Abstract
A unique cementing system is presented which provides improved cement bonding and zonal isolation in wells having bottom hole static temperatures (BHST) below 175° F. Selectively formulated with components common to the industry, this system is reliable and versatile.
Latex cement additives are excellent bonding aids, gas migration preventers, matrix intensifiers and fluid loss additives. They improve cement's elasticity and resistance to corrosive fluids. Thixotropic, expanding cements excel in providing annular fill, zonal isolation and lost circulation control. Combining these two technologies into a single, efficient, low cost system has provided technical and economic properties which have had significant impact on cementing operations. This new cementing system is hereafter referred to as LXT for latex, expanding, thixotropic cement.
The properties engineered into the LXT system provide better primary and remedial cementing applications through: (1) reduced invasion of permeable, unconsolidated or "weak" zones by whole cement or cement filtrate, (2) prevention of gas or fluid migration in hydrating cement columns, (3) greater zonal isolation between differentially pressured intervals separated by thin, shale barriers, and (4) rapid compressive strength development and minimal waiting-on-cement (WOC) time. Laboratory studies and case histories are presented to show the merits of this cement system over conventional low water loss (LWL) systems. Numerous applications in East Texas, West Texas (Permian Basin) and on the West Coast have resulted in marked improvements in job quality and success rates over prior cementing practices.
