The Effect of CaO and MgO as Expanding Additives to Improve Cement Isolation Strength under HPHT Exposure

Abstract

Cementing is one of the most important parts in oil-well drilling. Recent development in oil-well drilling technology has led to a more problematic case in cementing. High temperature cementing is one of the problems. High temperature cementing may cover steam recovery wells, geothermal wells and ultra deep wells. The use of expanding cements as an effort to improve the sealing efficacy of annulus cementing has been considered for a long time as a promising solution to the existing problems. CaO and MgO have been proposed as two of the most effective additives to create excellent expanding cement. The purpose of this study is to find the effect of adding up burnt pure CaO and MgO to the value of compressive strength and shear bond strength of API class G cement in high pressure and high temperature condition. The method that we used within this research is an evaluation of the data taken from a simulator that simulated within temperature range of 100-250 o C and pressure of 2000 psi. The conclusion is taken according to the results which saying that the addition of burnt pure CaO and MgO would increase the shear bond strength and the compressive strength on specific condition up to 200 o C temperature. The addition won't be effective for the condition of 250 o C temperature. The behavior of cement strength was also influenced by the length of curing time. Further more, research on expanding cement needs to be developed and extended whether to vary its compositions, temperatures, or curing time conditions. The compatibility when mixed with other additives together with silica flour has not yet been figured out.

Durability and Microstructure Properties of Concrete with Arabic Gum Biopolymer Admixture

“…It is reported in [38] that the addition of burnt pure CaO would increase the shear bond and the compressive strengths in specific conditions up to a 200°C temperature. CaO exhibited a modest increase of 0.3% that may not be significant enough to affect shear bond nor compressive strength.…”

Development of slurries and study of properties of cement mixtures to increase the quality of well completion

“…Chemically bounded water takes up less volume than the free one. As a result, there is a volume change, called contraction, is observed, which is approximately equal to the volume of water that has entered into a chemical reaction when the binder interacts with water and crystalline hydrates (neoplasms) are formed [23][24][25].…”

Recent Advances in Magnesia Blended Cement Studies for Geotechnical Well Construction—A Review

“…This benefits the shrinkage compensation when blending magnesia with Portland cement. In addition to the bulk shrinkage compensation capability, the shear bonding strength at cementing interfaces (between casing and cement sheath, between cement sheath and formation) can also be improved by the induced bulk expansion from magnesia hydration (Ghofrani and Plack, 1993;Rubiandini et al, 2005;Suhascaryo et al, 2005). Meanwhile, because of the in-situ magnesium hydroxide crystal growth in the pore matrix of the setting cement, the porosity and permeability of the hardened cement can be impacted based on different confining conditions.…”