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.

Fine anatomy of reservoir architecture of point bar in meandering river: a case study of Minghuazhen Formation in northern block of Q oilfield,Bohai Sea

In order to solve dynamic problems caused by the internal structure of fluvial reservoir,it is necessary to study the fine anatomy of point bar. Taking Minghuazhen Formation in the northern block of Q oilfield,Bohai Sea as an example,the authors studied identification marks,distribution pattern and scale of point bar based on coring,logging and dynamic data. The results show that the length of point bar and the width of lateral accretion body are 713--911 m and 71--111 m,respectively; the dip angle and the thickness of lateral accretion bedding are 3. 5°--5. 9° and 0. 1--0. 5 m. The lateral accretion beddings are the key factor affecting the seepage velocity of the tracer.

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.

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。

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。

渤海湾盆地埕岛东部新近纪火山活动及其油气地质意义

渤海湾盆地中部埕岛地区火山多期活动,对储层发育、油气运移及成藏等方面起到了一定的影响。目前研究主要集中在中生界火山岩储层上,对新近纪火山活动及油气成藏的影响认识不足,制约着埕岛东部油气的进一步勘探。本文综合区内应用测井、录井及地震资料,阐释了火山岩岩性、岩相及活动性等特征,并进一步探讨了火山活动对油气成藏过程的影响。研究区火山岩主要为灰黑色玄武岩,地震剖面上火山锥的形态较为清晰,平面上呈现串珠状或链状分布。结合地震相及钻井揭示岩电特征,将新近系底部火山岩岩相划分为火山通道相、爆发相、溢流相、火山沉积相和侵入相5种类型。火山活动始于新近纪早期,持续3~5 Ma即消亡,形成局部发育的角度不整合,并导致沉积环境由湖泊三角洲向辫状河的转变。研究区在火山活动和火山岩体作用下,重塑了油气输导及侧向遮挡条件,形成多种油气藏类型,与火山活动相关的岩性及火山岩体遮挡型油气藏是下一步勘探的重要方向。

渤海湾钻井液处理剂和钻井液体系生物毒性评价

我国环保形势日益严峻,油气田开发过程中环保压力越来越大,如何确保钻井液处理剂及体系无毒无害环境、环境可接受,最大限度减少钻井废物量,实施废物综合利用,满足钻井工程安全、优质、快速、高效需求,已经成为钻井作业的发展趋势,越来越受到重视。生物毒性检测试验是用于评价某种化学物质或混合物对环境的潜在污染物毒性危害预测的直接手段,室内对渤海湾常用的钻井液处理剂和体系采用发光细菌法进行了生物毒性检测评价,为环保钻井液研究和开发以及处理剂的优选提供了参考和技术保障。

BIODRILL S合成基钻井液在垦利区块首次应用

渤海油田垦利9-1区块地层岩性复杂,且存在断层带,钻井过程中易发生泥岩水化分散和砂岩层井眼缩径等问题,井壁垮塌风险极大。针对该区块地层岩性特点和技术难题并结合环保要求,制备了一种复合型封堵材料PFMOSHIELD,构建了BIODRILL S合成基钻井液体系。该体系流变性能良好,抗钙、抗岩屑污染达26%和15%,封堵性、沉降稳定性、润滑性优异,高温高压砂盘滤失量3.2 mL,静置7 d沉降因子为0.53,极压润滑系数0.082。BIODRILL S首次在渤海湾垦利9-1区块进行了现场应用,结果表明:该体系解决了垦利9-1区块泥页岩水化和砂岩层井眼缩径问题,垦利9-1北-3定向探井三开井段上部地层钻屑完整,钻屑达4~7 cm;井眼清洁性能良好,钻井液动塑比超过0.59 Pa/mPa·s,φ6和φ3读数均超过9,剪切稀释性强,提高了井眼净化效率,有效避免形成“岩屑床”;润滑性能优异,在大井斜段(55°、70°、67°)可实现直接起钻。

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。

渤海油田侧钻井轨道优化设计方法

渤海油田利用老井侧钻可实现老油田剩余油经济有效开发,不同的侧钻轨道设计方案决定着防碰风险大小、老井眼弃井工艺、侧钻后井身结构等等,如何选择最优的侧钻轨道至关重要。基于安全、经济、高效的设计准则,提出一种“井位匹配+自下而上的侧钻点优选”的渤海油田侧钻轨道设计方法,该方法应用于渤海某油田3口井的钻完井设计中,结果表明:该方法可实现轨道防碰风险降低、井控风险可控,降低成本100余万元,能够满足地质油藏所有需求。该方法在满足安全的前提下,可大幅提高侧钻井的经济性及方案设计的效率,为渤海油田侧钻井轨道设计提供了一种新思路。

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。

渤海油田浅层大位移井固井技术改进与应用

垦利16-1油田位于渤海南部海域,地质条件复杂,属于典型的“边、小、碎、深”油田。由于井斜较大、套管居中度差、地层承压能力差,固井过程中存在套管下不到位、漏失风险高、顶替效率低等诸多难题,严重制约着该区开发方案实施的进程。针对垦利16-1油田浅层大位移井固井难题,通过下套管技术改进、水泥浆体系优化,结合现场固井技术优化研究,提出了一套系统、成熟的浅层大位移井固井技术。该技术在现场实践中取得了显著效果,保障了该区块大位移井的固井质量,对于渤海湾海域类似情况大位移井固井具有重要的指导意义。

硬顶法压井技术在渤海油田的应用

【目的】海上油田钻井作业面临的地质条件、井下工况日趋复杂,部分井无法采用常规的压井方法实施压井,不仅增加了作业工期,而且可能形成井控风险。为了实现渤海油田复杂井安全压井,避免井控事故发生,在渤海油田应用了硬顶法压井技术。【方法】针对渤海油田的特殊工况,分析硬顶法压井技术适用的工况,指出硬顶法压井技术相关计算原则。通过分析硬顶法压井应用实例,提出该技术应用时的注意事项。【结果】研究结果表明,硬顶法压井技术适用于关井钻头离井底远、地层含有毒有害气体、钻具或钻头水眼堵塞、关井后发生井漏导致喷漏同存、长裸眼段测试后压井等五个方面,计算原则可从压井液密度计算、压井排量选择和过程计算等三个方面考虑。针对该技术在渤海油田A井的应用实例,提出了井口关键设备耐压等级的确定、上层套管鞋处地层承压能力、设备的选择、薄弱地层的处理四个方面需要注意的事项。【结论】研究结果明确了硬顶法压井技术使用原则和注意事项,可为硬顶法压井技术在复杂海上油田应用提供技术支持与参考。