Chemical kinetics evaluation and its application of natural gas generation derived from the Yacheng Formation in the deep-water area of the Qiongdongnan Basin,China

The natural gas generation process is simulated by heating source rocks of the Yacheng Formation, including the onshore-offshore mudstone and coal with kerogens of Type II2-III in the Qiongdongnan Basin. The aim is to quantify the natural gas generation from the Yacheng Formation and to evaluate the geological prediction and kinetic parameters using an optimization procedure based on the basin modeling of the shallow-water area. For this, the hydrocarbons produced have been grouped into four classes（C1, C2, C3 and C4-6）. The results show that the onset temperature of methane generation is predicted to occur at 110℃ during the thermal history of sediments since 5.3 Ma by using data extrapolation. The hydrocarbon potential for ethane, propane and heavy gaseous hydrocarbons（C4-6） is found to be almost exhausted at geological temperature of 200℃ when the transformation ratio（TR） is over 0.8, but for which methane is determined to be about 0.5 in the shallow-water area. In contrast, the end temperature of the methane generation in the deep-water area was over 300℃ with a TR over 0.8. It plays an important role in the natural gas exploration of the deep-water basin and other basins in the broad ocean areas of China. Therefore, the natural gas exploration for the deep-water area in the Qiongdongnan Basin shall first aim at the structural traps in the Ledong, Lingshui and Beijiao sags, and in the forward direction of the structure around the sags, and then gradually develop toward the non-structural trap in the deep-water area basin of the broad ocean areas of China.

Experimental study on characteristics of pore water conversion during methane hydrates formation in unsaturated sand

Understanding the pore water conversion characteristics during hydrate formation in porous media is important to study the accumulation mechanism of marine gas hydrate.In this study,low-field NMR was used to study the pore water conversion characteristics during methane hydrate formation in unsaturated sand samples.Results show that the signal intensity of T_(2) distribution isn’t affected by sediment type and pore pressure,but is affected by temperature.The increase in the pressure of hydrogen-containing gas can cause the increase in the signal intensity of T_(2) distribution.The heterogeneity of pore structure is aggravated due to the hydrate formation in porous media.The water conversion rate fluctuates during the hydrate formation.The sand size affects the water conversion ratio and rate by affecting the specific surface of sand in unsaturated porous media.For the fine sand sample,the large specific surface causes a large gas-water contact area resulting in a higher water conversion rate,but causes a large water-sand contact area resulting in a low water conversion ratio(C_(w)=96.2%).The clay can reduce the water conversion rate and ratio,especially montmorillonite(C_(w)=95.8%).The crystal layer of montmorillonite affects the pore water conversion characteristics by hindering the conversion of interlayer water.

Experimental investigation of hydrate formation in water-dominated pipeline and its influential factors

Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production.In this work,flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m.A 9-m section pipe is transparent consisted of two complete rectangular loops.By means of pressurization with gas-saturated water,the system can gradually reach the equilibrium conditions.The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles.When the circulation velocity is below 750 rpm,hydrate is finally deposited as a“hydrate bed”at upmost of inner wall,narrowing the flow channel of the pipeline.Nevertheless,no plugging is observed during all the experimental runs.The five stages of hydrate deposition are proposed based on the experimental results.It is also revealed that a higher driving pressure is needed at a lower flow rate.The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history.The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials.

Study of the Conditions of Formation and Forecast of the Perspective Areas of Hydrogen-Sulfide Water of Surkhandarya Depression

Increase in requirement of hydrosulphuric water for improvement of the population set the task of identification of places of their possible congestion for hydrogeological service. Earlier detection of such congestions was accidental at well-drilling of different function. Therefore, development of new methodical approaches of search and allocation of perspective zones of their formation was required. It was for this purpose necessary to study in what conditions and what factors have an impact on formation of underground hydrosulphuric water. So far, definition of communication attempts only with separate geochemical signs was known. Results of studying of influence on formations of hydrosulphuric water of such factors as lithologic and facial in combination with oil-and-gas content, the geological and structural and hydrodynamic mode are given in this work. It is established that the main sign for formation of hydrosulphuric water is existence of evaporite thickness and hydrocarbon congestions. Besides, it is shown that small depth (up to 2 km) of their bedding has to be an indispensable condition and existence of explosive violation on which there has to be a water infiltration (a geological and structural factor). In the Surkhandarya region, the hydrodynamic mode caused by inclined bedding of aquifers was also one of essential factors. Active water is an exchange process with washing away (oxidation) sulfate of the containing thicknesses and subsequently, its restoration in interaction with hydrocarbons with formation of hydrosulphuric water is described. The technique is developed and the expected card of perspective zones of formation of hydrosulphuric water is constructed.

