渤海灣埕海1-1區塊軟抑制鉆井液體系的研究與應用

摘" " 要：渤海灣埕海1-1區塊采用叢式井進行開發，二開作業期間普遍使用純鉀鹽聚合物鉆井液體系，鉀離子的晶格取代效應，會使井壁產生硬殼，但內部的泥頁巖會繼續水化膨脹，造成起下鉆困難甚至技術套管下入不到位等井下復雜。針對這種情況，通過在傳統純KCl聚合物鉆井液體系中引入小分子陽離子抑制劑BDSC-100L，提高了鉆井液抑制黏土水化分散的能力，同時采用低濃度KCl與高濃度NaCl復配，提高了鉆井液抑制黏土水化膨脹的能力，據此研發出軟抑制鉀鹽聚合物鉆井液體系。室內試驗表明，軟抑制鉀鹽聚合物鉆井液的巖屑回收率是純鉀鹽聚合物鉆井液的兩倍，且經過熱滾后，巖屑的外形基本保持完整；現場應用表明，軟抑制鉀鹽聚合物鉆井液在井眼穩定和井筒清潔方面優于純鉀鹽聚合物鉆井液。

關鍵詞：軟抑制；流變性；回收率；ECD

Research and application of soft-inhibitive drilling fluid system in Chenghai"1-1 block of Bohai Bay

ZOU Long， XIE Heping， XIE Lun

Drilling Branch of CNPC Offshore Engineering Company Limited， Tianjin 300451， China

Abstract：The Chenghai 1-1 block in Bohai Bay is developed using cluster wells. During the second spudding operation， a pure sylvite polymer drilling fluid system is widely used. The lattice substitution effect of potassium ions can lead to the formation of a hard shell on the wellbore wall， but the internal shale will continue to hydrate and expand， causing difficulties in tripping in and out and even resulting in complex downhole conditions such as the failure to lower the technical casing to the proper position. In response to this situation， the small molecule cation inhibitor BDSC-100L was introduced into the traditional pure KCl polymer drilling fluid system to improve the ability of the drilling fluid to inhibit the hydration and dispersion of clay. At the same time， the low-concentration KCl and high-concentration NaCl were combined to improve the ability of the drilling fluid to inhibit the hydration and expansion of clay. Based on this， a soft-inhibitive sylvite polymer drilling fluid system was developed. Laboratory tests show that the recovery of rock cuttings from soft-inhibitive sylvite polymer drilling fluid is twice that of pure sylvite polymer drilling fluid， and the shape of rock cuttings remains intact after hot rolling. Field applications indicate that soft-inhibitive sylvite polymer drilling fluid is superior to pure sylvite polymer drilling fluid in terms of wellbore stability and wellbore cleaning.

Keywords：soft inhibition; rheology; recovery; ECD

埕海1-1區塊位于埕海1-1人工島東側，共有Ⅰ期、Ⅱ期兩個井組。該區塊2018年開始施工，目前Ⅰ期井組開鉆16口井、完井15口，Ⅱ期井組已開鉆3口井、完井3口。對于埕海區塊鉆遇的大段明化鎮泥巖段，普遍使用的鉆井液體系為鉀鹽鉆井液，主要依靠鉀離子的強抑制性和晶格取代特性[1]，防止泥巖的造漿和水化膨脹，但在實際的施工過程中，常出現起下鉆困難及技術套管下入不到位等現象。

目前針對大段泥巖造漿率高、水化膨脹嚴重等問題，中海油使用改進型PEC鉆井液體系。但由于該體系采用置換鉆井液內受污染鉆井液的方式，因此成本相對較高。……