system based on the data standardization and digital seabed database, has the function to realize the standardization/conformity, input/output, inquiry and display of the multi-source and heterogeneous data and graphics, and provides multiple comprehensive analysis and application services, which will provide shared and scientific basic data for the marine engineering construction and oilfield engineering safeguard.

Research on Empirical Formula of Displacement Efficiency in Bohai Oilfield

Displacement efficiency is an important index of water drive oilfield. This article takes water drive oilfield as the object to analyze the influence factors of displacement efficiency in limit water cut stage of water drive oilfield. The displacement efficiency experimental data of 99 cores which come from 65 development wells of 34 oilfields have been collected. The authors use the method of multiple linear regression analysis to establish a new empirical formula of displacement efficiency. The relative error of the empirical formula is less than 7% compared to the experimental data.

Study on the Distribution of Interlayer in Thick Sandy Braided River under Large Well Spacing—A Case of C Oilfield in Bohai Sea

Using core, logging and other data, combined with field outcrop deposition, this paper studies the sedimentary genetic types and sedimentary stages of thick sandy braided river interlayer in C oilfield, and divides two stages of interlayer and three single-stage braided flow zones. On this basis, geostatistical inversion constrained by logging and discerning River quantitative knowledge base is carried out to predict the distribution range of the main interlayer in the two phases. The production performance test of the blind well and horizontal well shows that the coincidence rate of the prediction results of interlayer with thickness > 1.5 m is 75%. The research shows that the first stage is the main interlayer, mainly composed of mudstone of flood plain origin, with an average thickness of 2.1 m and relatively stable distribution. Based on the interlayer prediction results, the small layer of composite sand body 1 forms a residual oil enrichment area in the high part of the structure due to the wide range of interlayer shielding in the lower part, which is a favorable area for adjusting and tapping potential.

Sandbody architecture of the bar finger within shoal water delta front:Insights from the Lower Member of Minghuazhen Formation,Neogene,Bohai BZ25 Oilfield,Bohai Bay Basin,East China

Core, well logging and seismic data were used to investigate sandbody architectural characteristics within Lower Member of Minghuazhen Formation in Neogene, Bohai BZ25 Oilfield, and to analyze the sedimentary microfacies, distribution and internal architecture characteristics of the bar finger within shoal water delta front. The branched sand body within shoal water delta front is the bar finger, consisting of the mouth bar, distributary channel over bar, and levee. The distributary channel cuts through the mouth bar, and the thin levee covers the mouth bar which is located at both sides of distributary channel. The bar finger is commonly sinuous and its sinuosity increases basinward. The distributary channel changes from deeply incising the mouth bar to shallowly incising top of the mouth bar.The aspect ratio ranges from 25 to 50 and there is a double logarithmic linear positive relationship between the width and thickness for the bar finger, which is controlled by base-level changing in study area. For the bar finger, injection and production in the same distributary channel should be avoided during water flooding development. In addition, middle–upper distributary channel and undrilled mouth bar are focus of tapping remaining oil.

The Application of Pressure Coefficient in Judging Normal Pressure Reservoirs Connectivity—A Case Study of LD21-X and KL3-Xoilfield in Bohai Bay

Reservoir connectivity is a critical issue in the process of oil-gas exploration and development. According to the theory of fluid mechanics and the achievements of many scholars, a connected reservoir coincides with a unified formation pressure system;there is a linear relationship between formation pressure and depth in normal pressure system reservoir. However, in high-permeability or multi-phase fluid reservoirs, this method has poor applicability and limitations. Through theoretical analysis and formula derivation, a new method for judging the connectivity of normal pressure reservoirs is found, that is, the inverse proportional function relationship between the pressure coefficient and the depth. In this paper, the relationship between the pressure system and the inverse proportional function has been verified. The function of the same pressure system is unique, monotonic, and has unified asymptote and symmetry axis and vice versa. Examples show that the inverse proportional function is more accurate and reliable for judging reservoir connectivity than the linear function.

