Good Quality Material of Body
Choosing good quality steel to make drill bit body.
To improve the aggressivity and abrasive resistance, we weld wear resistance material on bit surface. Also we use 3D-integrated software to design, and adopt designs of spiral cutter displace, long crown profile, long gauge spiral wings, force balance cutting structure, reasonable cutters placement.
Using CFD and digital simulation technology to design wider flow area make PDC bits have good chip removal rate and bit balling resistance.
Dual-row Cutters
The back row cutters help to cut rocks, to protect matrix, to prolong lifetime and to deduct cost of PDC bit.
Analysis-Example of Choice of Drill Bits
In drilling, there are many complicated or uncertain factors. After safety evaluation, we can avoid many accidents, reduce drilling cost, improve management level of drilling.
Firstly, features of each bit will be designed with hardness of formation and well depth. We can add vice-cutters to PDC bits to improve the stability and wear resistance of bits. In hard and small rocks formation, we can choice bits as right picture.
After many tests on site, we extended the application field of PDC bits in Shengli Oilfield, and achieved success, forming extension model of application of PDC bits.
Test Results: which formations can not adopt PDC bits are high cementation gristone, conglomerate, density and hard mud rock, high plasticity mudstone, siltite, high shale content of carbonate formation.
Spiral Wings
Increase contact area between PDC bit and well wall to keep drilling stably, to decrease waste of drilling tools.
PDC Bit Directional Drilling
Recent years, directional drilling technology gets mature. Well drilling demand is increased.
The cut rock type of PDC bits lead to high reaction torque in sliding directional drilling, lead to interruptions and low ROP in deflecting.
When we use tricone bits for directional drilling, the ROP is slow and the bit lifespan is short. These restrict the drilling rate, increase the cost, request better drilling technology.
In view of above questions, our company, Wolfni Technology, have researched and developed a kind of special PDC drill bit for directional drilling. Adopting compact structure design and bottom hole flow field simulation technology, the bits have reduced the reaction torque in cutting, have decreased the unstability. So the bit has good directional ability, deflecting capacity in drilling. The technology of this type of PDC bits is advanced all over the world.
Field Test
Jiangsu Oilfield(water area) has bad surface condition, complicated subsurface structure. Main rocks are gritstone and mudstone. Bit balling easily in high dispersion rocks, which restrict the performance of conventional PDC bits.
To optimize drilling in Jiangsu Oilfield, we analyze the drill ability and hardness of oilfield with drilling core and logging information. The results show that the drilli ability is grade 1 to 6, hardness is 169-733 Mpa, formation is soft to medium.
Adopting design with 4 wings, deep inner cone, low density cutters placement, using CFD to optimize hydraulic structure of PDC bits, we designed out a PDC bit 9 1/2’’WS416DR with good effective.
From application in site, the ROP and drilling depth was increased 16% at least. This kind of PDC bit solved the bit balling and low ROP problem.
