Geochemical Variability of Saline Brines in South Texas

现在已知南德克萨斯州的盐水在盐度，离子和同位素组成方面表现出广泛的变化。一些地层水的形成可能是由于蒙脱石向伊利石的转化释放了水，干酪根产生了乙酸。很明显，非常咸的盐水来自下面的地层。在一个生长断裂带中，假设地热梯度升高是由于盆地深处盐水的垂直通量。有些卤水与中新生代层序下的基底岩相互作用。该项目旨在通过仔细和系统地描述来自14个县的生产油气田的盐水的主要元素和同位素组成，来测试这些不同的假设。空间变异性及其与构造的关系是解释地层水最终成因及其对成岩作用影响的关键变量。该地区的盐水取样已经超越了“侦察”阶段（Morton and Land, 1987），现在应该限制在可管理的小区域，这些区域已知存在重大问题，可以通过未来的“饱和”取样来解决。该项目将对我们了解DOSECC深钻附近地区的矿石成因、埋藏成岩作用、流体行为、石油生成和沉积地球化学具有重要意义。

Saline brines in South Texas are now known to exhibit wide ranges in salinity, ionic and isotopic composition. Some formation waters are hypothesized to form in shale-rich sections as water is released by the transformation of smectite to illite, and acetic acid is generated from kerogen. Very saline brines are clearly derived from underlying formations. In one growth fault zone it its hypothesized that elevated geothermal gradients are due to a vertical flux of brine from deeper in the basin. Some brines bear evidence of interaction with basement rocks which underly the Mesozoic-Cenozoic sequence. This project seeks to test these various hypotheses by carefully and systematically characterizing the major element, and isotopic composition of brines from producing oil and gas fields in a 14-county wide area. Spatial variability and relation to structure are critical variables interpreting the ultimate origin of the formation waters, and their role in effecting diagenesis. Brine sampling has proceeded beyond the "reconnaissance" stage in this area (Morton and Land, 1987), and now should be restricted to manageably small areas known to exhibit significant problems which can be addressed by future "saturation" sampling. This project will have significant bearing in our understanding of ore genesis, burial diagenesis, fluid behavior, petroleum generation and sedimentary geochemistry in a region close to DOSECC deep-drilling operations.