Reduced uncertainty in overpressures and drilling window prediction ahead of the bit

The knowledge-building project PressureAhead introduces new methods to reduce the uncertainties in geo-pressure prediction ahead of the bit. With better constrains on the pore pressure in the underground, it is easier to use correct mud-weight while drilling and this will result in cost reduction and safer drilling campaigns. Wrong assumptions regarding pressure and mud weight, may lead to non-productive time due to mud loss, stuck pipe and well control incidents. In this project the objective is to reduce the uncertainty in predictions of overpressures and mud window ahead of bit. Since the input data is uncertain and our understanding of the processes are limited, thousands of simulations are carried out to simulate the most likely pressure profile. Thereafter, the most likely mud weight window along the planned well path is generated. We aim to update pressure prognosis and mud window by using available real-time drilling data from logs to improve predictions ahead of the drilling bit. The project started in 2016, and will finalize early 2020. The new fast 3D pressure simulator are tested on a dataset from Alvheim, North Sea. Sensitivity on the input data for pore pressure and mudweight window prediction have been studied. A new method for conducting sensitivity analysis over the uncertainties involved in the mud-weight window assessment was developed by PhD student Jacopo Paglia. The most important input parameters for the mud density were investigated. This was done with the aid of value of information analysis, coupling the uncertain variables with drilling decisions in a trade off between costs and risks. Additional well data are valuable when they can materialize in improved decision making. A case study from an offshore field in the North Sea was investigated, with focus on a shale layer with potential drilling risk. SINTEF Industry led the project in close collaboration with NORCE, NTNU and Ècole des Ponts, Paris-Tech in France. It was funded by The Research Council of Norway and the DrillWell Centre (ConocoPhillips, AkerBP, Equinor and Wintershall).

Prosjektet har vært faglig utviklende; forskerne har videreutviklet en ny, rask simulator til å predikere vanntrykk i undergrunnen, og hva dette vil bety for vekt av boreslammet i en boreoperasjon. Forskerne har fått veldig positive tilbakemeldinger på konferanser internasjonalt. Det er jobbet mye på tvers, slik man har fått tett interaksjon mellom geologer, matematikere, ingeniører og bergmekanikere. SINTEF har hatt veldig tett dialog med NORCE, NTNU, Ecole de Pont i Paris, og ikke minst med industrien (Equinor, AkerBP, Wintershall, ConocoPhillips). For forskerne har det vært viktig å få innspill på hva som trengs for å få til billigere og sikrere boreoperasjoner, og hva som er status og behov i industrien i framtiden. Prosjektet har utdannet en doktorgradsstudent på Institutt for Matematiske fag, og en masterstudent i geologi (NTNU). På lang sikt håper vi prosjektet kan åpne for enda mer samarbeid internasjonalt, og at de nye metodene vil bli tatt i bruk av industrien.

Oil and gas exploration and production wells have been drilled on the Norwegian Continental Shelf for the last 45 years, both in hydrostatic and overpressured areas. Still, with long expertise, drilling teams experience large uncertainties in prediction of pore pressure and well stability, and this may lead to non-productive time due to unexpected events such as stuck pipe, mud losses and well control events. Water fluid pore pressure variations are still not fully understood, neither in exploration areas nor in mature areas. The project aim to get better constrains on the pressures and mud weight prognosis ahead of the bit, by introducing new methods and tighter interaction between existing simulation tools. By addressing uncertainty in pressure and stress prognosis upfront the drilling campaign, and update the prognosis while drilling, better prediction can be achieved. For the industry, better pressure prediction with real time update is a key challenge. Avoidance of pressure related accidents can save several days in drilling program. The proposed project has the potential to increase our knowledge on - pressure modelling, prediction and update while drilling - effect of pressure changes on stresses - better constraints on prediction of mud weight window If successful, this will take the industry a step forward in terms of understand pressure build up and changes. This could have a large contribution towards more cost efficient drilling campaigns. The project is planned with collaboration between SINTEF Petroleum, IRIS, NTNU and École des Ponts, Paris-Tech, France and with financial support from the DrillWell Centre with several industry partners (ConocoPhillips, Det Norske, Lundin, Statoil and Wintershall). A PhD student will be hired at NTNU with focus on uncertainty and statistical approached as part of the project.