Structural Characteristics and Evolution Process of the Metamorphic Buried Hill: A Case of BZ Oilfield in Bohai Bay, China

Bozhong oilfield which is abbreviated as BZ oilfield is the first oilfield with deep metamorphic buried hill that is discovered reserves of billion-ton in Bohai Bay. Affected by multi-stage tectonic movements, the distribution of fractures is very complex in this area, therefore it is significant to study the evolution of structures for understanding the distribution of fractures. In view of the complexity on the tectonic evolution of the buried hill region in the study area, the influence of tectonic movements on the formation of fractured reservoir is analyzed, and the research results lay the foundation for the efficient development in this type of the oilfield. The results show that main faults, which is formed during early Indosinian and Yanshanian period, are mainly developed in the BZ oilfield area, and the fracture strike has mainly east-west and north-east-east trend. Based on the analysis of the relationship among tectonic evolution, regional stress field and fracture development, it is considered that Indosinian extrusion is the main reason for the formation of main direction faults in the study area. Yanshanian strike-slip transformation and Himalayan reactivation further controlled the development of the fractured reservoirs in the later stage, and formed the present fracture network system. Well block 5 is located in passive plate system during Indosinian period, it is affected by Himalayan stretching and long-term activation of large faults in the later stage, so that the effective fractures are relatively developed. The result plays an important role in guiding the overall plan deployment of the BZ oilfield.

生物纳米增注技术在渤海油田中低渗储层的应用

海上油田注入压力高,注水量达不到配注要求,为此研制了生物纳米增注技术,该技术主要由改性纳米颗粒和生物分散剂构成。文中利用红外光谱分析、扫描电镜观察等手段对生物纳米增注体系的分散稳定性、耐受性、粒径分布和改性接枝特性进行了评价。实验结果表明:生物纳米颗粒为疏水性纳米二氧化硅SiO2,不同加量的生物纳米溶液放置12~360 h后,透光率均保持在95%以上;生物纳米体系平均粒径为58.10 nm,Zeta电位维持在-32 mV左右,可抑制地层水矿化度的影响,最高抗矿化度为75 g/L。对生物纳米增注体系注入工艺参数进行了优化,结果表明:纳米溶液最佳加量为10%,最优注入量为3 PV,最佳注入速率为0.50 mL/min。渤海K油田进行了生物纳米增注技术矿场试验,3个月后,目标井作业后储层平均吸水指数由12 m^(3)/(d·MPa)升至30 m^(3)/(d·MPa),中低渗小层启动压力由15.1 MPa降至6.5 MPa,井组累计增注量已达0.9×10^(4) m^(3)。该研究为解决海上中低渗油藏注水困难以及保证油田发展提供了新技术、新思路。

渤海B油田在线调剖乳液聚合物凝胶体系优选与应用

渤海B油田层非均质性日益严重,水驱指进现象严重,急需实施调剖作业用以延迟油层水淹速度和抑制油井含助剂提升。本文通过优选乳液聚合物、交联剂、交联助剂选出了成胶时间可调(2~9 d)、成胶强度可控(0.3×10^(4)~5×10^(4)mPa·s)的凝胶体系,具有“注得进、堵得住”的特点,成胶后封堵率可达到99%以上。该体系在渤海B油田C20H井组进行了矿场试验,调剖后井组综合含水率评价下降4.05%,日产油增加26.91 m3,效果显著。

渤海C油田馆陶组储层堵塞实验评价研究

为了分析明确渤海C油田导管架期间预钻井的12口生产井,在组块安装后投产产量达不到配产目标的原因,针对有机质沉积、原油乳化堵塞、流体配伍性、钻完井液漏失与返排等潜在储层伤害因素,开展了储层堵塞实验评价研究。实验结果表明:1)免破胶无固相钻开液(EZFLOW)漏失量越高渗透率伤害程度越大,同时考虑钻完井液漏失时,天然岩心的渗透率伤害程度为37%,伤害程度中等;2)有机质沉积对储层伤害较为明显,注入0.4 PV原油后渗透率伤害程度达到98%,且随有机质沉积量的增加,储层伤害越大;3)油包水型乳状液(W/O型)驱替对岩心渗透率伤害程度高达75.01%,水包油型乳状液(O/W型)驱替对岩心渗透率伤害程度为25.21%,低含水层受原油乳化堵塞影响较明显。综合分析认为,渤海C油田12口预钻井低产原因为导管架预钻井后待组块安装期间关井静置过程中有机质沉积和原油乳化伤害。同时,渤海C油田12口预钻井目的层馆陶组储层物性因子较小,产液指数较低是导致低产的原因之一。研究结论为后续增产措施以及方案提供了依据。

渤海油田深井深层防漏堵漏技术策略研究

通过分析渤海油田近三年来漏失事件的漏失程度及类型,从工程角度提出渤海深井深层防漏技术策略和堵漏工艺选择策略,针对渤海深井深层漏失情况,从工程角度对漏失程度及类型进行统计分析,并结合现场情况和堵漏技术,提出渤海深井深层防漏技术和工艺选择策略,以提高钻前避漏的有效性和堵漏工艺的高效性,给海上油气田勘探开发提供一种安全、经济和高效新的思路。

