Abstract

A life-of-well comprehensive methodology for production optimization is demonstrated through two Gulf of Mexico stimulation treatments in formations requiring sand control. The approach considers the full well history in the process of well evaluation and candidate selection. The treatments were designed for remediation of damage caused by a time-dependent disruption of formation sand and/or sand-control mechanism, including fines migration, proppant instability, and scaling.

Traditionally, data from permanent bottomhole gauges have been used as a valuable tool for well and reservoir management. As demonstrated in this paper, the data can be crucial to the assessment of the evolution of time-dependent skin. The practical result of well or reservoir surveillance and diagnosis from permanent gauge or traditional production data is shown to produce better decisions on stimulation and production management, while maintaining life-long well integrity.

Introduction

Completion optimization for sand control has been discussed in the literature by several authors.1,2 This paper deals with the identification and the remedial actions to reduce or remove completion damage associated with sand control for wells with and without permanent downhole pressure gauges (PDGs). With the balance required between the value of imformation and the overall economics of a development and exploitation project, it becomes extremely important to capture all events during the life of a well and to utilize all information to the fullest extent.

The use of high-frequency data or continuous information has a great impact in the expansion of the traditional time scale, from the usual snapshot approach to a continuous evaluation and remedial action process. This process can lead to real-time production managemement and decision making.

The integration of historical well information from different sources and continuous or high-frequency data, and their availability for practical use through proper evaluation tools, remains a challenge. However, the lessons learned are quickly developing a knowledge base that can greatly impact well and reservoir management in the future.

Life-of-Well Approach

Several factors play significant roles when dealing with completion decisions, especially in the offshore and deepwater environments. The feasibility for any development project rests not only on available reserves but also on the longevity and integrity of well completions. Critical early time and baseline well fingerprinting information is sometimes not available, or not recorded, which can significantly impact the decision-making process on all downstream operations. This situation is equally applicable to single- and multiwell cases.

Completions requiring sand control are especially prone to time-dependent degradation due to the evolving formation and proppant mechanical conditions, which at the end impairs hydrocarbon production through the gravel pack and/or frac-pack elements. It is extremely important to be able to forecast realistic dynamic operating well conditions when planning a sand-control completion. Planning enables the selection of the most appropriate completion method, including the corresponding hardware configuration and job execution program to achieve the expected results.

Fig. 1 presents the life-of-well approach for completion and production optimization. This continuous, perennial process is initiated at the early exploratory and development stages and continues until depletion and abandonment. Below is a brief description of the basic elements of this approach.

WCP Forecast

The life-of-well process begins with the well completion productivity (WCP) prediction that uses all reservoir static and dynamic information. The data are fed into the reservoir module of the predictive model, which will also include information about heterogeneity, lateral extent, and expected drive mechanism. In unconsolidated formations and/or those with stress-dependent porosity and permeability, a sand prediction model and a geomechanical model may be needed on a sandface or regional basis.

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