随钻伽马测井快速正演算法及地质导向应用

在定向井及水平井钻井过程中,常采用地质导向技术;地质导向的关键在于实时确定地层界面和产状、实现地层模型的实时更新和井眼轨迹的及时调整,从而最大限度地提高油层的钻遇率.利用基于地层模型的测井响应正演曲线与随钻测井曲线进行对比是确定地层界面的有效方法;本文基于伽马射线在地层中的衰减规律,导出了不同地层模型中随钻伽马测井响应快速正演算法,克服了目前难以将蒙特卡罗算法用于实时随钻伽马测井正演的困难.应用实例表明该方法可以有效地辅助实时判定实际地层界面,更好地实现地质导向.     

基于Ganley理论含有衰减特性零偏VSP正演研究及修正

含有衰减的VSP资料能够提供丰富的地下岩层和岩性信息,本文根据Ganley理论对其进行了正演计算.引入品质因子Q值,考虑界面发生反射和透射,对震源位于地表及地下某一深度进行讨论,分别计算水平层状介质中的下行波和上行波.与不含有衰减特性的正演记录及其时频分析对比可以看出,高频成分的吸收、主频的降低、较多的能量衰减揭示了地...     

“地-电离层”模式有源电磁场一维正演

“地-电离层”模式有源电磁法由于其在地球物理勘探和地震预报方面的良好应用前景,成为地球物理电磁法研究新的热点.近年来国内开始了“地-电离层”模式有源电磁法研究,作者已经实现了当地球层为均匀半空间时的正演,但实际上地球并不是均匀半空间.本文在此基础上,采用R函数法进行公式推导,以高采样密度的Hankel滤波系数实现数值模...     

论几种常用重力异常正演公式的计算精度及速度

本文讨论了四种常用重力异常正演公式的计算速度以及用另外三种形体公式拟合立方体公式的计算精度。其结果表明,在通常情况下,用直立线元公式代替立方体公式进行正演计算,除保证一定计算精度外,还可提高计算速度近20倍。     

Groundwater age,life expectancy and transit time distributions in advective–dispersive systems; 2. Reservoir theory for sub-drainage basins

Groundwater age and life expectancy probability density functions (pdf) have been defined, and solved in a general three-dimensional context by means of forward and backward advection–dispersion equations [Cornaton F, Perrochet P. Groundwater age, life expectancy and transit time distributions in advective–dispersive systems; 1. Generalized reservoir theory. Adv Water Res (xxxx)]. The discharge and recharge zones transit time pdfs were then derived by applying the reservoir theory (RT) to the global system, thus considering as ensemble the union of all inlet boundaries on one hand, and the union of all outlet boundaries on the other hand. The main advantages in using the RT to calculate the transit time pdf is that the outlet boundary geometry does not represent a computational limiting factor (e.g. outlets of small sizes), since the methodology is based on the integration over the entire domain of each age, or life expectancy, occurrence. In the present paper, we extend the applicability of the RT to sub-drainage basins of groundwater reservoirs by treating the reservoir flow systems as compartments which transfer the water fluxes to a particular discharge zone, and inside which mixing and dispersion processes can take place. Drainage basins are defined by the field of probability of exit at outlet. In this way, we make the RT applicable to each sub-drainage system of an aquifer of arbitrary complexity and configuration. The case of the well-head protection problem is taken as illustrative example, and sensitivity analysis of the effect of pore velocity variations on the simulated ages is carried out.     

Lava effusion rates from hand-held thermal infrared imagery: an example from the June 2003 effusive activity at Stromboli