渤海稠油油田热化学复合吞吐增效技术研究与应用

针对渤海稠油油田在生产稠油井存在的原油黏度大、胶质沥青质沉积造成储层有机堵塞严重、产量递减快、边底水突进、含水上升快等问题,通过室内实验研究分析、物理模拟与参数优化开展了海上热化学复合吞吐增效技术研究。结果表明:随温度升高,胶质、沥青质扩散系数增大,石英石表面对重质组分的吸附能力减弱,有助于胶质沥青质解离;热气化学复合解堵后,岩心水测渗透率均可恢复到初始岩心水测渗透率的60%~70%;热(80℃)+气(溶解)作用下,与50℃脱气油相比可使原油黏度降低约80%;在热和化学剂作用下,原油形成低黏水包油乳状液,稠油黏度由2000 mPa·s降低至30 mPa·s,降黏率为98.5%;稠油相渗曲线测试实验(100℃)结果显示,化学剂注入后使稠油相渗曲线等渗点右移,两相共渗区域增大,油相渗透率变大,水相渗透率降低,残余油饱和度降低,开发效果改善;在热水驱过程中,注入泡沫堵调后,高渗填砂管和低渗填砂管采收率均有明显提高,低渗管采收率提高约11个百分点,高渗管采收率提高约8个百分点。模拟吞吐实验结果表明:在热+化学+气协同作用下,可至少降低含水20%~30%,采油指数由0.90 mL/(min·MPa)提高至1.95 mL/(min·MPa),可显著改善低产稠油井的开发效果。热化学复合吞吐增效技术已在渤海稠油油田现场取得成功试验,措施井含水最高降低73.4个百分点,有效期150天,平均日产油较措施前提高2.9倍,有效期内累增油4300 m^(3),为渤海稠油冷采井增储上产提供了新的技术思路和方向。

渤海海域BZ19-6区块变质岩潜山储层特征与优势岩性序列探讨

对渤海BZ19-6区块变质岩潜山数口钻井的铸体薄片、常规物性等数据展开综合分析,依据矿物组成和岩石结构、构造等建立该区块变质岩的岩性划分方案。研究结果表明:除黑云二长片麻岩、黑云斜长片麻岩和黑云钾长片麻岩外,其余变质岩的浅色矿物(石英、长石为主)含量均较高,暗色矿物(黑云母等)含量较低;有效储集空间主要为构造运动产生的未充填裂缝和斜长石的粒内溶孔;当石英含量为25%~35%(体积分数)、斜长石比率为0.4~0.6时,物性最好;碎裂岩、二长片麻岩、二长混合花岗岩、斜长混合花岗岩的浅色矿物含量高,孔隙度和渗透率高,是形成优势储层最有利的变质岩岩性。但是,各岩性之间的浅色矿物含量、物性、抗压强度等相差不显著,指示岩性确实起到基础作用,但是构造作用可能是有利储层形成最主要的控制因素之一。

渤海油田低渗储层开采技术研究进展与展望

海上低渗油田的高效开采已成为海洋油气增储上产的重要方向。从2006年开展低渗储层压裂先导试验开始,渤海油田经过十余年的攻关与实践逐步总结出适应于渤海低渗储层特征的开采策略,并针对常规低渗储层、低渗/特低渗储层和复杂岩性低渗储层特征形成压裂开采技术体系,包括常规低渗储层整体压裂技术、防砂卡精细分层压裂技术,低渗/特低渗储层复杂裂缝改造技术、分层暂堵压裂技术,复杂岩性低渗储层缝控压裂技术、水力喷射压裂及防砂技术、裂缝蚀孔酸压技术。“十四五”期间渤海油田将重点攻关特低渗储层注气开采、大规模低成本压裂和裂缝监测等核心技术,持续推动渤海低渗储量实现规模化高效开采,为中国海上低渗油田开采技术的进一步发展提供参考。

