1. IEEES7 - http://www.univ-valenciennes.fr/evenements/ieees7
Control of cement slurry formulation for oil well in critical geological layer
1* S. Bechar, 2 D. ZERROUKI
1 Ouargla University, Applied Science, Department of Process Engineering , Dynamic Interactions and Reactivity of Systems laboratory, 30000, Ouargla, Algeria *
CONCLUSION
Abstract
In this study we are interested in the cementing of 9” 5/8 casing corresponding to 12” ¼ drilling section from oil well drilled in the field of Hassi Messaoud in the southern Algeria. This section is located in a very critical geological layer named LD2 (Horizon B) which is characterized by the production of calcic chloride waters very aggressive and virulent. Therefore the complexity of the geological formation encountered when drilling which implies a very precise pumping process to check pore pressure and the venus. This constraint has imposed to work with high density to avoid the dilution of cement slurry by chloride calcic waters; As a consequence; particular attention must be given to the proper control of the properties of cement slurry such as adequate rheology in order to achieve the target whose obtain a sustainable cement sheath. The cement type has a great important on performance. In this work we have used a mixture of Salt Saturated Water with some basis additives and a combination of three materials; Dyckerhoof cement class G blended with the Silica Flour and Hematite powder as a powerful additive to maintain the density of slurry.
Keywords : Formulation, Cement Slurry, Rheology, Stability, Chloride Calcic water
RESULTS
The correct introduction of the cement slurry between the drilled hole and the casing in place, good control of rheological properties therefore the mastery of additives compromise and the precise prediction of pumpability time are crucial factors for the success of the cementation job and sustainability of the sheath hardened as well as the longevity of well and production reliability. This paper is an initiative study to understand the behavior of weighting cement slurry in several constraint at downhole, many perspectives were targeted from this study to begin to work to improve the sustainability and strength of the cement hardened face the complexity of the geology in Hassi Messaoud field.
The Seventh International Exergy, Energy and Environment Symposium
IEEES7 -
April 27-30, 2015, University of Valenciennes et du Hainaut-Cambrésis - ENSIAME - Valenciennes - FRANCE
BACKGROUND INFORMATION
Temperature of this well takes account of the recording at the bottom. The bottom hole static temperature (BHST) has been esteemed at 120°C and from which one it has been predicted the bottom hole circulating (BHCT)=88°C.The temperature gradient is 2.73°C/100m
The water in the geological formation which cause the dilution of cement slurry during its introduction was sampled and analyzed and the results are shown in table 01
Ions
Chloride calcic waters
HCO3- (mg/l)
1370
Cl- (mg/l)
So4- - (mg/l)
Ca++ (mg/l)
Mg++ (mg/l)
10000
Ba++ (mg/l)
Na+
63300
K+ (mg/l)
9240 Ph 6
Density à 25°C
1.28
Depth (m)
Fig. 2 (a,b): Typical well profile and lithology of a typical case (hassi messaoud field)
Fig. 1 :BHCT simulation
Table. 1: Analysis of the water taken from the geogical layer Horizon B (LD2)
Plastic Viscosity /Yield Value and : Pv = 67,5 Cp / Yv = 27,5 lbf/100ft2
Multitude of tests have been carried out in order to get suitable thickening time which was at 05Hr but it is strongly recommended to have enough thickening time for Safety Margin
The transit time from the slurry is inversely proportional to the compressive strength, this formulation has developed good mechanical resistance (1500 PSI)
Fluid loss and Free Water
FL: 66 cc/ psi
FW: 0% cc
Gel Strength
Gel at 10 min: 50 (lbf/100ft2)
Fig. 4 Compressive strength and transition time recordes by the Ultrasonic Cement Analyser
Fig. 3: Consistency varying according time