混合压裂在苏里格致密气藏水平井的应用

苏里格致密砂岩气资源量巨大,压裂水平井是重要的开采手段之一。常规水力压裂形成的高导流短裂缝对于致密砂岩储层或低渗砂岩储层Ⅲ,Ⅳ类井增产效果较差,另外,高黏度交联冻胶压裂液对储层伤害较大。通过借鉴混合压裂工艺在国外致密气田的成功案例,结合苏里格致密砂岩气藏的地质特征,使用StimPlan软件模拟常规压裂和混合压裂裂缝形态,并借助井下微地震监测结果,分析了2种压裂工艺井的裂缝展布特征,验证了压裂施工效果。最后,通过苏里格东区致密气藏60余口水平井的试气和生产产量对比,得知混合压裂比常规压裂增产效果明显,且降低了施工成本。混合压裂工艺由于"低伤害、控缝高、造缝长、低成本"等特点,是苏里格致密砂岩气藏开发中的有效增产手段之一。

鄂尔多斯盆地致密油层混合压裂簇间干扰研究

针对鄂尔多斯盆地致密油层施工排量和簇间应力干扰作用对形成复杂缝网的影响开展了相关研究。采用离散缝网模型及有限元软件进行模拟分析,选择产层相同、压裂增产方案相近的2口试验水平井,进行压裂设计参数对比、产量对比及微地震监测结果对比。研究表明,施工排量过小,压裂效果以常规双翼缝为主,大排量是保证复杂缝网形成的条件;储层存在实现复杂缝网的临界排量,大于该临界排量时,主裂缝变短,次生缝网增加,带宽变大;多簇压裂时,主裂缝不同步开裂易引起主裂缝不同步延伸,率先延伸的主裂缝会抑制周围主裂缝的延伸甚至开裂,后延伸的主裂缝周围易产生剪切诱导的次生裂缝,利于形成复杂缝网。因此,选取大于临界排量的施工排量有利于增加储层改造体积,而多簇压裂时开裂延伸的主裂缝数量有可能小于设计簇数。

利用CO2混合压裂技术提高无支撑裂缝储层的产量--新型CO2混合压裂技术可以将油藏的采收率提高25％，充分利用了CO2低黏度的特性尽可能接触到更多储层的优势

超致密储层经过多级水平压裂后，井筒和裂缝系统的连接区域、近井裂缝区域及远井裂缝网区域的属性与产量密切相关。远井裂缝网区域的支撑剞不足、裂缝网状态复杂，包括大量无支撑裂缝，但是该区域贡献了主要的裂缝面积，还决定了排烃的范围。实验验证，CO2是一种极具潜力的压裂液，可增加改造裂缝的数量和密度，提高无支撑裂缝的导流能力，使无支撑裂缝储层获得高产。为了评价CO2混合压裂技术对常规水基压裂设计的优化作用，建立了储层模型考察复杂裂缝网对增产的影响。结果表明，CO2低黏度的特性可以接触到更多的储层，有效提高无支撑裂缝的导流能力，从而增加产油区的排泄面积。该技术可将油藏的采收率提高25％。

吉7区块深层致密砂岩气藏压裂改造技术研究与应用

吐哈盆地丘东洼陷侏罗系致密砂岩气藏储层具有埋藏深、高压、储层破裂压力高、地温高、特低孔特低渗、非均质性强、横向储层厚度变化大、纵向分布多等特点,储层加砂困难,增产改造工艺技术面临极大挑战。针对区块储层改造难点,优化了针对性的压裂工艺技术:针对致密砂岩储层特低孔特低渗、岩石致密,采用滑溜水+胶液混合压裂工艺技术,滑溜水形成复杂体积缝,胶液携砂增大砂浓度并提高导流能力;采用分簇射孔+复合桥塞分层压裂工艺实现分层改造,取得了一定的改造效果,对探索深层致密砂岩气藏储层改造技术具有重要借鉴意义。

新型压裂技术在页岩气开发中的应用

先进的压裂技术是页岩气藏得到商业开发的关键。目前页岩气藏压裂大多采用水基压裂液,存在清水用量巨大,回收、处理困难的问题。在分析清水压裂的特点和中国压裂条件的基础上,指出页岩气压裂的约束条件和发展方向。通过深入调研国外最新技术,从研发背景、施工工艺、技术特点和应用效果等方面介绍了新兴的混合压裂、纤维压裂、通道压裂、CO2压裂和液化石油气压裂技术,并针对中国页岩气开发现状进行适用性分析。认为清水压裂对于验证中国页岩气可采性和进行试探性开发具有不可替代的作用;新型压裂技术能够不同程度解决清水压裂的现存问题,这些技术的研究和应用价值将在中国水资源匮乏、环境污染严重、设备运输问题的现状和页岩气长期商业开发的实践中日益凸显;分析认为在引进国外技术的同时应加快新型压裂技术的自主研发和试验,这样才能尽早使中国页岩气的成功开发成为现实。

