Wednesday, December 06
Lost circulation is rarely completely unexpected. What can we do to prepare ourselves? Offset data, end-of-well reports, and previous experience in the area, are clearly vital to tell us where to expect drilling and cementing problems and do we extract the maximum value from them? Can we get more detailed and specific information from geological sources, from seismic interpretations, from well logs?
The more that we know in advance about the likely problems and solutions, the more we can plan on the engineering side to ensure that disruption and delay in the well construction process are minimised. For example, understanding the loss mechanisms and the potential apertures of the channels responsible can help us design the mud and any additives, to ensure we have appropriate solids control in place, to ensure compatibility with downhole drilling tools, and to allow for contingency planning with, for example, a bypass sub.
In this session we will discuss how to learn more about what we face, and how to use that learning, more effectively, in planning.
In recent years, the industry has adopted improved approaches to mitigating the increasing lost circulation challenge, from the classic approach based on volume of losses to one based on the loss mechanism. This differentiates matrix losses from fracture losses, the latter being more challenging and, therefore, the main focus of this session. Case histories are presented to highlight the most challenging differences between drilling into natural fractures and drilling with induced fractures, including diagnostics and impacts on well construction—drilling, running casing, and cementing. The emphasis will be on fracture behaviour in carbonate formations. The different ways of mitigating these fracture losses are discussed, and their impact on zonal isolation for both reservoir and non-reservoir sections is emphasised. The session is concluded with a discussion on the ways to plan and prepare for natural fractures and induced fractures or the prevention of those, as much as possible, along with different approaches to cure the different loss scenarios, if they do occur.
Laboratory testing of lost circulation materials (LCMs) plays an important role in designing new products and technologies to mitigate or eliminate downhole losses. These types of tests also serve as a means to select solutions for anticipated lost circulation incidents in the well planning stage. Given this level of importance in planning and drilling, these tests are seldom understood and often downgraded in terms of routine well design and product selection. The objective of this session is to initiate a discussion on the benefits of the laboratory testing of LCMs in the areas mentioned above. In this session, both operators and service companies will be providing insights into the testing and design of LCMs as well as the specific properties that are of particular importance to the selection of LCMs and how they relate to the testing protocols for different types of LCMs such as particulates, fibres and chemical sealants. Discussions will range from simple bench-top devices to large scale yard tests as well as criteria related to field trials of new LCM technologies. The information in this session will aid attendees in developing their own test methods and criteria to evaluate the application/effectiveness of lost circulation materials both in the lab and in the field.
Even though lost circulation is a major cost of drilling non-productive time, there are few universities or petroleum operator companies conducting research in this area. The limited development and testing being done by petroleum service companies is covered in Session 3. Session 4 focuses on current work being done at selected universities and research institutes.
Thursday, December 07
Traditional remediation techniques range from various types of cement plugs, particulates, and fibres to various types of downhole acting solutions. The industry has adopted many remediation techniques over the years for both natural and induced fractures. These traditional solutions range from material found on the rig to secret formulations to complex laboratory formulated solutions. These traditional techniques have focused over the years on many different types of materials to effect the lost circulation cure. This session will review some of these historical solutions, used with variable success for both reservoir, non-reservoir, and, depleted and non-depleted formations. A focus on the criteria needed to evaluate their performance will be discussed through case histories.
There is no one way to remediate against losses, and while the ideal uniform solution does not exist, each available solution may have its pros and cons. Efforts are needed to understand the loss scenario, to better select and prepare for the solution to match those downhole conditions. This introduces the need to engineer solutions, model conditions, evaluate performance for plugging and assessment of the sustainability during drilling, and running casing and cementing treatments to provide the long lasting zonal isolation needed. This session will highlight the latest advances in engineered solutions, expected performance, and any modelling or testing to aid in the selection of the optimum treatment and placement procedures to meet downhole conditions.
This session highlights successful engineering solutions used in the fields with particular attention to Managed Pressure Drilling (MPD) and Underbalanced drilling (UBD) applications. This session will focus on the identification of risks, their evaluation in terms of likelihood and impact, and applicable mitigation strategies. The presented papers will then serve as a starting point to share experiences with applied techniques or discuss boundary conditions in their execution.
Severe losses encountered in fractured or vugular zones call for innovative techniques and solutions to save the well and continue drilling. One example of such techniques is pressurised mud cap drilling, whereby mud is deliberately pumped into the lost circulation zone with no returns to surface. Another example is the application of a flow bypass system designed to inject large quantities of lost circulation material through the annulus into the loss zone. Innovative and aggressive engineering techniques designed to combat catastrophic mud losses will be covered in this session.
Session 9 will allow participants to attend one of four breakout sessions to discuss what was presented in the sessions on planning and case histories (sessions 1 and 2), technology development (sessions 3 and 4), remediation (sessions 5 and 6), and engineering management of lost circulation (sessions 7 and 8).
During these discussions the needs and concerns for each area should be identified - what is working and what needs improvement? Flip chart notes from these discussions will be condensed and included as a part of the report on the workshop.