This paper describes the improvement in well production from using advanced well-construction techniques compared to conventional techniques. The advanced technique uses an engineering approach including finite element analysis (FEA), specialized erodability testing, rock mechanics lab testing, and conformance reservoir simulation predictions. In a highly permeable and very mobile water-drive environment where natural hydraulic seal is practically non-existent, an effective cement sheath imposes a very good mechanical seal to shut the water influx. In this case, the cement sheath is not only a well-construction or pipe-stability issue, it is a final or well-termination product for enhancing well life or last-recovery production. The FEA analysis studies the mechanical interaction among the formation, cement sheath, and casing while applying different stresses on the system. Pressure and temperature changes inside the casing during the life of the well affect the behavior from the cement sheath. To address the performance from the cement system design, the well history for water production requires review. Production and simulated data from reservoir simulators are compared to determine if water production is as expected or not. Conformance reservoir simulators give a good comprehensive criterion to predict water behavior in the reservoir and predict at earlier stages when water will affect well productivity. In the study presented in this paper, three advanced solutions were applied to address an optimization in a highly active water-drive reservoir as:spacer efficiency study,cement-sheath characterization through measured mechanical properties/FEA analysis, anduse of conformance simulators to determine the productive capacity of the well. Results are compared with the real production data to determine whether this engineering design improved well productivity. Results of using all new practices were evaluated by CBL logs and production; production results were close to the expected, with low water cut. Yuralpa Field can become uneconomical if cement sheath quality and reservoir standoff to oil-water contact are not suitable. Introduction The Hollin Sandstone formation is the primary objective in the Yuralpa Field. The productive mechanism is bottom-water drive, which maintains almost a constant pressure during the well's productive life and actively influences early water breakthrough. The importance of a good cement job can help maximize early oil production before water entrance. However, if the cement sheath is not competent or debonds after cementing, water channeling behind the casing and next to the formation during well production is almost immediate once production begins, with an exponential growth in just a few days. To improve cement job results, multiple best cementing practices have been identified and applied throughout the decades. Currently, many best practices have been implemented at field operations using a score-card template, assigning different values to each particular practice depending on its importance. A final grade for each job's local score card enables comparison of different jobs under the same criterion (Table 1). Considering that each field has different work methods and risks associated, a single score card cannot be used for all fields. Input from field personnel is important in identification of key points and establish a special score card for each field. Following best practices alone does not guarantee the best results for a cement job. Rheology from fluids needs to be designed to comply with high displacement efficiency. One commonly used method to improve annulus mud displacement is to design the fluids' yield point (YP) in a hierarchical manner, beginning with the lowest YP on mud and increasing it on the spacer, lead, and tail cement, respectively. However, one important question arises: what should be the adequate rheological properties for an optimum displacement? Erodability gives a clue of how to determine optimum rheological properties to erode the gelled mud and soft filter cake from the annulus. Using erodability theory, spacer can be designed to obtain the required shear stress to displace gelled and dehydrated drilling mud and any soft filter cake from the annulus, using actual well conditions as hole/casing geometry and flow rate.

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fax 01-972-952-9435. AbstractThis paper describes the improvement in well production from using advanced well-construction techniques compared to conventional techniques. The advanced technique uses an engineering approach including finite element analysis (FEA), specialized erodability testing, rock mechanics lab testing, and conformance reservoir simulation predictions.In a highly permeable and very mobile water-drive environment where natural hydraulic seal is practically nonexistent, an effective cement sheath imposes a very good mechanical seal to shut the water influx. In this case, the cement sheath is not only a well-construction or pipe-stability issue, it is a final or well-termination product for enhancing well life or last-recovery production. The FEA analysis studies the mechanical interaction among the formation, cement sheath, and casing while applying different stresses on the system. Pressure and temperature changes inside the casing during the life of the well affect the behavior from the cement sheath. To address the performance from the cement system design, the well history for water production requires review. Production and simulated data from reservoir simulators are compared to determine if water production is as expected or not. Conformance reservoir simulators give a good comprehensive criterion to predict water behavior in the reservoir and predict at earlier stages when water will affect well productivity.In the study presented in this paper, three advanced solutions were applied to address an optimization in a highly active water-drive reservoir as: (1) spacer efficiency study, (2) cement-sheath characterization through measured mechanical properties/FEA analysis, and (3) use of conformance simulators to determine the productive capacity of the well. Results are compared with the real production data to determine whether this engineering design improved well productivity.Results of using all new practices were evaluated by CBL logs and production; production results were close to the expected, with low water cut. Yuralpa Field can become uneconomical if cement sheath quality and reservoir standoff to oil-water contact are not suitable.

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