塔河油田MTT区块火成岩地层井壁失稳原因分析

Causes for wellbore instability in igneous formations in MTT region, Tahe Oilfield

刘彪 潘丽娟

Liu Biao Pan Lijuan

中国石化 西北油田分公司, 乌鲁木齐 830011

SINOPEC Northwest Company, Urumqi, Xinjiang 830011, China

为了确保塔河油田MTT区块安全钻井,需要找到火成岩井壁失稳原因,以便找到应对措施.通过分析MTT区块岩石物性、地应力状态、压力剖面、测井数据、井径数据等资料,结合火成岩地层掉块特征,评价钻井液性能与地层岩性的配伍性以及封堵材料的封堵能力.认为引起井壁失稳的主要因素为:(1)火成岩夹泥岩井段与水基钻井液作用易导致泥岩水化;(2)火成岩内部微裂缝发育,而钻井液封堵能力不足,使钻井液容易侵入火成岩内部;(3)该区地应力状态为走滑型应力场,构造作用强,抑制井壁坍塌需要的钻井液密度高.三方面综合因素的影响导致了火成岩井壁失稳.

The causes for well instability in igneous formations in MTT region of the Tahe Oilfield were discussed to ensure production safety. Based on the analyses of formation lithology, geostress status, pressure profile, logging data and caliper data, combined with the collapsing features of igneous formations, it was evaluated in this paper the matching of drilling fluid property and formation lithology as well as the sealing ability of plugging materials. The causes for wellbore instability were concluded as followed. (1) Mudstones which interbedded with igneous formations changed to slurries when they met drilling fluids. (2) Micro-fractures were widespread in igneous formations, and drilling fluids could easily expand into igneous formations when their sealing ability was poor. (3) Strike-slip geostress field existed in the study area, showing strong tectonic forces, which desired for drilling fluids with high density.

https://doi.org/10.11781/sysydz2014S1110