Abstract

Over the last six years nondamaging fluids, primarily inorganic salt blends, have proved to be very primarily inorganic salt blends, have proved to be very cost effective in numerous applications to drilling and production operations. A natural progression to high density, high cost non-damaging fluids has occurred. Successful application of these high cost fluids requires better planning and improved operational procedures, a better understanding of the physical properties of the fluids, and an evaluation physical properties of the fluids, and an evaluation of the optimum economic benefit of the fluid at project termination. The aim of the present discussion project termination. The aim of the present discussion is to recommend a pre-operation planning procedure. A discussion of the physical properties of the fluids is presented to maximize the number of economic alternatives. The considerations governing whether fluid will be disposed, sold, or stored and reused are reviewed.

Introduction

The benefits of a non-damaging fluid have been recognized by the oil and gas industry for many years. The numerous applications include use as a packer fluid, a completion/workover fluid and as a drilling and drill-in fluid.

Early applications of these fluids proved to be successful because they provided the necessary density, contained no solids, would not cause chemical damage, had low corrosion rates, tolerated additives, were relatively safe for users and tore cost effective. Further, because these fluids represented a new system or process, the initial users studied the limitations and properties of the products, generally understood the system and anticipated any shortcomings. And, as in any new process, the planning was thorough and adherence to recommended procedures was strict. However, the quality of prior planning tends to deteriorate and project implementation becomes more relaxed when the process becomes routine. In the case of these non-damaging fluids, the adverse consequences of these problems are compounded because of the increased acceptance and use of the higher density and higher cost systems.

As a result of this routine attitude, not only is the cost effectiveness of the process decreased, but also the formations in the wellbore are subject to contamination because of lax quality control. Thus, a valuable industry tool that meets the necessary specifications is discredited. Less acceptable fluids that are more likely to cause formation damage and productivity impairment begin to be considered.

Thus, the necessity for planning operations from pre-spud through completion and recognizing the relationship one operation has to other operations is significant. Additionally, specific planning for handling non-damaging high cost fluids should help to remedy potential problems, result in better completion, improve economics, minimize contamination and loss, and save manpower and rig-tins.

It will also be shown that a thorough understanding of the physical properties of the non-damaging fluids can improve operations and reduce cost.

Finally, an evaluation of alternatives is reviewed to determine the most economical disposition of the fluid at project termination.

PRE-OPERATION CONSIDERATIONS PRE-OPERATION CONSIDERATIONS Prior to any application utilizing a non-damaging fluid, the primary objective should be reviewed. This objective is to achieve the designed production while holding cost to a minimum. Means production while holding cost to a minimum. Means for achieving this objective should be evaluated from a short-term and long-term perspective.

For example, should a separate fluid handling system be used for a drill-in application versus using an existing mud system? This decision will require considerations of safety, fluid quality control, available space, reduced rig-time, reduced surface loss, etc. versus the higher cost of the additional system.

Other considerations prior to project initiation must be made for multiple well completion/workover operations on platforms.

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