深盆气藏及其勘探对策

Exploration strategy for deep basin gas reservoirs.

深盆气藏是在致密储集层中发育的具有“气水倒置”关系的气藏，普遍储量丰富，我国很多盆地都具有发育该类气藏的基本地质条件。深盆气藏与常规气藏差异巨大，需要有特殊的勘探对策。其勘探流程应是：按照深盆气藏的形成条件和基本特征，重点论证盆地的储集层、气源、构造和气水分布条件，与已知成功勘探实例类比，确定是否存在深盆气藏；明确深盆气藏的生储盖组合，圈定气水边界，寻找气藏甜点，建立成藏模式；从深盆气的角度重新认识盆地，估算天然气储量，研究甜点与次生常规气藏的分布规律，预测有利含气带，测算开采效益，为开发提供决策依据。在我国深盆气藏的勘探开发中应注意：有选择地借鉴北美深盆气勘探开发的经验与理论，争取少走弯路；新探区深盆气藏与常规气藏勘探应并重，老探区中含煤丰富的碎屑岩盆地应重点解剖深盆气藏形成条件；探讨并建立适合我国盆地特点的深盆气成藏模式；勘探、开发的全过程应贯穿经济评价和工程分析，统筹考虑储量增长目标、技术条件和经济效益，既要避免止步不前，也要防止盲目上马。

Deep basin gas reservoir is a type of gas accumulation formed in relatively tight reservoir beds with a reversal of gas water relationship, and abundance of gas accumulation generally. There are many basin having such geological conditions in our country. Deep basin gas reservoir differs greatly from the conventional gas reservoir and requires special exploration strategy. The exploration flow diagram should be: ①According to the formation condition and the basic characteristics of deep basin gas reservoir put the emphasis on the reservoir beds, gas origin, structures, and distribution of gas and water, a comparison to those conditions of successfully explored reservoir should be made to ascertain whether the deep basin gas is present or not; ②Make clear the assemblage of source reservoir capping beds, delineate the gas water contact, find out “sweet point” of gas reservoir, and establish a model of the formation of deep basin gas reservoir; ③Recognize the basin again from the viewpoint of deep basin gas reservoir, estimate the gas reserves, study the occurrence of the “sweet point” and its relationship to the distribution of secondary and conventional gas reservoirs, predict favorable gas bearing belt, and estimate profit of exploitation so as to give a basis for development decision making. In the exploration and development of deep basin gas reservoir, the experiences and theories obtained in those successfully explored and developed ones in North America should be studied so that less crooked way is avoided. In new exploratory region equal stress should be laid on both deep basin gas reservoirs and conventional gas reservoirs. In the explorations of rich coaliferous clastic basins in already explored region stress is placed on the conditions for forming deep basin gas reservoirs to be dealt with, and establish the model of deep basin gas reservoir formation. Economic evaluation and technical analysis should be made through the whole process of exploration and development and the object of reserve increase, technical conditions, and economic profit should be overall considered so that both stopping and too fail steps in exploration will be avoided. Subject