高含硫喷漏同存气井钻井与完井工艺技术研究

STUDY ON DRILLING AND COMPLETION TECHNOLOGY APPLIED TO HIGH SULFUR-CONTENT GAS WELLS WHERE WELL KICKS AND LOSSES COEXIST

天东109高含硫天然气井喷漏同存,需要实施堵漏压井技术对气层漏失进行暂堵,但该井属高含硫大产量天然气井,既没有安全钻井液密度窗口,又不具备完井条件,情况复杂,为此研究了固井技术与完井工艺及应急预案,通过认真组织施工,取得了成功经验。指明了应用放喷泄压技术从安全的角度考虑应注意的主要问题:①对长裸眼层段存在多压力系统发生井漏与溢流,应分析各层段的地层压力与承压能力,确定漏失层与气层,为制定堵漏与压井施工方案提供科学依据;②在钻井施工中进行堵漏作业,应认真分析漏失层岩性特征、漏失原因与机理,针对性地选择堵漏材料与堵漏工艺;③对喷漏同存的井,应将堵漏与压井进行综合考虑和有机结合,保持井内动态液柱压力始终高于漏层压力,即气层发生井漏实施吊灌技术;④若漏失层为非产层,在不构成伤害油气层前提下,可选择堵漏固化后强度高的永久性堵漏材料,若漏层为产层,确需堵漏则选择能最大限度保护产层的暂堵材料;⑤高含硫气井喷漏同存复杂条件下,固井与完井工艺选择既要符合气田采气技术要求,又要有利于安全施工。

Well kicks and lost circulations coexist in Well Tiandong-109, a natural gas well with high sulfur content. Plugging and killing technologies are necessary for temporary plugging of the thief gas zone. However, this well is a high-potential sour gas well, no safe drilling fluid density window and no conditions for completion, the operation scenario is very complex. So emergency planning was made regarding cementing and completion techniques. Through careful organization and execution, successes were made on this well. Major safety concerns when draining and venting are also introduced in this paper, including: 1) regarding to well kicks and lost circulations easy to occur in the multi-pressure system of the long open hole, the formation pressure and load capacity of each interval should be analyzed to determine the thief zone and gas zone, providing scientific evidence for planning of plugging and killing program; 2) to conduct plugging during drilling, the lithologic properties, loss causes and mechanism of the thief zone should be carefully studied, so as to decide the LCMs and plugging technique selectively; 3) for wells with both kicks and losses, plugging and killing should be considered comprehensively and organically combined to keep the dynamic fluid column pressure always higher than the formation pressure of the thief zone,; 4) permanent LCMs with high set strength can be selected for non-pay zones on condition the hydrocarbon-bearing zones will not be damaged, and the LCMs with maximum reservoir-protection capability should be selected for pay zones; 5) for wells with kicks and losses, the cementing and completion techniques to be selected should comply with the requirements of both gas production and safe operation..