Analysis of the world oil and gas exploration situation in 2021

The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries;second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly;third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins;fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.

Low resistivity oil(gas)-bearing reservoir conductive model——Dual water clay matrix conductive model in the north area of Tarim Basin, Xinjiang, China

Shaly sands reservoir is one of the most distributive types of the oil(gas)-bearing reservoirs discovered in China, and low resistivity oil(gas)-bearing reservoirs are mostly shaly sands reservoirs. Therefore, shaly sands reservoir conductive model is the key to evaluate low resistivity oil(gas)-bearing reservoirs using logging information. Some defects were found when we studied the clay distribution type conductive model, dual-water conductive model, conductive rock matrix model, etc. Some models could not distinguish the conductive path and nature of microporosity water and clay water and some models did not consider the clay distribution type and the mount of clay volume. So, we utilize the merits,overcome the defects of the above models, and put forward a new shaly sands conductive model-dual water clay matrix conductive model (DWCMCM) in which dual water is the free water and the microporosity water in shaly sands and the clay matrix(wet clay) is the clay grain containing water. DWCMCM is presented here, the advantages of which can tell the nature and conductive path from different water (microporosity water and freewater), in consid-eration of the clay distribution type and the mount of clay volume in shaly sands. So, the results of logging interpretation in the oil(gas)-bearing reservoirs in the north of Tarim Basin area, China with DWCMCM are better than those interpreted by the above models.

准噶尔盆地腹部地层水化学特征与油气成藏关系

油气的生成、运移、聚集、保存和散失都是在地层水的环境里或是在地层水的参与下进行的。地层水运动是油气运移聚散的动力和载体,其化学成分直接或间接地反映出油气赋存的环境与条件。地层水与油气在地质历史进程中的活动是相互依存、制约的因果关系。从水文地质观点和角度研究油气水的演化,剖析水和油相互作用的关系,掌握地层水对油气藏形成和分布的作用,同时利用地层水的某些离子特征和特征系数来反映油气的保存条件、地层的封闭程度、油气的运移有着密切的关系,旨在利用水化学的变化特征来寻找有利的油气聚集带。研究不同地区不同层系的油田水文地质,是寻找油气藏的方法之一,同时也是进行含油气远景评价的必备基础。

砂岩储层清水和污水混注对储层损害的实验评价

注入水中乳化油含量和悬浮颗粒含量及粒径一直是控制砂岩油藏注入水水质的重要指标。利用正交试验原理,通过实验系统评价了乳化油和悬浮颗粒共存时乳化油滴浓度、固相颗粒含量及粒径、渗透率及注入孔隙体积的相互作用及其对中高渗储层吸水能力的影响。结果表明,对于污水回注或清水、污水混注的砂岩地层,乳化油和悬浮颗粒共存比其单一存在时对地层吸水能力的损害要严重。当油滴粒径小于10μm时,岩心损害程度大于70%,油滴粒径大于30μm时,岩心损害程度低于50%。对于给定孔喉的岩心,有一个临界颗粒粒径。临界固相颗粒粒径随渗透率(即孔喉大小)的变化而变化,而临界油滴粒径基本不随渗透率变化,粒径约为15μm。

克拉玛依百口泉油田地层水化学特征与油气成藏关系

石油(天然气)与地层水是一对孪生姐妹,油气的生成、运移、聚集、保存和散失都是在地层水的环境里或是在地层水的参与下进行的[1]。地层水运动是油气运移聚散的动力和载体,其化学成分直接或间接地反映出油气赋存的环境与条件。地层水与油气在地质历史进程中的活动是相互依存、制约的因果关系。从水文地质观点和角度研究油气水的演化,剖析水—油相互作用的关系,掌握地层水对油气藏形成和分布的作用,同时利用地层水的某些离子特征和特征系数来反映油气的保存条件、地层的封闭程度、油气的运移规律。研究油田水文地球化学的目的在于寻找不同水文地质条件下油气运聚的水化学特征及其变化规律,而后利用水化学的变化特征来寻找有利的油气聚集带。因此研究不同地区不同层系的油田水文地质,也是寻找油气藏的一种方法,可为油气勘探提供依据,直接为生产服务,同时也是进行含油气远景评价的必备基础。