中拐石炭系压裂增产配套技术的研究与应用

新疆油田中拐石炭系储层物性差,属于低孔、特低渗类差储层,油井的自然产能低,常规压裂方法难以达到理想的增产效果。为了提高储层油气获取率,通过对压裂液体系优化,采用多缝控高压裂增产技术、混合液大规模压裂技术、控压排采技术,形成了一套适合中拐石炭系储层特征的压裂增产配套技术。该技术在JL10井区应用7井次,施工成功率100%,增产效果明显,7井获得工业油流,单井最高日产量达60 m3/d以上。

混合牙列期咬合不正和早期矫治需求性分析研究

目的分析混合牙列期咬合不正和早期矫治需求性。方法评估2013年1月至2015年12月于该院牙科就诊的162例6~12岁儿童混合牙列期咬合关系,并对早期矫治需求进行评估。结果25.9%的儿童上颌前牙排列良好,且女童显著多于男童,差异有统计学意义(P<0.05);牙列重度拥挤和重度间隙的发生率分别为5.0%和11.7%;有56例(占34.6%)儿童下颌前牙排列良好;下颌弓牙列重度拥挤发生率14.2%,女童显著高于男童,差异有统计学意义(P<0.05);重度间隙发生率1.9%,男童显著高于女童,差异有统计学意义(P<0.05);覆发生率为65.4%,覆盖异常率为64.8%;咬合异常占比35.8%,有不良口腔习惯的儿童占比43.2%;存在单一研究对象需求多种治疗,需要活动矫治器的例数占19.8%、习惯矫正器占24.7%、2×4技术(单牙弓)占11.7%、2×4技术(双牙弓)占14.8%。结论轻度深覆盖和前牙旋转是较为频繁的咬合异常,这2种异常不仅影响美观,也可能会增加牙齿创伤的可能性;某些个体还需要接受多种治疗,治疗方案包括拔牙、佩戴矫治器或者防护牙托、2×4技术、扩展牙弓、间隙保持、接受定期检查和心理疏导。

延安地区陆相页岩气勘探开发关键技术

陆相页岩气是我国页岩气资源的重要组成部分,具有良好的发展前景。针对陆相页岩气面临的一系列技术难题,开展了理论研究与关键技术攻关。研究结果表明:1)陆相页岩有机碳含量高,有机质类型为Ⅱ_(2)型、Ⅲ型干酪根,生气能力强,低成熟条件下仍然能够大量生气,具有“源储保”三元富集特征;2)通过核磁测井、等温吸附-声波联测和岩石力学实验等方法,建立了陆相页岩储集性、含气性及可压性等“三品质”测井综合评价技术,气层判识率达到94%;3)研发了页岩气水平井全井筒防塌、防漏钻井技术,以及适合于陆相页岩的水基钻井液技术、一次上返固井技术等,形成了页岩气高效低成本钻完井技术,钻井成本降低24.3%;4)针对陆相页岩塑性强、水力压裂效果差的问题,创建了CO_(2)混合压裂技术,云页平5井试气产量达到6×10^(4)m^(3)/d;5)构建了陆相页岩气表观渗透率计算方法和产能预测模型,符合率达到85%以上。关键技术应用后,共部署实施页岩气水平井5口,平均单井产量是原来的3倍,取得了显著效果。

国外复杂气藏增产技术新进展

随着天然气需求的不断增加,常规天然气已不能满足发展需求,非常规气、深层气的作用越来越重要.因此提高非常规气藏及深层气藏的开发水平,实现高效、工业化开发,是实现我国天然气业务持续有效发展的重要保障.对于非常规气藏,由于地质条件复杂,尽管在四川盆地及鄂尔多斯盆地取得了显著进展,但现有理论及工程技术仍与国外存在较大差距;对于深层气藏,现有耐高温、高压增产改造技术和采气技术及配套工具仍需进一步完善和创新.针对上述问题,通过相关的技术调研,重点介绍近年来国外天然气开采新技术、新工具,包括国外气田排水采气工艺技术、气井完井新工艺新技术、酸化压裂新工艺新技术等.为解决我国天然气开发生产中遇到的类似技术难题提供参考.