渤海油田化学驱注入井解堵剂构建、性能和注入工艺

渤海J油田经历长期化学驱,注入井储层低渗透部位堵塞严重,常规解堵措施效果较差,亟待开发新型解堵剂和解堵工艺。为此,以渤海油田目标油藏聚合物驱水井返排堵塞物为研究对象,开展了化学驱注入井解堵剂构建、性能评价和工艺研究。结果表明,目标油田化学驱水井返排堵塞物由87.77%水、3.83%原油、2.76%聚合物和5.64%无机垢构成,其中无机垢主要包括59.1%SiO_(2)、25.9%CaCO_(3)和11.4%MgCO_(3),同时含有少量的BaCO_(3)、SrCO_(3)、BaSO_4、SrSO_4和Fe_(2)O_(3)。根据堵塞物成分,构建了由有机溶剂、解聚剂和溶垢剂等组成的新型解堵剂。优选出的有机溶剂为甲苯与正戊醇的混合物(质量比9∶1~7∶3),解聚剂为0.5%~1.0%过硫酸铵,溶垢剂为5.46%溶垢剂1(α-环糊精包合体和β-环糊精包合体)+0.54%柠檬酸。3种类型解堵剂依次加药的溶垢效果好于复配加药方式,按解聚剂+有机溶剂+溶垢剂(质量比为1∶2∶3)的加药顺序,对堵塞物的溶垢率为98.1%。岩心解堵实验结果表明,新型解堵剂对无机混合垢和聚合物堵塞的解堵率超过80%。与单独解堵作业相比,无机凝胶调剖+解堵联合作业兼具“堵”和“疏”双重功效,采收率增幅提高6.9百分点。

注聚合物井解堵剂及工艺措施解堵效果

渤海L、S和J油田经过长期注水注聚开发,储层的非均质性进一步增强,聚合物在储层内发生滞留,导致储层吸液能力大幅度下降,解堵是缓解当前情况的有效技术手段之一。为满足渤海化学驱解堵技术需求,评价了由解聚剂、酸和螯合剂组成的复和解堵剂和溶垢剂的解堵效果,探究了注入方式、注入压力和调剖措施对解堵效果的影响及作用机制。结果表明,将1.0%过硫酸铵与0.5%无机缓蚀剂组成解聚剂,当其质量分数为1.0%、段塞尺寸为0.05 PV时,聚合物堵塞岩心渗透率恢复率可达90.31%,解聚效果较好。将0.54%柠檬酸与5.46%螯合剂组成溶垢剂,当其质量分数为6.0%和8.0%时,对3种无机垢堵塞岩心渗透率恢复率超过80%,溶垢效果较好。提高解堵剂注液速度可提升注入压力和改善解堵效果,注入压力升高至3.0倍和3.5倍水驱压力时的采收率增幅为0.74百分点和0.88百分点。但提升注入压力后大部分液体仍会进入储层高渗透部位,低渗透层吸液量增幅十分有限,进而影响解堵效果。为此,提出调剖+解堵联合作业工艺措施,即在注入解堵剂之前先进行调剖。与单纯解堵相比,当注入0.3、0.6 PV无机凝胶调剖剂时,调剖+解堵联合作业的采收率增幅分别为7.7百分点和12.19百分点。

多层合采油藏层间非均质性表征研究

大井段多层合采开发往往面临严重的层间干扰问题,准确描述层间非均质性是解决层间干扰问题的关键。洛伦兹方法是描述层间非均质性最常用的手段,但其在开发领域适用性尚不明确。针对这一问题,运用数值模拟方法及油藏工程理论开展洛伦兹方法开发适用性研究。研究发现:洛伦兹方法表征非均质性与开发效果相关性不强,仅在局部敏感区间内对开发效果产生剧烈影响;同时,当洛伦兹系数相等时,曲线形状对开发效果也有影响,但传统方法无法有效表征。因此,对洛伦兹方法进行了修正,并对修正方法开展了物理模拟实验及油田数据验证。实验结果表明:修正后大大扩展了洛伦兹系数的敏感区间,使得水驱开发效果与洛伦兹系数之间的相关性显著增强。实例应用表明:修正前后,KL-A区洛伦兹系数与采收率相关系数从0.48增至0.87,KL-B区相关系数从0.74增至0.87,可见层间非均质性与开发指标的相关性显著增强。

渤海油田稳产增产钻完井技术进展与展望

为了解决渤海在生产油田面临的井槽、井筒资源紧张,储层产能释放程度受限,水淹储层高含水加剧等问题,通过技术攻关和工程实践,形成了以井槽、井筒高效利用,海上压裂增产,水淹储层高效控水为代表的渤海油田稳产增产钻完井技术体系。主要技术成果指标包括:中短半径侧钻技术全角变化率可达到18.97°/ 30 m,近钻头测斜盲区由23 m缩短至0.6 m,突破技术瓶颈;压裂充填技术可实现177.8 mm套管内的1趟6层压裂充填作业,突破作业极限;可充填式自适应防砂控水一体化技术创新采用“双层筛管、内层基管不打孔”的形式结构,实现了控水和防砂双重目标。基于油田未来面临的工程技术难题,建议在浅水水下井口开采模式、精细化可控超短半径侧钻技术、海上大规模压裂作业模式和多专业协同控水模式等方面持续攻关,为渤海油田实现稳产增产目标提供技术保障。

渤海湾盆地埕岛东部新近纪火山活动及其油气地质意义

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