东北油气田可重复利用地层水基压裂液

针对东北油气田压裂液配液水缺乏及地层水重复利用难的问题,开展了东北油气田地层水特征分析及可重复利用压裂液研究。地层水特征分析以及地层水压裂液优选实验结果表明:苏家屯等几个区块地层水呈弱碱性,生物活性强、Ca2+、Mg2+含量高,使得常规稠化剂溶胀速度慢甚至沉淀、配制的基液稳定性差并且交联无法控制、交联液耐温能力差。最终确定了能采用地层水配制的BCS分子自缔合压裂液及130℃配方:0.55%稠化剂BC-S+0.45%稠化增效剂BL-S+0.3%金属离子稳定剂BCG-5+0.2%高温稳定剂B-13+0.3%高效阻垢剂BC-3。性能评价结果表明:BCS压裂液在130℃、170 s-1下剪切120min黏度可达35 m Pa·s以上,耐温抗剪切性能良好,携砂性能优于HPG压裂液,并且破胶彻底,破胶液残渣含量仅为1.5 mg/L,表面张力为24.32 m N/m。采用60%的自来水稀释压裂返排液后,配制的BCS压裂液能达到原130℃配方的标准,从而实现地层水的多次重复利用。

含水油藏的形成、评价和勘探——关于一种可能的新油藏类型的探索

含水油藏一般见于中 -低孔、低 -特低渗透率碎屑岩储层中。严重的非均质性是其突出特点。微观上 ,碎屑岩内部具有赋存液态石油的自流孔喉系统和饱和着原生地层水的滞流孔喉系统双重孔隙结构。其中 ,自流孔喉系统中含有自由水 ;滞流孔喉系统中主要赋存有微细孔隙水、微孔隙水、死孔隙水、和分子结合水。滞流孔喉系统在岩石孔隙体积中占有相当大的比例 ,制约着油水的产出情况 ,并导致了多数含水油藏的含油饱和度不足 5 0 %。含水油藏 (层 )形成的地质条件主要与二连中生界裂谷盆地群碎屑岩结构、组分成熟度过低及因成岩作用而物性急剧变差有关。在当前经济和技术条件下 ,含水油藏尚处于商业开采边沿 ,因此 ,应依据岩心含油、岩心滴水试验、气测录井、薄片鉴定、物性分析、压汞试验、核磁共振测量、油层测试等方面的特征 ,尽早对含水油藏 (层 )进行动态识别与评价 ,以避免实物工作量的无效投入。

淡化系数方程在稠油水淹层测井评价中的应用

孙德明等：淡化系数方程在稠油水淹层测井评价中的应用，测井技术，１９９６（５）２０，３４１～３４４。稠油水淹层为蒸汽吞吐开采，地层压力下降，地层水因蒸汽注入而淡化。由于稠油在井下保持凝固状态，用常规产水率来判别水淹层的方法在稠油层无法使用。本文用淡化系数方程求剩余油饱和度，用建立的过滤电位方程对ＳＰ曲线进行校正，然后利用校正的数据计算地层混合液电阻率。该模型共处理几十口井，水淹层解释符合率达８４．６％，填补了稠油层的水淹测井解释在国内的空白。

综合录井技术在油气田勘探中的应用

综合录井技术可应用于油气钻井的全过程 ,实时性是其最大优势。它利用气测参数、钻井液参数、工程参数等资料 ,可及时识别、评价油气水层 ,实时检测地层压力 ,预报异常高压地层 ,为钻井提供合理的钻井液密度 ,并实时监测、预报钻井工程事故隐患及事故。该技术对胜利油区油气储层解释的符合率达 79.8% ,监测预报各类工程事故及事故隐患成功率达 98%以上。