非常规油气二氧化碳压裂技术研究进展

非常规油气作为我国油气资源的战略接替,具有储量大、分布集中、开发技术革新快等特点。由于其储层物性普遍较差,'三低'特性和水敏、水锁等现象严重,常规水基压裂技术不可避免地对储层造成较大伤害,增产效果不理想,开采难度较大。二氧化碳压裂技术充分利用二氧化碳流动性强、增加地层能量、降低原油黏度和置换吸附甲烷等特点,具有对储层伤害小、增产幅度大、埋存二氧化碳和节水环保等优势,成为非常规油气开发的研究热点。通过对二氧化碳压裂技术的不断研究与应用,增产机理的深入探索和分析,产生了包括增稠二氧化碳干法压裂技术、二氧化碳混合压裂技术、常压混砂准干法压裂技术等新技术,非常规油气二氧化碳压裂技术的发展进入了新时代。

Refracturing candidate selection for MFHWs in tight oil and gas reservoirs using hybrid method with data analysis techniques and fuzzy clustering

The selection of refracturing candidate is one of the most important jobs faced by oilfield engineers. However, due to the complicated multi-parameter relationships and their comprehensive influence, the selection of refracturing candidate is often very difficult. In this paper, a novel approach combining data analysis techniques and fuzzy clustering was proposed to select refracturing candidate. First, the analysis techniques were used to quantitatively calculate the weight coefficient and determine the key factors. Then, the idealized refracturing well was established by considering the main factors. Fuzzy clustering was applied to evaluate refracturing potential. Finally, reservoirs numerical simulation was used to further evaluate reservoirs energy and material basis of the optimum refracturing candidates. The hybrid method has been successfully applied to a tight oil reservoir in China. The average steady production was 15.8 t/d after refracturing treatment, increasing significantly compared with previous status. The research results can guide the development of tight oil and gas reservoirs effectively.

Evidence of fluid evolution of Baoshan Cu−Pb−Zn polymetallic deposit:Constraints from in-situ sulfur isotope and trace element compositions of pyrite

In-situ LA-ICP-MS and S isotopes of pyrite from the Baoshan Cu polymetallic deposit were conducted to investigate the ore-forming process and the enrichment mechanism of elements.Three generations of pyrite (Py Ⅰ,Py Ⅱ,and Py Ⅲ) in the skarn-type ores and pyrite in the carbonate-hosted sulfide ores from central,western,and northern(C_Py,W_Py,and N_Py) mining districts are selected for comparison.Compared with Py Ⅰ and Py Ⅲ,the contents of most elements in Py Ⅱ are apparently higher.The As and Se contents are high within a wide range and are decoupled in the growth band of the C_Py.The highest As,Se,and Pb contents were found in W_Py and N_Py.These results indicate the drastic changes in the temperature and fluid mixing during the mineralization.The occurrence of fluctuation and change in temperature and f(O_(2)) was triggered by intermittent pulses of magmatic-hydrothermal fluids,mixing with meteoric water,and water-rock interactions.The sulfur isotopes of all species of pyrite indicated the magmatic source.The change in the f(O_(2)) conditions caused slight differences in the sulfur isotope compositions.Consequently,a metallogenic model was proposed to explain the ore-forming processes.

Performance of EDAB-HCl Acid Blended System as Fracturing Fluids in Oil Fields

Due to the high price and formation damage of the guargum fracturing fluid, many oilfields are more and more interested in surfactant based fracturing fluids. The rheological properties of erucicamide dimethyl amidopropyl betaine （EDAB）-HC1 acid blended system and its suitability as fracturing fluid were investigated in this work. The effects of pH, concentration of EDAB, and temperature on the rheological properties of the blended system were studied. The results show that addition of EDAB improved the viscosity of the system from less than 10 mPa. s to about 400 mPa. s, which could retard the acid-rock reaction to about one half at 60℃ and one quarter at 90℃ comparing to straight HC1 acid, suggesting that there is sufficient time for the blended fluid to react with formation rock when it is used as fracturing fluid in an oil field. Core flow tests demonstrated that the EDAB-acid blended fluid could divert itself from high permeability formation core to low permeability one, thus ensuring proper acid placement in the target reservoirs.

Mixing ratio design of emulsified asphalt cold recycled mixture based on gyratory compaction molding

In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.

Cleavage of catalytic ally grown carbon nanofibers into hydrophilic segments by oxidation in a mixture of concentrated HNO3-H2SO4 in an autoclave

The catalytically grown carbon nanofibers were treated by a mixture of concentrated nitric aid and sulfuric aid in an autoclave at temperature 333, 363 and 423 K. It was found that the samples treated at 363 K and 423 K were still well dispersed in water 15 hours later, indicating that carbon nanofibers can be made hydrophilicy. It was also found that the dispersion was destroyed when the pH value was lowered by adding acid. The results are significant when the carbon nanofibers are used as enhancing component in polymer composite material because several hundreds of nm are perfect size and the hydrophilicity controls the dispersion of CNFs in the polymer media. It is concluded that the amount of the oxygen-containing groups on the surface and the hydrophilicity of the carbon nanofibers can be controlled by the treatment temperature, and that the carbon nanofibers can be cleaved into uniform segments.