From 2009 to 2010, there was an increase in the number of well-control incidents on the Norwegian continental shelf reported to the Petroleum Safety Authority Norway (PSA). This, together with the Deepwater Horizon accident in 2010, prompted PSA to initiate a comprehensive investigation into the causes and possible mitigating measures related to well-control incidents. This paper details the findings of the study.
Introduction
The PSA report Trends in Risk Level in the Norwegian Petroleum Activity (RNNP) has been released on an annual basis since 2001. The RNNP aims to measure and improve health, safety, and environmental conditions in the Norwegian petroleum industry both offshore and onshore. The project includes indicators related to major accidents, personal injuries, and working-environment factors.
The project monitors risk level through the use of a number of indicators: incident data (well-control incidents, hydrocarbon leaks, and personal injuries), data describing performance of technical barriers, maintenance data, and working-environment indicators (noise, ergonomics, and chemicals). Multiple methods, both quantitative and qualitative, are used to investigate and monitor changes in risk level. Interviews, field work, and a survey targeted at all employees on facilities onshore and offshore are used alongside more-traditional incident and near-miss reports.
Organizational details about the Norwegian petroleum industry that were fundamental to the collaborative effort that made the study possible are detailed in the complete paper.
The main research questions addressed in the present study included the following:
- What are the key human, technical, and organizational causes of well-control incidents?
- What are the most important measures proposed/implemented to reduce the number of well-control incidents?
- Is there correspondence between identified causes and proposed/implemented measures?
- How can the petroleum industry improve its efforts to reduce the number of incidents further?
Method
The study was conducted by an experienced interdisciplinary research team on behalf of PSA. An interdisciplinary expert group was established simultaneously within PSA. The expert group participated in the study design, ensuring that relevant literature and important problems were addressed, and followed the study as it progressed through different phases. All data were collected under a strict confidentiality agreement.
A total of 12 well-control-investigation reports and 21 event reports for the period from 2003 to 2010 was analyzed. Various reports and written documentation from research-and-development institutions, consultants, authorities, and industry organizations were reviewed. An important part of this material consisted of written assessments of important causes and mitigating measures related to well-control incidents submitted by drilling experts in 18 companies (eight operating companies and 10 drilling contractors). Information was acquired on the basis of a form for description and assessment of implemented measures and assumed causes.
Interviews were conducted with 33 drilling experts onshore and offshore from three operating companies and three drilling contractors. The interviews covered both planning and operational phases.
Finally, the correspondence between causal factors and measures suggested from the overall findings in the investigations reports, the company-experts’ assessments, and the interviews were assessed. As a basis for the review of investigation reports and other information related to incidents, a classification form was developed for indicated causes and proposed measures. The categories used in the review of triggering and underlying causes and the type of measures are shown in Figs. 1 through 3 of the complete paper.
Results From the Review of Investigation and Incident Reports.Triggering causes identified from the investigation reports are dominated by technical factors (67%). The three most common technical causes are technical failure of, or imperfect, primary barrier/mud column (22%); geology and reservoir (19%); and technical failure of, or imperfect, kick detection (13%).
It should be noted that the triggering causes, particularly the first two, are closely linked. As a result of unforeseen conditions in the subsurface/reservoir, a consequence could be use of the incorrect mud weight, and this could contribute to a well kick. Failed or deficient well-kick detection could, in turn, mean that the situation becomes more critical than necessary.
Underlying causes are related to circumstances and conditions that are present before the actual well-control incident. It is therefore reasonable that organizational factors play an important part. In the review, it was observed that organizational factors constitute as much as 78% of the defined underlying causes. The main contributors within this category are found to be deficient planning/preparation (23%), deficient risk assessments/analyses (13%), deficient communication/cooperation interfaces (7%), and deficient work practice/operational follow-up of barriers (7%).
Deficiencies in planning/preparation and risk-assessments/analyses constitute as much as 36% of the underlying causes. Deficient planning and risk assessment are also closely linked with the H (“Human”) category of “Cognitive error (caused by deficient competence and risk understanding),” which constitutes a considerable 9%. Deficient assessments before and/or during the operations are connected with deficient competence and risk understanding, and, together, these categories constitute 45% of underlying causes in our survey.
The report (Fig. 1 above) provides a juxtaposition of direct triggering causes, underlying causes, and suggested measures from the incident reports. The top five categories of proposed measures are improved procedures and documentation (19%), increased or improved control/check/verification (12%), strengthening of competency and increasing volume of training (10%), improved work practice/operational follow-up of barriers (9%), and improved technical well design (9%). Measures connected with improvement of procedures and governing documentation constitute the largest category of measures, with a total of 19%.
An important issue the authors highlight in this study is the extent to which there is correspondence between identified causes and the measures described in the investigations. Immediately, one can see that there is no direct correspondence between triggering and underlying causes and type of measures.
The percentage of technical measures is small if seen in relation to contributions from technical faults and deficiencies in triggering causes. Weaknesses in the mud column, which is an important triggering cause, often deal with deficient pore-pressure predictions rather than technical equipment failure, and that is why it is natural that this has been followed up only with technical measures directed at the actual mud-treatment systems. Inadequate proactive focus for measures has also emerged because a limited percentage of the measures is directed at better planning, preparation, and risk assessment, despite such factors contributing to a total of 36% of the underlying causes.