视电阻增大率在南八仙油气田油气水研究中的应用

南八仙油气田油气水分布规律复杂,不同层段的典型水层电阻率明显不同,有时会误判储层。针对此问题,认为视电阻增大率判断油气水层方法的关键是分层统计南八仙油田水层电阻率,把细分层段后的地层电阻率与同层段典型水层电阻率之比定义为视电阻增大率。然后在视电阻增大率-声波时差及视电阻增大率-补偿密度2个交会图上标出所有层段的试油、试采的油气水结论,建立起储层评价综合解释的统计经验判别标准,供认识油田的油气分布规律和编制开发方案时参考。

复杂水系下储层油气评价技术及应用

利用自然电位幅度差值ΔSP与视地层水电阻率Rwa交会图 ,确定复杂地层水系下高阻地层的地层水电阻率 ,计算储层含油饱和度 ,判断油水地层。该方法在苏丹南部穆格莱德盆地FL凹陷成功的应用 。

RFT资料在多井储层评价中的应用

本文以东濮凹陷马厂地区为研究工区着重论述重复式地层测试(RFT)资料在多井储层评价中的应用。利用压力资料可定性、定量判断储层的渗透性,估算渗透率值可用于油层有效厚度标准研究,压力随深度梯度变化转换为密度变化来了解流体性质、确定油水界面,从而验证测井多井解释结论。研究表明,应用效果明显,解释结论得到试油试采证实,解释符合率提高,研究成果有助于研究工区油藏综合评价,部分成果已用于油田生产。

注入水水质对SN-1井区油藏采收率影响研究

针对准噶尔盆地SN-1井区油藏存在的油井普遍高含水、部分井注水受效差以及清污混注后油水井渗透率下降等问题,开展了SN-1井区油藏水驱采收率影响因素研究。通过开展水质对岩心的伤害、岩心驱替及注水水质指标分析等室内实验和注水优化数值模拟,分别从微观尺度、岩心尺度和宏观尺度,对注入水造成的储层伤害进行了研究,揭示了导致油水井渗透率下降的伤害机理,认识到注入水中固相堵塞造成的储层伤害是导致水驱采收率低的主控因素,发现固相堵塞不仅影响微观驱油效果,还会使流度比增加,降低波及效率。因此,SN-1井区油藏回注水质不达标是注水受效差的主要因素,应将悬浮固体质量浓度作为首要水质控制指标。多尺度评价方法提高了结果的可靠性,对提高油田水驱开发效果具有指导性,可为油田稳产开发提供技术储备。

求取剩余油饱和度的一种实用方法

分析了水驱油田地质、测井及开发动态特征，提出了用生产井含水率资料结合测井资料求取产层平均剩余油饱和度的方法。阐述了该方法的基本模型和计算过程，并以实例计算说明了这种方法的实际应用效果。结果表明，该方法操作简便、实用性强、计算结果可靠，且能准确反映储层的剩余油分布特征。这种方法也避免了水淹层混合液电阻率、岩电系数和水淹层电阻率求取值失真的影响。

港中浅层低电阻率油层成因及识别方法

针对港中浅层存在的低电阻率油层现象开展研究,分析了构造、岩性、地层水性质及钻井液性能等影响地层电阻率的主要因素,探讨了评价低电阻率油层的技术对策。通过综合利用测井、测试及地质资料开展精细地层对比,分析各套油水系统的分布规律,有针对性地进行油水层综合评价,突破传统油层评价观念束缚,充分挖掘各类油气信息,重新制定了该区的油气层解释图板,现场实施取得了比较好的效果,为该区类似油气层的重新评价提供了借鉴。

岩心离子探测技术在油水层识别中的应用研究

地层流体分析是贯穿于油气勘探开发全过程的一项基础性工作,先期的地层流体分析和认识对于试油选层、工程设计有很大的影响。地层含水分析在地层流体分析和识别中具有突出的地位,但目前却缺乏相应的技术手段和方法,针对这种现状研究开发了岩心离子探测技术,建立了基于离子探测技术的地层含水分析方法,首次推导出利用岩心离子探测数据计算地层含水饱和度的公式,并以实际资料验证了该方法的可行性,实际应用情况表明其效果良好。