Abstract Higher circulating pressures result in increased wear on mud pump parts, subsequently causing rig downtime for pump maintenance. The paper presents the field experience gained with mounting high-frequency mud pressure transducers and analyzing the pressure signatures of Triplex Mud Pumps to identify pump wear in time for running routine maintenance and service. By comparison with recorded drilling data, every operating condition can be allocated to pressure curves. The characteristics of typical pump wear as expressed in these signatures are discussed together with suggestions how to automate the monitoring system. In addition, mud pumps have been fitted with vibration sensors for supplemental information.
Introduction While equipment condition monitoring and associated preventive machine maintenance is already used in many parts of the industry, oilfield mud pump monitoring today is still done pretty much the same way as during the last twenty years, i.e. "listening" to the pump and replacing worn parts after they failed. New materials have somewhat increased pump efficiency and life time of wear parts, and further engineering efforts reduced maintenance time and cost.
Miller investigated pump suction stabilization in 1975. Even the simplest pump installation in reality is a complex hydraulic system, where improper system engineering can be extremely costly in terms of reduced volumetric efficiency and sharply increased maintenance costs. High speed and capacity requires careful system design in general, and effective stabilization in particular. The use of well designed stabilizers provides a relatively large volume of liquid right at the pump and isolates the effect of suction lines. By eliminating valve slamming and other effects of vibration, stabilizers can double the life of other pump system parts.
Wachel, Szenasi and Denison presented results of field tests and acoustical analysis. Many vibration and failure problems in reciprocating pumps in oil pipeline application according to their findings were caused by system related acoustical resonance which caused high level pulsations in the suction and discharge piping. Commercially available accumulators and pulsation dampeners can be quite effective in controlling pulsations, while liquid acoustic filter systems can be designed for practically any suction and discharge system to minimize pulsations. Filters are advantageous for some installations since they require practically no maintenance once they are installed. Testing showed that an increased static pressure level lowered the level of the pulsations in the pump manifold and inhibited cavitation. The testing also revealed that the pulsation levels increased with speed. When pulsation and vibration problems occur in a reciprocating pump application, field data can be obtained to define the basic cause from which these pulsations originate.
Wachel and Price reported on studies about problems that cause increased maintenance and unreliable operation. Investigation of accumulator design was performed to develop a basic understanding of the acoustic behavior of accumulators used in pump systems. An accumulator near the flanges of the suction or discharge manifold creates a new acoustical system. One major resonance that is introduced is a natural frequency which is a function of the distance from the end of the manifold to the entrance of the accumulator and the speed of sound in the fluid. This natural frequency will be excited by the higher plunger harmonics and can cause numerous problems. The majority of cavitation problems on suction systems are caused by this acoustical mode since most systems have some kind of accumulator near the pump flange.