Uses of Small Particle Size Cement In Water And Hydrocarbon Based Slurries

Abstract

Abstract Small particle size cement (SPSC) has found a number of uses in production and injection well technology. The fineness of the cement particle allows the resultant slurries to penetrate areas in the well bore and surrounding formation that are inaccessible with conventional cement. This penetration capability leads to SPSC application in production and injection well casing repair. By this placement of a permanent seal across casing leaks, mechanical integrity tests mandated by regulatory agency requirements may be satisfied. In addition to use in a water based slurry, new applications have been developed by placing SPSC in a hydrocarbon carrying fluid. This technique allows the SPSC to be used as a permanent water shutoff and conformance control material. Because the hydrocarbon slurry will only set in the presence of water, oil-producing sections of a reservoir can remain relatively damage free after water shutoff. This paper presents a review of the penetrating properties of SPSC including a comparative-study of water base versus hydrocarbon base slurries. In addition, case histories are presented as confirmation of successful applications of the recently introduced material. Introduction After initial completion of an oil and/or gas well, a number of factors may contribute to a decrease in the economic life of the well. A major concern is the premature appearance of produced formation Water in the well. This may be the result of leaks in the casing, due to corrosion or some other mechanical wearing, communication of the producing zone with water bearing strata through channels in the casing cement sheath, or communication of water through natural fractures or channels in the formation. Typically leaks in casing are repaired using a standard Portland cement and placing it with a "squeeze" technique. Many times this may be a very small or "tight" leak and standard cement will achieve only a limited penetration into the leak due to the size of the particles in the standard cement. Because of this, the procedure may be repeated a number of rimes and still not achieve success. When water is being produced through channels or fractures in the cement sheath or formation, a common water shutoff treatment is placement of a standard cement within the fracture using a hydrocarbon carrying fluid. Only when this slurry comes in contact with water will it set and form a plug. That slurry which does not contact water will not set and thus will be produced back out of the zone leaving it relatively undamaged. The size of the standard cement has also limited the success of placing it in many of TABLE 1: Physical properties. Table 1 Available In Full Paper. TABLE 2: Water based slurry properties. Table 2 Available In Full Paper. these small fractures and channels. Because of the size restrictions inherent with these applications, SPSC has been introduced as a replacement for standard cements in these treatments. Small Particle Size Cement Properties Small particle size cement can be defined as a cementitious material containing particles that are considerably smaller than those contained in standard oilfield cements.