Ensuring Zonal Isolation in Cementing Jobs of Gas Well

Abstract

One of the critical conditions in cementing operations of gas wells, is the underbalance that generates the entry of preflush in the annular space, especially with the use of in the fluid train, therefore, trying to ensure the pore Pressure control incorporating to the fluid system, only an extensive volume of Spacer. In this way a possible gas inflow is avoided that would lead to enormous economic losses, however in terms of a good removal, just having a spacer in the preflush system would only be Fulfilling a single function that is the drag of suspended solids. in the annular space without being able to disperse and reduce its solid structures. Our methodology has been proven in fields with high GOR and good petrophysical and reservoir conditions, which intend to add a volume of washes to the preflush system, thus Hydrostatic Balance with a low Rheological Spacer volume behind the mud. The preflush system is by batch and pumped at 4.0 bpm continuous, considering a volume of 20 barrel máximum to generate a contact time greater than five minutes, thus improving the conditions of removal, diluting, dispersing and moisturizing the wellbore and casing external. It evaluates Primary cement Using bond logs that was run three days after the cementing operation. The logging results indicate an average amplitude of around 5 mV, so the 5 ½" in. Casing cement job had 90% average bond index. Good zonal isolation was achieved. In addition, Mechanical factors such as reciprocating the casing once carried to Depth, and casing centralization with Standoff greater than 80%, guarantee zonal Isolation in the área of productive. The addition of a Surfactant to the formulation of the washes favors the water wettability of the wellbore in fron of cement. The use of surfactants in preflushes entrain invading gas downhole and créate a stable foam. This foam then presents significant resistance to flow, thereby limiting upward migration (Marrast et al, 1975). With regard to the properties of grouts dominate the rheologic behavior, with filtrations less than 50 cc /30 min, and compressive strength greater than 1,100 psi