Successful Application of Non-Intrusive Solids Detection Monitor in High Rate Gas Wells

Abstract

Solids production problems in the petroleum industry are well documented and several effective methods have been developed over the years to alleviate these problems. These issues become more costly and disastrous when dealing with high rate sour gas wells. Uncontrolled solids production in these types of wells can lead to choke cut-outs, eroded flowlines and damaged production facilities. Under conditions of high pressures and high rates, the ability to determine the solids production and controlling it is of paramount importance for reasons of safety, protection of the environment and the asset plus the attendant economic considerations. Solids monitoring was attempted during the first phase of Saudi Aramco's first offshore Non-Associated Gas (NAG) field operations.. However the monitoring equipment failed to detect large particulates during the clean-up operations resulting in erosion of some of the choke trims. Fortunately, upon inspection there was no damage to the choke bodies or flowlines. These solids detectors were used on one well together with the Solids Management System (SMS) utilized for cleaning up the wells to 50 MMSCFD with the rig on location to confirm its ability to measure the solids production. For the second phase of operations, the solids detectors were recalibrated based on the previous findings and lessons learnt. The experience proved invaluable in the wells' ramp-up operations, which were completed safely and without incidents. This paper describes the process and procedures employed in the ramping up operations of the wells to 120 MMSCFD without adversely affecting the production surface facilities. Furthermore, the lessons learnt and enhancements to the solid detectors resulting in the successful implementation are presented. This is the first time in the industry that these non-intrusive monitoring devices have been used successfully for this type of application. Introduction Saudi Aramco embarked on the drilling campaign of its first offshore non-associated gas development project in 2008. The field is located in the Arabian Gulf about 100 km from Dhahran with a water depth of +50 meters, Fig. 1. The primary focus of the project was to drill 21 wells on five nine slots platforms from which the production flows through 20" flowlines to a tie-in platform and then to onshore treating facilities via a 38" pipeline. The targeted formation is a deep, high pressure carbonate reservoir of the Permian era with an average thickness of +1,000 ft. The top of the reservoir is +10,500 ft. TVD with average pressure and temperature of 8,900 psig and 290oF. The formation fluids contain 4% H2S and 2.5% CO2. The wells were drilled using mud weights of 125 pounds per cubic ft. (pcf) with 35% barite and several of the wells had losses in excess of 10,000 bbls. Using several rigs, the wells were batch drilled and completed with 7" tubing and uncemented perforated liners across the formation1. Ceramic disks were installed in the tubing to facilitate installation of the topsides prior to hooking up and opening the wells for production, Fig. 2. The wells were subsequently cleaned-up to 50 MMSCFD using the rig and a Solids Management System (SMS) comprising of desanders, sand filters, separator and a cyclone for measuring the amount of solids recovered during the exercise. The flow rates were considered solids free when the solids production was 0.1 lbs. per MMSCFD based on the measurements from the cyclone2.