This paper aim to identify potential for improving the process of gathering trajectory directional survey data, recalculating of current wellbore position based on new information by automating the process, performing collision avoidance analysis scanning and providing feedback by using machine recognition of risk while minimizing human interaction with the dataset. The envisioned result was seen as a system where wellbore survey data would flow seamlessly from acquisition at rig site into company directional survey calculation system, where programming would use the dataset to update the definitive survey listing, update forward planned surveys, run collision avoidance scan on updated planned surveys against identified offset wellbores and verify current position in relation to plan and possible deviation to same based on company policies for survey and collision avoidance and produce output for end user(s). The project outcome was a software that acts as an intermediate between field data set repository and company directional survey software package. When data set becomes available in repository, a 30-second interval repeating query recognizes the change and updated directional survey data is moved to correct wellbore, used in defining trajectory and original plan is modified allowing collision avoidance verification to run based on new wellbore survey information. The project outcome also included machine review of the collision avoidance results based on programmed company policy values, which added to the process. The project saw substantial time delay during creation due to issues identified in the challenges part below but is now running full time for company covering all offshore rigs and associated wellbore surveying activities. Learnings during the execution of the project showed both short comings of current systems, inconsistent API (Application Programming Interface) support for legacy software, and several opportunities for further improvements to the originally identified goal and potential for creating an advisory system based on current policies, further reducing the sometimes-arbitrary decision making which can result from large variation in experience levels related to understanding risk associated with directional surveying and directional drilling.
Wellbore surveying is critical while drilling in order to assure the drilled well is following the plan and is penetrating the geological target. Additionally, wellbore surveying is the key to allowing a well to be drilled safely, avoiding other wells drilled in the same field, and optimizing reservoir production. Standard wellbore surveying accuracy is increasingly inadequate for optimizing the well placement in real time to maximize the reservoir recovery due to maturity of the field. The other disadvantage of the standard wellbore surveying often requires running an additional wellbore surveying tool to improve the accuracy in order to manage the collision avoidance with nearby wells in the same field, introducing unwanted time and costs. Hence, this article presents the advanced wellbore surveying technology that is successfully implemented in offshore fields of Abu Dhabi to overcome the limitations of the standard surveying accuracy without compromising rig time. Magnetic measurement while drilling (MWD) surveys are common standard and utilized in every directional well in this operation. To overcome the standard accuracy limitation, advanced survey correction to the magnetic MWD surveys is introduced. This includes in-field referencing to provide a higher resolution magnetic reference to calculate a more accurate well direction, correction to the effect of the steel components in the bottom hole assembly on the magnetic MWD surveys, correction to the errors associated with survey sensors calibration, and correction to any misalignment between the survey tool and the wellbore. Correcting the surveys in real-time while drilling is the key to placing the well accurately and to avoid offset wells in the close proximity. The details of the corrections methodology are discussed. Advanced magnetic survey correction procedures in real-time are outlined and mapped out. Finally, results of improving the magnetic surveys while drilling in placing the wells and minimizing the collision risk of offset wells are presented. This advanced survey technology allows drilling previously un-drillable wells in these offshore fields, and the allowance for increased density of wells in the reservoir gives the operator opportunity to maximize production recovery and extend the life of reservoir. Higher accuracy of wellbore surveys is an increasing requirement in mature fields to safely allow more accurately placed wellbores with the required production rates. This allows for improved well placement along the trajectory facilitating adjustment at control points and landing points to maximize the hydrocarbon production. In addition, it allows controlling the probability of collision with any nearby wells. The enhanced wellbore surveying accuracy is achieved by advanced magnetic survey corrections in real time. This is controlled by a stringent novel process and communication protocol in order to meet the accuracy objectives.
Most of the industry operators and service companies have developed and implemented a directional drilling collision avoidance rules based on strict controls to prevent well collisions and subsequent human and environmental damage. These rules are formulated based on best practices and mitigation procedures across the industry experience. However, these rules are sometimes found to be severely restricted to the optimal wellbore positioning of wells representing mainly the safe drilling to prevent surface or deep collision risks with offset wells. Historically ADMA-OPCO and ZADCO were adapting the basic collision avoidance rules from its shareholders policy and mainly depends on service companies' internal policy to rely on execution phase which was creating huge well spacing among drilled wells resulting in extreme narrow path for future well placement which was affecting field development severely. The need for a comprehensive collision avoidance practice and policy was eminent when the world- class ERD project with artificial Islands as drill centers was commenced in 2013, which instigated the process for developing a Wellbore positioning and collision avoidance policy for ADNOC offshore concessions operated by ADMA and ZADCO. In general the collision avoidance procedure should define on how to maximize the safety by avoiding or managing the collision with critical offset wells during the planning and execution phases of the drilling program. The scope of this document includes, but is not limited to, a set of anti-collision policies including standards, practices and guidelines to manage the master database structure and integrity, position uncertainty, surface location, survey program, collision avoidance procedure, wellbore survey operation, quality assurance, data integration and communication protocols to the interested parties, etc. Developed policies helped the drilling team to standardize the technical and operational consistency for safe planning, supervision and execution of directional drilling operation activities greatly. Outlining the roles and responsibilities of the well collision avoidance and wellbore positioning procedures eased the operation greatly in an offshore Artificial Island drill center environment with 100s of ERD wells being planned to be drilled. The brief technical details of verity survey technologies and surveys management advancements are covered in the guidelines to get an general education on subject matter to the end user which will help them to identify and finalize the survey program to drill the well safely. The detailed collision risk matrix and risk mitigation procedure guidelines has helped the drilling engineers to conduct the required risk assessment and mitigation plans in place during planning phase itself and supervise it during execution with enough control measures in place. The roles and responsibilities of each service companies involved is categorically mentioned in the policy allowing all parties to implement their contribution without failure.
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