A safe, easy and rapid method to calculate lava effusion rates using hand-held thermal image data was developed during June 2003 at Stromboli Volcano (Italy). We used a Forward Looking Infrared Radiometer (FLIR) to obtain images of the active lava flow field on a daily basis between May 31 and June 16, 2003. During this time the flow field geometry and size (where flows typically a few hundred meters long were emplaced on a steep slope) meant that near-vertical images of the whole flow field could be captured in a single image obtained from a helicopter hovering, at an altitude of 750 m and ∼1 km off shore. We used these images to adapt a thermally based effusion rate method, previously applied to low and high spatial resolution satellite data, to allow automated extraction of effusion rates from the hand-held thermal infrared imagery. A comparison between a thermally-derived (0.23–0.87 m³ s⁻¹) and dimensionally-derived effusion rate (0.56 m³ s⁻¹) showed that the thermally-derived range was centered on the expected value. Over the measurement period, the mean effusion rate was 0.38±0.25 m³ s⁻¹, which is similar to that obtained during the 1985–86 effusive eruption and the time-averaged supply rate calculated for normal (non-effusive) Strombolian activity. A short effusive pulse, reaching a peak of ∼1.2 m³ s⁻¹, was recorded on June 3, 2003. One explanation of such a peak would be an increase in driving pressure due to an increase in the height of the magma contained in the central column. We estimate that this pulse would require the magma column to attain a height of ∼190 m above the effusive vent, which is approximately the elevation difference between the vent and the floor of the NE crater. Our approach gives an easy-to-apply method that has the potential to provide effusion rate time series with a high temporal resolution.Editorial responsibility: M. Carroll     

前方交会坐标方位角法在水域沉桩定位测量中的实际应用

在水域沉桩施工中，测量放样方法众多，常用的方法有直角交会法、角度交会法、前方交会法，通常比较实用的方法是前方交会坐标方位角法。通过工作实践，总结得出一套方便适用的、统一的前方交会坐标方位角计算公式，虽然较为简单，但对于常规施工测量来说却很适用。     

利用走时反演二维多孔介质渗透率

综合利用直接方法和优化方法研究二维多孔介质渗透率反演问题. 问题的提法与前人不同,是由区域内各点流体渗透的走时来反演渗透率. 该反问题的求解可分成两步进行,归结为两个相应的子问题进行研究. 首先由流体走时反演二维多孔介质速度场的数值算法,然后由二维多孔介质速度场反演二维多孔介质渗透率的数值算法,最后给出数值例子. 数值结果表明了所用数值方法的正确性和有效性.     

大斜度井和水平井井地三维电阻率数值模拟和联合反演

井地电阻率成像法利用井套管作电流源向井下供入大功率直流电流,在地表测量由地下介质的电性变化形成的电位分布,通过反演可得到地下介质的电阻率分布.针对大斜度井和水平井开展井地三维电阻率数值模拟和反演研究,对油田注水及压裂效果监测具有重要意义.基于井地电阻率成像法原理,采用有限差分法和不完全切勒斯基共轭梯度法进行了三维正演模拟,研究了大斜度井和水平井的井地电位响应特征.提出了采用层状约束阻尼最小二乘法由浅到深地进行大斜度井和水平井的多层联合反演,并对实际水平井井地电位各个层段数据进行了三维反演.模拟结果表明,倾斜线源和水平线源会对地面电位响应产生明显影响,在反演中需要考虑线源形态.实际水平井井地电位反演成像表明,考虑倾斜线源或者水平线源的联合反演得到了准确的水平井三维注水层成像图,得出注水层的真电阻率分布,能够判断注水运移方向.     

四川盆地北部地区飞仙关组鲕粒滩地震响应特征与分布预测

井下钻探和地震资料显示表明四川盆地北部下三叠统飞仙关组发育多套鲕粒滩储层, 该套储层也是飞仙关组主要的天然气产层.通过鲕粒滩储层发育段井震标定, 并结合鲕粒滩储层地震正演数字模型分析结果, 建立了飞仙关组不同层段鲕粒滩储层发育所对应的4种地震响应模式, 总结了不同地区鲕粒滩储层地震响应的异常特征.在此基础之上分别对飞仙关组一段、二段、三段开展连片二维地震测线地震相分析, 通过地震相与沉积相对应关系分析, 恢复四川盆地北部地区飞仙关组一段、二段、三段沉积相特征, 综合鲕粒滩储层地震异常特征与沉积相分布区, 预测了飞仙关组鲕粒滩储层在该地区的分布特征.飞仙关组一段、二段存在环陆棚相的台地前缘斜坡-台地边缘鲕滩相-开阔台地相沉积体系, 台地边缘鲕滩相在陆棚相东、西两侧沿北西向呈条带状展布, 分布面积大于4400km², 飞仙关组三段全区演变成开阔台地沉积, 鲕粒滩分布广阔, 主要分布在龙岗-元坝、剑阁、九龙山、河坝-黑池梁、普光-铁山坡等大部分地区, 面积达15000km², 因此, 四川盆地北部下三叠统飞仙关组鲕粒滩气藏勘探潜力巨大.