In Fig. 1, multiple measures are classified under the category “Control/check/verification,” while this contributes little with respect to causes. Several measures are classified under “Competency/training,” while this category contributes little with respect to causal factors. An explanation of this is that errors in relation to deficient competence are classified under “Human,” while training and competence-strengthening measures are classified under “Organization.”
Results From the Review of Written Documentation From the Industry. A general picture of how the operating companies and drilling contractors perceive the effect of implemented measures is also provided. Several companies highlight the following causes:
- Deficient risk assessment, particularly in connection with changes to plans
- Deficient competence, communication, and change management
- Deficient planning and poor mapping of reservoir conditions that could result in an insufficient margin between pore pressure and fracture pressure
- Unexpected shallow gas when drilling and shut-in gas under plugs and behind casings when re-opening existing wells
Deficient risk assessments followed by deficient competence and communication are the most-recurring underlying causes, according to the responses from the operating companies. According to reports from drilling contractors, recurring causal factors include a deficient understanding of phenomena and deficient competence in relation to conditions during well control. This is often attributed to the use of consultants and partially inexperienced personnel in key positions.
Informants from the operating companies express a somewhat limited belief in the effect of making more-thorough risk analyses. There is a greater belief in measures for improving competence to reduce the number of well-control incidents. An important factor is the use of measures that ensure involvement of the correct technical competence in relation to challenges during operation. Competence-improving measures are mostly related to topics such as well integrity and verification of barriers during different drilling and well operations.
Among the drilling contractors, risk assessments are generally not discussed as measures. They have the greatest belief in measures directed at improvement of procedures and instructions and compliance with these. The drilling contractors also have great belief in training measures and experience sharing.
Results From Interviews With Experts From Drilling and Well Operations. In general, the informants largely focused on the human element when asked to point to main causes of well-control incidents. More specifically, in relation to humans’ roles in well-control incidents, the following factors were emphasized repeatedly:
- Competence: The formal competence is generally in place, but practical experience and qualifications may be lacking.
- Attention/awareness: Experience from different incidents shows that the warning signals were there, but these were for various reasons not perceived or taken into account.
- Compliance: The procedures are generally perceived as adequate, but are not always followed.
- Planning: These are failures during the planning phase, in relation to both deficient reservoir or pressure predictions and inadequate risk assessments.
- Culture: Some corporate cultures accept constructive criticism better than others.
The conversations with the experts within drilling and well operations revealed that each person’s experience with well-control incidents was limited. Some had experience from two incidents, but rarely more than three, and these were generally not considered serious enough to warrant investigation.
In regard to the industry’s viewpoint on new technology, “reserved skepticism” might be the appropriate term. We are left with an impression of an industry that is fully aware of the risk potential inherent in well-control incidents, and which works practically and systematically on becoming better, but which also believes it maintains quite good control.
Discussion of Results From Interviews and a Review of Investigation Reports. Two areas stand out as particularly inconsistent when one looks at the explanation of causes of well-control incidents in investigations compared with the interviews: competence and the significance of technical causes.
A key cause of well-control incidents mentioned in several interviews was deficient competence and practical experience related to operational personnel. Reference was made to quick promotions, a general boom in the industry, and also the current work-shift, which is the reason that operational personnel sometimes lack practical experience. When we analyze the investigations, however, we find that only 4% of underlying causes can be explained by deficient competence or training.
Why does this discrepancy exist? One possible explanation is that the interview situation is more informal than the environment that emerges in an investigation, and that participants in an investigation may be hesitant to point out conditions that could be perceived as politically incorrect and problematic for the companies. Another possible explanation is related to the fact that informants in an interview situation will primarily speak on the basis of their daily operational experiences and their own assessments of what could cause well-control incidents. Another difference between results from investigations/incident reports and results from the interviews is related to technology and technical causes. From the investigations, we can see that a significant number of the incidents have technically triggering causes, much related to the mud column (as a result of deficient reservoir predictions), but also related to well-kick-detection systems. However, in interviews, the greatest focus is clearly on the human factor in the form of deficient competence and compliance with procedures.
Four Main Challenges in Maintaining Well Control. On the basis of results from the study, the industry is facing four key challenges in relation to further reducing the number of well-control incidents. These are discussed in greater detail in the complete paper.
- Stronger efforts are needed in terms of technical measures to improve safety.
- Increased focus on planning, barrier management, and more-adaptive risk analyses is needed.
- More focus on major-accident risks (more incident investigations) is needed.
- Conditions for good collaboration in the operator/supplier hierarchy must be created.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 163775, “Risk of Major Accidents: Causal Factors and Improvement Measures Related to Well Control in the Petroleum Industry,” by Elisabeth Lootzand Monica Ovesen, SPE, Petroleum Safety Authority Norway, and Ranveig Kviseth Tinmannsvik, Stein Hauge, Eivind H. Okstad, and Inge M. Carlsen,SPE, SINTEF, prepared for the 2013 SPE Americas Exploration and Production Health, Safety, Security, and Environmental Conference, Galveston, Texas, USA, 18–20 March. The paper has not been peer reviewed.