Field Evaluation of an Impermeable Cement System for Controlling Gas Migration

This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleu m Engineers, its officers, or members. Papers presented at the SPE meetings are subject to publication review by Editorial Comm ittee of Society of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohi bited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where and whom the paper was presented. Write Liberian, SPE,

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Role of Cement Fluid Loss in Wellbore Completion

Bannister

Lawson

1985

SPE Annual Technical Conference and Exhibition

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occurs after cement PIacement. Sufficient delays in the loss of pressure are obtained for an API fluid-The fluid-loss behavior of cement slurries 1oss requirement in the range of 10 to 30 mL/30 min against permeable formations and its relationship to with the actual value dependent upon wel1bore geominterzonal fluid migration have been investigated. etry, overbalante pressure, mud fluid-1oss properties Static fluid-loss testing, designed to simulate cement and cement S1urry design. PIaced in a wal1bore, has shown that the cement fluid-10SS rate through a deposited mud filter cake decreases with time.This decrease in fluid-loss rate INTRODUCTION is dependent upon the designed fluid-1oss properties of the cement S1urry, and significantly influences the During the dril1ing and completion of oil and gas loss of hydrostatic pressure required to control reservoirs, formation fluids are contained by the formation fluids. Once the pressure starts to decay, hydrostatic pressure exerted by the wellbore fluids. formation fluids can potentially enter the wellbore The loss of hydrostatic pressure during drilling causing ineffective zonal isolation and, in some operations can result in well blowouts and "gas kicks" cases, gas migration to the surface. at the surface.1 Hydrostatic pressure loss after wellbore completion also permits the invasion of The mechanism described indicates that hydroformation fluids into the wellbore.2'3 Unlike drilstatic pressure is initially transmitted after cement ling operations, the problem of fluid migration after placement.During this period, fluid loss to the completion is compounded since the cement has been surrounding formation is compensated for by an equal permanently placed in the wellbore. The result may be decrease in slurry volume.The resulting changes in poor zonal isolation, annular pressure buildup, gas the solid-to-water ratio and gelation properties flow to surface and conrnunication with nonproductive coupled with the growth of the cement filter cake or productive zones. cause the pressure against the formation to eventually decrease.The rate of pressure decrease is dependent Several investigators have assumed that the upon the fluid-loss rate and the slurry's compress-hydrostatic pressure loss is due to volumetric changes ibility.Once the pressure approaches the formation associated with cement hydration and fluid loss to pressure, interzonal fluid flow through the cement permeable formations.2-lg Other reported reasons for slurry occurs with its rate initially governed by the fluid flow are poor cement placeinenttechniques,q high cement fluid-loss rate. cement free water [sedimentation], ll cement gellin properties12-16 and excessive thickening times.~9 Several correlations have been made relating

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Field Evaluation of an Impermeable Cement System for Controlling Gas Migration

Cited by 10 publications

References 8 publications

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Role of Cement Fluid Loss in Wellbore Completion

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