在生态文明建设与长江经济带发展战略不断推进的背景下,从流域尺度开展三峡库区生态系统定量评估,是库区生态保护修复策略制定的科学基础,对库区未来“自然-经济社会”可持续发展具有重要意义。基于多元遥感影像,综合采用生态模型、统...在生态文明建设与长江经济带发展战略不断推进的背景下,从流域尺度开展三峡库区生态系统定量评估,是库区生态保护修复策略制定的科学基础,对库区未来“自然-经济社会”可持续发展具有重要意义。基于多元遥感影像,综合采用生态模型、统计分析等手段,对三峡库区流域生态系统格局、质量与服务演变趋势进行了时空分析。结果表明:①2000~2020年间,三峡库区流域水体面积增加了283.25 km 2,主要由农田、城镇及森林转换而来。②流域上游区区域水源涵养量、水土保持量呈现增加态势,占流域总面积的64.5%;流域中下游山区局部地区水土流失仍然较为严重,靠近城市主城区及周边地区水源涵养能力、生物多样性维持和固碳服务有所下降。③库区生态系统稳定性总体逐渐提升,但在西部农田区域及长江岸带,由于受到人类活动胁迫,稳定性变差。为提升三峡库区流域生态系统整体的稳定性,建议按照“大流域统筹、子流域分区、差异化施策”的流域治理思路,做好“精准施治,一河一策”,提升上游自然区域森林、草地生态质量,调整河岸带湿地群落结构,从而提升上游地区水源涵养能力、岸边带与消落区生境功能与水土保持能力,这将是未来三峡库区流域生态系统稳定性提升及流域可持续发展的重要方向。展开更多
With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to r...With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to reservoir damage and wellbore instability.In this paper,micronized barite(MB)was modified(mMB)by grafting with hydrophilic polymer onto the surface through the free radical polymerization to displace conventional API barite partly.The suspension stability of water-based drilling fluids(WBDFs)weighted with API barite:mMB=2:1 in 600 g was significantly enhanced compared with that with API barite/WBDFs,exhibiting the static sag factor within 0.54 and the whole stability index of 2.The viscosity and yield point reached the minimum,with a reduction of more than 40%compared with API barite only at the same density.Through multi-stage filling and dense accumulation of weighting materials and clays,filtration loss was decreased,mud cake quality was improved,and simultaneously it had great reservoir protection performance,and the permeability recovery rate reached 87%.In addition,it also effectively improved the lubricity of WBDFs.The sticking coefficient of mud cake was reduced by 53.4%,and the friction coefficient was 0.2603.Therefore,mMB can serve as a versatile additive to control the density,rheology,filtration,and stability of WBDFs weighted with API barite,thus regulating comprehensive performance and achieving reservoir protection capacity.This work opened up a new path for the productive drilling of extremely deep and intricate wells by providing an efficient method for managing the performance of high-density WBDFs.展开更多
文摘在生态文明建设与长江经济带发展战略不断推进的背景下,从流域尺度开展三峡库区生态系统定量评估,是库区生态保护修复策略制定的科学基础,对库区未来“自然-经济社会”可持续发展具有重要意义。基于多元遥感影像,综合采用生态模型、统计分析等手段,对三峡库区流域生态系统格局、质量与服务演变趋势进行了时空分析。结果表明:①2000~2020年间,三峡库区流域水体面积增加了283.25 km 2,主要由农田、城镇及森林转换而来。②流域上游区区域水源涵养量、水土保持量呈现增加态势,占流域总面积的64.5%;流域中下游山区局部地区水土流失仍然较为严重,靠近城市主城区及周边地区水源涵养能力、生物多样性维持和固碳服务有所下降。③库区生态系统稳定性总体逐渐提升,但在西部农田区域及长江岸带,由于受到人类活动胁迫,稳定性变差。为提升三峡库区流域生态系统整体的稳定性,建议按照“大流域统筹、子流域分区、差异化施策”的流域治理思路,做好“精准施治,一河一策”,提升上游自然区域森林、草地生态质量,调整河岸带湿地群落结构,从而提升上游地区水源涵养能力、岸边带与消落区生境功能与水土保持能力,这将是未来三峡库区流域生态系统稳定性提升及流域可持续发展的重要方向。
基金This work was supported by the National Natural Science Foundation of China(Grant No.51991361)the foundation of China University of Petroleum(Beijing)(Grant No.2462021YXZZ002).
文摘With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to reservoir damage and wellbore instability.In this paper,micronized barite(MB)was modified(mMB)by grafting with hydrophilic polymer onto the surface through the free radical polymerization to displace conventional API barite partly.The suspension stability of water-based drilling fluids(WBDFs)weighted with API barite:mMB=2:1 in 600 g was significantly enhanced compared with that with API barite/WBDFs,exhibiting the static sag factor within 0.54 and the whole stability index of 2.The viscosity and yield point reached the minimum,with a reduction of more than 40%compared with API barite only at the same density.Through multi-stage filling and dense accumulation of weighting materials and clays,filtration loss was decreased,mud cake quality was improved,and simultaneously it had great reservoir protection performance,and the permeability recovery rate reached 87%.In addition,it also effectively improved the lubricity of WBDFs.The sticking coefficient of mud cake was reduced by 53.4%,and the friction coefficient was 0.2603.Therefore,mMB can serve as a versatile additive to control the density,rheology,filtration,and stability of WBDFs weighted with API barite,thus regulating comprehensive performance and achieving reservoir protection capacity.This work opened up a new path for the productive drilling of extremely deep and intricate wells by providing an efficient method for managing the performance of high-density WBDFs.
