Not the least of these is the strategic abandonment of potential new developments and a much greater focus on making the most of existing assets. Ross Brackenridge, Technical Director, Lloyd’s Register, explains that as change accelerates, operators may increasingly seek to take ownership of a specialized area of well technology: cased hole data analysis. .
Note: Article was first published in Hart E&P Magazine
Supporting well integrity, safety and production objectives, casedhole analysis has always had a role to play in helping operators achieve their fundamental objectives – and its status as a value-added activity can only grow in a rapidly changing industrial environment.
It could be said that cased hole logging and analysis has so far been a poor relative of its open hole equivalent, and this is due to a variety of influencing factors.
Open pit logging – in effect, the process of acquiring representative reservoir data immediately after the well has been drilled and before it is cased and cemented prior to production – has traditionally taken center stage when exploration activities and development were very important.
Casing tools and techniques have long been available, serving to maintain casing and cement condition monitoring as well as supporting high production performance through the provision and analysis of key downhole data of hole. And they assume greater importance today in an industry increasingly defined by maturing assets.
In addition to enabling operators to monitor well integrity, expert interpretation of well logging data helps them determine well properties as they relate to production – from identifying downhole production zones to calculating volumes of gas, water and oil at each reservoir depth. It is also used to identify production problems and then support the formulation and execution of corrective actions.
Historical Obstacles to Appropriation
Thus, the benefits of applying cased hole solutions throughout the life of the well are commonly recognized in the industry. Why, then, have operators often chosen not to take direct responsibility for interpreting cased hole data when they generally have for open hole analysis?
There may be various reasons why they preferred to leave the interpretation work to the logging providers. Responses to cased hole data can vary from supplier to supplier – unlike the open hole equivalent, which is quite standardized – and this in turn can present interpretation challenges for operators.
In the past, many types of cased hole data required specialized bespoke software, with consequent implications in terms of cost, resources and skill development for operators seeking to support the analysis business in internal. This is especially acute if you work with several different vendors running different software packages with different outputs.
There is also the question of where it sits within an individual organization. As a discipline, casedhole logging evaluation falls somewhere between the traditional underground specialties of petrophysics, reservoir engineering, and petroleum engineering. Because it is not solely focused on asset geology and encompasses issues such as casing and cement, where does it fit?
Operators can now actively tackle these issues as they increasingly recognize the gains in safety, integrity and production optimization to be ensured by pursuing the in-house route.
House Rules: The Benefits of Taking Direct Responsibility
The safety of their personnel and assets, as well as their environmental commitments are their areas of primary concern. And of course, they still retain formal legal responsibility for safety and environmental protection; even if they outsource the services, they do not outsource these essential obligations. So given that casedhole activities provide key information on all of these topics – extending to the overriding issue of reputation protection – then taking ownership of them directly is the logical approach. With strong guidelines in place for well integrity management, for example, operators may find it fair and sensible to take full practical responsibility for compliance with them.
In technical terms, in-house data analysis lends itself to standardization, consistency, efficiency and adoption of best practices across the enterprise: it eliminates the need to reconcile results analytics across regions or multiple vendors.
Critically, the introduction of a one stop shop – an integrated software package – covering both open hole and cased hole data interpretation offers a succession of additional benefits.
It not only streamlines software requirements, but also empowers teams of operators with more and better data that accelerates insights and improves decision-making – and incrementally realizes cost savings.
These have been the principles behind the development of cased hole analysis suites within our industry: they have certainly shaped and informed ours as we have developed and demonstrated its capabilities in international energy regions.
To use as an example, our Interactive Petrophysics (IP) for Cased Hole Analytics software includes a set of modules covering all key areas: cement evaluation, production logging, casing inspection and pulsed neutron analysis (which determines the water saturation of the reservoir through the casing). .
We have invested in our cased hole analysis proposition precisely because we anticipate the market will increasingly turn to such solutions as operators seek to get the most out of their investment in producing assets.
Figure 1 – Interactive petrophysics (IP) software showing a composite plot of open hole data and a variety of different cased hole datasets.
‘An immediate and value-added option’
We are convinced that such a global solution will more than prove its worth in the years to come. It serves as an internal data center on individual wells – supporting the development of the collective knowledge of the team and representing a valuable asset in itself.
It grows as an internal resource as new data is accumulated, and accumulating multiple data sets in one place provides more substantial – more comprehensive – information about well performance. Only by comparing it with cased hole production logging data, for example, can one gain a full understanding of open hole interpretations in areas such as permeability, saturation height and hydraulic flow. Similarly, well underperformance can only be fully investigated with access to both open hole formation evaluation and cased hole production logging, as the problem may very well be associated with the formation and/or completion of the well.
Its internal status facilitates subsequent querying of master data or resulting analysis at any time to provide new insights, and – with 24/7 operator access to analysis capabilities – it offers a faster path to interpretive results that underpin operational decisions.
Commercially, we can anticipate that casedhole data analysis will become a more expensive line item to source from third parties due to growing industry demand for specialist integrity support. wells and production optimization. Operators can seek to secure longer term savings with their own in-house software package and associated skills.
There is also a broader benefit for operators – and staff – already working to advance the energy transition agenda, or planning to do so: the casing drilling software and accompanying technical skills are certainly transferable to other new alternative underground areas such as carbon capture, use and storage.
In the meantime, in our maturing oil and gas industry, in our experience, operators are exploring the potential of in-house cased hole data as an immediate, value-added option as they seek to maximize economic recovery – in a safe and efficient way – before ultimate abandonment.
IP in action
Situation: An oil production well suddenly starts producing a lot of water. A quick diagnosis is needed to determine the source of the water and if it can be shut off.
At first glance : Interpretation of the production log suggests that water enters the borehole at the deepest perforated zone while temperature suggests fluid movement below this lower perforation.
A more in-depth review: Cement bond log data identifies a potential channel in the cement. From the accompanying pulsed neutron data – key inputs of which include clay volume and porosity from the open pit petrophysical analysis – it is confirmed that the lowest perforated zone is still oil bearing and that the water source is indeed under the perforated area and moves through the channel in the cement.
A holistic approach to data: If each of the casedhole and openhole datasets had been interpreted at different times in different software packages by different analysts, the problem might not have been correctly diagnosed.
Figure 2 – An illustration of the conclusion drawn from Figure 1: Water enters the well at the middle zone but the source of the water is actually the deepest unperforated zone below.
By using a unique software package such as Lloyd’s Register’s IP, interpretations can be made simultaneously by the same person, creating much more complete information to support a correct diagnosis. Without the knowledge gained from interpreting the variety of cased hole datasets together – and doing so alongside the available open hole data, it would have been easy to assume that the lowest perforated zone was the source of the water, which led to a misguided decision. to close an oilfield, with the potential for disastrous commercial consequences.
The above represents just one of many scenarios where a holistic approach can bring direct gains, not only in business terms but also in the area of safety by helping operators avoid potentially serious risks.